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Topic: Tutorial: Deck fittings and butyl tape sealant techniques  (Read 3347 times)

0 Members and 1 Guest are viewing this topic.

Wilfite

  • Rockfish
  • ****
  • Fish'n's good, Catch'n's better.
  • Location: Columbia City, OR
  • Date Registered: Oct 2017
  • Posts: 119
Hi Y'all,

I've messed about in boats a good part of my life prior to getting my kayak.  In that time, I've gotten WAY over the fear of drilling holes in my boats :-)  I'm no expert, by any means, but I'd like to give back to the community as well as I can.  This will come in two parts.  Part 1 is a discussion on mounting methods for fittings and some considerations to take into account.  Part 2 will be a review of an installation I recently completed using my chosen method.  I have 26 years of experience rebuilding and repairing boats of many types so I am not a noob coming into this, but I AM just getting into kayaks and I welcome discussion around my conclusions or if there are other solutions I may be overlooking.

Part One:  Bolts, screws and sticky things

In the process of researching kayak-specific issues, I've noticed most folks are using the same approach: silicon-based adhesives to seal deck fittings like rod mounts, deck hatches and the like, in combination with one of 4 hardware approaches.  For me personally, the thought of putting silicon on my boat causes eye twitches and horrific nightmares from years of frustration with having to sand or grind off surfaces that had silicon applied by previous owners before I could do something useful with epoxy or paint on the surface.  :-)  While I understand the main reason something like "Goop" is used is because our boats are PE (which doesn't want to stick to anything), my first response is..."there's got to be another way!"

In looking for an alternative, let's consider the 4 main methods used for attaching hardware to our yaks.  I will analyze each based on my own experience in boats and what research I've done on kayak-specific issues.  I certainly welcome feedback from other folks as well.

  • Molded-in threaded inserts installed during the molding process.  Does not require sealant because it is "in" the hull.  Easy to use, but too much torque or load can spin or pull out the insert.  This would be difficult or even impossible to repair, depending on where in the hull it occurred.  In addition, it isn't feasible to add an insert to a hull after it comes off the production line in all but a few specific instances so it's not a good aftermarket attach solution.
  • Rivets.  Allows for blind attach, generally reliable but can be finicky to install and difficult to maintain.  Requires sealant.  For two thin, hard surfaces like an aluminum mast and a fitting, rivets are a great solution.  They form a backing surface when compressed, are basically permanent and don't catch lines.  For a soft material like the polyethylene hull of a kayak, on the other hand, they don't inspire confidence in me.  The backside of the rivet is not much larger than the hole and any induced play in the rivet will cause the hole to stretch and eventually the rivet to pop out.  I've seen this in fiberglass, which is much harder than PE so I would think for PE the problem would be worse.  Lastly, unless you have hull access it's very difficult to inspect this type of hardware over time for maintenance issues so a failure is often a surprise.  I only use rivets in very specific circumstances.
  • Sheetmetal Screws driven directly into a hull (with a pilot hole) with no backing method.  Allows for blind attach, easy to maintain but only threads into the plastic hull.  This is only conjecture, but when combined with an adhesive sealant I would suggest that it is mostly the adhesive rather than the screws that is doing the job of holding the fitting in place.  My preference is for a more positive mechanical connection, the fact that it is reliant on only a few threads for all it's strength of attachment concerns me.
  • Thru-bolt.  Requires hull access and a backing method.  Requires sealant.  More labor-intensive than #2 & 3, but far more secure mounting solution.  Too much torque can damage the deck due to crushing or cutting forces from the nut and washer or other backing solution.

3 out of the 4 methods above are useful for aftermarket fittings.  We will ignore the molded nuts, since not everyone has them and they are not always in the right position.  Of the 3 methods we are interested in, all three require sealant.  I believe strongly in maintenance when dealing with something my life depends on.  Not being able to periodically re-tighten or inspect a rivet is a deal-breaker for me when it could leave a hole in my boat if it failed. 

That leaves us with two methods.  Method #3 is simple, it requires only a stainless screw and a pilot hole (You ARE drilling pilot holes, AREN'T YOU????! :blob6:).  IMO, this method is acceptable only for the very simplest application (like adding a nameplate).  When working with a thick wooden hull, using an aggressive wood screw to hold a fitting makes perfect sense.  I don't know about your boats, but my hull is only 1-2mm thick.  That means just 1-2 threads are actually being engaged to hold the fitting.  While there are probably a few unique circumstances I would consider using a screw it's just not secure enough, in my opinion, to be considered a "general use" technique.

This leave us with method 4, which is the recognized "do it right" method for any big boat.  When the fitting and the surface it is attached to are both moving (which is the case for our 'yaks) I really want the security and reliability of a thru-bolted solution.  Add on to that any kind of pressure on the fitting itself (like a cleat with an anchor-line attached or the big lever of a long camera boom!) and I'd suggest you really want to seriously consider the risk/reward of options #2 and #3 before committing.

So, this leads us to sealants and adhesives.  Any time there is a gap in the hull of a boat, it is standard practice to use a sealant of some type to make that opening air and water-tight.  For a lot of years now the "old standby" for knowledgeable folks has been 3M 4200, Lifecaulk or one of several other lesser known brands.  For many folks just starting out, 5200 is the leading inducer of headaches during future maintenance efforts.

STORYTIME!!!
For just a moment, allow me to digress.  I have an acquantance in Maine who rebuilt classic fiberglass boats for a living.  He severely dislikes 5200 because he says it is not a sealant, it should be viewed as a permanent adhesive.  You CAN remove it, but the chemical needed comes in small amounts and costs a bit.  So...this gentleman decided to add an anchor platform to the bow of his 28' sailboat.  It was beautiful.  2 thicknesses of mahogany laminated together to make a ~2.5" thick board and the whole thing was thru-bolted to the deck and sealed with a generous amount of 3M 5200.  All season long it withstood use and wear and was expected to last the life of the boat.  That IS why he used 5200.  Fast forward to winter and a Nor'easter came through.  His boat rode it out on a mooring and the next morning it looked ok.  When he went out on the launch, however, he noticed a gash in the new paint job all across the bow from a dangling anchor and the overhanging portion of the new anchor platform was broken off and nowhere in sight.  To repair this, he had to remove the remaining part of the anchor platform.  This took TWO DAYS of scraping and levering, even with the use of Antibond, and he would up tearing the deck surface in the process.  So...5200 is permanent.  On PE it's probably not as permanent, but I'm not willing to even experiment.  So if you like 5200, you're on your own :-)


So, back on task.
There are generally 3 "go to" sealants I use when doing boat work.  3M 4200 adhesive polyurethane or Lifecaulk polysulfide sealant for applications where I really want an adhesive in addition to a sealer (note the difference!) and for something under the waterline.  I'm sure most of you already know about these two, so I won't spend much time on them.  For most other above-deck uses, I like to use something called Butyl Caulk Tape.

In all the forums I have read through, I find it curious no one seems to be using Butyl tape on a kayak.  At first I thought there was something about PE that precluded using it but after testing, I found it was plenty sticky on PE.  I'm left with the thought that it is simply an unfamiliar sealant to many, since it fell out of fashion with all but high-end boat builders because it's easier and cheaper to stick to a single polymer-type sealant for everything.

To start with, butyl caulk tape (also called butyl adhesive tape) is NOT the same thing as the tube of butyl caulk or mastic you can get at the big box store.  That stuff is meant for roofing, and it dries out and hardens with time.  Same with plumber's putty.  Butyl tape (for short) is a non-hardening, permanently elastic solvent free rubber-based compound that is UV resistant and capable of a wide temperature range.  It is moldable and compresses under pressure to form a very good air and water-tight seal between two surfaces.  The compressed material will also squeeze into texture and small gaps.  Note that butyl tape IS adhesive, but only mildly so.  It relies on a thru-bolted connection that will compress the butyl tape between the two surfaces.  There are two types: white and gray.  Gray is a bit denser and maybe stickier and is the preferred one over white for marine use, but either will work.  Both of my rolls are white so that's what I'm going to use.  Stay away from the big box stores, the stuff they sell (if it's even named right) is usually pretty poor quality.  You can get it at any marine store or glass supply store or probably RV parts store.

I really like butyl tape for 4 reasons:
  • It is super easy to use.  As long as your hands are clean (I wear gloves, but just because the gloves are clean) you can handle it just like you would a tub of play-dough.
  • It doesn't harden.  This means if your wife calls you away to dinner mid-project, you know you can go back later and find it just as you left it.  After a couple of days it will form a bit of a skin on the surface, but it never truly hardens.  This elasticitity means that as your fittings and deck flexes, the sealant will flex with it to keep those small gaps closed.
  • No chemical cleanup.  Since Butyl is solvent free and easily scrapes off the hull all you need is the pressure of a finger rubbing against excess material to get it up.  In a few cases where it has been there a while and skinned up or for areas of the deck where you might have some stuck in texture, a bit of acetone will make it lose the stickiness and ball up and it's easily removed.
  • It lasts a long time.  I know of boats with butyl caulk on the same fitting for more than 25 years that haven't leaked.  Because it doesn't harden, it also has a long shelf life.  I've had two rolls of the stuff for years and they are just as good as if I bought them yesterday.  No more half-used tubes of 4200 to reluctantly throw away!

As you probably can tell, I've chosen to use thru-bolting and butyl tape as my preferred fitting-up approach.  In part II, I will cover the installation of a 5" deck plate and two thru-deck rod mounts, describe the process of using butyl tape and throw in a few tips and tricks and gosh, I wish I woulda's.  I know that "ye 'ol rod holder install" has been covered a dozen times, but I think I have a little twist on the approach.

See y'all soon!
 :banjo:


EDIT 11-24-17:  Re-wrote the sheetmetal screw section to make more sense, somehow missed an edit when doing the original post.
« Last Edit: November 24, 2017, 09:57:13 AM by Wilfite »
-Tony

Wilderness Systems Thresher 15.5 (Yellow)
Old Town Predator MK, (Lime Green Camo)


sher715

  • Plankton
  • *
  • Date Registered: Aug 2017
  • Posts: 7
Hi Y'all,

I've messed about in boats a good part of my life prior to getting my kayak.  In that time, I've gotten WAY over the fear of drilling holes in my boats :-)  I'm no expert, by any means, but I'd like to give back to the community as well as I can.  This will come in two parts.  Part 1 is a discussion on mounting methods for fittings and some considerations to take into account.  Part 2 will be a review of an installation I recently completed using my chosen method.  I have 26 years of experience rebuilding and repairing boats of many types so I am not a noob coming into this, but I AM just getting into kayaks and I welcome discussion around my conclusions or if there are other solutions I may be overlooking.

Part One:  Bolts, screws and sticky things

In the process of researching kayak-specific issues, I've noticed most folks are using the same approach: silicon-based adhesives to seal deck fittings like rod mounts, deck hatches and the like, in combination with one of 4 hardware approaches.  For me personally, the thought of putting silicon on my boat causes eye twitches and horrific nightmares from years of frustration with having to sand or grind off surfaces that had silicon applied by previous owners before I could do something useful with epoxy or paint on the surface.  :-)  While I understand the main reason something like "Goop" is used is because our boats are PE (which doesn't want to stick to anything), my first response is..."there's got to be another way!"

In looking for an alternative, let's consider the 4 main methods used for attaching hardware to our yaks.  I will analyze each based on my own experience in boats and what research I've done on kayak-specific issues.  I certainly welcome feedback from other folks as well.

  • Molded-in threaded inserts installed during the molding process.  Does not require sealant because it is "in" the hull.  Easy to use, but too much torque or load can spin or pull out the insert.  This would be difficult or even impossible to repair, depending on where in the hull it occurred.  In addition, it isn't feasible to add an insert to a hull after it comes off the production line in all but a few specific instances so it's not a good aftermarket attach solution.
  • Rivets.  Allows for blind attach, generally reliable but can be finicky to install and difficult to maintain.  Requires sealant.  For two thin, hard surfaces like an aluminum mast and a fitting, rivets are a great solution.  They form a backing surface when compressed, are basically permanent and don't catch lines.  For a soft material like the polyethylene hull of a kayak, on the other hand, they don't inspire confidence in me.  The backside of the rivet is not much larger than the hole and any induced play in the rivet will cause the hole to stretch and eventually the rivet to pop out.  I've seen this in fiberglass, which is much harder than PE so I would think for PE the problem would be worse.  Lastly, unless you have hull access it's very difficult to inspect this type of hardware over time for maintenance issues so a failure is often a surprise.  I only use rivets in very specific circumstances.
  • Sheetmetal Screws driven directly into a hull (with a pilot hole) with no backing method.  Allows for blind attach, easy to maintain but only threads into the plastic hull.  The fact that it is reliant on only a few threads for all it's strength of attachment concerns me.  Any installation requires sealant that will fill the voids around this only conjecture, but when combined with an adhesive sealant I would suggest that it is really the adhesive rather than the screws that is doing the job.
  • Thru-bolt.  Requires hull access and a backing method.  Requires sealant.  More labor-intensive than #2 & 3, but far more secure mounting solution.  Too much torque can damage the deck due to crushing or cutting forces from the nut and washer or other backing solution.

3 out of the 4 methods above are useful for aftermarket fittings.  We will ignore the molded nuts, since not everyone has them and they are not always in the right position.  Of the 3 methods we are interested in, all three require sealant.  I believe strongly in maintenance when dealing with something my life depends on.  Not being able to periodically re-tighten or inspect a rivet is a deal-breaker for me when it could leave a hole in my boat if it failed. 

That leaves us with two methods.  Method #3 is simple, it requires only a stainless screw and a pilot hole (You ARE drilling pilot holes, AREN'T YOU????! :blob6:).  IMO, this method is acceptable only for the very simplest application (like adding a nameplate).  When working with a thick wooden hull, using an aggressive wood screw to hold a fitting makes perfect sense.  I don't know about your boats, but my hull is only 1-2mm thick.  That means just 1-2 threads are actually being engaged to hold the fitting.  While there are probably a few unique circumstances I would consider using a screw it's just not secure enough, in my opinion, to be considered a "general use" technique.

This leave us with method 4, which is the recognized "do it right" method for any big boat.  When the fitting and the surface it is attached to are both moving (which is the case for our 'yaks) I really want the security and reliability of a thru-bolted solution.  Add on to that any kind of pressure on the fitting itself (like a cleat with an anchor-line attached or the big lever of a long camera boom!) and I'd suggest you really want to seriously consider the risk/reward of options #2 and #3 before committing.

So, this leads us to sealants and adhesives.  Any time there is a gap in the hull of a boat, it is standard practice to use a sealant of some type to make that opening air and water-tight.  For a lot of years now the "old standby" for knowledgeable folks has been 3M 4200, Lifecaulk or one of several other lesser known brands.  For many folks just starting out, 5200 is the leading inducer of headaches during future maintenance efforts.

STORYTIME!!!
For just a moment, allow me to digress.  I have an acquantance in Maine who rebuilt classic fiberglass boats for a living.  He severely dislikes 5200 because he says it is not a sealant, it should be viewed as a permanent adhesive.  You CAN remove it, but the chemical needed comes in small amounts and costs a bit.  So...this gentleman decided to add an anchor platform to the bow of his 28' sailboat.  It was beautiful.  2 thicknesses of mahogany laminated together to make a ~2.5" thick board and the whole thing was thru-bolted to the deck and sealed with a generous amount of 3M 5200.  All season long it withstood use and wear and was expected to last the life of the boat.  That IS why he used 5200.  Fast forward to winter and a Nor'easter came through.  His boat rode it out on a mooring and the next morning it looked ok.  When he went out on the launch, however, he noticed a gash in the new paint job all across the bow from a dangling anchor and the overhanging portion of the new anchor platform was broken off and nowhere in sight.  To repair this, he had to remove the remaining part of the anchor platform.  This took TWO DAYS of scraping and levering, even with the use of Antibond, and he would up tearing the deck surface in the process.  So...5200 is permanent.  On PE it's probably not as permanent, but I'm not willing to even experiment.  So if you like 5200, you're on your own :-)


So, back on task.
There are generally 3 "go to" sealants I use when doing boat work.  3M 4200 adhesive polyurethane or Lifecaulk polysulfide sealant for applications where I really want an adhesive in addition to a sealer (note the difference!) and for something under the waterline.  I'm sure most of you already know about these two, so I won't spend much time on them.  For most other above-deck uses, I like to use something called Butyl Caulk Tape.

In all the forums I have read through, I find it curious no one seems to be using Butyl tape on a kayak.  At first I thought there was something about PE that precluded using it but after testing, I found it was plenty sticky on PE.  I'm left with the thought that it is simply an unfamiliar sealant to many, since it fell out of fashion with all but high-end boat builders because it's easier and cheaper to stick to a single polymer-type sealant for everything.

To start with, butyl caulk tape (also called butyl adhesive tape) is NOT the same thing as the tube of butyl caulk or mastic you can get at the big box store.  That stuff is meant for roofing, and it dries out and hardens with time.  Same with plumber's putty.  Butyl tape (for short) is a non-hardening, permanently elastic solvent free rubber-based compound that is UV resistant and capable of a wide temperature range.  It is moldable and compresses under pressure to form a very good air and water-tight seal between two surfaces.  The compressed material will also squeeze into texture and small gaps.  Note that butyl tape IS adhesive, but only mildly so.  It relies on a thru-bolted connection that will compress the butyl tape between the two surfaces.  There are two types: white and gray.  Gray is a bit denser and maybe stickier and is the preferred one over white for marine use, but either will work.  Both of my rolls are white so that's what I'm going to use.  Stay away from the big box stores, the stuff they sell (if it's even named right) is usually pretty poor quality.  You can get it at any marine store or glass supply store or probably RV parts store.

I really like butyl tape for 4 reasons:
  • It is super easy to use.  As long as your hands are clean (I wear gloves, but just because the gloves are clean) you can handle it just like you would a tub of play-dough.
  • It doesn't harden.  This means if your wife calls you away to dinner mid-project, you know you can go back later and find it just as you left it.  After a couple of days it will form a bit of a skin on the surface, but it never truly hardens.  This elasticitity means that as your fittings and deck flexes, the sealant will flex with it to keep those small gaps closed.
  • No chemical cleanup.  Since Butyl is solvent free and easily scrapes off the hull all you need is the pressure of a finger rubbing against excess material to get it up.  In a few cases where it has been there a while and skinned up or for areas of the deck where you might have some stuck in texture, a bit of acetone will make it lose the stickiness and ball up and it's easily removed.
  • It lasts a long time.  I know of boats with butyl caulk on the same fitting for more than 25 years that haven't leaked.  Because it doesn't harden, it also has a long shelf life.  I've had two rolls of the stuff for years and they are just as good as if I bought them yesterday.  No more half-used tubes of 4200 to reluctantly throw away!

As you probably can tell, I've chosen to use thru-bolting and butyl tape as my preferred fitting-up approach.  In part II, I will cover the installation of a 5" deck plate and two thru-deck rod mounts, describe the process of using butyl tape and throw in a few tips and tricks and gosh, I wish I woulda's.  I know that "ye 'ol rod holder install" has been covered a dozen times, but I think I have a little twist on the approach.

See y'all soon!
 :banjo:

Is it just me or are we missing the first part of your post?


Sent from my iPhone using Tapatalk


Wilfite

  • Rockfish
  • ****
  • Fish'n's good, Catch'n's better.
  • Location: Columbia City, OR
  • Date Registered: Oct 2017
  • Posts: 119
Hi Y'all,

I've messed about in boats a good part of my life prior to getting my kayak.  In that time, I've gotten WAY over the fear of drilling holes in my boats :-)  I'm no expert, by any means, but I'd like to give back to the community as well as I can.  This will come in two parts.  Part 1 is a discussion on mounting methods for fittings and some considerations to take into account.  Part 2 will be a review of an installation I recently completed using my chosen method.  I have 26 years of experience rebuilding and repairing boats of many types so I am not a noob coming into this, but I AM just getting into kayaks and I welcome discussion around my conclusions or if there are other solutions I may be overlooking.

Part One:  Bolts, screws and sticky things

In the process of researching kayak-specific issues, I've noticed most folks are using the same approach: silicon-based adhesives to seal deck fittings like rod mounts, deck hatches and the like, in combination with one of 4 hardware approaches.  For me personally, the thought of putting silicon on my boat causes eye twitches and horrific nightmares from years of frustration with having to sand or grind off surfaces that had silicon applied by previous owners before I could do something useful with epoxy or paint on the surface.  :-)  While I understand the main reason something like "Goop" is used is because our boats are PE (which doesn't want to stick to anything), my first response is..."there's got to be another way!"

In looking for an alternative, let's consider the 4 main methods used for attaching hardware to our yaks.  I will analyze each based on my own experience in boats and what research I've done on kayak-specific issues.  I certainly welcome feedback from other folks as well.

  • Molded-in threaded inserts installed during the molding process.  Does not require sealant because it is "in" the hull.  Easy to use, but too much torque or load can spin or pull out the insert.  This would be difficult or even impossible to repair, depending on where in the hull it occurred.  In addition, it isn't feasible to add an insert to a hull after it comes off the production line in all but a few specific instances so it's not a good aftermarket attach solution.
  • Rivets.  Allows for blind attach, generally reliable but can be finicky to install and difficult to maintain.  Requires sealant.  For two thin, hard surfaces like an aluminum mast and a fitting, rivets are a great solution.  They form a backing surface when compressed, are basically permanent and don't catch lines.  For a soft material like the polyethylene hull of a kayak, on the other hand, they don't inspire confidence in me.  The backside of the rivet is not much larger than the hole and any induced play in the rivet will cause the hole to stretch and eventually the rivet to pop out.  I've seen this in fiberglass, which is much harder than PE so I would think for PE the problem would be worse.  Lastly, unless you have hull access it's very difficult to inspect this type of hardware over time for maintenance issues so a failure is often a surprise.  I only use rivets in very specific circumstances.
  • Sheetmetal Screws driven directly into a hull (with a pilot hole) with no backing method.  Allows for blind attach, easy to maintain but only threads into the plastic hull.  The fact that it is reliant on only a few threads for all it's strength of attachment concerns me.  Any installation requires sealant that will fill the voids around this only conjecture, but when combined with an adhesive sealant I would suggest that it is really the adhesive rather than the screws that is doing the job.
  • Thru-bolt.  Requires hull access and a backing method.  Requires sealant.  More labor-intensive than #2 & 3, but far more secure mounting solution.  Too much torque can damage the deck due to crushing or cutting forces from the nut and washer or other backing solution.

3 out of the 4 methods above are useful for aftermarket fittings.  We will ignore the molded nuts, since not everyone has them and they are not always in the right position.  Of the 3 methods we are interested in, all three require sealant.  I believe strongly in maintenance when dealing with something my life depends on.  Not being able to periodically re-tighten or inspect a rivet is a deal-breaker for me when it could leave a hole in my boat if it failed. 

That leaves us with two methods.  Method #3 is simple, it requires only a stainless screw and a pilot hole (You ARE drilling pilot holes, AREN'T YOU????! :blob6:).  IMO, this method is acceptable only for the very simplest application (like adding a nameplate).  When working with a thick wooden hull, using an aggressive wood screw to hold a fitting makes perfect sense.  I don't know about your boats, but my hull is only 1-2mm thick.  That means just 1-2 threads are actually being engaged to hold the fitting.  While there are probably a few unique circumstances I would consider using a screw it's just not secure enough, in my opinion, to be considered a "general use" technique.

This leave us with method 4, which is the recognized "do it right" method for any big boat.  When the fitting and the surface it is attached to are both moving (which is the case for our 'yaks) I really want the security and reliability of a thru-bolted solution.  Add on to that any kind of pressure on the fitting itself (like a cleat with an anchor-line attached or the big lever of a long camera boom!) and I'd suggest you really want to seriously consider the risk/reward of options #2 and #3 before committing.

So, this leads us to sealants and adhesives.  Any time there is a gap in the hull of a boat, it is standard practice to use a sealant of some type to make that opening air and water-tight.  For a lot of years now the "old standby" for knowledgeable folks has been 3M 4200, Lifecaulk or one of several other lesser known brands.  For many folks just starting out, 5200 is the leading inducer of headaches during future maintenance efforts.

STORYTIME!!!
For just a moment, allow me to digress.  I have an acquantance in Maine who rebuilt classic fiberglass boats for a living.  He severely dislikes 5200 because he says it is not a sealant, it should be viewed as a permanent adhesive.  You CAN remove it, but the chemical needed comes in small amounts and costs a bit.  So...this gentleman decided to add an anchor platform to the bow of his 28' sailboat.  It was beautiful.  2 thicknesses of mahogany laminated together to make a ~2.5" thick board and the whole thing was thru-bolted to the deck and sealed with a generous amount of 3M 5200.  All season long it withstood use and wear and was expected to last the life of the boat.  That IS why he used 5200.  Fast forward to winter and a Nor'easter came through.  His boat rode it out on a mooring and the next morning it looked ok.  When he went out on the launch, however, he noticed a gash in the new paint job all across the bow from a dangling anchor and the overhanging portion of the new anchor platform was broken off and nowhere in sight.  To repair this, he had to remove the remaining part of the anchor platform.  This took TWO DAYS of scraping and levering, even with the use of Antibond, and he would up tearing the deck surface in the process.  So...5200 is permanent.  On PE it's probably not as permanent, but I'm not willing to even experiment.  So if you like 5200, you're on your own :-)


So, back on task.
There are generally 3 "go to" sealants I use when doing boat work.  3M 4200 adhesive polyurethane or Lifecaulk polysulfide sealant for applications where I really want an adhesive in addition to a sealer (note the difference!) and for something under the waterline.  I'm sure most of you already know about these two, so I won't spend much time on them.  For most other above-deck uses, I like to use something called Butyl Caulk Tape.

In all the forums I have read through, I find it curious no one seems to be using Butyl tape on a kayak.  At first I thought there was something about PE that precluded using it but after testing, I found it was plenty sticky on PE.  I'm left with the thought that it is simply an unfamiliar sealant to many, since it fell out of fashion with all but high-end boat builders because it's easier and cheaper to stick to a single polymer-type sealant for everything.

To start with, butyl caulk tape (also called butyl adhesive tape) is NOT the same thing as the tube of butyl caulk or mastic you can get at the big box store.  That stuff is meant for roofing, and it dries out and hardens with time.  Same with plumber's putty.  Butyl tape (for short) is a non-hardening, permanently elastic solvent free rubber-based compound that is UV resistant and capable of a wide temperature range.  It is moldable and compresses under pressure to form a very good air and water-tight seal between two surfaces.  The compressed material will also squeeze into texture and small gaps.  Note that butyl tape IS adhesive, but only mildly so.  It relies on a thru-bolted connection that will compress the butyl tape between the two surfaces.  There are two types: white and gray.  Gray is a bit denser and maybe stickier and is the preferred one over white for marine use, but either will work.  Both of my rolls are white so that's what I'm going to use.  Stay away from the big box stores, the stuff they sell (if it's even named right) is usually pretty poor quality.  You can get it at any marine store or glass supply store or probably RV parts store.

I really like butyl tape for 4 reasons:
  • It is super easy to use.  As long as your hands are clean (I wear gloves, but just because the gloves are clean) you can handle it just like you would a tub of play-dough.
  • It doesn't harden.  This means if your wife calls you away to dinner mid-project, you know you can go back later and find it just as you left it.  After a couple of days it will form a bit of a skin on the surface, but it never truly hardens.  This elasticitity means that as your fittings and deck flexes, the sealant will flex with it to keep those small gaps closed.
  • No chemical cleanup.  Since Butyl is solvent free and easily scrapes off the hull all you need is the pressure of a finger rubbing against excess material to get it up.  In a few cases where it has been there a while and skinned up or for areas of the deck where you might have some stuck in texture, a bit of acetone will make it lose the stickiness and ball up and it's easily removed.
  • It lasts a long time.  I know of boats with butyl caulk on the same fitting for more than 25 years that haven't leaked.  Because it doesn't harden, it also has a long shelf life.  I've had two rolls of the stuff for years and they are just as good as if I bought them yesterday.  No more half-used tubes of 4200 to reluctantly throw away!

As you probably can tell, I've chosen to use thru-bolting and butyl tape as my preferred fitting-up approach.  In part II, I will cover the installation of a 5" deck plate and two thru-deck rod mounts, describe the process of using butyl tape and throw in a few tips and tricks and gosh, I wish I woulda's.  I know that "ye 'ol rod holder install" has been covered a dozen times, but I think I have a little twist on the approach.

See y'all soon!
 :banjo:

Is it just me or are we missing the first part of your post?


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The second part :-)  I will update with part 2 today.  Work got in the way.

Sent from my SAMSUNG-SM-G930A using Tapatalk

-Tony

Wilderness Systems Thresher 15.5 (Yellow)
Old Town Predator MK, (Lime Green Camo)


crash

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Damn man. Great conversational style of writing, useful and thought provoking content. Anticipates questions and answers them. With just about the right amount of overthinking.

I’m looking forward to part 2. Could you also take time to explain why butyl tape is better than marine goop on a functional level, if it is?  I get the cleanup is easier, but goop is cheap and ubiquitous and comes off of PE easily enough with careful work using a heat gun and a putty knife. I think most of us use t, and I’ve even attached a bracket using only marine goop without any screws at all. It’s made it through a season and still feels bombproof.

Again, nice topic and writing style.


Tinker

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I agree with crash here, but I believe the advantage of GOOP or other sealants is they're thin-layer sealants and don't add a (relatively) thick flexible layer to the assembly.
I expected the worst, but it was worse than I expected...


pmmpete

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How thick is butyl tape, and how much can it be squished down?  I haven't used it.  However, many surfaces on the hull of a kayak aren't flat, so perhaps an advantage of using Goop is that it can seal the area between a flat fitting and a curved section of kayak hull.


gnomodom

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Butyl tape sounds a lot like after market sound deadening that car audio people use to deaden the body panels in their car, such as Dynamat, or eDead. Those are buytlene rubber sheets with aluminum backing. Pretty sticky stuff, but mostly just enough to be self-adhesive. Not to sustain torsional or axial stress / load. I can see it working as a water sealer under backing plates and such.


Tinker

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How thick is butyl tape, and how much can it be squished down?  I haven't used it.  However, many surfaces on the hull of a kayak aren't flat, so perhaps an advantage of using Goop is that it can seal the area between a flat fitting and a curved section of kayak hull.

The thin butyl tapes I've seen were offered varied from 6mm to 3mm thick.  We weren't using it in a way that we'd squish, but I don't think it would flatten by more than 50 percent and probably not that much.  I could see it used as a sealant around fittings on a metal hull but maybe not very suitable for a plastic or composite hull.

I guess there could be thinner tapes, but I've never personally seen any thinner than 3mm. 
« Last Edit: November 23, 2017, 04:52:27 PM by Tinker »
I expected the worst, but it was worse than I expected...


Wilfite

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Part II: Cuttin’ Plastic & Fillin’ Holes
And we’re back!  Amazing how work and holidays conspire to get in the way of things :-)

I’d like to start part 2 with a reply to a few of the comments.  This is not an attempt to prove “Butyl is better”.  It is just one of many options.  Different types of sealants excel in different circumstances.  It seemed to me from the various related forums that few in the kayak fishing community seem to be aware of butyl and its properties.  To me, it seems a good fit to use a sealant that doesn’t rely on “stickiness” to do its work when things don’t like to stick to our ‘yaks in the first place.  Due to the dough-like nature of the material, it can be shaped and fitted into thinner and narrower sizes than it is delivered in.  You only need enough material such that when the fitting is tightened down the butyl will compress and squeeze into any air-gaps like around screws.  The tape I am using is ~2-3mm, I think.  I didn't measure it.  You'll see below that I got in a hurry and forgot to do this step, so I had an extra step at the end to squeeze out the additional material.  If the layer is a little thick it doesn't compromise the seal, however it increases the chance of dirt and other thin particles getting caught up in the seam.  I will be upfront and say that, while I’ve used butyl tape for probably 10 years on various boats, this IS the first time I’ve used butyl on a PE surface, and I will update this tutorial after several months of use with any new findings but in my experience, it has always been very reliable.

As an aside, if someone has a chunk of PE material from a broken kayak it might be interesting to do some objective testing of different sealant compounds to test their stickiness, resistance to pressure and repeated motion to definitively say if one is definitively better than the others.  Might be a fun project for the community at large.  I would be willing to team up with someone to do this work.

To answer the question asked with regards to my feelings about “Goop”, I have grown an anti-silicon bias over the years so I personally will only use silicon-based products as a last resort or for the very few cases where it is truly the right compound for the job.  I have not been able to find an ingredient list, however based on the behavior and composition, Goop acts like a silicon-based product so I will treat it so.  If anyone knows different please speak up. 😊

STORYTIME!!
While living aboard in 2003, I had to tear out the entire interior of the main salon in a 32’ sailboat and grind a layer off of the inner hull in order to do what should only have been a couple of days of repairs because the previous owner used a silicon-based adhesive to glue polystyrene insulation to the hull.  Nice idea to insulate, but the wrong choice in adhesive and insulation resulted in melted insulation, created a surface nothing would stick to and left about a billion little balls of polystyrene in every crevice.  We removed everything on the port side of the boat down to the hull, drape it all in plastic and grind away.  Eventually it was just more effort than we were willing to give/put up with while living aboard and we sold the boat and moved back to land with the project left unfinished (I still miss that boat). That amount of effort leaves a mental mark 😊.  In general, I would say this:  If you think you will ever need to paint, glue or otherwise re-finish a surface, silicon is your enemy.  It gets into microscopic pores and is almost impossible to completely remove once cured without removing the surface layer.

So, let’s get to it, shall we?



First off, a bit of info on our patient.  My kayak is a Wilderness Systems Thresher 155 that I got used out of demo stock.  The boat has a large rectangular console with hatch in the cockpit that allows for rod and other storage in-hull and I picked up a storage bin that fits into this console.  From my sailing dinghy days, anything that sticks up from the boat and can catch water makes recovering from a turtle harder.  I am trying to get away with NOT using a crate.  I can fit most of my fishing gear within the hull, so I really only need some rod holders and a small storage box for dirty stuff like my anchor and for my 360 light mount.  (I will do a write-up on the 360 light at another time.)  The only thing I want sticking up above deck level are my rods and light, if possible.

First, let’s locate the install points: 
Just aft of the seat there is a nice flat spot for up to 4 rod mounts and a nice angled flat spot for an inspection hatch to be able to reach the back of the rod holders for thru-bolting.  I am only installing 2 flush-mount holders for now, but have left enough room for 2 more if needed in the future.

I purchased the flush mount rod holders off of Amazon, they are sold as “KSTON flush mount rod holder” and come in a pair for about $10 bucks.  They are made of ABS plastic, have a rounded, closed bottom to avoid rod bounce and come with a rubber gasket and plug.  I ended up cutting the plug off to keep from catching lines, but I will keep the plugs for storage.  The 5” inspection port I already had in my box O’ stuff.  It is made by Victory Products, model AA13561 5” Deck Plate.  Truthfully, I’m not in love with it and will probably replace it with a black one at some point in time, but the various inspection ports have common mounting patterns so I’ll go ahead and use what I have for now.  This is one area where butyl tape excels. It’s easy to remove and retrofit with few headaches later.

The First Incision:
To start, we need to identify the center of where the hatch will be installed to mark and cut out the right size hole in the deck.  Wilderness includes molded-in center points for hatches in several areas, so that made it easy in this case.  If you don’t have these marks already then you will have to do some careful measurements.  One method is to place the hatch where you want it, mark the holes with a pencil then remove the hatch and cross lines between the mount points to identify where to drill the pilot hole.

TRUST, BUT VERIFY! – I was so pleased to have these marks already, I didn’t verify it was truly centered.  Either the mark was a bit off-center or my drill point drifted just a hair so my hatch ended up about 1/8” off-center.  Changing the orientation of the bolt pattern makes it basically invisible.

Go-Go-Gadget Hole Cutter!
I have this nifty gadget I bought last year.  It’s made for cutting perfect circles in drywall to install can lights.  I used it last year to put lights in my kitchen and it worked really well.  When considering how to drill the holes in my ‘yak I realized I didn’t have the right size hole-saws.  Using a Dremel works but there is some risk of accidentally scoring the deck should the bit slip so if I can use a hole saw I prefer to.  Since PE is a soft material, I figured the blades of this tool would work just fine even though they are supposedly for “drywall only”.  I used it to cut out the inspection hatch hole and it came out beautifully!  I couldn’t use it for the smaller holes because it wouldn’t go small enough so for those I used a Dremel with a grinding bit and took my time to get it right.  I definitely recommend this gadget as a preferred method for cutting large circles in PE cleanly.  It cuts PE very cleanly.  (If you do use a hole saw, I suggest a smaller pilot hole for the hole saw bit and go slow.)  Next, I put the mounting ring into the hole to mark and drill the locations of the mounting screws.  This is when I discovered the opening I had cut out was very slightly off-center.  I spent some time with a micrometer measuring the distances from holes to nearby features to ensure my mounting arrangement would be level and aligned horizontally.
 






Measure Twice…Cut Once
After drilling out the mounting screw spots I used a razorblade to trim off a few bits of plastic along the edges the cutting process had squeezed up and moved on to locating and cutting the openings for the rod mounts.  For this there were no pre-located pilot points, so I used the aft rails and the molded lip as a reference point to roughly place the rod-holder position using the rubber gasket as a template to mark the opening and bolt positions.  Next, I used a drafting triangle to create reference lines to mark and measure the first set of holes to ensure the mount would be properly centered and at the right angle.  Once finalized, I measured distance along and inwards from the rail in mm and used those numbers to transfer the same locations to the port side location.  This approach worked well and both mounts appear to be in identical positions port and starboard.
In researching this project, there didn’t seem to be a community “standard” for positioning these types of rod holders.  I chose to mount mine 45 degrees off-center to better reach items stored there and to be able to troll from these holders if desired.





The Hole Truth – When checking the marks for the machine screws, I realized I had drilled the rod mount openings perpendicular to the hull but because my rod mounts sit at an angle, the flange didn’t sit flat against the deck when I checked the fit.  I went back with the Dremel tool and beveled the leading and trailing edges of the rod mount holes until the rod holder would sit flat against the deck.  With this adjustment, the screw positions shifted slightly so be careful here!  This is why I didn’t drill the holes for the machine screws until the main opening was correct.  Measure Twice, Cut Once, folks!  When all was said and done, one hole fit the rod holder perfectly and the other had no more than about 1mm play.  The butyl tape was more than sufficient to fill the gap.

Putting it all together…
Once the rod mounts fit flush, I drilled out the screw locations using a drill bit slightly smaller than the machine screw.  If this were a thicker hull I would have drilled it out larger or tapped it to fit the screw, but with the PE hull it is soft enough to cut into easily with the machine screw so I didn’t want to pre-drill too large.  The tighter the screw hole, the less chance of any water intrusion should there be a problem.  Once this was done I readied three 5/8” #8 machine screws to install the first rod mount.  Cutting off short strips of butyl tape, I wrapped them around the body of the screw so that as I screwed it into the backing nut, the butyl tape would squeeze into the gap between the screw and rod mount flange to further water-proof the installation.  You want this gap to allow for a little bit of flex and movement.  These fittings came with rubber mounting gaskets so I did not have to add a layer of butyl under the flange, just for the machine screws.



I had planned to use fender washers in all three spots during the rod mount install, but the body of the rod holder interfered.  Instead, two of the three screws got a regular washer and one a bigger fender washer at the base.  If I hadn’t been able to use at least one fender washer I probably would have manufactured some kind of threaded backing plate.  Standing rods may exert a lot of torque on this fitting so I want to make sure it is reliable.  Reaching through the inspection port, I threaded on the washers and nut and held the nut in place with a short wrench while I screwed in the machine screw.  Be careful here not to over-tighten the mounting hardware; you don’t want to crush or cut the plastic hull.  Depending on the screw and sealant used, it might be better to hold the screw in place with a screwdriver and turn the nut.  This is another advantage to butyl, you can turn the screw to tighten it even after installation without compromising the seal.  Once a polymer like 4200 or goop solidifies, turning the screw will tear the seal.  Once the mounts were installed and torqued, I removed off the excess butyl sealant by hand.  The act of screwing the hardware in actually cut it off, so this part was easy.  Balling up a bit of the excess butyl tape, I used that to pick up little bits that were left behind.



Once the rod mounts were installed, I moved on to the inspection port install.  The first step was to wipe down the deck around the opening drilled previously with a paper towel and 99% denatured alcohol.  This makes sure that skin oil and other smutz that may have contaminated the deck surface is cleaned off.  I did the same on the backside of the ring for the inspection port and earlier for the rod mounts.  Once things had fully dried I pulled a long piece of butyl tape off of the roll and began pressing it into the grooves of the inspection port mounting ring.  When fully wrapped, I cut the tape with an exacto knife to make a butt-joint.  Next, I cut off excess material around the edge and used a small punch to poke a hole through the butyl where the screws would go.  This helps avoid getting butyl in the screw threads as you drive them in.  If you don’t do this step it’s not the end of the world but it can make getting the nut screwed on more difficult.









Once the mounting ring was prepared, I pushed it gently but firmly into the opening, made sure the machine screws and holes lined up and carefully pressed it into place until the butyl tape began to squeeze out slightly all around.  I used standard SS washers and locknuts here.  Since there are 8 machine screws to hold this in already, I didn’t think larger washers were required in this application.  I torqued the screws down in an opposing pattern (like you would for a tire or an engine block) to ensure the same pressure was applied all around.  This is easily judged by the amount of butyl squeeze-out all around.  You should see quite a lot of squeeze out here, that is ok. You don’t want an excess of material left if you can avoid it.



OOPS – While I was putting the butyl tape on the mounting ring, I got in a hurry and forgot I was dealing with a very thin deck so I really should have used less butyl material.  When I bolted the whole thing together, I got a scallop pattern in the squeeze-out around the edge because the deck was too flexy to withstand the clamping pressure of the solid inspection port mounting ring without deforming.  My solution to this was to use a C-clamp and wine cork to apply pressure in the areas where the deck had flexed to squeeze out more material and flatten the deck opening.  I didn’t have to do this, it would have sealed fine without it but it bugged me and I didn’t like the scalloped appearance around the edge of the port.  Because butyl tape stays soft, it can collect dirt over time.  This is one area you have to watch that is not as much of a consideration for other sealants.



Once all of the screws were tightened equally (judging by squeeze out of sealant and how tight they felt) I screwed the inspection port plate in and used a small screwdriver to gently scrape away the squeezed out butyl material.  I balled up the left-overs and used them to clean up little bits and pieces I missed earlier.  I did have to use a little bit of acetone to get some stubborn bits out of a couple of scratches in the hull, but other than that there was no chemical cleanup needed.



After standing back and admiring my work a bit, I cleaned up the bilge and deck and the surrounding areas.  I will save the 3 pieces of deck I removed when cutting the openings against future repair needs.  Lastly, I couldn’t help but sit down in the cockpit and play around with rods and my net to make sure the install went as I intended.  With the 45 degree off-angle, I don’t have to reach out so far to grab the rods or net, but it’s not so much of an angle that the rods really stick out too far.  I’m quite pleased so far with this install and greatly looking forward to getting back on the water when it warms up again!



So, we’ve reached the end of our saga!  I hope this is helpful to anyone who might have questions on this sort of install.  As you’ve seen, butyl tape is pretty easy to use and very forgiving.  Regardless of whether you use butyl, goop, 4200 or another sealant, most of the installation steps are quite similar.

Keep the dry side up, the wet side down and your lines tight!
Kind Regards,
Tony

« Last Edit: November 24, 2017, 10:06:31 AM by Wilfite »
-Tony

Wilderness Systems Thresher 15.5 (Yellow)
Old Town Predator MK, (Lime Green Camo)


Wilfite

  • Rockfish
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  • Location: Columbia City, OR
  • Date Registered: Oct 2017
  • Posts: 119
Butyl tape sounds a lot like after market sound deadening that car audio people use to deaden the body panels in their car, such as Dynamat, or eDead. Those are buytlene rubber sheets with aluminum backing. Pretty sticky stuff, but mostly just enough to be self-adhesive. Not to sustain torsional or axial stress / load. I can see it working as a water sealer under backing plates and such.

They use a butyl-rubber material as a base for these, but then impregnate the panels with some other high-mass material.  At one point in time lead dust might have been used, not sure what they use now.  My truck was treated with this stuff and I remember it being a different consistency than the butyl tape I use for sealing fittings.
-Tony

Wilderness Systems Thresher 15.5 (Yellow)
Old Town Predator MK, (Lime Green Camo)


Wilfite

  • Rockfish
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  • Location: Columbia City, OR
  • Date Registered: Oct 2017
  • Posts: 119
I agree with crash here, but I believe the advantage of GOOP or other sealants is they're thin-layer sealants and don't add a (relatively) thick flexible layer to the assembly.

I think this depends on the amount of sealant you use.  I mention in part 2 that you can shape the butyl to fit the application.  In fact I got in a hurry and forgot this step because I'm used to working with thicker, firmer decks were the clamping pressure of thru-bolting the fitting will squeeze out any excess.  I learned in this process that you definitely need to thin out the tape somewhat prior to install to avoid a thicker layer between the fitting and deck.
-Tony

Wilderness Systems Thresher 15.5 (Yellow)
Old Town Predator MK, (Lime Green Camo)