Flotation in an SOT Kayak?

lol, I appreciate the thoughts and the technical clarification.  I have what I was looking for, which was some good ideas of what others are doing and hope new kayakers have some information as well. 

I did find this link before posting and had some of the technical down, this is just interesting reading if you're curious.  Turns out a 75-lb yak might not need 75-lbs of flotation once in the water:
http://www.screamandfly.com/archive/index.php/t-53895.html

exactly, the density of the material is a key part of the calculation, which is why a PDF with 19# floatation is plenty for a 200# human being.  also why a log weighing several thousand pounds can float...

Just so people aren't misguided by the idea of flotation, it's important to remember that this will only keep your kayak from sinking completely. Just a few gallons of water in the hull will generally cause your kayak to be so unstable that you'll be tipping over on a consistent basis.

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Just so people aren't misguided by the idea of flotation, it's important to remember that this will only keep your kayak from sinking completely. Just a few gallons of water in the hull will generally cause your kayak to be so unstable that you'll be tipping over on a consistent basis.

When whitewater kayaking, I have had my spray skirt blown off in big water, and have pulled my skirt in a effort to get out of a very sticky hole, and can attest that paddling a kayak which is full of water is difficult, because the water sloshes around in the kayak and makes it very unstable.  I haven't experimented with filling one of my sit-on-top kayaks with water, because it doesn't seem like that would be at all fun, but I imagine that they would be just as unstable, despite their greater width, because of the higher center of gravity of a sit-on-top kayak. Sloshing water would be particularly problematic in a pedal kayak, unless you quit pedaling and start paddling so you can brace yourself upright every time the water in the kayak makes the kayak lurch.

The advantage of having a lot of flotation in a kayak is that the flotation will reduce the amount of water which can get into the kayak, which will make it float higher in the water, and will make it easier to recover from whatever mishap resulted in the kayak being full of water.  But emptying water out of your kayak when you're out on the water without assistance from other kayakers is pretty difficult.  In calm conditions, you can pump water out of a kayak with a bilge pump from the area below your seat.  But I would hate to try to pump water out of a kayak in rough conditions, because you'd be floating low in the water, and would be lurching from side to side, and might take water in the open hatch faster than you could pump it out.  In sit-on-top kayaks which have a hatch in front of the seat, if the kayak is floating low enough in the water, the hatch will be below water level, and water can come in the scupper holes, fill up the cockpit, and flow into the hatch if it's open.  Does anybody have an educational story they can tell about attempting to pump water out of a kayak while out on the water?

If somebody's kayak fills up with water, the best way to get the water out when you're on the water is for two or more kayakers to flip the kayak over and pull it up on top of their kayaks, draining water out in the process, which is tough because a kayak full of water is very heavy.  And this would be exciting in rough conditions.  Does anybody have an educational story they can tell about doing this?  I've dumped water out of a lot of whitewater kayaks on shore (most of them not my kayak, fortunately), but have never tried doing it out on the water.

here is the calculations:

 density of air at about 70 deg F at sea level is roughly 1 kg/m^3
 density of fresh sea water is roughly 1000 kg/m^3

 a cubic foot is .0283 cubic meters meaning it will hold up ~28 kg (~62 lbs)





Source(s):
 http://hypertextbook.com/facts/2002/EdwardLaValley.shtml
 http://www.onlineconversion.com/ 
the

 The net boyant force is the difference between the two weights...the mass of water displaced - mass of the displacing substance multiplied by gravity. However, if we instead think about the net "lifting power", if you will, and consider the mass which will be able to be supported by the net boyant force, we can ignore gravity (but remember why we are doing it).
 28320 grams - 18.22 grams = 28301.78 grams.
 28301.78 grams = 28.30 kg.

 Now, going back and finding the net boyant FORCE, multiply by gravity (9.81 m/s^2),
 28.30 kg * 9.81 m/s^2 = 277.6 Newtons

 Thus, 1 ft^3 of air would be able to support an object weighing 277.6 Newtons.
 The object to be supported would have a mass of 28.3 kg (62.3 pounds).

Isn't Mr. Google just  wonderful!!...warf 

here is the calculations:

 density of air at about 70 deg F at sea level is roughly 1 kg/m^3
 density of fresh sea water is roughly 1000 kg/m^3

 a cubic foot is .0283 cubic meters meaning it will hold up ~28 kg (~62 lbs)

Speak English!

 The net boyant force is the difference between the two weights...the mass of water displaced - mass of the displacing substance multiplied by gravity. However, if we instead think about the net "lifting power", if you will, and consider the mass which will be able to be supported by the net boyant force, we can ignore gravity (but remember why we are doing it).
 28320 grams - 18.22 grams = 28301.78 grams.
 28301.78 grams = 28.30 kg.

 Now, going back and finding the net boyant FORCE, multiply by gravity (9.81 m/s^2),
 28.30 kg * 9.81 m/s^2 = 277.6 Newtons

 Thus, 1 ft^3 of air would be able to support an object weighing 277.6 Newtons.
 The object to be supported would have a mass of 28.3 kg (62.3 pounds).

Isn't Mr. Google just  wonderful!!...warf

I think I just hurt my drain trying to READ that let alone comprehend it 

 The net boyant force is the difference between the two weights...the mass of water displaced - mass of the displacing substance multiplied by gravity. However, if we instead think about the net "lifting power", if you will, and consider the mass which will be able to be supported by the net boyant force, we can ignore gravity (but remember why we are doing it).
 28320 grams - 18.22 grams = 28301.78 grams.
 28301.78 grams = 28.30 kg.

 Now, going back and finding the net boyant FORCE, multiply by gravity (9.81 m/s^2),
 28.30 kg * 9.81 m/s^2 = 277.6 Newtons

 Thus, 1 ft^3 of air would be able to support an object weighing 277.6 Newtons.
 The object to be supported would have a mass of 28.3 kg (62.3 pounds).

Isn't Mr. Google just  wonderful!!...warf

I think I just hurt my drain trying to READ that let alone comprehend it 

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 The net boyant force is the difference between the two weights...the mass of water displaced - mass of the displacing substance multiplied by gravity. However, if we instead think about the net "lifting power", if you will, and consider the mass which will be able to be supported by the net boyant force, we can ignore gravity (but remember why we are doing it).
 28320 grams - 18.22 grams = 28301.78 grams.
 28301.78 grams = 28.30 kg.

 Now, going back and finding the net boyant FORCE, multiply by gravity (9.81 m/s^2),
 28.30 kg * 9.81 m/s^2 = 277.6 Newtons

 Thus, 1 ft^3 of air would be able to support an object weighing 277.6 Newtons.
 The object to be supported would have a mass of 28.3 kg (62.3 pounds).

Isn't Mr. Google just  wonderful!!...warf

I think I just hurt my drain trying to READ that let alone comprehend it 

Mojo, if you read it using your brain instead of your drain, you'll realize that what Warf said is "light things float."

 The net boyant force is the difference between the two weights...the mass of water displaced - mass of the displacing substance multiplied by gravity. However, if we instead think about the net "lifting power", if you will, and consider the mass which will be able to be supported by the net boyant force, we can ignore gravity (but remember why we are doing it).
 28320 grams - 18.22 grams = 28301.78 grams.
 28301.78 grams = 28.30 kg.

 Now, going back and finding the net boyant FORCE, multiply by gravity (9.81 m/s^2),
 28.30 kg * 9.81 m/s^2 = 277.6 Newtons

 Thus, 1 ft^3 of air would be able to support an object weighing 277.6 Newtons.
 The object to be supported would have a mass of 28.3 kg (62.3 pounds).

Isn't Mr. Google just  wonderful!!...warf

I think I just hurt my drain trying to READ that let alone comprehend it 

Mojo, if you read it using your brain instead of your drain, you'll realize that what Warf said is "light things float."

Nope still incomprehensible for my simple mind... can I get it in a picture? BTW2SOT (stay on topic) I have about 12 or so pool noodles in my Jackson Big Tuna

Thanks guys, I think I'll just use my noodle(s) and hope for the best...

After looking at the size of the hatches on the trident 13, if sitting in one of the hatches to lower the center of gravity to keep from continued tipping is in the plan, I'm not putting any long noodles in the large oval one in the front for sure!
I'm done...

Thanks guys, I think I'll just use my noodle(s) and hope for the best...

After looking at the size of the hatches on the trident 13, if sitting in one of the hatches to lower the center of gravity to keep from continued tipping is in the plan, I'm not putting any long noodles in the large oval one in the front for sure!
I'm done...

I never ever thought of trying to sit in the front hatch of my Trident 13 for any reason whatever.  It would be a seriously bad idea.

The best place to stuff pool noodles in a sit-on-top kayak is under the rear cargo area, because that keeps the pool noodles right on the bottom of the kayak, where they do the most good.  And there isn't much you can do with that space anyhow.  Pool noodles will keep items of gear from sliding back under the cargo area where you can't reach them.

I stuffed the rear of my outback with large bubble wrap that came in a package. I couldn't throw it away because it took up my whole garbage can so I recycled it as flotation. My revo has Amazon air pillows stuffed inside. Free and free.  The best price. And so far, they have lasted for years.

Now if some math wizard could figure the length, diameter less the center hole to come up with the something or other to get the floatation value of one noodle we would have it made!!..lol..All I know is one noodle will float a fat lady in a swimming  pool,,,,warf

 The net boyant force is the difference between the two weights...the mass of water displaced - mass of the displacing substance multiplied by gravity. However, if we instead think about the net "lifting power", if you will, and consider the mass which will be able to be supported by the net boyant force, we can ignore gravity (but remember why we are doing it).
 28320 grams - 18.22 grams = 28301.78 grams.
 28301.78 grams = 28.30 kg.

 Now, going back and finding the net boyant FORCE, multiply by gravity (9.81 m/s^2),
 28.30 kg * 9.81 m/s^2 = 277.6 Newtons

 Thus, 1 ft^3 of air would be able to support an object weighing 277.6 Newtons.
 The object to be supported would have a mass of 28.3 kg (62.3 pounds).

Isn't Mr. Google just  wonderful!!...warf

I think I just hurt my drain trying to READ that let alone comprehend it 

Shannon, you think this is bad you should have been here about 6 years ago when we had a discussion on leverage of fishing rods from a kayak....that qualified as pure geek speak after about the 2nd page