new to kayaking....power for my fish finder, blue? lithium or sla battery help?

craig i really like that! i looked up battery info all morning and never came across that, good info...may have to splurge a little more. i wish like the orange box demo on you tube video i could rig up a cig lighter port as well as light, i for some reason really like the idea, but if this could run my fish finder for a extended camping trip would be good enough for sure , plus i like the smallness of it. can this thing be charged up with solar? this thing just might be my ticket, thanks for posting it.

If you don't want to spend $50 on each battery then just buy one of these with free shipping for about$19. Stuff it in a dry bag or even a heavy plastic bag, call it good. Go fishing, don't waste your days drilling holes in little plastic boxes and filling them with silicone.

It will probably last about 40 hours on your FF between charges. I use a big screen FF that pulls 650 mah with the screen dim. I burn the juice - but hey, mine's bigger than yours. I have 3 batteries, usually bring 2 for the long days.

Go catch some fish!

I wanted something light weight and easy to secure inside the the yak that wouldn't pound the crap out of the inside (and the things inside) if I were to huli in the surf. Rory, Demonic, and many others pointed out newer technologies allowing me to do this, as well as great locations and methods to mount them in a Hobie.  Also, my old method was the battery pack in the dry bag.  However, after ruining one battery due to a small leak of salt water into the dry bag I decided to splurge and spend $4.96 on a small dry box.  Then, I spent all of about 20 minutes soldering a couple wires and laboriously drilling two 1/8 inch holes in a little plastic box on my kitchen counter while hanging out with the kiddos when my wife was at a meeting.  I figured Child Protective Services would frown on me leaving the 8 year-old in charge of the 6 and 4 year-old while I left to go fishing.  Plus, my oldest boy, like me, likes to do things himself and got a good lesson on how to make/fix stuff himself and I didn't get bored.  My dad taught me the same things and it has been very profitable for me.  If I can't fish, the next best thing is building shit (IMHO).

craig i really like that! i looked up battery info all morning and never came across that, good info...may have to splurge a little more. i wish like the orange box demo on you tube video i could rig up a cig lighter port as well as light, i for some reason really like the idea, but if this could run my fish finder for a extended camping trip would be good enough for sure , plus i like the smallness of it. can this thing be charged up with solar? this thing just might be my ticket, thanks for posting it.

I would think if you had a solar charging station of some sort it could be charged.  I can't remember if it has a car charger or not.  I think it did.

Just remember a D-cell size LI battery has the explosive potential of a 1/4 stick of dynamite and it will go off if soaked in water long enough. Just make sure that box is sealed tight.

Been there done that when it comes to defusing soaked lithium batteries at sea, and seen many of them explode. I'll be sticking to lead bricks, thanks!

Good Point Yaktrap, but keep in mind that your cellphone, VHF, GPS, and other electronics most likely have lithium batts as well.

They're safe, just treat them nicely. Worst things are if they get smashed crossways (internal short) and bad chargers; of course dunking them in saltwater = a short as well.
I too have seen many lithium batteries vent and or ignite, and i'm sure it could melt through a plastic boat. However, I still keep my cell phone in my front pocket just inches away from my most favorite possession.

craig,
is that a fuse connection in the box with your battery? is fuse necessary with one of these? if so what size? am ordering the pack here shortly.

for some reason cannot (i know, its a dampainter thing!) copy and paste a link for this battery pack....on amazon am seeing a "instapack" mp3450E  13,500 mAh.....or
"instapack"mp3450E-60 27,000 mAh dual. what do you all think? these doable? or am i gonna blow my fishfinder... or me up? what fuse would i need if any? 

The fuse,  just like the breakers in hour homes electrical panel, are to prevent more current from going over the wiring than those wires are designed to carry.  In the case here,  you may want to use a fuse rated not only low enough to protect the wires, but to blow before you have exceeded what the battery is rated to provide.  My FF draws around 250 ma with the backlight at the brightest setting.
My battery is rated to provide 12 volts at 1000 ma.   I am running a 750 ma fuse.

Since I typically fish fresh water only, I don't worry much about corosion so I just use standard 1/4" spade connectors to attach directly to the Dewalt battery pack.  I just toss the battery pack into the battery bag in the nose of my kayak.

craig,
is that a fuse connection in the box with your battery? is fuse necessary with one of these? if so what size? am ordering the pack here shortly.

Yes it is a fuse.  It is the fuse that came with the fish finder.  As the other craig said, a fuse will protect your devices.  Your owners manual should say what size fuse you need if a fuse and fuse holder did not come with it.