Lowrance Power Cable too Short

I got a Lowrance Hook 4x too install in a sit-kayak and wanted to install the battery behind my seat, but the power cord that came with is only 3 feet long and I need 10 feet. What can I use to splice a extension to the battery box?

I would use 14 gauge wire(marine wire is best but you can use automotive wire, 1- inline fuse holder,1-3amp fuse, 3- 14ga. butt connectors easiest (or best to soldier and use heat shrink tubing), 2 alligator clips or whatever to hook wire to battery. With the inline fuse right at the battery on the positive side of battery. Now this is just my two cents worth. And there is several other ways and sizes of wire that can be used.

What Scrat said. 14 be fine for that finder.

Thanks guys , just went to my local West Marine Store and was looking at marine grade 18ga 2 wire. I've bought some shrink wrap , butane torch {my old die} and solder for my connection.
Now for a another quick question : Battery box , he bought one all done from Bass Pro but I need to tie it down will Marine Goo hold straps down like glue ounce it sets?

I bought some industrial strength Velcro patches from Lowes, about 3"X4", and put one side against where I wanted my cable to stay, and the other on the bundled cable, and stuck them together. It works great and you don't have a mess with the Marine goo when you need to remove it. I had a Lowrance but changed it out to a MinnKota and it came out real easy when I swapped them.