Securing finder battery

Just got my new outback and am almost done kitting it out. One thing I want to figure out a good solution for is how to secure the battery. 

I want something that will keep it off the bottom, and that will keep it from thrashing around in there. I use a few different size cases.

I was thinking of a block of closed-cell foam (like the stuff newer hobies have inside). It could have a space hollowed out i could drop the battery in.  I could also belcro it to the bottom. That way I could remove it if I had to store gear in the hatch (which is almost never). But I have no idea where one would come across such materials. My searching has yielded only insustrial suppliers who sell in large quantities.

Does anyone know where I might procure a block OR have any other/better ideas?

You can run wires back to your rear hatch and fit your battery to a gear tub. 
Or make a holder attached to the underside of your front hatch cover.

i put my battery box inside a cheap drybag, then clipped the dry-bag via caribiner to a loose zip-tie secured to my adventure's inner mast post, although you could use any securing point inside, like what fungunnin suggested

Rear hatch use a gear tub or Hobie makes a battery holder for the hatchets.  I like the tub because it stay pretty dry. 

Dana

Rear hatch use a gear tub or Hobie makes a battery holder for the hatchets.  I like the tub because it stay pretty dry. 

Dana

+1

They beat me to it.  https://www.austinkayak.com/products/12544/Hobie-Fishfinder-Battery-Holder.html

I am going to give the hook and loop adhesive velcro a try.  Adhere it to the underside of the deck, with mating strips on the Plano battery box, and stick it fore or aft of the rear hatch.  Not sure there's room aft of the hatch what with the curved radius of the deck, but there should be space somewhere in there. 

This hook and loop stuff is pretty amazing if you haven't ever used it.  They have tons of different types, with adhesives designed to match almost anything you want to stick.  Some are activated by heat, some chemically, or you can peel and stick some types.  With the right stuff strategically applied, I doubt you could do anything with the boat to make it inadvertently separate. 

I've always liked what OK and Jackson done with the hanging battery trays. The space at the tip of the hull rarely gets used so maybe make a little hammock or shelf for it up there?

Ya'll would laugh at my redneck batterie holder..... It's a water resistant military belly bag that gets lashed to the top of my deck on the bungie  line my transducer is scupper mounted and the exes cord and battery (with inline fuse) are in a ziplock bag in the army bag. 

mojo - if it's stupid, and it works, it ain't stupid.

I like putting it in her rear hatch too.

I have mine in the round hatch right in front of me.  I have my phone in the box also and I want to be able to reach it for pictures and for access to my music that I stream to a waterproof Bluetooth speaker.  I dont have it attached to anything yet but with all of the foam below deck it isn't gonna go far...

I like the tub-in-hatch idea alot. Only slight concern is the back of the kayak is usually already overloaded. When using the SLA batt it adds even more weight. Trying to figure out a way to utilize the generally un-used space fore. Some sling with cinch straps may be the key.

I have mine in the round hatch right in front of me.  I have my phone in the box also and I want to be able to reach it for pictures and for access to my music that I stream to a waterproof Bluetooth speaker.  I dont have it attached to anything yet but with all of the foam below deck it isn't gonna go far...

Wait... what?!, a waterproof Bluetooth speaker?  I want to see how that's attached.  Sounds like an awesome idea.

Velcro here for quick swap out to a back up encased battery.  Nothing important gets wet that way