Nice find, twisted. I cut an inspection hole in mine, but on the outside of the stringer, thats why I thought it was too shallow. Im thinking now, cut some holes like u did, epoxy up
The edges, use the cut outs as hatch lids and gain some storage. Can u post some pics with your camera in the hole facing forward & aft

Thanks

Ok here we go should be able to see much better now.

Ok so the whole thing is rectangular. The bottom slants away so the measurement to to the top of the slant. That is not how the battery will sit just dropped it in to show the fit.

Awesome !

Totally solves my trolling motor issue (unless I go 36v). Thanks !

No problem, I did forget to mention that the cavity space is equal dimensions on both sides.
At least in my boat!

I would not put the battery's up there, I would put in a hatch and use it for storage for something light, I don't like the weight and corners of the battery's resting on the hull , that's just my opinion

So how much room is there between the top of the battery and the underside of the deck? Obviously don't want to just drop the battery into a hole with an uneven bottom - will need to fabricate a base with a built in angle to compensate.

I'm thinking maybe a sandwich made up of 1/2" rubber mat on the botom, 3/4" plywood, expanding foam to make up the angle and a 3/4" plywood top for the battery to sit on. That means that a minimum of 2" of clearance in the shallowest corner. Is there enough?

Could probably get away with a 1/4" mat and 1/2" ply for a total of 1.25" if need be..

Follow up question - do you see any reason why I couldn't cut the access hole in the side of the step down rather than the top of the deck? Harder to get to but I have milk crates bolted to the deck in the cuddy and wouldn't want to move them, even occasionally for battery access.

Absolutely! In no time at all you can stick the trolling motor right through the large holes that will be in the hull...you could troll from inside the cuddy!
Brilliant...

Yea pretty sure a properly bedded and secured battery won't be much of a risk in my situation. But thanks for your kind guidance. I'll let you know next time I'm in RI -maybe we can hook up again..

It was a word of caution to the OP...as many have noted on this thread what he is proposing is somewhat risky.
That is a heavily concentrated load at the end end of the lever arm, without proper bracing this could be a disaster. In any case I wouldn want all that weight (somewhat) permanently mounted up in the bow area.
Sometimes we have to accept that the designers actually knew what they were doing.

The comment on your trolling motor was a joke...hope you enjoyed the bourbon.

Merry Christmas to All!

Bill