Help on adding 1 more battery for TM in limited space?

I'm thinking of going to a 24V TM but have limited space to add another battery. The boat is a Stratos 176.




I'm thinking of putting a plank of some sort from the TM side to the Cranking side and putting the 2nd TM battery holder on it.

Questions:

1. What would I use for the plank strong enough to hold one battery and not rust or rot? Can't be too thick.

The original TM battery and cranking battery would still be on the shelf but mounted on the plank?

2. How to attach the plank to the Fiberglas shelf on each side so it doesn't come loose?


3. Would it hold if I use longer bolts through the battery holders on the shelves now, through the plank and
into the glas shelves?

The 2nd Batteries full support would be from the plank. If the battery were to fall it would wipe out the bilge pump.

Looks like it would be easier just to relocate the onboard charger and use that space for the extra battery. You could bolt the charger to the underside of the lid

Not enough space from shelf to lid for battery height.

I would buy a piece of starboard 3/4 inch and cut it to make a cover for the bilge area and set the third battery on it. You could make it long enough to sit all the=ree batteries on it. Also i have my optimia batteries laying on there sides.

The bilge area should be covered with a plate. Mine is aluminum sheet with L bracing on bottom side to prevent sag. It will hold at least 2 batteries in that space.

? Its hard to tell what needs to be built by using pictures. Looks like the bilge cover plate is missing.?

I have a three battery Optima battery box if you think it will fit. Ten bucks and its yours

Here is a picture of the box

There isn't any plate over the bilge pump. That's the area I would be covering up.

Yes. Then use that flat area to mount batteries. Bruce has a good deal there for $10. That box would also just add strength to support batteries weight & charger could stay up where its at now.