Mounting Batteries in Bow

[brightnight]

Considering moving my batteries to the bow of my 1994 seafarer 228G since I'm repowering with a Yamaha F250XSB motor which is a bit heavier at 610lbs compared to my previous Mercuary optimax 200xl at 517lbs. I weight tested it by adding sand bags to my engine and it's definitely sitting lower than I like, and that's without two guys in the back corner, waves, and only a half tank of gas. I've found a few related posts on here where people have done the same such as the picture and link below:
https://www.greatgrady.com/threads/battery-relocation.23349/

If I moved my batteries to the cabin, how would I secure them to the floor? From reading online it sounds like a good approach might be starboard on the floor with some type of bolt/clamp to keep the batteries held down to the starboard. How would I attach the starboard to the boat? It's not clear to be if I would screw the startboard into the floor, how deep I could go, or if I would screw it into the sides/walls only. Doing the math out I should be fine to run 2 awg marine grade wire. I also was planning on connecting the wires to the larger stud terminals of the batteries, it frees up the screw terminals for lower current devices and I don't see a down side but open to suggestions.

Picture from link:


Bow of my boat (would probably try to use the compartment closest to the stern):

 

[Sardinia306Canyon]

Moving the batteries to the bow to counterbalance the extra weight of new motors is basically a good idea.
However, if wet lead-acid batteries overcharge they produce hydrogen what is highly inflammable/explosive.
I hosted a finnish sailor who's sailboat caught fire when the battery box exploded when he wanted to start the engine as sea became too rough and assisted my buddy when his flooded car battery exploded when he tried to jump start it for a while.
That teached me that wet flooded batteries should be in a ventilated compartment with air circulation above the batteries.
Chris

 

[seasick]

In addition to the risk of explosive gasses , the new wiring has to be carefully planned. If you want the install to be ABYC compliant, not only do the batteries have to be moved but so do the battery switch(s), accessory feeds and main breaker and the fuse/breaker for the automatic bilge pump.

Finally, the cable gauge may need to be increased. The added back and forth run of battery cables may required larger cable size.

All that said, the weight that would be moved forward is only about 80 pounds .
If you weight anywhere near twice that number ( lets say 160 pounds), go stand (squat) in that forward space and see how the hull sits and where the scuppers are

 

[Fixit]

you will need battery boxes to secure the batteries, and you should use agm batteries so they won't offgas. I contemplated doing this in my old boat but never did get around to it.
I would use the stud terminals for my wiring. if you need small current stuff consider adding a small buss bar (I like the Z buss bars by Marinco) or a fuse block. keeps the extra connections at battery to a minimum. whatever you do, spend some time researching the components you like, current and future electrical needs and plan it out well

 

[Halfhitch]

If you want more weight forward, I recommend you put sandbags up forward somewhere.

Don't subject flooded cell batteries to the pounding they would incur up forward. If you do move batteries to the front at least change to absorbed glass mat batteries like Fixit said and check with the manufacturer how they should be oriented to best stand the pounding.

 

[DennisG01]

In theory, good idea. In reality... not the best. Hydrogren gas... bad for the batteries (harder bouncing/pounding). PLUS the $$$ for large cables... which will likely need to be larger than current... and the length of the cables... and the time/labor to do this....... there are much better ways.

BUT... you could mount battery trays to the floor - just check your clearance. Or fab side mount to the vertical walls. It's not logical to mount the trays to the starboard only to have to mount the starboard to something.

However... the easiest thing would be to just put some dead weight in the bow. I have heavy vinyl bags that are meant to be filled with ballast (sand/lead, etc) and used to weight down a portable/pop-up sunshade/tent. I used clean, small gravel and none of the small gravel has leaked out. Cheap and easy wins the game!

 

[Sardinia306Canyon]

However... the easiest thing would be to just put some dead weight in the bow. I have heavy vinyl bags that are meant to be filled with ballast (sand/lead, etc) and used to weight down a portable/pop-up sunshade/tent. I used clean, small gravel and none of the small gravel has leaked out. Cheap and easy wins the game!

Good to hear that someone understand the importance of a correctly weighted boat, COG is the word
On my Venture 34 in Costa Rica i used normal pvc tarp fabric "watertight" bags, the one with the roll to close opening and filled them with the heavy, black, fine volcanic sand and dropped them in the bow locker below the anchor rope. Worked nice and same would work under a chain as long the added volume would not disturb how the chain piles up.

Ex owner put all SS chain in the chain locker and momentary i have also the 100lbs raft between the two fish boxes under the bow deck.
As long i don't have all tanks full i don't need to trim down or use tabs, except it's very choppy

Chris

 

[Beyond A Wake]

How about looking at lighter weight batteries? Drawback is that you need to make sure the new motors could charge them, and maybe replace onboard shore charger. And of course more $$
H

 

[SmokyMtnGrady]

That's a negative ghost rider. Don't do it. The shorter the cable run between the motor and batteries the better. Even if you run 2AWG. Like others said flooded batteries will drop a plate with all the bouncing in the bow. The bow is what takes the force of the wave energy and disperses it across the rest of the hull.

It's your boat and stuff ,but I would not do it . I would get a 4 blade prop to improve your stern lift and hole shot. The 4 blade prop on my boat improved low and mid range performance.

I suggest repowering and running the boat to see how it handles before moving batteries.

 

[glacierbaze]

SMG Bob, I sent you a PM on the 10th.

 

[Beyond A Wake]

I thought most thruster batteries are mounted up front to shorten cable length to a minimum? They take the beating and so do car batteries. Real hard pounding like hard crash is of course different for everything.

 

[brightnight]

Since I'm getting a new heavier motor I decided now is the time to move the batteries and see how she rides. Worst case it will be easy to move them back. Moved the battery switch into the botton left of the cabin and added a new 40A fuse for the aux 12V power. Ignore the mess of wiring that will get cleaned up: