Battery box over prop shaft

[Jaxn]

I ripped out a rats nest electrical system and am starting over from scratch in my O'Day 272.

I am working on the design and placement of a battery box for 2 Group 24 batteries, and the best place (low and centered) that I can find is this bilge area behind the engine and over the prop shaft. While it would be nice to have them right behind the engine, I think I would regret making it harder to access the impeller and stuffing box.

But after the prop shaft goes into the hull, there is enough room.

Would it be a bad idea to build a battery box either over, or in the bilge area?

I am on an inland lake and only motor in and out of the marina, but if I can find a trailer I would like to take her to the Gulf sometimes. The batteries are AGM, so shouldn't be bothered by the vibration.

Is there an error in my thinking here? Or is this ok?

 

[dlochner]

While it would be nice to have them right behind the engine, I think I would regret making it harder to access the impeller and stuffing box.

This. You will need to access the stuffing box from time to time to service it. The harder it is to service, the less likely it will be serviced. And in an emergency? How will you get to the stuffing box?

Batteries don't like heat. If the batteries are in the engine room they will get hot and will be more resistant to accepting a charge.

What's wrong the original placement? Usually Naval Architects balance the weight in the boat, for example putting batteries on one side and something else of about equal weight on the other.

 

[PaulK]

Do you want that much weight that far aft? Where were the batteries originally?

 

[Jaxn]

Good questions.

Let me clarify the placement. I am proposing placing the batteries side-by-side in the top 25% of the photo posted. For exactly the reason you mention of accessing stuffing box in an emergency. That would leave plenty of room for access.

As for the original location, it wasn't great. Boats with the second battery option had one in the starboard laz and one under the starboard settee. But that isn't even what I inherited. Both were in the laz and one was in the wrong orientation.

Some of these boats, mine included, are bow-heavy. Water doesn't fully drain from the cockpit. Weight distribution can be improved. Maybe it was better balanced in 1986, but that was before an electric head, pressurized water, and various other changes were made by previous owners.

As for heat, I don't think that would be an issue in this spot. Originally, this location was a double berth, not really the engine room. I don't have a cushion for the berth and will just convert it to a single if I get a cushion later.

 

[dlochner]

Thanks for the answers.

What's under the inspection port? Is that something that needs to be accessed? Will the batteries interfere?

 

[Jaxn]

Do you want that much weight that far aft? Where were the batteries originally?

I think that might be an improvement. They were previously a couple feet starboard, 1-3 feet forward, and a few inches higher. So not a big change

 

[Jaxn]

Thanks for the answers.

What's under the inspection port? Is that something that needs to be accessed? Will the batteries interfere?

The batteries will be in the bilge area, so will not interfere with the inspection port. And I think it is access to the support that connects to the shaft outside the hull.

I do have to be careful of the transmission control cable which is running along the side. It's about a foot too long (recently replaced and moved the controls). I have a new cable on the way and will figure out a cable channel as part of this design.

 

[Garbonzo]

That would work fine and it is best to keep the batteries close together and the jumpers between them short anyways.

 

[Jaxn]

That would work fine and it is best to keep the batteries close together and the jumpers between them short anyways.

Thanks for the feedback!

 

[Scott T-Bird]

I think it looks like a good location. I assume that clearance under the cockpit might be limiting. If there is room to lift batteries in and out of position without too much difficulty it should work fine.