The battery box is one component of a complete re-wire of my boat. I plan to cruise extensively in the future and my current electrical system is woefully inadequate (it was probably great 32 years ago). I decided that I wanted four "Lifeline" 6 Volt AGM batteries for my house bank. They will be wired in series and parallel thus the need to have them all in one location. The Lifeline batteries are approximately the same size as a car battery except they are about 2 ½" taller. The location under the engine cover seemed like a perfect spot. As you can see they fit quite nicely.

The holes you see in the under-floor frame are drain holes into the bilge. I made them because when I cut out the existing battery box there was about three gallons of water sitting there. The holes are cut into a frame which is located at the aft end of the bilge. I cut three more holes below the existing holes because I was initially going to build a "box" to house the batteries and it would have covered up the existing holes.

The white "material" is 3/4’ plywood. The fiberglass walls that come up from the sole of the cabin are only about a quarter inch thick and I did not feel they were adequate to support the 260 pounds the batteries weigh. The plywood is to re-enforce and stiffen the walls of the battery enclosure. I painted the plywood with bilge paint and glued them in place with 3M’s fast drying 5200.

The straps are 10 gauge (1/8") stainless steel. I had them fabricated by a welder using a "blocking machine" to create the right angles (it is a machine you do not want to get your hand caught in). He also drilled the holes for 5/16" bolts.

I used 5/16" "barrel nuts" to secure the straps. This may sound like overkill but I did not want the straps touching the hull of the boat (they are about an inch off the hull). Initially I was going the put the batteries in a box and set them on the hull surface. I then learned about "hinging" or the problems with placing a hard edge on the surface of the hull.

Finally, the bottom step will be re-attached by thru bolting the one inch hinged wood piece, which is attached to the step, to the top lip of the enclosure wall. I will use a 1/4’ barrel nut. I want to be able to remove the step easily.