Electric Re-power Progress Update 2
25 10 2011 Posted by Daniel
The electric re-powering continues apace, with another major step completed this past weekend: the removal of the existing upper diesel tank to make room for the batteries. Incidentally, this tank used to be the primary water tank for the boat - and I wish it still was, since I wouldn’t remove it if so!
The tank was ensconced under the cabin sole, so the first step was to drill out the bungs, remove the screws, and pry up the center of the cabin sole to access the tankage:
As you can see, the tank is pretty firmly held in place by several significant fiberglass straps and is trapped further by the floor stringers. Fortunately in my case, the fiberglass straps were all on the top of the tank, and the floor stringers are not integral to the hull structure, so I can cut and replace the straps and stringers without much problem.
Cutting the fiberglass straps and the end cap loose was probably the hardest and most annoying part of the process. It took nearly 3 hours of various contortions, hand saws, power tools, and other devices to get through the tough fiberglass in a safe manner without damaging the hull. With no welded on lifting tabs or other help, we threaded a soft shackle through the eyes on the access/inspection port and lifted the tank in that manner. Fortunately the access port was strong enough - I was not concerned about the shackle as it has close to 3000 lb breaking strength!
Once the tank was cut free as best as we could determine, my friend Ed and I hauled on a 4:1 tackle slung to the main boom and our combined weight easily popped the tank free after a few tugs. After that, the tank could be lifted with a firm grip and one hand. We cut the first few stringers as well in the hope that we could get enough angle on the tank to avoid cutting the rest:
Sadly, we needed to remove all of the stringers thanks to dimensional constraints. Ed shows off his “fierce” look here, as we prepare the hoisting strap:
After freeing the tank from the stringers and fiberglass, she lifted neatly out of the companionway.
We used the main boom as a crane and swung the tank over to the finger dock.
A quick cleaning made a big difference in the sludge and dust left behind (pardon the blurriness):
But then I went and ground down the hull so I could mount the battery tray, and made an even bigger mess:
After cleaning again, I was able to glass the mounting blocks to the hull:
I used 404 high density adhesive filler to help bond the mahogany blocks to the hull. There’s a nice 1/4” fillet on the top edge and a finger fillet along each side and the bottom. Having ground the hull side down to bare glass, there should be plenty of mechanical “keying” between the two surfaces for a good solid grip, and I’ll further distribute the load and reinforce the bond by tabbing the blocks to the hull with several layers of glass. After sanding/filing them down to a nice level surface, I”ll seal their surface with thickened epoxy, and then bolt down a plywood plate to form a base for the batteries. The batteries will be strapped to the plate, and will then be effectively an integral part of the hull, allowing them to remain stable and secure in the event of a knockdown or worse.
The reason I’m bolting the plate down rather than further glassing the plate in place is that I want to be able to remove the plate in the future for access to the diesel tank stored below it. I’m keeping that smaller (40 gal) tank in place in the event that I wish to add a genset, diesel heater or galley stove at some point in the future. 5/16” lag screws into an epoxied matrix in the wood should hold the batteries in place just fine, even upside down.
In the future I may also get a poly tank for water storage (probably about 40 gallons or so) to fit up forwards of the batteries.
Stay tuned…
_______ /) ____________
Categories : Maintenance / RepairsThe tank was ensconced under the cabin sole, so the first step was to drill out the bungs, remove the screws, and pry up the center of the cabin sole to access the tankage:
As you can see, the tank is pretty firmly held in place by several significant fiberglass straps and is trapped further by the floor stringers. Fortunately in my case, the fiberglass straps were all on the top of the tank, and the floor stringers are not integral to the hull structure, so I can cut and replace the straps and stringers without much problem.
Cutting the fiberglass straps and the end cap loose was probably the hardest and most annoying part of the process. It took nearly 3 hours of various contortions, hand saws, power tools, and other devices to get through the tough fiberglass in a safe manner without damaging the hull. With no welded on lifting tabs or other help, we threaded a soft shackle through the eyes on the access/inspection port and lifted the tank in that manner. Fortunately the access port was strong enough - I was not concerned about the shackle as it has close to 3000 lb breaking strength!
Once the tank was cut free as best as we could determine, my friend Ed and I hauled on a 4:1 tackle slung to the main boom and our combined weight easily popped the tank free after a few tugs. After that, the tank could be lifted with a firm grip and one hand. We cut the first few stringers as well in the hope that we could get enough angle on the tank to avoid cutting the rest:
Sadly, we needed to remove all of the stringers thanks to dimensional constraints. Ed shows off his “fierce” look here, as we prepare the hoisting strap:
After freeing the tank from the stringers and fiberglass, she lifted neatly out of the companionway.
We used the main boom as a crane and swung the tank over to the finger dock.
A quick cleaning made a big difference in the sludge and dust left behind (pardon the blurriness):
But then I went and ground down the hull so I could mount the battery tray, and made an even bigger mess:
After cleaning again, I was able to glass the mounting blocks to the hull:
I used 404 high density adhesive filler to help bond the mahogany blocks to the hull. There’s a nice 1/4” fillet on the top edge and a finger fillet along each side and the bottom. Having ground the hull side down to bare glass, there should be plenty of mechanical “keying” between the two surfaces for a good solid grip, and I’ll further distribute the load and reinforce the bond by tabbing the blocks to the hull with several layers of glass. After sanding/filing them down to a nice level surface, I”ll seal their surface with thickened epoxy, and then bolt down a plywood plate to form a base for the batteries. The batteries will be strapped to the plate, and will then be effectively an integral part of the hull, allowing them to remain stable and secure in the event of a knockdown or worse.
The reason I’m bolting the plate down rather than further glassing the plate in place is that I want to be able to remove the plate in the future for access to the diesel tank stored below it. I’m keeping that smaller (40 gal) tank in place in the event that I wish to add a genset, diesel heater or galley stove at some point in the future. 5/16” lag screws into an epoxied matrix in the wood should hold the batteries in place just fine, even upside down.
In the future I may also get a poly tank for water storage (probably about 40 gallons or so) to fit up forwards of the batteries.
Stay tuned…
_______ /) ____________
