tiltrider1
Guru
- Joined
- Aug 2, 2017
- Messages
- 4,358
- Location
- Pacific North West
- Vessel Name
- AZZURRA
- Vessel Make
- Ocean Alexander 54
An OA here in the marina found a very small quantity of diesel leaking into their bilge. I recommended placing oil absorbent cloths is various places to trace the source of the leak. After a few days we traced it to an inaccessible portion of the bilge. At this point I deduced it had to becoming from the main fuel tank.
I was pretty perplexed by this as the main tank sits on a sheet of plywood in a very dry area. I couldn't understand why the tank was leaking and why I couldn't see any visible signs on the plywood but there was nowhere else the fuel could be coming from.
We off loaded the main tank fuel into the secondary tank and then started disconnecting the vent, fuel return, engine supply line and the filler hose. After that we were able to hoist the tank out of its hole and give it a good inspection.
Sure enough I found a small weep on the stern end of the tank about 3" from the bottom. Now the tank is too big to leave the boat. Major surgery would be needed to remove and replace the tank. So how to best deal with this situation.
One option would be to weld a patch. However, there just isn't anyone I know willing to do mobile welding right now. The other option would be to use an aluminum epoxy patch.
After wire brushing the damaged area we ended up with a 1/4" diameter hole in the tank. First we used an aluminum epoxy putty to fill the hole and all the pitting area. We then used West Systems Gflex 650 aluminum epoxy resin and applied it to a 9x30" area. Added two layers of glass and wetted it out with West Systems 105 epoxy resin.
I then went looking for the source of water that did all the damage. The damaged area of the tank fits up to the stern bulkhead underneath the Master stateroom. The other side of the bulkhead is the rear lazarette. Under close inspection I could see were some one with a 1" hole saw had drilled through the bulkhead. Upon discovering they drilled into the fuel tank they simply glued the wood plug back in place. Now this would have probably been just fine except they never sealed the pilot hole.
Over the years water managed to find its way through the pilot hole and started doing its thing to the aluminum tank.
We have sealed the pilot hole and most of the bulkhead with an epoxy patch.
I was pretty perplexed by this as the main tank sits on a sheet of plywood in a very dry area. I couldn't understand why the tank was leaking and why I couldn't see any visible signs on the plywood but there was nowhere else the fuel could be coming from.
We off loaded the main tank fuel into the secondary tank and then started disconnecting the vent, fuel return, engine supply line and the filler hose. After that we were able to hoist the tank out of its hole and give it a good inspection.
Sure enough I found a small weep on the stern end of the tank about 3" from the bottom. Now the tank is too big to leave the boat. Major surgery would be needed to remove and replace the tank. So how to best deal with this situation.
One option would be to weld a patch. However, there just isn't anyone I know willing to do mobile welding right now. The other option would be to use an aluminum epoxy patch.
After wire brushing the damaged area we ended up with a 1/4" diameter hole in the tank. First we used an aluminum epoxy putty to fill the hole and all the pitting area. We then used West Systems Gflex 650 aluminum epoxy resin and applied it to a 9x30" area. Added two layers of glass and wetted it out with West Systems 105 epoxy resin.
I then went looking for the source of water that did all the damage. The damaged area of the tank fits up to the stern bulkhead underneath the Master stateroom. The other side of the bulkhead is the rear lazarette. Under close inspection I could see were some one with a 1" hole saw had drilled through the bulkhead. Upon discovering they drilled into the fuel tank they simply glued the wood plug back in place. Now this would have probably been just fine except they never sealed the pilot hole.
Over the years water managed to find its way through the pilot hole and started doing its thing to the aluminum tank.
We have sealed the pilot hole and most of the bulkhead with an epoxy patch.
![20230107_121330[1].jpg](/data/attachments/120/120155-50a287915c0a11ec64cb7c1b678684b4.jpg)
![20230107_142521[1].jpg](/data/attachments/120/120156-5da97a11b400df8fdd891f3f427d26f5.jpg)
