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"Temporary" Fuel Tank Repair The Pearson 40 fuel tank can only be removed when the engine has been removed from the boat. The tank slides forward through the engine compartment once the engine is removed. I found that the fuel tank on "Passion" was leaking somewhere near the bottom of the tank but I was not ready to remove the engine so I needed another way to repair the tank temporarily (for several years) until I either pulled the Westerbeke 40 for a rebuild or I decided to repower. After some research I decided I had two options, repair the tank from the inside by patching with epoxy or by repairing the tank from the outside by fiberglassing it. I decided to fiberglass the tank. The first step is to get access to the tank bottom. I did this as follows:
Once I removed the front, sides and slats, I was able to slide the tank around and get it tipped with the top facing starboard. At this point I cut holes for two tank cleaning access plates in the top of the tank. There is a baffle in the middle of the tank, running thwart-ships, so you must install two access plates to get at the entire tank.
Aft access hatch (starboard) Forward access hatch (port) Cutting and installing the access hatches was quite easy with the tank top "cocked" to starboard. My access plates are 8" x 10" and are secured with many #10-32 machine screws and RTV gasket material. Once the access holes are cut, you can get to every corner of the tank and remove all the old diesel and other crud. And let me tell you, there was a ton on crud. I sopped up the fuel with paper towels and then cleaned the inside of the tank with isopropyl alcohol. Once the crud was gone, I could see numerous points of corrosion all over the tank. When I flipped the tank over to glass it, I found that a number of the points of corrosion had perforated the tank. Some were caused by water in the tank but others appeared to be galvanic corrosion. I had read on the Pearson 424 site that the 424 fuel tank had numerous problems with fuel leaks that were related to galvanic corrosion. Seems Pearson used copper or bronze staples to hold the black plastic or rubber that you see under the metal straps holding the tank down. Well that black rubber runs under the tank as well and is held in place by those staples and when the rubber begins to compress over time or the staples began to work out of the wood, they came in contact with the aluminum tank and bingo, you have corrosion. Ditto on the Pearson 40. I removed the rubber and all of the staples. I was now ready to repair the tank. Even with the side and front of the tank box removed, you can't get access to the entire tank bottom and sides at one time. You will need to move the tank around and work on sections at a time. I started by power sanding the bottom and 4 sides of the tank with a random-orbit sander and the coarsest disks I could find (50 grit I think) to rough up the aluminum to hold the epoxy and fiberglass. Once the outside was roughed up, I applied slightly thickened epoxy to the bottom. I covered this thickened epoxy with a layer of glass cloth which draped over the 4 edges by 2 or 3 inches. I applied more slightly thickened epoxy to the cloth and worked the epoxy over the edges to hold down the overlapping glass cloth. This was allowed to cure overnight. The next day I did the same process on one of the sides. Before I put the epoxy on, I lightly re-sanded the aluminum and I roughed-up the epoxy/glass on the bottom to insure proper adhesion. Once roughed-up I applied the same slightly thickened epoxy to the tank side, laid glass on that side and allowed it to overlap the bottom and two sides by 2 to 3 inches. On went more thickened epoxy and then I put on a layer of 4 inch glass tape on all three edges along with a bit of thickened epoxy. I repeated this process on all sides until I had completely glassed the 4 sides and bottom. I now had a complete fiberglass shell surrounding the old aluminum tank. Time to reinstall the tank. Since the old side and front of the box, as well as the slats, were diesel soaked, I needed to make new components. I did this using the originals as patterns. Once built, I epoxy coated the new plywood pieces so they would not absorb diesel or water. I first installed the new slats to the original wood cleats still attached to the boat. All of the parts were direct replacements of the originals with the exception of the starboard side. When I removed the starboard side, I ended up leaving about a 3 inch stub section of the side still glassed to the hull because the saber saw could not cut flush with the hull. I cut the new side so that it fit reasonably well with the still in-place stub section of the old side and then I attached the new side with a "sister" piece of wood screwed into the stub and the new side. This can be seen ion the pictures below. Once the side was in-place, I reattached the new front of the box, fuel lines, hold-down straps and fuel filler and the job was done.
Starboard side showing "sister" piece View showing starboard aft corner and sister piece Forward side of tank and access plate It is great! No more diesel smell below and no more diesel in the bilge... |
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