Ken, I am currently making plans to install new aluminum fuel tanks on our 1984 49 Defever RPH and will be obtaining quotes. We did have surface rusting on the tops caused by the air intakes on the outside of the hull. The PO had these closed off and the air is now drawn from the walkway area along side of the house. Although the tops had surface rust, we did not have any large flaking on the tops and had that been the only problem, I would have cleaned and re-coated the tops or possibly fiberglass the tops. Our problem was with the lower seams. The drain valve was located about an inch above the bottom and even with draining, water would always be present in the lowest portion of the tank. This leads to corrosion of the welds and small leaks. Also check how the tanks are mounted and if there is any other place where water can be trapped. Removing the tanks to gain access to the problem areas is the biggest problem. You can't get to where the problem is. Due to their size, our aft tanks will have to be cut out. Since new aluminum tanks are relatively cheap, and the removal and reinstallation is the major cost, I determined that replacement is the best solution. (I hope the quotes I get back me up on this one) First determine if any problems may exist on the bottom seam welds. I was told our tanks are 1/4", however, after removing the access cover, I measured only 3/16 inch. Even so, if the water had not set in the bottom for years, the tanks could have lasted much longer. Rather than getting a surveyor to look at the tanks, assume that there is a problem and get quotes on installing new tanks. Use this number in your negotiations. Ken Tischler wrote: >We are currently looking at a 1980 49' Defever Pilothouse. ......However, >on my last inspection I did find a >problem with the fuel tanks. >She has four saddle tanks. Sides and bottoms look great, but three of the >four tanks have what appears to be fairly extensive rusting. The rust is >extensive enough that the steel is scaling off in large chunks. The decks >over the tanks were leaking at one time, but have been repaired and seem to >be fine now. >Does anyone know the thickness of the steel used in these tanks? >Is there a way to determine the thickness of the remaining good steel? >Assuming there is enough of the plate left what is the best way to seal the >tank tops to prevent further determination? >If I have to pull the tanks, would it be less expensive to just have the >tops cut off and new plates welded on, or replace the tanks altogether? >We have not hired a surveyor yet, I wanted to check out things myself >first. Gary Brobst m/v Waypoint 49' Defever RPH Oak Harbor Marina Slidell, LA