I had noticed small signs of leakage of diesel fuel just forward of the fuel tank for years. It probably dribbled into the bilge and mixed with other fluids before it was pumped overboard by the bilge pump.
|Oily leakage thru bulkhead just forward of fuel tank|
Lately, I noticed the bilge had more oil content. The last time I changed the filter element in the Racor fuel filter (September) I noticed some type of oily substance caked on the filter element (it looked like a oil-soaked plastic foam). These two things coupled together created a serious concern about the integrity of the 30-year old aluminum fuel tank.
|Label on old fuel tank captured with a point and shoot camera|
It turns out that the original tank holds 32 gallons (probably only 30 usable gallons) and it was 0.090 inches thick. Florida Marine Tanks told me the minimum thickness for a replacement today is 1/8-inch thick (0.125 inches). I had no idea when the leak had started since it is encapsulated with fiberglass structure on the lower two thirds of the tank. So, I decided that 1/4-inch was the thinnest replacement tank I would consider and got a quote on the upgraded replacement (over $500). Because it was such a big job to replace the tank (the steering quadrant and below deck auto pilot had to be removed for installation), I asked my regular boatyard for a quote on the job with me supplying the tank--the estimated cost of replacement is 10 to 20 times the cost of the tank!