I was transferring fuel recently from one of the main tanks to the 55 gal day tank, monitoring the process as usual when I heard the oil can sound from the tank. I stopped transferring and inspected the day tank and found that a small crack had formed near the top edge when the tank was only indicating 3/4 full. I opened the inspection plate and there was a release of air. This pointed to a problem with the tank vent. The air pressure was not equalizing and as the fuel increased, the air compressed and , well…you can guess the rest.
I had the boys down to the boat and Darcy quickly came to the same conclusion as me. We decided that the best course of action was to just replace the tank so a new one that matches the dimensions of the original is being fabricated out of aluminum. We’ll address the dissimilar metal issues when we install and ensure the bonding / venting is done correctly. I had planned on replacing this tank over the winter so it is nice to get it out of the way earlier.
Since we removed a small portion of the sole to gain access to the tank, I’ve decided that the sole will be completely refinished throughout the boat at the same time.
We’ll acetone underneath the tank to address the diesel residue, and then put a couple fresh coats of bilge paint under the new tank before installation. This will look after any lingering diesel smell.
Here are some pictures of the old day tank removal.