Aluminum Fuel Tank Conquest 305

[chippyken]

Auxiliary fuel tank corroded through at lowest point causing possible contamination of foam in void with 30 gallons of gasoline!

Anybody with previous knowledge please.

[Jefecinco]

Virtually all the spilled gasoline will have evaporated by the time the leaking tank has been removed. Based on that I doubt there is any unusual danger of fire or explosion.

I lack the knowledge to address the potential, if any, damage to the foam caused by prolonged contact with gasoline. I believe the foam currently used in Boston Whalers is closed cell foam but don't know if that was the case when your Conquest was built.

I'm sure a more knowledgeable member will chime in with better information.

[picflight]

Fuel and foam over a long period is not a good situation to be with.

Are you seeking to clean up or fix something?
Pictures help.

[chippyken]

Thank you for the comments and assistance.

Core sampling of the inner hull completed and happy to report no gasoline found even though there was a break in the inner hull integrity in the limber hole.
Therefore a 'lot' of evaporation over the period the vessel was in storage.

regards

Ken

[AussiePatriot]

Hi Ken,
I just purchased a 305 Conquest in Australia, and after putting 5 gallons in the aux tank to test it, I had a cabin full of fumes. Mechanic pulled the rear covers and has confirmed a leak in the Aux tank. Any information you have on the damage and repairs you had done would be appreciated. Interesting that my boat was manufactured in 2004, and the current fuel tank has a mfg date of 11/2008, so it looks like it is the second Aux tank. Is this a common problem?. Appreciate any general comments about your experiences with your 305.
Thanks
Paul

[Phil T]

Fuel tanks are foamed into place in a recess that is finished and gel coated. While there may be some fuel in the foam, it will not reach the hull.

[AussiePatriot]

Looking at the now exposed nameplate on the tank from Florida Marine Tanks, the manufacture date was 11/08, so it was suspicious as my 305CQ is a 2004, that this concern Ken has had may have happened before in my boat. I found a few BW owners on The Hull Truth and here was the detailed response I received from a THT member who had experienced the same concern, the very helpful SouthFla:

I think there is a design flaw in the construction of the center/auxiliary tank area (the '04/'05 was first model year for 305CQ). The fuel tank sits in a molded well underneath the midship bunk. While this compartment has a drain hole to the midship bilge area by the stairs, because of the way the boat sits in the water it really doesn't drain well. So all of the condensation which constantly forms on the outside of the fuel tank just pools around the bottom of the tank. This leads to the pitting and corrosion of the tank which was my, and presumably your, problem. The fact that your tank is an '08 means that the corrosion (assuming that was/is your problem) happened initially in ~3-4 years and again in ~7-8. Ours made it to about 7 years before leaking from the pitting.

The GOOD news is that the port/starboard saddle tanks are mounted in a much better fashion and consequently don't have this concern. Also, the center tank is MUCH easier to remove and replace-a one day job (you'd have to cut fiberglass to remove the saddle tanks *UGH*). Taking the center tank out of service is a good start-use and enjoy the boat, and when you have a few weeks you can remove the stairs and unscrew and remove the flooring underneath the bunk and replace the center fuel tank.

However the center tank, at least in the States, was a custom not "off-the-shelf" design, so you may need someone to fabricate a new tank to specification for you. WHEN YOU DO (assuming you are going to keep the boat for a while), design/replace the new tank in such a way that it sits an inch or so off the molded bottom-then you won't have to worry about future corrosion from it sitting in liquid.