Fuel tanks

[Full Moon]

The other night after working on my watermaker pump mounted between the fuel tanks I put the cover back on it and tried to put a plastic milk box back between the port fuel tank and the pump cover. It had originally been there but had been out while I worked on the pump. It wouldn't fit and the space was about 1 inch less than before. I ran out of time and gave up. We had made a trip a couple of weeks ago and we encountered some rough seas. I got to thinking, did the fuel tank shift???? I haven't been able to get back to investigate so I thought I'd ask the experts.
My boat is a 1970 41 ft. Convertible. There are two, 200 gal. tanks under the cockpit floor. How are these mounted? I don't remember seeing any straps or any tie-downs, or are they fiberglassed in?

 

[67hat34c]

In my 1967 34c they are glassed in , small glass straps to the stringers.

 

[Maynard Rupp]

Could it be that you added fuel since you removed the milk crate? I am sure that all those fiberglass tanks grow when fuel is added. They aren't very thick and have to grow when that much weight is added. I am sure they don't move around or the fuel lines would fatigue and break and you would see lots of fretting in the mounting area.

 

[hattitude]

I would bet that the tanks swelled with fuel.. however..

I had two of my outboard 8D batteries, in the stock fiberglass boxes that are glassed to the battery shelf, break loose in rough weather and land on their side up against my engine...

I am sure the tanks are glassed in better than the battery boxes ... BUT .... FWIW

Bernie

 

[Genesis]

My tanks ('85 45C) has the tanks on plywood shelves that are on top of the stringers, and they are glassed to the shelves. If you've got an issue with one of yours breaking loose find and fix that problem NOW. Its not a big deal to fix the tabbing that bonds them in place, but the LAST thing you need is a fuel tank with a half-ton of fuel in it shifting around below deck!

 

[Nonchalant1]

If you had a SeaRay, I'd say that the problem is that you removed the factory installed plastic milk case put there to hold the fuel tank. But since it's a Hatteras, the fiberglass tank hold-downs must have broken and need replacing with carefully laid fiberglass. You'll be able to see if and how the tank shifted and where it needs to be re-glassed. The problem, as with everything on a boat, is going to be getting at it to see and work on it. Hatteras used fiberglass extensively to connect wood and fiberglass things together and luckily, it can be re-glassed if necessary. Be sure to grind the old glass down to a good rough surface to re-glass it so the new one will hold better than the original.

Doug

 

[Genesis]

And use epoxy. Never attempt to glass to an existing structure with polyester. It will not hold.

 

[34Hatt]

My 67 34C also glassed in with tabs been in those tanks they are pretty thick doubt that they swelled.

 

[Full Moon]

You're right, these things sound like thumping on the side of the hull. It's about to drive me nuts not being able to get back and check this out. Just started work full time after retiring in 2001 and traveling around for a while. Got bored and went back to the daily grind, boy does this screw up my boating schedule! Thanks for the insight.

 

[Lucky Dog]

My 1967 41' convertible has a pair of 150 gallon tanks. Are your tanks original? If so, I guess there was a option for bigger tanks - sure wish I had 'em.

 

[old41]

My '65 41C, as reported on the survey, has 2 150's but I had a '67 41 that I sold in the late 70's that I thought had 2 200's. The previous owner of this Hatt did some extensive refurbishing that included adding a 125 between the existing saddle tanks which makes it difficult to get an accurate tape on them. They are also somewhat tapered which makes it even more difficult to get a measurement.

Were all the old 41's the same size?