Re: T&T: Replacing Fuel Tanks
I have carefully read all of the suggestions for repairing or replacing fuel
tanks. Some of the repair suggestions have been ingenious, and I have saved
them to my library on this particular topic. Some of the suggestions were
utterly ridiculous, such as cutting open the stern to slide the mid-ship
located tanks out of the boat. Gotta give the guy credit for thinking out of
the box!
However, there is another option that no one mentioned and which I think
deserves consideration, and that is mounting an external fuel tank on the aft
cabin roof of a classic trawler.
Instead of spending $12,000 to $14,000 removing two engines and a generator,
consider this option that can cost considerably less than one BU.
Six years ago, when I purchased my MT44, the fuel tanks were 23 yeas old. I
suspected they would have to be replaced by the time they reached the age of
25 years. I had no problems with them, but I did clean them out, and brushed
off the rust from the top of the tanks and treated them with Ospho. Note, the
Marine Trader fuel tanks frequently have leaks high up on the tanks as a
result of leaking teak decks. I solved that problem by removing the teak decks
and sealing the decks with epoxy, etc.
However, I was still concerned that I would have catastrophic failure, so I
purchased a new 100 gal aluminum tank and mounted it over the stern cabin.
It's dimensions were: 64.5 X 24.0 X 15.5 = 23,994 ci / 231 = 103.87 gal. It
made a nice seat, as I left it parallel to the hull. I could easily manage a
second tank. In any event, with my average consumption just under 3 gal per
hour, 200 gal would give me a cruising range of 67 hours, or about 500 miles
at my average speed of about 7.5 kt. I also obtained and installed the proper
fuel hose, fuel manifold and electric fuel pump for completing the
installation. (The fuel lift pump on a Lehman cannot lift the fuel from a
top-feeding tank that far away from the engine.)
That's more than enough range for a coastal cruiser. Let's face it, most of us
cannot use the 500 gal, 1,000 mile range that we have. We like it, but in
reality we do not use that capacity.
With the external fuel tank option, once you have the components, anyone can
make this installation in a half day. You would then empty your leaking tanks
and leave them unused. At some time in the future when the boat is getting
repowered, that would be the time to remove the old tanks.
For two years, I cruised with that spare tank on the back deck. So far, I have
not had any leaks from my main tanks that are going to be 30 years old next
year. When they do start leaking, I will just stop using them.
Critics will say the extra weight aloft will affect handling. Nonsense. A
40,000 pound vessel is not affected by the weight of 800 pounds per tank,
especially if you balance the weight out by putting two tanks, one on each
side. Again, they make great seats and can be enclosed with an attractive
cover. Martin Veiner
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Critics will say the extra weight aloft will affect handling. Nonsense. A
40,000 pound vessel is not affected by the weight of 800 pounds per tank,
especially if you balance the weight out by putting two tanks, one on each
side. Again, they make great seats and can be enclosed with an attractive
cover. Martin Veiner
Nonsense, maybe. But, the reality can't be dismissed quite so easily.
The change in moment is about 4000 pounds, one foot above the center of
gravity (CG); per tank ( 800 x 5 feet). The center of the tank being
about 5 feet above CG; at least 5 feet, maybe 6 or 7. If it's 7 feet,
make that 5600 pounds of moment, per tank.
The destabilizing effect is about that of 5 people sitting on the cabin
top. There is also the torque effect on the cabin sides and framing.
All these numbers don't mean too much at the dock or in calm water. But,
if you ever get into rough conditions, they will have a big impact. And
the torque effect will be magnified as well. I recall a 50' steel boat a
couple of years ago where the previous owner had mounted a 1000 pound
dinghy on the cabin top. No reinforcement had been installed to support
the cabin top and there was visible cracking of the supports.
There is nothing wrong with a little corner cutting, as long as you know
accurately what you are cutting.
Regards,
Mike
Capt. Mike Maurice
Beaverton Oregon(Near Portland)
Gentleman/Woman
Not too very long ago I was in the process of
pricing tank removal/replacement on a trawler we were
having surveyed....the ensuing discussions became a
research project, as so many things are....
One of the most unique approaches.... I have not
heard discussed here...
Cutting the top off the existing tanks and
installing a "bladder"...Its not as crazy as it might
sound...especially given the newer types of reinforced
rubber/polymers....that can be found today.....
Anyone try this?
Pat Fitzsimmons
SweetBasil, Blairstown NJ
I would think bladders to be a great idea as long as your tanks didn't
have baffles, which I believe most do.
Cole
patrick fitzsimmons wrote:
Gentleman/Woman
Not too very long ago I was in the process of
pricing tank removal/replacement on a trawler we were
having surveyed....the ensuing discussions became a
research project, as so many things are....
One of the most unique approaches.... I have not
heard discussed here...
Cutting the top off the existing tanks and
installing a "bladder"...Its not as crazy as it might
sound...especially given the newer types of reinforced
rubber/polymers....that can be found today.....
Anyone try this?
Pat Fitzsimmons
SweetBasil, Blairstown NJ
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I would think bladders to be a great idea as long as your tanks didn't
have baffles, which I believe most do.
And then if you do use a bladder, by taking out the baffles, IT won't
have any; baffles. Catch 22, anyone?
Mike
Capt. Mike Maurice
Beaverton Oregon(Near Portland)
I would think bladders to be a great idea as long as your tanks
didn't
have baffles, which I believe most do.
And then if you do use a bladder, by taking out the baffles, IT won't
have any; baffles. Catch 22, anyone?
So you'd have to cut out the baffles before installing the bladder(s).
If the bladders were tall and relatively narrow, and interconnected
at the bottom, you could install multiples and the combination would
have the benefits of baffled tanks.
Incidentally, this isn't new technology, having been in use in
aircraft since at least the late forties. It's even possible to
provide manhole access for repair and cleanout.
All that's needed is (big) money.
Terry
Tamarack
About 4 years ago I removed my water tanks and replaced them with
Turtle-Pac bladders (http://www.turtlepac.com/). The water tanks have
no baffles, but they also have no vents, so the bladders deflate as
the water is used. I don't know if the fuel bladders are made the
same way. When it's time to replace my fuel tanks I'll definitely
consider replacing them with bladders.
Phil de l'Etoile
West Sacramento, CA
On Feb 4, 2008 12:47 PM, Mike Maurice mikem@yachtsdelivered.com wrote:
I would think bladders to be a great idea as long as your tanks didn't
have baffles, which I believe most do.
And then if you do use a bladder, by taking out the baffles, IT won't
have any; baffles. Catch 22, anyone?
Mike
Capt. Mike Maurice
Beaverton Oregon(Near Portland)