Repairing weeping FG Diesel tank

1) Are you absolutely SURE you have located the source of the leak? You
said you saw and felt GRP fibers, but you didn't say you saw or felt
diesel. Is it possible a fitting somewhere leaks?

2) If the layout has imperfections, the leak could travel several (or
more) inches inside the laminate before appearing. Fixing one spot on
the exterior would thus be problematic, especially if the diesel is
attacking the epoxy.

How big is the tank? How old? How is it built: Cored (eg. plywood)?
Access ports? Baffels? How is it installed/supported? Was any protective
coating applied inside the tank? Do you only have the one fuel tank, or
do you have a second separate tank that will serve if the repair gets
too interesting to complete quickly?

Given the access you have to the tank, can you do the GRP repair well
enough for this demanding application? If you're not sure, is it worth
the gamble or would it make more sense to open up the access some more,
even it it makes it harder to button it all up again? Also, given the
access (or lack), how much of the surface of the tank can you see, and
is it likely there are other leaks?

Rufus
 >> Stay informed about: Repairing weeping FG Diesel tank 

Rufus Laggren wrote:

 >1) Are you absolutely SURE you have located the source of the leak?

No, but 98%

 > You
 >said you saw and felt GRP fibers, but you didn't say you saw or felt
 >diesel.

Oh, I saw and felt the Diesel, all right. It goes into the bilge.

Is it possible a fitting somewhere leaks?

No. I pressure-tested the tank, fittings and hoses. The leak is in the tank;
all fittings are in the access plate on top.

 >2) If the layout has imperfections, the leak could travel several (or
 >more) inches inside the laminate before appearing. Fixing one spot on
 >the exterior would thus be problematic, especially if the diesel is
 >attacking the epoxy.

I can't get at the exterior; only the inside.

 >How big is the tank?

75 gallons

 >How old?

25 years

 > How is it built: Cored (eg. plywood)?

The tank is a centerline tank, vee-shaped, 26" deep and about 4' long. It was
made using 1-1/2 oz mat on refrigerator cardboard form, then 3 layers of 24 oz,
fabmat and 4 layers of 1-1/2 oz mat, and insulated with 1/2" urethane foam
before being lowered into the eggcrate. Inside, it was coated with a "special
chemical-resistant resin." I believe it was epoxy, but whatever it was, it
"responded to the catylist so quickly and hardened so much that it resisted all
sanding/grinding attempts."

 >Access ports?

One SS on top, approx 18" X 8"

Baffels?

Yes

How is it installed/supported?

The tank rests on glassed ply 2" above the fabmat which forms the top of the
keel ballast.

 > Was any protective coating applied inside the tank?

see above

 > Do you only have the one fuel tank, or
 >do you have a second separate tank that will serve if the repair gets
 >too interesting to complete quickly?

I have two others, each 25 gal. But I sailed her all last winter and just kept
wringing out a blige sock into a bucket every week. It isn't a big leak, just a
PITA, and I don't like Diesel in my bilge; dangerous and it stinks.

 >Given the access you have to the tank, can you do the GRP repair well
 >enough for this demanding application?

I'm sure I could if I choose the right materials.

 > If you're not sure, is it worth
 >the gamble or would it make more sense to open up the access some more,
 >even it it makes it harder to button it all up again?

Perhaps. I hadn't thought of that. But if I open it that much I may be able to
stuff a blivet in there.

 >Also, given the
 >access (or lack), how much of the surface of the tank can you see, and
 >is it likely there are other leaks?

I can see most of the inside (if I were there - she's in the Caribbean and I'm
in the States now) through the access port, except way down behind the baffles.
Since the leak stops when the fuel level gets low, I believe I can see where
there's a problem.

John<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Repairing weeping FG Diesel tank 

Check aircraft spruce for randolph sloshing compound or brushable
pro-seal. Both are fuel proof coatings used in aircraft tanks and
either one should fix your problem.

 >Rufus Laggren wrote:
 >
  >>1) Are you absolutely SURE you have located the source of the leak?
 >
 >No, but 98%
 >
  >> You
  >>said you saw and felt GRP fibers, but you didn't say you saw or felt
  >>diesel.
 >
 >Oh, I saw and felt the Diesel, all right. It goes into the bilge.
 >
 > Is it possible a fitting somewhere leaks?
 >
 >No. I pressure-tested the tank, fittings and hoses. The leak is in the tank;
 >all fittings are in the access plate on top.
 >
  >>2) If the layout has imperfections, the leak could travel several (or
  >>more) inches inside the laminate before appearing. Fixing one spot on
  >>the exterior would thus be problematic, especially if the diesel is
  >>attacking the epoxy.
 >
 >I can't get at the exterior; only the inside.
 >
  >>How big is the tank?
 >
 >75 gallons
 >
  >>How old?
 >
 >25 years
 >
  >> How is it built: Cored (eg. plywood)?
 >
 >The tank is a centerline tank, vee-shaped, 26" deep and about 4' long. It was
 >made using 1-1/2 oz mat on refrigerator cardboard form, then 3 layers of 24 oz,
 >fabmat and 4 layers of 1-1/2 oz mat, and insulated with 1/2" urethane foam
 >before being lowered into the eggcrate. Inside, it was coated with a "special
 >chemical-resistant resin." I believe it was epoxy, but whatever it was, it
 >"responded to the catylist so quickly and hardened so much that it resisted all
 >sanding/grinding attempts."
 >
  >>Access ports?
 >
 >One SS on top, approx 18" X 8"
 >
 >Baffels?
 >
 >Yes
 >
 >How is it installed/supported?
 >
 >The tank rests on glassed ply 2" above the fabmat which forms the top of the
 >keel ballast.
 >
  >> Was any protective coating applied inside the tank?
 >
 >see above
 >
  >> Do you only have the one fuel tank, or
  >>do you have a second separate tank that will serve if the repair gets
  >>too interesting to complete quickly?
 >
 >I have two others, each 25 gal. But I sailed her all last winter and just kept
 >wringing out a blige sock into a bucket every week. It isn't a big leak, just a
 >PITA, and I don't like Diesel in my bilge; dangerous and it stinks.
 >
  >>Given the access you have to the tank, can you do the GRP repair well
  >>enough for this demanding application?
 >
 >I'm sure I could if I choose the right materials.
 >
  >> If you're not sure, is it worth
  >>the gamble or would it make more sense to open up the access some more,
  >>even it it makes it harder to button it all up again?
 >
 >Perhaps. I hadn't thought of that. But if I open it that much I may be able to
 >stuff a blivet in there.
 >
  >>Also, given the
  >>access (or lack), how much of the surface of the tank can you see, and
  >>is it likely there are other leaks?
 >
 >I can see most of the inside (if I were there - she's in the Caribbean and I'm
 >in the States now) through the access port, except way down behind the baffles.
 >Since the leak stops when the fuel level gets low, I believe I can see where
 >there's a problem.
 >
 >John
 >
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Repairing weeping FG Diesel tank 

It will not make any difference what you do on the outside. You have a
problem that MUST be solved from the inside of the tank. When diesel
gets past the surface barrier it can migrate along the glass fiber for
several feet before it shows up outside the tank. Once the diesel gets
into the layup it will find a way out. That is the main reason why
integral fuel tanks are discouraged.

Drew has the right idea for a sloshing or brushable sealing compound for
the inside. It is NOT easy to use but that is going to be your only
solution.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com
 >> Stay informed about: Repairing weeping FG Diesel tank 

Idon'twantanyspam@thankyou.com (Drew Dalgleish) might have written:

 >Check aircraft spruce for randolph sloshing compound or brushable
 >pro-seal. Both are fuel proof coatings used in aircraft tanks and
 >either one should fix your problem.

Holy freholies Batman! I didn't know there was such a '90s fix available!

I just discovered however that the original resin is polyester and not epoxy.
Comments?

Thanx,

John<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Repairing weeping FG Diesel tank 

Glenn Ashmore gashmore3 DeleteThis @cox.net might have said:

 >It will not make any difference what you do on the outside. You have a
 >problem that MUST be solved from the inside of the tank. When diesel
 >gets past the surface barrier it can migrate along the glass fiber for
 >several feet before it shows up outside the tank. Once the diesel gets
 >into the layup it will find a way out. That is the main reason why
 >integral fuel tanks are discouraged.
 >
 >Drew has the right idea for a sloshing or brushable sealing compound for
 >the inside. It is NOT easy to use but that is going to be your only
 >solution.

Hi Glenn,

I recognize your name from, I think, the old cruising group from mid
nineties...?

Well, the tank is not integral; it was built and set into the eggcrate, so I
can't fix from outside without removing it. So, you're right, it must be fixed
from inside.

As posted as reply to Drew, resin is polyester, not epoxy; hopefully this
sloshing ariplane stuff will work.

Nice website - hell of a boat. I have a lot of respect for you builders - you
build em - I'll sail 'em years later! I'm an engineer by trade; hate sticky
itchy stuff, but don't mind heat and grease! Always liked the saildrive - had
one on an O'Day 28 years ago.

Hope to see you cruising in the Eastern Caribbean someday...

Good sailing,

John<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Repairing weeping FG Diesel tank 

Truelove39 wrote:

 > Hi Glenn,
 >
 > I recognize your name from, I think, the old cruising group from mid
 > nineties...?

Yep, back in the old C-serve OLYC days.

 > Well, the tank is not integral; it was built and set into the eggcrate, so I
 > can't fix from outside without removing it. So, you're right, it must be fixed
 > from inside.

I wasn't assuming your tank was integral, just that the principle is the
same. Before I decided to build I looked at a lot of boats. Found one
with integral diesel tanks that had started weeping diesel from an area
a good 6' from the tank.

 > As posted as reply to Drew, resin is polyester, not epoxy; hopefully this
 > sloshing ariplane stuff will work.

That will probably be your only choice. It doesn't take but a single
pinhole in the gel coat for the fuel to get through. Then it will
search out the path of least resistance and follow it where ever it goes.

 > Nice website - hell of a boat. I have a lot of respect for you builders - you
 > build em - I'll sail 'em years later! I'm an engineer by trade; hate sticky
 > itchy stuff, but don't mind heat and grease! Always liked the saildrive - had
 > one on an O'Day 28 years ago.
 >
 > Hope to see you cruising in the Eastern Caribbean someday...
 >
 > Good sailing,
 >
 > John
 >
 >
 >

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: <a style='text-decoration: underline;' href="http://www.rutuonline.com" target="_blank">http://www.rutuonline.com</a>
Shameless Commercial Division: <a style='text-decoration: underline;' href="http://www.spade-anchor-us.com" target="_blank">http://www.spade-anchor-us.com</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Repairing weeping FG Diesel tank 

On 10 Jun 2004 01:49:31 GMT, truelove39 RemoveThis @aol.com (Truelove39) wrote:

 >Idon'twantanyspam@thankyou.com (Drew Dalgleish) might have written:
 >
  >>Check aircraft spruce for randolph sloshing compound or brushable
  >>pro-seal. Both are fuel proof coatings used in aircraft tanks and
  >>either one should fix your problem.
 >
 >Holy freholies Batman! I didn't know there was such a '90s fix available!
 >
 >I just discovered however that the original resin is polyester and not epoxy.
 >Comments?
 >
 >Thanx,
 >
 >John
I'm pretty sure the pro-seal won't react but like all the
manufacturers say test on an inconspicuos area first.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Repairing weeping FG Diesel tank