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steneck 04-01-2013 11:20 PM

Fuel tank longevity
 
Hi Folks,

A friend of mine in a PSC 37 just had his fuel tank let go 25 gallons of diesel into his bilge. Ugh.

He is getting a replacement from Thumper and heard that the aluminum tanks last only about 20 years.

Mine is a bit over 20 years and looked OK last time I checked.

Do any of you have any idea how many years you can get out of your aluminum fuel tanks? Have any of you upgraded to fiberglass or PVC?

Bob Steneck
PSC 34 Alaria
Christmas Cove, Maine

Norstar 04-02-2013 06:45 AM

Re: Fuel tank longevity
 
Bob,
We have a 1990 34 hull # 201 with the original aluminum tank. That would put it at 23 years old! Still visually appears to be in good condition. I think the main problem is boats that have bilge water in contact with aluminum especially if in a salt water environment. We keep our bilge bone dry. The tank is also elevated about 2" off the bottom of the bilge and no contact with the keel bolts. If I ever do have to replace I would go with the new factory provided molded fiberglass tanks.

John S
PSC 34
Norstar

jameswilson29 04-02-2013 06:53 AM

Re: Fuel tank longevity
 
My original Monel tank looks fine at 36 years old. Monel is better than fiberglass or aluminum or PVC. Perhaps you could find a tank from a salvage. Pearson was installing them as original equipment.

Maine Sail 04-02-2013 07:15 AM

Re: Fuel tank longevity
 
A properly installed & maintained aluminum tank can easily last 40+ years. The sad reality is that the vast majority are improperly installed and maintained.

* Tanks need to be 100% isolated from where they sit. I use 1/4" to 1/2" G-10 bedded/sealed to the tank bottom with Sikaflex 291. This prevents the tank from sitting in any moisture and creates an air layer around the tank to keep it dry.

*Water must be kept out of the tank. Change the fill cap o-rings regularly.

*Tank must be periodically cleaned.

*No dissimilar metals can fall into the tank. I have seen fill cap chains rot out a tank. I remove my fill cap chains before they become an issue.

*Any production shavings, filings, slag etc. should be vacuumed out of the tank before installation.

*No copper alloys should be used with an aluminum tank. All tank fittings should be aluminum including the pick up, return, shut off valves & barbs. If you must use a copper alloy it needs to be isolated from the tank.

*Avoid going with the bare minimum wall thickness (most factory tanks are a .090 wall). I would suggest .125 as a bare minimum.

*When building a new tank I would always advise installing at least one extra pick up/supply fitting. This way you can add a dedicated fuel polishing system. If you are in the North add a third for a future heater. Easpar, Webasto etc. DO NOT like to be connected via a "T" fitting.


I am currently replacing a 31 year old tank on a Sabre. The tank is 100% fine but the owner wanted to remove it and fully inspect it as he does some off shore racing and did not want a "failure".. For the $500.00 he decided to just replace it, while it was out. He added two more pick up tappings and we upped the tank wall thickness.....

wsmurdoch 04-02-2013 07:24 AM

Re: Fuel tank longevity
 
Original 1988 tank still in use.

Bill Murdoch
1988 PSC 34
Irish Eyes

thor 04-02-2013 11:59 AM

Re: Fuel tank longevity
 
I have a 1988 PSC34. Upon pulling the fuel tank for inspection there was one spot with a little bit of pitting. It was in a spot that a patch could be welded over. Pressure tested and then had it Rhino coated before putting it back in. (Changed out the dissimilar metal fittings as well.)

BMLipiec 04-05-2013 07:14 PM

Re: Fuel tank longevity
 
We just pulled ours (1994 PSC34) and it still looked new. The previous owners had pulled it about 10 years ago and had it prepped (alodine, I think) and painted. He had also installed a support under the tank (some PVC) so that it did not rest on the stainless keel bolts. Lastly, he installed a small diameter hose under the tank (lowest point in the bilge) connected to a water pump (like the one in the pressure water system). This pump is connected to a manual switch that I run after a sail for a minute or so to drain the water out of the bilge, which keeps the underside of the fuel tank dry.
The normal bilge pump hose is too big to get the last inch or so of water out of there, but the little pump works pretty well. The discharge hose is also clear so I can see when all the water has been sucked out.

jnewcomer 04-07-2013 01:43 PM

Re: Fuel tank longevity
 
Our C37 is a 1980 and we replaced the tank around 1990 because of seepage due to corrosion. The older installations had a single walled tank sitting on a piece of 1/4 plywood which sat on top of the keel bolts--essentially a battery after you add enough seawater. I agree with the other post that a dryer bilge would have prevented or at least delayed this process.

Our replacement tank was made by the original supplier in Huntington Beach but had a double thickness of aluminum on the bottom. Robin (Thumper's predecessor in SoCal) recommended putting schedule 80 PVC pipe in the bilge for the new tank to sit on which we did. I also put PVC caps on top of the keel bolts just in case the PVC ever collapses. I etched and Alodined the bottom 1/4 of the tank and put 4-5 coats of WEST epoxy on thickened with Aluminum powder. I'd go with a Rhino coat these days.

After 20 years it would be worth having a look at the bottom of the tank and insuring it is not in contact with the keel bolts. If you are not living aboard you could probably lift the tank out and set it on a drop cloth in the salon to Rhino coat it. Otherwise it does fit through the sliding hatch, at least ours did.

John
s/v Pelagic
1980 C37 Yawl #22

svjobeth 04-08-2013 06:40 AM

Re: Fuel tank longevity
 
The tank in our 1984 PSC 34 is the original tank. So far, so good.

We're pretty diligent about tank cleanliness and inspections. I use a scope camera to do inspections on the underside, and to make sure there's no contact with the tank bottom and keel bolts. The old tanks do 'belly' a bit as time passes. Keeping the bilge as dry as possible, already mentioned, is also key to tank maintenance.

steneck 04-10-2013 11:20 PM

Re: Fuel tank longevity
 
To all who replied (so far),

Thank you for sharing your collective wisdom. Sounds like keeping a dry bilge, protecting the tank from bolts and other things that will turn the tank into a "battery" along with regular inspection all define optimal standard operating procedures.

I did pull our tank a few years ago and it looked great. The former owner did install hemicylindrical pvc to keep it from moist surfaces.

I'll take another look at it before I shove off for 8 months.

I'm curious what sort of camera is used to conduct inspections. Is it fiber optics?

Again - thanks to all of you who shared your wisdom and this message is NOT intended to stop the thread. I'd love to hear more - if there's more to tell.

Bob Steneck
PSC 34 Alaria
Christmas Cove, Maine


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