Recommissioning Fuel Tank in Keel

[GILow]

Originally Posted by Winf

Thanks for all the responses. Much appreciated.



I'll give it a few more rinses, dry it out then try a bit of a final diesel rinse.



Access hatch wise, thinking i will fabricate my own from ply and epoxy. Interesting about the perspex as an option. Will give that some thought.

Perspex also makes for a very budget friendly and reliable fuel gauge.

[RaymondR]

I had a perspex lid on the top of my DIY sea water strainer on my old boat, it made it very easy to check for detritus in the strainer.

[pre]

Hi Winf,
I’ve recently purchased a SC36 and have discovered the keel diesel tank. PO had decommissioned the keel tank and installed additional tanks in the aft lockers port side saloon seat. A total capacity of 80L. I’m in the process of refitting the boat, and would like to reinstate the keel diesel tank. How did you go with yours?

Pre

[Winf]

Hi Pre

Not as good as hoped - yet

I cut an access into the keel tank under the transmission, cleaned it thoroughly, allowed it to dry - no sign of any water. Sealed it back up and installed a level sensor.

Installed a pump to transfer from keel tank up to the 100L quarter berth tank via a filter. ¼ berth tank overflows back to the keel tank. Idea was a basic sort of fuel polish system - fuel is filtered from keel to quarter berth, filtered again out of quarter berth tank, filtered again at the Yanmar fuel filter.

Was a pain in the ass to work on, not much room, difficult access. Access hole I cut in top of keel tank was maybe 100 x 150mm and sloshing out the gunk and cleaning the tank (degreaser, mop head on short broom stick, rags methylated spirits etc) was not easy.

All seemed fine. But after I had it all sealed back up and added clean fuel, the filter from keel tank to quarter berth tank became badly contaminated with water. That water got transferred to the quarter berth tank and the engine got a good dose of water and stalled out.

Only thing I can think of is that my sealing up of the keel tank or the level sensor seal was not good enough. I get a trickle of water from the stern gland to the bilge that will run over the sealed section but we are not cruising atm, just running engine every week or so. I was washing/flushing of the bilge with water hose and engine degreasing so lots of opportunity for water to enter keel tank if seal/sensor seal not adequate.

No slick and nothing leaking when we had on hard so looks to be solid between keel tank and water. Must be the seal/level sensor.

I have gone back to just the ¼ berth tank for the moment after cleaning it out. Fuel lines flushed out and engine restarted ok. Will tackle keel tank again when I get inspired but pretty disappointed as was looking forward to not carrying a heap of deck jerry cans.

Not sure this helps.

[boatpoker]

Originally Posted by GordMay

ABYC has a standard for Diesel Fuel Systems in ABYC H-33.
➥ https://law.resource.org/pub/us/cfr/....H-33.1989.pdf

Static Pressure Testing:
“... After installation, the fuel system of every boat shall be pressure checked to at least 3 psi or at 1.5 times the maximum hydrostatic head to which it may be subjected in service, whichever is greater.
The fuel system shall evidence no leakage under such testing, checked at a minimum of 5 minutes* after application of the test pressure, for systems of 50 or less gallons capacity, with one additional minute for each increment of 10 gallons, or fraction thereof, from 50 to 500 gallons...”

* I’d highly recommend at least 4 Hours.

That refers to new tanks.

Pressure testing a compromised tank may destroy it.

[Rustic Charm]

Originally Posted by pre

Hi Winf,
I’ve recently purchased a SC36 and have discovered the keel diesel tank. PO had decommissioned the keel tank and installed additional tanks in the aft lockers port side saloon seat. A total capacity of 80L. I’m in the process of refitting the boat, and would like to reinstate the keel diesel tank. How did you go with yours?

Pre

I reinstated a keel tank in my steel French 1980 Bieroc ketch about 5 years ago. It’s such a narrow deep tank that accessing it all to clean was not possible. I ended up using a product called Fuel Right which did an amazing job in cleaning the diesel and the steel tank. Just my2 cents worth.