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Fuel tank inspection & cleaning

AJA

Jul 20, 2009
1
2 37' Center Cockpit Ketch Apponaug Harbor, RI
I’ve got an Irwin 37’ CCKetch, the diesel tank is glassed in under the salon floor. I need to inspect the tank so I am thinking of taking a jig saw and cutting in an inspection port. Is this sane? Will it help my to clean the tank or is the tank divided up by baffles to subdue rolling?
I bought the boat 10 years ago - it had sat unused beside a barn in Maine for 17 years with its 100 diesel tank nearly full. Oddly, the fuel turned out fine but with such a large tank it takes me a few years to use it ( it stops feeding the fuel line when I get down to about 15 gallons left. )
Anyway, I changed my filters recently and found so much gunk in the racor secondary filter that I was compelled to remove it, disassemble it, and clean it. I’m sure there must be gunk like that in the bottom of my tank. Oddly as well, the filters need to be changed only about every 90 hours ( for me that’s about 3 years). I have not had clogging problems.
The one exception is that last week there developed a blockage in the line coming from the diesel tank to the racor filter. I just blew about 90lbs if compressed air through it and things were fine again. That was the first and only time I’ve had that problem in 12 years of running the engine. (A VolvoPentaMD2040
Any ideas on inspecting and cleaning the tank?
Thanks
John Bianchi USCG 100T master.
 
Jun 3, 2012
545
Hunter 33 Bay Pointe, Quincy
Just replaced my 39 year old diesel tank. When I had it out I carefully inspected the inside and found nothing. My new tank has a clean-out but maybe I will never need it.
 
Feb 21, 2013
95
Hunter 46 Point Richmond, CA
Consider having your fuel polished primary and secondary fuel filters replaced. That is what I did on my Sprindrift motoryacht, which had 4 100-gallon tanks and on my Hunter 386, which had a 30-gallon tank after extended storage.
 
Jun 3, 2012
545
Hunter 33 Bay Pointe, Quincy
Mike, My 39 year old tank was aluminum .090" thick. It was laying on unpainted plywood. That plywood was wet throughout with both water and diesel. Eventually tiny corrosion holes developed on several places on the tank bottom caused by the trapped moisture. Leak, when discovered, was slow seepage eventually showing up in the bilge. We were accustomed to a slight diesel smell inside the boat but thought nothing of it until the diesel could be seen in the bilge.
 
Dec 28, 2015
476
Laser, Hunter H30 Standard Tacoma
Mike, My 39 year old tank was aluminum .090" thick. It was laying on unpainted plywood. That plywood was wet throughout with both water and diesel. Eventually tiny corrosion holes developed on several places on the tank bottom caused by the trapped moisture. Leak, when discovered, was slow seepage eventually showing up in the bilge. We were accustomed to a slight diesel smell inside the boat but thought nothing of it until the diesel could be seen in the bilge.
My exact situation
 
Dec 28, 2015
476
Laser, Hunter H30 Standard Tacoma
Assuming it is aluminium.....use a bi-metal hole saw of the size you want. Take a toilet bowl wax ring (use a new one) and form it to the size of the hole. Drill through the wax and into the tank at low a low speed. The wax will lub the bit and collect the shavings. We do this to drill tank trucks with gasoline.
 
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