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Old 12-20-2018, 09:40 AM   #57
Northern Spy
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City: Powell River, BC
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 4,075
Two points. Both disparate.

1. I had a leaky deck fill that allowed several liters of water go into one of my fuel tanks. Fuel pick up is at the bottom of tank (1981 boat). Engine stopped due to fuel starvation as the water couldn't get past the Racor. Aquabloc coating worked! Pumped out as much of the water as I could with a barrel pump through the deck fill. Ballasted the boat so that the fuel pick up was at the low point. Ran the engine until the water level came up in the filter. Stopped engine, drained filter. Repeated ad infinitum. Gave tank a shot of Biobor. Dip tanks with sounding rod with Kolor Kut paste on bottom. No repeats, no growth. Have boroscoped my tank many times and have never seen crud. Filter runs clean on a regular basis. Tank is clean. Change filter annually to ensure Aquabloc coating is still present.

2. Nuclear powered submarines have a tank separating the reactor compartment form the forward compartment. It is called the NFO (normal fuel oil) tank. It provides shielding and stores fuel for the ND 8 1/8 Fairbanks Morse diesel engine. The tank is always full as it is topped off (bottomed-off?) with seawater. It would be a bad thing to have ullage in your shield tank. The tank has an equalization tank vented inboard to accommodate temperature and hull contraction changes. The fuel in the NFO could be there for years. It was a big tank. We pumped fuel from the NFO tank to the DFO (Diesel Fuel Oil) tank through a duplex filter for use in the engine. No centrifuges. No biocide. Go figure. Now maybe the old ND 8 1/8 could burn a combination of horse urine and roofing tar and it just wouldn't matter. Or maybe, having cooties in your fuel tank doesn't really matter, as long as it is filtered.

Shrug.
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