Moving the fuel tank

Rum Run

Rum Run

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My 22' boat was designed to have an outboard in a well but has a diesel inboard retrofitted. The 30l fuel tank was fixed in a cockpit side locker with the bottom roughly level with the cockpit floor and somewhat above the level of the engines' lift pump. It all works fine, but with a full tank it is difficult to trim out a bit of a list and the weight is quite high up.

I am considering moving the tank from the locker to a spot on the centre line below the cockpit floor which already has good access via a hatch. The tank is stainless, with all the connections in the top. The new position will be close to the water lock and wet exhaust pipe. I would also like to put the filler cap under the hatch as the current position on the coaming would be need a long filler pipe. The breather could stay as-is. The maximum lift from the tank bottom to the engine fuel pump would be around 15".

So the question is: are there any pit falls, gotchas or points to beware of in making the move?

Thanks in advance

Rum Run
 
Many boats have their fuel tanks low in the boat, suggesting that in principle there is no problem with this arrangement. The beauty of having a tank higher than the engine is that the pump will prime by itself, often useful when carrying out maintenance. Several owners of tanks placed low in the boat find that a squeezy bulb pump, as used on outboards with separate tanks, is a big help.
 
Sorry to drift your thread a bit, Rum, but I'm thinking of doing something similar as my ageing diesel tank's mild steel, and would make a huge mess if it failed - It's only 20litres, but that's probably more than the bilge would contain.

I was thinking of using a plastic, outboard-type tank and locating it lower in the bilge, but wondered if anyone had done this and found cause to regret it later?
 
Corribee Boy said:
Sorry to drift your thread a bit, Rum, but I'm thinking of doing something similar as my ageing diesel tank's mild steel, and would make a huge mess if it failed - It's only 20litres, but that's probably more than the bilge would contain.

I was thinking of using a plastic, outboard-type tank and locating it lower in the bilge, but wondered if anyone had done this and found cause to regret it later?
Click to expand...

I had wondered about using one of those myself - maybe a Hulk tank - which at £30odd is much cheaper than the equivalent size Osculati plastic job. Do they have a fuel return fitting though?
 
I couldn't find one with the return built in but it shouldn't be too problematical to put one in.

However I've tried fitting tank flanges to other things in the past and have had to make up special tools to get the inside fitting threaded assembled.

I did wonder about the temperature of the return fuel but my current tank doesn't seem to get too hot.
 
vyv_cox said:
Many boats have their fuel tanks low in the boat, suggesting that in principle there is no problem with this arrangement. The beauty of having a tank higher than the engine is that the pump will prime by itself, often useful when carrying out maintenance. Several owners of tanks placed low in the boat find that a squeezy bulb pump, as used on outboards with separate tanks, is a big help.
Click to expand...

Would the squeezy bulb also act as a non-return valve?
 
Rum Run said:
Would the squeezy bulb also act as a non-return valve?
Click to expand...

It incorporates two of them in order to work as a pump, so I suppose it would, yes. Shouldn't normally be necessary, though (the valve, that is - a priming pump is certainly useful).

Pete
 
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