97 C80 - Fuel line length

[Friz Freleng]

The engine is on a 20' pontoon. I am putting it back together after redecking. I have moved the fuel tank from stern starboard to mid ship port. I have done this to level out the trim. I put the boat in the water and filled the tank with water. It sets a lot more level. So far, so good.

I will need about 15 feet of fuel line from the tank to the engine. Is this going to be a problem due to length? I am planning to use 5/16 line. Before I spend the money on this much line I wanted some advice on whether or not it would work.

Thanks in advance, Friz

[boats.net]

Thats about twice the length of original fuel hose but it may work, may have to go with 3/8 fuel hose.

[Friz Freleng]

Why would you recommend 3/8 vice 5/16? I am not sure if this is in line with the laws of physics but I would think that using a larger diameter hose would cause the pump to have to move a larger volume of fuel over the same distance hence work harder. Also I don't how the pump operates - electric, mechanical, pneumatic or whatever.

[tmann45]

Why would you recommend 3/8 vice 5/16? I am not sure if this is in line with the laws of physics but I would think that using a larger diameter hose would cause the pump to have to move a larger volume of fuel over the same distance hence work harder. Also I don't how the pump operates - electric, mechanical, pneumatic or whatever.

The pump will be moving the same amount of fluid only it will be moving it slower with the larger diameter hose.
Diameter does not affect static pressure or suction, only friction due to flow and the larger the diameter, the less flow velocity and less friction, thus less strain on the pump.

Go with the 3/8" diameter and don't worry about it.

[Friz Freleng]

Thanks for the help. I am convinced. Pascal couldn't have said it better himself. Thanks for clearing it up. I will go with the 3/8 line.