Fuel tank pickup

[Sabre27Admin]

Iain C
United Kingdom
181 Posts

Posted - 07/10/2011 : 09:20:44
Last year, whilst motorsailing back from Brighton with 30 knots dead on the nose we lost the engine. Turned out that the fuel pickup from the diesel tank is on the port side of it, about 2" from the bottom...which basically means that with anything less than half tanks with a lot of heel, the engine is going to suck air.

It happened again a few weeks ago, which was annoying as we'd not been using the engine until we brought the boat level and dropped the sails going into Lymington. In both cases, adding spare fuel and a quick bleed sorted it.

Has anyone else had this issue or know how to fix it? My current plan is to add another pipe on the stbd side, and join the pipes in a Y fitting fairly low in the engine room. So in theory, regardless of fuel level or heel, one side will be immersed.

Any thoughts?
sabre27
178 Posts

Posted - 07/10/2011 : 20:39:31
Hi Ian,

Yes, this may solve most of the problem, but there still remains another, less obvious but very important, to bear in mind. When motor sailing in these conditions the rough motion will ‘aerate’ the diesel to an increasing degree as the fuel level drops, so these air bubbles will still be carried through and accumulate in the filter and pipe-work until ….silence!

It is prudent every few hrs, to bleed off this air from where it first accumulates, the filter. If you have a glass filter bowl, you can visually check the filter, if not, you must make your own judgement as to if, and when.

This first happened to me in the early hrs, motoring to windward off a rocky French shore, with an ‘uncertain’ position, prior to GPS or Decca. My first thought was, ‘run out of fuel ***t!?!

Never got caught again!

Paul Howard. S27OA Technical Officer.

jerryo
Ireland
70 Posts

Posted - 08/10/2011 : 22:48:46
Iain,
Cant help with any advice as PQ's fuel supplied by gravity only, and I never let the tank drop below half full.
There must be a mathematical calculation involving the measurements of the tank and how far down the feed pipe goes and its position in the tank which would let you know the min amount of fuel you would need given the worst condition..however have no idea what that calculation would be. Sorry
Jerry
PS The filing cabinet discovery could be quite exciting.

Mike T
67 Posts

Posted - 10/10/2011 : 23:49:16
Iain,
Surely having a pipe either side of the fuel tank is going to make your problem worse as you are guarenteeing that one side will be out of the fuel when you are healed? Yes one side will be submerged but i wouldve thought that the pipe would suck from the air side rather than the diesel side as this is the one with the least resistance?
Please somebody prove me wrong but i wouldnt think it would work.

Mike


Peter OD
United Kingdom
50 Posts

Posted - 11/10/2011 : 07:24:52
Yes, Iain must be right there. What about the solution that a model helicopter would use, which could be in all sorts of attitudes in the air - including inverted. A flexible pipe is used, weighted at the end, so that it is always at the lowest part of the tank. Shouldn't be too difficult to achieve.

Peter O'D
Sanda Isle


sabre27
178 Posts

Posted - 11/10/2011 : 10:13:38
quote:
Originally posted by Mike T

Iain,
Surely having a pipe either side of the fuel tank is going to make your problem worse as you are guarenteeing that one side will be out of the fuel when you are healed? Yes one side will be submerged but i wouldve thought that the pipe would suck from the air side rather than the diesel side as this is the one with the least resistance?
Please somebody prove me wrong but i wouldnt think it would work.

Mike

Hi Mike,
This is a gravity fed fuel supply. The pump, if there is one, has a constant supply in virtually all sailing angles of heal.

Off sailing for a few days now, so have fun on the forum.

Paul Howard. S27OA Technical Officer.