Reply
 
Thread Tools Search this Thread
 
Old 10 April 2006, 06:25   #1
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
Fuel tank breather

I seem to have a problem on my RIB with the fuel tank leaking at the top when it is full or nearly full. I spent a nervous period yesterday with about half a pint of spilled petrol and a battery between my legs and decided it needs sorting before I have an involuntary thermic castration (not to mention maybe having to swim home!)

The tank appears to be sealed with no separate breather (though I can't see the front of it) and the filler cap seals with a cork gasket, so I assume it's coming out the breather widget, which is a thing on top of the tank cap. After I mopped the mess up when I came back in I had a fiddle and the breather is a sort of screw in thing with a tiny notch in the side of the thread, that was unscrewed about 2 turns (which was how it was when I got it from the previous owner). I screwed it right in tight which I hope will stop the leak (and violently rocking the boat from side to side didn't produce any fuel), but I guess it will also stop any air getting in.... though I haven't been anywhere yet and it is tipping with rain today so probably won't be!

So I wondered about a remote breather - bit of plastic tubing or something - that would go on to the cap and vent a bit higher up - I think the fuel is "slopping" in the tank and coming out the breather.

What breather arrangement does everybody use? Or if you use a thing like the above arrangement, do you just tighten it and crack it off a fraction of a turn?

Of course I could just not fill the tank right up but it disappears fast enough as it is without running it half empty

Thanks

Stephen
__________________

__________________
BogMonster is offline   Reply With Quote
Old 10 April 2006, 06:33   #2
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,855
I have a seperate breather take off from the tank which attaches to a long piece of pipe that coils around once and terminates high in my console. I've never had a problem with this setup. I think this is a quite common arrangment on RIB's.
__________________

__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 10 April 2006, 06:43   #3
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
Thanks ... I suppose mine might have the same thing but fitted at the front of the tank (you can't see that as it is under the console) and maybe the breather thing on top of the cap is supposed to be kept tightly closed?

Does anybody else with a Humber Destroyer (or in fact probably any sort of Humber - chances are they would all use the same arrangement) with an underseat tank, know the answer? I don't think I could get at the front of the tank to be able to check, without taking the console off the deck.

I was thinking of a similar idea, a fitting on top of the tank, something like windscreen washer tubing running up to a small inline filter mounted a few inches above the tank, this way if a small amount did get up into the filter it would drain back down in next time the air in the tank contracted, rather than blowing out the top, and the filter would also stop any muck getting in.
__________________
BogMonster is offline   Reply With Quote
Old 10 April 2006, 07:34   #4
Member
 
Country: UK - England
Town: Chertsey
Boat name: Aqua Legends I
Make: Avon Searider 5.4m
Length: 5m +
Engine: Yam 90
MMSI: 235035787
Join Date: Mar 2006
Posts: 129
I am just redesigning my console with a new fuel tank built in and I have decided to have a remote vent as well but using a console mounted vent, see picture, available from tek-tanks.com for about 7.

As I understand the vent is for both directions, pressure build up due to temp change and also inlet vent for when using fuel. I was relunctant to put the vent inside as I thought fumes could build up, and being in close to the electrics.... . I may be wrong on this, can anyone elaborate?

I am going to locate the external vent in a place that should be splashed in a minimum way. Hose length will be about 24 inches with loop in the middle.
Attached Images
 
__________________
_______________________________________
Diving is Life, the rest is just surface interval.
Nitrogen Narcosis is for Christmas -
Oxygen Toxicity is for Life

_______________________________________
Narcosis is offline   Reply With Quote
Old 10 April 2006, 07:38   #5
RIBnet supporter
 
LURCHER's Avatar
 
Country: UK - England
Town: Tisted Hampshire
Boat name: Hot Lemon
Make: Scorpion
Length: 8m +
Engine: Inboard
MMSI: 235
Join Date: May 2002
Posts: 766
Send a message via MSN to LURCHER
Humber

I also have a destroyer with your console as well and to be really sad have your sunset picture as my desktop background !

The tank in mine has a simple vent on top which will let a little petrol out when very full or hot , I have no means of venting elswhere without making another hole . I think plenty of ventilation is the answer .
__________________
www.hiremarquee.co.uk
LURCHER is offline   Reply With Quote
Old 10 April 2006, 08:41   #6
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
Quote:
Originally Posted by Narcosis
I was relunctant to put the vent inside as I thought fumes could build up, and being in close to the electrics.... . I may be wrong on this, can anyone elaborate?
I've got the same concern ... I'm rather attached to the bits of me that would bear the full force of the explosion and while the only connections in that compartment are battery, fuel gauge and the isolator, it also has holes through into the front compartment where all the electrics are ....

that external vent sounds like a very good idea ... after all it would only take a loose battery connection or something, one good spark and boom, suddenly you're into aviation in a big way... though I have to say, once I mopped the mess up and left it with the seat off to vent for a while, you couldn't really smell fuel in the underseat compartment, and when the engine is running presumably you'd not be venting fumes because the tank will need to draw in air to replace the fuel. At all other times I leave the master isolator (also in that compartment) firmly off, so there shouldn't be a problem apart from when I am using the thing.

On a simpler level, another idea that occurred to me just now would be to run a vent up to the rear of the console, then make a little U-bend out of some small diameter pipe (copper brake pipe is what I had in mind) drill a small hole in the back and feed the U-bend out through, so the open end was pointing downwards, it should be well protected from any spray in that position and would mean all the nasty little airborne petrols would be dispersed out into the air.

Lurcher, so have I
__________________
BogMonster is offline   Reply With Quote
Old 10 April 2006, 09:05   #7
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
Quote:
Originally Posted by BogMonster
while the only connections in that compartment are battery, fuel gauge and the isolator, it also has holes through into the front compartment where all the electrics are ....
you will be telling us next that the battery cables and the petrol fuel line are fed down the same trunking either across the deck or underneath it.

Most petrol tanks vent to the outside of a console terminating in a flame proof fitting like Narcosis pictured. Petrol vapour is heavier than air, if the tank is leaking petrol its also filling your console up with petrol vapour.

This is a pm Claus sent last year:

Sad news.....She blow up last week. I had orderes a guy to weld on the fueltank, and it blow up...he spend 4 days in the hospital and the next 12 weeks with his arm i bandages. I was almost finish with her after spending more than 200 hours rebuilding her this winther...and she blow up 2 days before entering the sea...(So sad...I cryed for a week.) Im trying to get the insurance company to rebuild her, and therefore i needed the hull year.

I think you need to get the petrol and electrics well separated in different compartments and the fuel tank area well vented.

Pete
__________________
.
Ribnet is best viewed on a computer of some sort
Pete7 is offline   Reply With Quote
Old 10 April 2006, 09:44   #8
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
I guess so then - there is only one bundle of cables and things going to the motor, though it isn't in trunking, it just comes out a big conduit, goes across the deck and down one side.

I assume the whole layout is as Humber (or Oakley Marine who I believe supplied the whole thing) built it - the engine was supplied with the boat when new and I am fairly sure neither of the previous owners would have interfered with anything fundamental while they had it. That suggests that it is built the way that they build all of their boats, which in a way I guess is a bit worrying!

It doesn't strike me as a good or safe design either - but as there's nowhere else to put anything, I'm not sure what the options are really. Believe me I ain't too happy about sitting on it though - hence the original question!
__________________
BogMonster is offline   Reply With Quote
Old 10 April 2006, 09:54   #9
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
If the cables go though a bulkhead in the console to the front then some witches hats and sealant would be better stops the wires fretting on the grp too, fit another to the throttle control box where the wires go into the console. Finally how about some ply and glass at the back of the console to separate the fuel from the battery. Post some pics and see what we can come up with.

Pete
__________________
.
Ribnet is best viewed on a computer of some sort
Pete7 is offline   Reply With Quote
Old 10 April 2006, 10:11   #10
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Is it too obvious to say that you shouldn't fill it quite so full???
__________________

__________________
codprawn is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 06:52.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.