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Old 07 June 2004, 15:35   #1
Seb
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Engine Vents

Im still looking for a way of venting an engine box on a diesel RIB that is actually watertight...

So, as so many have been to RIBex, i was wondering if anybody had noticed any clever (but actually simple) methods of doing this?

If so, i would appreciate it if someone could explain or post a picture.

Are water ingress proof vents available or am i just wanting the impossible?

I see that some diesel RIBs dont seem to even have vents. Are they actually necessary?

Louver vents seem to be the most popular...anyone had any experience with their effectiveness in big seas where spray ingress and swamping is likely?
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Old 07 June 2004, 17:14   #2
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I have seen some RIBs with the air intake built into the A-frame, although I'm not convinced that they really allowed enough air flow to be efficient.
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Originally Posted by Seb
I see that some diesel RIBs dont seem to even have vents. Are they actually necessary?
They must have some sort of vent or the engine won't run!
Quote:
Louver vents seem to be the most popular...anyone had any experience with their effectiveness in big seas where spray ingress and swamping is likely?
As long as they are sufficiently baffled they'll work fine. Some water may get into the engine box, but if it is diverted straight into the bilge and pumped out then it's not a big problem.

John
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Old 07 June 2004, 18:06   #3
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Hi Seb, emailed this to you but can now post it so here it is for anyone else!

There is an inner and outer drum with a flat plate on either side, flat plate has a hole in to allow air in or out with a cover over. The ones in the photo have a gauze as well as a flashback arrester. The ball (red) is just smaller than the hole in the plate and the distance between side plates,so if it floats it'll block the hole in the top of the inner drum (fitted with gasket, green) The bottom edge of the inner drum is exactly at the same level as the bottom of the hole in the side plates to allow water to drain out.

Grey is engine box / lid / deck, fetching pink / purple is louvred plate

First pic is steel vent as used on ships, 2nd is adapted for back of P22 enginebox. (Side elevation) All right So I've uploaded them the wrong way round...
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Old 07 June 2004, 18:13   #4
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On reflection, this is OTT isn't it?
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Old 08 June 2004, 02:51   #5
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If you have a Type 42 Destroyer they are fine

On a more serious note someone explained to me that the air flow should be sucked in rather than forced in. So the direction of the air intake should be pointing away from the boats direction.

Regards

Mark
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Old 08 June 2004, 04:27   #6
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Thanks for that.....

Any of the manufacturers out there got a simple solution?

Cheers
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Old 08 June 2004, 04:44   #7
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Seb

It depends on your engine box and layup of the boat. Whatever you go for I would reccomend have the air intake above the water line and try to seal the engine box.

That way when you stuff the boat, and fill it up with water, you won't block off the air supply or drown the engine.

Cheers

Mark
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Old 08 June 2004, 05:17   #8
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Seb, whats wrong with the standard Halmatic engine box vents ? couldn't think of anything simpler. However both Vetus and Volvo do a catalogue with vents that have a back plate to stop water entering.

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Old 08 June 2004, 07:32   #9
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Quote:
Originally Posted by MarkWildey
On a more serious note someone explained to me that the air flow should be sucked in rather than forced in. So the direction of the air intake should be pointing away from the boats direction.
Mark, would you like to explain that one?

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Old 08 June 2004, 09:03   #10
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Presumably he is taking about some sort of ram air effect aka F1 race car, but don't think its going to make much difference to 2 tonnes of Pacific Rib @ 25 knots. The halmatic vents are reversable and one P22 at Ribex had them facing forward (Rib Juju).

Pete
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