fume ventalation system design question

Designs for inboard or outboard power

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Jimbob
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fume ventalation system design question

Postby Jimbob » Mon Nov 06, 2017 11:41 am

Here's my question.
On my barrelback I will have two intake scoops forward of the engine, and two rear facing exit scoops after the engine. Do I connect hose from both the intake scoops taking the fresh air down to the low point of the bilge, leaving the hose open where it rests on the bilge? For the exhaust vents, I have two inline vent fans which I am planning to attach hose from the low point in the bilge to the fans and then up to the exhaust exit scoops. Should one of these hoses be further back in the bilge? Should any of the vents not have a hose attached? I can't find a simple diagram. I want to make sure that I have adequate ventalation once I am under way. I will probably leave the fans on anyway.
As always, your input will be appreciated.
Jim
Jim Neeley
Building a Barrelback in Sacramento, CA
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jenko
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Re: fume ventalation system design question

Postby jenko » Mon Nov 06, 2017 1:45 pm

Jim I would go with no hose on intakes and fan on exhaust with hose sucking from bottom .

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Roberta
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Re: fume ventalation system design question

Postby Roberta » Mon Nov 06, 2017 2:31 pm

I didn't use hose on the intake. I mounted one fan down in the bilge area and one a bit higher near the fuel tank and ran hose out a vent in the rear for both fans. Another vent is used as a draft vent with no hose. Both vents are aft facing and will draw when underway.

Roberta
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Rich Coey
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Re: fume ventalation system design question

Postby Rich Coey » Mon Nov 06, 2017 9:18 pm

I have two front facing vents, no hose. Two rear facing vents, one with no hose and one with a hose down in the bilge with a blower. I run the blower before I start the engine, but not while running. Just as important I open the hatch once in awhile to visually check everything and smell for fumes.

Rich

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Bill Edmundson
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Re: fume ventalation system design question

Postby Bill Edmundson » Tue Nov 07, 2017 5:26 am

Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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Milhouse
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Re: fume ventalation system design question

Postby Milhouse » Wed Dec 13, 2017 10:07 pm

Thanks for this thread Jim! I didn't even consider ventilation on my 1963 16' Skiboat Restoration (probably because it was non-existent). Looks I need to measure my Engine box now. The net compartment volume (after subtracting the volume of the battery and the motor) might just be small enough to be OK without a blower since one entire side of the compartment is open to the atmosphere (behind the front seat). The Coast Guard even has provisions for adjoining compartments (perhaps the bottom of the seat is considered a compartment).
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Motor Compartment.jpg
Jim
16' Ski Boat Restoration
17' Overnighter Sloop

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chugalug
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Re: fume ventalation system design question

Postby chugalug » Thu Dec 14, 2017 8:04 am

:D A gas fume detector would be handy to have.also don't forget the water detector as well in case of hull leaks or water hoses on those inboard motors.the boat galley has a few articles on those.I'm gonna use those on "Chug" :DI think some of those gas fume ones can be wired to blower so if fumes detected turns blower on.Thoughts? :roll:
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Jimbob
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Re: fume ventalation system design question

Postby Jimbob » Thu Dec 14, 2017 9:42 am

One thing to keep in mind is that gas fumes accumulate at a low point. My thinking is that even though your compartment is open, fumes might be sitting somewhere waiting for a spark. Inline blowers are small and cheap. Most boats have labels near the ignition switch that say run blower for 5 minutes before starting. I do like the idea of having a fume detector.
Jim
Jim Neeley
Building a Barrelback in Sacramento, CA
viewtopic.php?f=15&t=28089#p172969

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Milhouse
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Re: fume ventalation system design question

Postby Milhouse » Thu Dec 14, 2017 11:06 am

I calculated the Net Compartment Volume and the Open Area and I have > 3.5x the required open area per the USCG.
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Vented Area.jpg
Jim
16' Ski Boat Restoration
17' Overnighter Sloop

I'd rather have a $h!tty meal than an $h!tty resume because a totally awesome resume will feed me steak one day - Steve Poltz


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