Malahini bilge blower

Designs for inboard or outboard power

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Hercdrvr
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Malahini bilge blower

Postby Hercdrvr » Mon Mar 13, 2017 7:44 pm

Need advice
Installing a blower system under the rear hatch where the gas tank will be. I'm not crazy about the idea of drilling 2 big holes in my rear deck for intake and exhaust.

How about this idea.....I install the blower under the rear seat and put round intake and exhaust grates between the seat bottom and the flooring. So the air vents are behind your heels.

I know this really doesn't exhaust potential fumes overboard, it moves the heavier than air gas fumes forward where they can descend again to the bilge.

Concern.... will it pass Ranger Rick's safety inspection for the registration process.

Non-concerns....blowing up the boat. How much risk is there, it's an outboard? How often to boaters actually activate the blower prior to start?

I'm reminded of the Myth Busters episode where they were trying to blow up a gas tank. The fuel/air conditions needed for combustion were very difficult to achieve.

Don't hold back, blow my idea apart with both barrels, I can take it.

Matt B
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Hercdrvr
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Re: Malahini bilge blower

Postby Hercdrvr » Mon Mar 13, 2017 9:09 pm

After some combing through blower ventilation regulations It only requires the blower intake to be in the lower 1/3 of of the compartment and above the normal bilge water level. There's no reference to where it exits the compartment.

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billy c
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Re: Malahini bilge blower

Postby billy c » Tue Mar 14, 2017 4:25 am

With an outboard no need for a blower
...do vent the built in tank using its fitting to the outside of the compartment terminating with something like this
Image
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Roberta
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Re: Malahini bilge blower

Postby Roberta » Tue Mar 14, 2017 9:33 am

Yup.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Hercdrvr
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Re: Malahini bilge blower

Postby Hercdrvr » Tue Mar 14, 2017 10:49 am

Great responses, just what I wanted to hear. The problem is, when I was at the Port Aransas boat show with my Squirt the coast guard inspector gave me a demerit for having fuel in an invented compartment.

Another twist in the equation...my fuel tank doesn't have a vent line. It only vents through the cap when it reaches 5psi inside the tank.

Matt B
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Hercdrvr
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Re: Malahini bilge blower

Postby Hercdrvr » Tue Mar 14, 2017 10:51 am

Nonvented not invented compartment

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billy c
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Re: Malahini bilge blower

Postby billy c » Tue Mar 14, 2017 11:35 am

Screen Shot 2017-03-14 at 2.32.22 PM.png


here is the USCG boatbuilders handbook in pdf format
http://uscgboating.org/regulations/asse ... LATION.pdf
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BillW
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Re: Malahini bilge blower

Postby BillW » Tue Mar 14, 2017 11:49 am

If it does not have a means to vent the tank, the engine would not draw fuel.
So, that tank has a vent check valve in the cap?

But, a potential problem is that outboard motors typically have a rather wimpy fuel pump. The pump may not like
trying to overcome a check valve. For example many outboard motors don't like anti-siphon valves in the fuel line.

So, If a 2-stroke does not get correct fuel flow, it will run too lean at high speed, a bad thing $$$$.
Is it a 2-stroke? I would want a normally vented tank.

All the above applies to vintage outboards; I would think that newer ones have these issues to some degree.
Bill

Hercdrvr
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Re: Malahini bilge blower

Postby Hercdrvr » Tue Mar 14, 2017 3:23 pm

I think the cap let's air in, it only prevents it from escaping .
I'm going with my plan and adjust as necessary after a summer on the water.
Thanks for the reference to the regulation.

Matt B

Hercdrvr
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Re: Malahini bilge blower

Postby Hercdrvr » Fri Mar 17, 2017 3:47 pm

This how it turned out. The stainless louvered vents are kinda cool looking. For anyone wondering about cost, the whole blower system was about $85.
Matt B
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