1998 Wellcraft Excel bilge venting

[ckaiser]

Hi all. New-to-me boat. 4.3 mercruiser. When I got it, the bilge blower hose was set up wrong (torn to shreds, not in the bilge, flowing the wrong way). I'm working on getting that set up properly.
This boat has 4 3 inch vents, all directly above the engine compartment. Only one had a hose on it. All the vents face forward. No aft facing vents anywhere. (See photos for vent setup)

I'm wondering how I should run this. I obviously need 1 vent line with a blower that goes down to the bilge area.
Do I need a second hose from another vent down to the bilge without a blower?
Should it be one hose on each side? or both on one side?
And given the vent setup, how does air actually vent out of this compartment? Is there a venturi effect from the cutouts in the seat cushion?

Thanks.
Charlie

 

[captainbr]

Re: 1998 Wellcraft Excel bilge venting

You are correct that the line with the blower should be run to the lowest point of the bilge so any fumes are sucked out.

Some boats have hoses on the intake side which end above the blower hose. I have seen a number of boats where there is no hose on the intake side.

Another answer:
http://forums.iboats.com/showthread.php?t=308442

 

[Fireman431]

Re: 1998 Wellcraft Excel bilge venting

Every boat I have owned (with bilge blowers) has no tubing on the intake side, only on the exhaust side.

 

[wire2]

Re: 1998 Wellcraft Excel bilge venting

My '84 Glastron had a long blower pick-up tube, a long inlet tube from the other side and one 12" tube on each side.

The vent louvres were typically on the side, blower facing rear, intake facing forward.

 

[ckaiser]

Re: 1998 Wellcraft Excel bilge venting

I think I didn't explain it well enough.

Yes, the inlet vents should be un-ducted to allow fresh air in at the top.

There's always one vent with a hose attached to the blower for low speed and prestart operation. But I've seen others with a second hose for high-speed operation. That way air can come in the two un-ducted openings and exit through the ducted one that doesn't have the blower in it.

I'm wondering if anyone knows if this is how this boat should be set up...

Thanks.
Charlie

 

[Fireman431]

Re: 1998 Wellcraft Excel bilge venting

You're vents aren't directional as a louvered type vent (see pic). They are all facing forward so anytime the boat is moving, fresh air is being channeled in. You should only need to vent the exhaust side.

P.S. Is there beer in that fridge behind the boat?

 

[ckaiser]

Re: 1998 Wellcraft Excel bilge venting

That's the key question. Since the exhaust vents face forward, how does it clear the bilge? All 4 vents are mounted above the seat as shown in the photos. There are no exhaust vents anywhere else.

I even called Wellcraft. They didn't have anyone who remembered what this setup was about.

For now I've put 2 hoses in; one on the starboard outer vent to the blower (blowing out) with an inlet going down to the bilge, and the other from the starboard inner direct to the bilge. I'm going to use the two port vents as air intakes.

Given the construction of the boat, I'm thinking the side compartments also play a role in bilge ventilation. There are openings in the plywood at the rear of the side lockers that might help to route some air back there.

But I sure would like to know for sure how it's supposed to work given that all the vents on the boat face forward and none face aft...

Charlie

 

[Fireman431]

Re: 1998 Wellcraft Excel bilge venting

The pressure and CFM from the bilge blower would be comparable (depending if it was 3" or 4") to the air intake of you running WOT. At slower speed, the exhaust put out by the blower side will override any ambient air being channeled into the ducts.

You basically could do with a piece of blower hose from the lowest portion of the bilge into one side of the blower motor, the output from the blower motor to an exhaust vent, and utilize the other 3 openings as fresh air intakes.