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TOPIC: Lousy Bilge Vents

Lousy Bilge Vents 20 Jun 2009 16:52 #1

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In another thread, dealing with a rotted-out battery platform, someone commented, "The worthless bilge vents allow rain water to enter right in. I'll bet you can trace a water stain down inside the hull from the bilge vents and find a "pool" stain at around your rotted area."

In my 2750, the rainwater from the foredeck runs down the walkways on the sides of the boat until it hits a little divirsion rib right above the bilge vents, where it then flows directly into the engine room. Why are the bilge vents angled upward like that?????

I have pondered this for nearly as long as I've owned the boat, and I've considered possible solutions, such as attaching a rigid flap of some kind onto the top surface of the vent so that water won't drop straight into the upturned openings. I've also contemplated making a mold for a wedge-shaped spacer to go between the hull and the plastic vent, so that the vent will sit in a vertical position rather than it's stupid upward angle.

It does seem like such a dumb design that somebody, sometime must have come up with an aftermarket correction. Does anyone out there have an answer?

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Ken & Linda, Canemah Oregon
1984 Bayliner 2750 "Patriot"

Lousy Bilge Vents 20 Jun 2009 17:09 #2

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Why are the bilge vents angled upward like that???

??
Could they be installed upside down? Or could they be reversed?

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Blue Highways
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Lousy Bilge Vents 20 Jun 2009 17:12 #3

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Ken, it's not the prettiest solution, but it is a solution to this very common issue with many hulls.... not just Bayliner.
I had a friend make these up for me from light gage SS sheet metal and he seamed them at what would otherwise be sharp edges.
They work!

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Lousy Bilge Vents 20 Jun 2009 21:18 #4

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To build the vents properly would have cost a couple of bucks more in materials and labor. To keep rain or spray out of the engine compartment, you need what I think is called a dorade box.

It acts as a gutter inside the vent opening - You know, the gutter "U" shape, but more of an "L" with the vent opening forming the missing side of the "U". The gutter is as long as the vent opening and the bottom of the gutter slopes up from the vent opening (5 degrees would be enough). Of course the ends of the gutter must be closed off, just like on a house.

Air enters the vent and is not at all obstructed, just flows over the open top of the dorade box into the engine compartment. Rain, drips or spray can't make that turn, so the drops hit the box and drain back out the vent.

If you're lucky, a good boating supply store may have a molded plastic dorade box that will be a close fit for your opening. If not, it should be fairly simple to fabricate boxes out of very light sheet aluminum or plastic. I say "should" because I've been meaning to make them for my 2655 for nine years now and still haven't "gotten around to it".

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Lousy Bilge Vents 21 Jun 2009 01:26 #5

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MikeValent;312521 wrote: To build the vents properly would have cost a couple of bucks more in materials and labor. To keep rain or spray out of the engine compartment, you need what I think is called a dorade box.

It acts as a gutter inside the vent opening - You know, the gutter "U" shape, but more of an "L" with the vent opening forming the missing side of the "U". The gutter is as long as the vent opening and the bottom of the gutter slopes up from the vent opening (5 degrees would be enough). Of course the ends of the gutter must be closed off, just like on a house.

Air enters the vent and is not at all obstructed, just flows over the open top of the dorade box into the engine compartment. Rain, drips or spray can't make that turn, so the drops hit the box and drain back out the vent.

If you're lucky, a good boating supply store may have a molded plastic dorade box that will be a close fit for your opening. If not, it should be fairly simple to fabricate boxes out of very light sheet aluminum or plastic. I say "should" because I've been meaning to make them for my 2655 for nine years now and still haven't "gotten around to it".


You are right on the money, I have seen this problem on many Boats. They should all have dorade boxes for inboards! Pat

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Pat says: DO-IT-RIGHT THE FIRST TIME!

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Lousy Bilge Vents 21 Jun 2009 01:43 #6

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I'm thinking about replacing my vents on my 2855 with stainless louvered vents and will have to come up with new boxes for it. I'm going to run two 4" blowers, one out each side. Only 20 bucks a piece for 240cfm and it's good insurance.

There definitely needs to be a better solution to the factory boxes for water intake issues!

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Lousy Bilge Vents 21 Jun 2009 02:07 #7

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ishiboo;312596 wrote: I'm going to run two 4" blowers, one out each side./QUOTE]
If you're going to use 2 blowers put them on the same side so that the other vent will allow air in, otherwise you are making it worse not better.

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Lousy Bilge Vents 21 Jun 2009 02:29 #8

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On my 2850 there are two large vents on each side. The lowers (exhaust) are angled aft and the uppers are angled towards the stern.

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2005 Crownline 316 LS "The Lucille"

Lousy Bilge Vents 21 Jun 2009 02:47 #9

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A little confusing here. Aft is toward the stern. Are you saying the two vents are one above the other? My 2655 has two vents on each side but the two are in line along the blue accent stripe.

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Lousy Bilge Vents 21 Jun 2009 02:53 #10

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Haha sorry, don't know where that came from.

Yes, my 2855 has two vents on each side in-line (vertically) with eachother.

ex: http://www.boat-world.com/photos/352785362/thb352785362_1.jpg

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2005 Crownline 316 LS "The Lucille"

Lousy Bilge Vents 21 Jun 2009 14:34 #11

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Normally that style of vent has internal fins, the starboard usually points aft for exhaust and the port side usually points forward for fresh air intake. It is done this way to promote engine room air exchange while underway without using the blower. The vents are reversible by rotating them 180 degrees.

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:cool: Doug
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Lousy Bilge Vents 21 Jun 2009 16:43 #12

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in various sizes; you can just add them or make your own. My 3058 came with them OEM and they terminate in a 4' duct. Stock it only had a hose on the one, of four, connected to the blower. I've put hoses on the other three that turn slightly up and then go down to the bilge. That keeps cold air from sinking in when it is cold and keeps wind-driven rain mostly out, and that which gets in just goes down to the bottom of the bilge where it can't hurt any thing. It also makes the boat noticeably quieter. If I lived somewhere where engine compartment temp or intake temp was an issue, I might run two of them high for cold air intake.

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Lousy Bilge Vents 22 Jun 2009 19:21 #13

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I too had water leaking into the engine compartment, but I covered the engine vents with plastic during a rain storm and still found water under the batteries. In my case it was the cockpit drains that were leaking. I removed all four cockpit drains, removed the worthless silicone sealer, re-sealed them with non-hardening putty and now the engine compartment is dry. You might want to check and see if your drains are leaking.

Pat

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