87 Trojan Int Express- side louvered vent functionality?

davescarrs · Post by **davescarrs** » Sat Feb 04, 2012 5:54 pm

My boat is a Trojan 1987 Express 10 Meter International

I was looking at removing the radar arch to fortify the arch sides that had some rotten wood.

I found that the louvered vents, as pictured below, are not functional and there is a factory style piece of plastic covering the hole. Upon further inspection, it does not appear that the vent, even without the plastic in it, would lead to the engine room. There was no air duct hose or channel for the air to flow into the engine room. It seems to have no function. The other vents perhaps fulfill the duties and the louvered vents were designed for use in a different model?

I searched some old posts and found RWS mentions the topic and says that the vents do "vent" along with the metal colored vents lower down that the blower is connected to on one side.

RWS remarks: "On the express cruiser w/o mid cabin, air gets into the engine room via the two rectangular vents on the sides of the boat. The mid cabin shares these same vents."

There is plenty of discussion regarding midcabin and F style boats and their louvered vents, but not much about the 10 Meter International Express. The engines don't seem to become overly warm and the engine room gets air flow by other lower vents with the metal grill on them, just wondering if anyone has noticed this?

the interior view you can see the plastic piece.

aaronbocknek · Post by **aaronbocknek** » Sat Feb 04, 2012 6:41 pm

so they are just for decoration? just curious.
aaron in baltimore

RWS · Post by **RWS** » Sat Feb 04, 2012 7:59 pm

there are two reasons for the vents.

1. to allow the bilge BLOWER the ability to suck gasoline fumes from the lowest part of the bilge as the gasoline fumes are heavier than air and they sink to th ebottom of the bilge - there is no escape

2. when the engines are running they breathe in air and expel exhaust via the exhaust system.

A 454 cubic inch engine will daw in 454 cubic inches of air for each revolution it spins.

the engines will draw in a great deal of air when running. Maybe someone weants to run the calculation for 2 454 engines running at 3000 RPM each .

You may notice the Internationals have an abundence of sound insulation in the gunnel area. This is beacuse those rectangular vents are delivering air that is being sucked into the engine room via that channel that exists above that wooden gunnel filler.

So here is the simple answer:

the blower sucks the air (and fumes) from the lowest part of the bilge, the vents allow fr that air that was removed to be replaced as does the non blower stainless deco grill.

with the engines running, those rectangular vents allow the engiones to breathe.

TRUST ME - they ARE functional !

RWS

larryeddington · Post by **larryeddington** » Sat Feb 04, 2012 8:10 pm

I believe that a 454 cubic inch 4 cycle engine will draw in 454 CI of air for every two revolutions not each revolution.

jefflaw35 · Post by **jefflaw35** » Sat Feb 04, 2012 9:04 pm

Yea what he said! I agree! Sure!

davescarrs · Post by **davescarrs** » Sat Feb 04, 2012 9:08 pm

I understand the premise and the why, just didn't see the path the air would travel to get down there.
I gotta take a closer look. Just the fact the plastic pieces were present I couldn't believe and it threw me for a loop. No matter what, the vents aren't functioning on my boat cause they are closed with plastic pieces on the inside.

Thanks!

jefflaw35 · Post by **jefflaw35** » Sat Feb 04, 2012 9:16 pm

I was kidding, I acutely just gutted my f-25 and all 4 vent holes had hoses leading to under my motor and rear section, rear vents were tied into what was the. Blower motor, keep in mind my boat is new to me and has been butchered up. May not be right at all

larryeddington · Post by **larryeddington** » Sat Feb 04, 2012 9:16 pm

1748.19 Cubic feet a minute for two 454 at 3000 rpm. quite a large volume which also pumps hazardous fumes out the exaust as well which is a good thing.

RWS · Post by **RWS** » Sat Feb 04, 2012 9:19 pm

the plastic pieces are at the bottom to keep the water out.

Remove the vent from the side of the boat anbd you will see how this works.

trust me on this...

RWS

captainmaniac · Post by **captainmaniac** » Sat Feb 04, 2012 11:19 pm

In general, the boat needs vents for two reasons - to provide positive air pressure and flow to blow any fuel vapours or fumes out of aft-facing vents while running, and to allow adequate air flow for the engines / carburetors.

I don't have an International, so RWS knows more about your config than me, but the vents on all boats serve the same purpose.

On my F32 the 'intake' vents are boxed on the inside of the hull to direct air flow to the base of the bilge - to help displace any 'heavier than air' gas fumes that may be sitting there. Even if yours don't boxes or hoses to direct the air to the lowest areas of the bilge, as long as they can provide air to the engine compartment they will help.

I have seen some boats with protective covers over the vents on the outside (to guard against rain water, bugs, and spiders), but not on the inside. In your pic re the interior view I think I can see the vent and louvers, so doesn't look like a heavy piece of 'factory plastic' is covering it to me. Maybe its just hard to see in the pic.

Is the obstruction like a painting drop-sheet? Any chance a previous owner decided to add a sheet of plastic to control air flow for winterizing or something? The vent certainly would not be sealed from the factory.

RWS · Post by **RWS** » Sun Feb 05, 2012 8:11 am

if you remove those two plywood panels covered with insulation at the gunnels, you will find the means by which the airflow moves from those vents into the engine room.

those 454's consume a lot of CFM.

If there is a lack of air, try lifting a hatch at say 3200 RPM and see if the tachsincrease a bit. That will tell you that there is a fresh air flow restriction.

RWS

davescarrs · Post by **davescarrs** » Mon Feb 06, 2012 9:23 am

RWS- I do trust you and was hoping you would reply. The photo I posted is a view from under the gunnel with the insulation and panel removed. My vents have a piece of plastic plexiglass material on them that should not be there.

Upon further inspection I found the air travels along the gunnels and is picked up by regular vent tubes on the other side of the bulkhead and comes back in to the engine room from the stern side of the bulkhead in each corner of the engine room. I expected to see the air traveling on the engine room side, but it does end up there. There are two other hoses that come in from the floor on the other side of the bulkhead. These vent holes are located in the bulkhead close to the bilge area.

Thanks all, I will remove those plastic pieces immediately.

RWS · Post by **RWS** » Mon Feb 06, 2012 9:52 am

Those vents have a definate UP or DOWN

This is related to the base of the vent as a means to keep (most) of the rain water/wash water/spray from getting into that area.

Plexiglass?

Must have been an unknowledgable prior owner.

Also,

in my case, those wooden gunnel filler panels were damaged from water getting in around those vents. One of the few places for wood on these ships !

It will be interesting to see if you notice a performance improvement once you allow te engines to breathe better

RWS

aaronbocknek · Post by **aaronbocknek** » Mon Feb 06, 2012 11:32 am

i'm not an international owner but i find this post most fascinating. when i bought my tri cabin, unlike my dads that had vent hoses running every which way, there are only 5 vent hoses on my 82 tri cabin. four (4) 2 p and 2 s are located at the back of the boat to vent the fuel tank area. midships there is a hose that runs to the bilge blower. there are 8 vents along the hull, 2 sets of 4 port and starboard. for the life of me i could not figure out where these vents entered the boat. my mechanic then explained that there are large fiberglass covered 'boxes' that run along the interior of the bilge, hug the gunnel then merge at the forward engine room bulkhead. this is a ducting system and something that i've never seen before. when phil and i were bringing the boat from long beach marina to parkside, we throttled her up a bit and i went below to see what these ducts do..... to my amazement, there was quite a bit of airflow coming in from the forward facing ducts and there was an 'exhaust' ventry effect from the two sets of ducts at the back of the bilge. i took a piece of toilet paper and held it there and it actually pulled the paper into the duct as i held onto it. pretty neat. so, it does work after all.
aaron (always learning new things)

yorklyn · Post by **yorklyn** » Sun Feb 12, 2012 12:17 pm

davescarrs, I just ordered new louvers from west marine as well as the collector boxes for the the hoses to connect to. my 1987 10 meter is a mid cabin which typically is different than the express. I have my engines and tanks out right now. I'm actually getting ready to redo the collector boxes on my boat (the west marine ones were much smaller than the existing rotted out ones so I'm going to make my own). I will take some pics for you as I have great access with the tanks out. mine has two flex hoses off of each louverd vent as well as two more off each of the the aft moulded in vents. So basically I have a total of eight vent hoses in my bilge. only one is connected to the blower. I'm adding a second back up blower for safety. I'm also going to remove or at least shorten two hoses. eight is overkill in my opinion.