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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through November 17, 2003 » black air vent hose - necessary??? what is it? « Previous Next »
By matt moss (mossy44) on Friday, August 29, 2003 - 6:07 am:    Edit Post Delete Post
in my '02 xstar, there are two black hoses that go from the hole down into the bilge area. one is behind the kick panel in front of the driver, and the other is underneath the passenger seat. are these absolutely necessary to have?

i just installed a sub box in front of the drivers feet, and now the box is blocking the hole and is preventing me from putting the hose back on. is it ok to leave it off? my box is waterproof, so i am not worried about rain water. just worried about air flow or whatever purpose it served.

By Phaeton (phaeton) on Friday, August 29, 2003 - 7:13 am:    Edit Post Delete Post
Those holses vent the engine compartment. I would not block them.

By matt moss (mossy44) on Friday, August 29, 2003 - 7:21 am:    Edit Post Delete Post
i apologize. let me rephrase that.

the hole in the floor is not blocked. the hole in the top of the fiberglass is not blocked. the box is touching the bottom edge of the hole, so i cannot get the hose and clamp back around it.

but, air can still pass through it. it just wont be directly to the bilge area. it will be to the area under the seats.

By Paul Brothers (phat_in_cincy) on Friday, August 29, 2003 - 8:41 am:    Edit Post Delete Post
Do you have more than 1 intake leading the forces air to the engine compartment?
With hose disconnected you are no longer "ramming" air into the engine compartment to get the nasty fumes out. I wouldn't risk it.

By Marty McFly (mcfly) on Friday, August 29, 2003 - 8:50 am:    Edit Post Delete Post
Plus, the Indmar engines run much better the more fresh air you get to them. I suggest reconnecting the hose as well.


By Chaun Keating (big_poppa_pump) on Friday, August 29, 2003 - 9:57 am:    Edit Post Delete Post

I have had both those hoses disconnected for 2.5 years now on my 1999.

I will agree that ramming cool air into a hot humid engine compartment will help out performance, but I really doubt these things were designed to accomplish that since (at least in mine) they just go back to the front of the fuel tank and not anywhere even close to the FI intake.

Also, the engine compartment is not really sealed at all, there are large areas to each side of the rear bench that are open to ambient air and also a vent or two in the back, the engine seems to draw plenty of air through those areas alone. Add that to the fact that we open and close that hatch about every 15 minutes and there is not really a chance for heat/humidity to build up.

My view is that if you have enough leakage in your fuel system where vapors are building up in your engine compartment, there is a lot more things you should be worring about than a couple disconnected vent hoses.

I guess I could see where a boat that sat moored in the water for a long time or on a boat lift for weeks at a time *could* build up enough vapors to blow, but in that situation, the boat will not have any forward movement and those fresh air ducts will not be doing any good anyhow. Oh yeah, isn't that what the blower is for. :-)

By Shawn K. (zipe) on Friday, August 29, 2003 - 10:42 am:    Edit Post Delete Post
And this, my friends, is what leads to the future unfortunate thread:

"My boat blew up when starting it, what happened?"

It is even specified BY LAW according to the Coast Guard the have a ventilation system, and it is very specific WHY.

Good attempt at rationalization Chaun, but there is a reason the system is designed as it is. Boats have blown up before and I wish I could find the specific article.

Anyway, we all have free will to make our choices. I just hope your boom of the stereo doesn't result in the "boom" of your boat.

By matt moss (mossy44) on Friday, August 29, 2003 - 11:10 am:    Edit Post Delete Post
shawn - i will admit, i am only looking forward to one of those "booms" you are talking about.

i do have the hose on the other side still connected. i guess i will go home tonight and try to duct tape (fixer of all things) the hose to the hull, instead of clamping it. i know the clamp wont work. its hard enough just to crawl through the front seat to get to where i need to go. if i have trouble duct taping it, i am not sure what i am gonna do

By Chaun Keating (big_poppa_pump) on Friday, August 29, 2003 - 12:48 pm:    Edit Post Delete Post

I realize that boats have blown up before, in fact my wife works in the ER and has taken care of a few jet skiiers that this has happened to. BTW, they did not modify their compartment vents at all and did ask the question "My boat blew up when starting it, what happened?"

Well, I can tell you what happened, they were rentals and the fuel system was leaking...which brings me back to my point. How are a couple of crappy vent tubes going to help you out if you are leaking fuel all over the floor.

Any what electrical component was not properly shielded that produced the spark that ignited that fuel? And did anyone bother to open the engine compartment and give a sniff every once in a while to see if it smelled gassy?

BTW I also violate the Coast Guards max capacity sticker that is put there BY LAW by about 1300 lbs or so.

Anyhow, I still have the hoses in place, they are just not connected to the engine compartment anymore. So they now vent the observers compartment and driver's side console.

The engine compartment still has two large openings for air in the front, and smaller exhaust outlets put in the back (one of which is for the blower).

By Rod McInnis (rodmcinnis) on Tuesday, September 02, 2003 - 11:23 am:    Edit Post Delete Post

The requirements for the fuel system, electrical, and ventilation provide for a "triple redundant" safety system. The fuel system, including the pump, is designed so that it won't leak fuel into the boat. The ventilation system is designed to remove the vapors that might accumulate, and the electrical system is designed so that it won't ignite any fuel vapor.

Any time you defeat one of the safety devices you increase the risk. You can install an automotive fuel pump, and it will be fine, at least until the diaphragm ruptures and it starts leaking. You can replace the alternator or starter with a non marine version and everything is great, as long as you haven't spilled any fuel. And you can disconnect your ventilation system and probably be OK. Note the word "probably".

Gas vapors are heavier than air, and they will settle to the bottom of the boat (which, by the way, is where your starter is......). The blower should be connected so that it draws air from the lowest part of the boat that is above the "high water" level for normal bilge operation. A fresh air intake, normally located towards the front of the boat, should direct fresh air into the bilge space so that there is a continuous flow of air to keep things mixed up.

Removing the hoses that bring fresh air into the bilge space wouldn't necessarialy make the boat "unsafe" but it would make it "less safe".

One thing to keep in mind: If your boat does blow up and cause injury and/or property damage, and an investigation determins that a required safety item had been removed and/or defeated, it could certainly change the outcome of any lawsuits that might result and/or how your insurance company pays......

By Chaun Keating (big_poppa_pump) on Tuesday, September 02, 2003 - 2:59 pm:    Edit Post Delete Post

I understand what you are saying. But what I am getting at is that these hoses are really not the sole source for engine compartment ventilation. There are other (much larger) openings around the rear bench and in the rear of the engine to let fresh air in.

Also, the most dangerous time for an explosion would be on initial startup. Since the boat is not really moving (unless being trailered) these "ram" air intakes are essentially doing nothing for you. Air intake would come from the less restrictive openings to the engine compartment and going out the blower exhaust (assuming its been turned on). Once underway, the engine sucks in an incredible volume of air and any high concentration of gas fumes would diffuse out of the floor and either into the air intake or be vented out the rear exhast grates.

Add to that, that these hoses are some really cheap, brittle, POS material. The one in the driver's side console you can get to stay hooked up fairly well, but whenever someone throws a backpack or something into the observers area, it will either knock off the hose clamp that attaches it to the (much too short) floor attachment, or it will rip the hose material...which in the latter case means that the plastic will unravel.

I would never use, or advise anyone to use a non-marinized version of starter or alternator...heck the marinized versions really are not all that expensive if you know where to look. I also doubt it would be possible to find an automotive replacement for the fuel pump in the X-Star...I think it is pretty specific to that vehicle. Regardless, I would not replace a fuel pump with a non-marinized substitute.

I am redoing the inside of the observer's compartment and will probably wall off the area just behind the attachment point on the floor for this hose. At that point, I could hook that hose back up without fear of it getting knocked off every other trip.

Really, if it were that important, I believe that these would be much sturdier in design.

P.S. If my boat catches on fire, the first things to go will be these duct hose, they would last about 1/2 second in any type of fire. Good luck to the investigator determining that as a cause.

P.P.S I also do not attach the engine kill lanyard to my life vest when I am driving.

By TY-one-on (typhoon) on Tuesday, September 02, 2003 - 3:01 pm:    Edit Post Delete Post
maybe to allow ventilation for drying purposes.
By Patrick (faceplant409) on Saturday, September 06, 2003 - 10:14 pm:    Edit Post Delete Post
Those hoses work in conjunction with the blower (you know, that switch on the dash you are supposed to use before startup and below cruising speed) to clear fumes from the engine comp.

Maybe the investigator wont find the cause, but I'd start thinking up a good story to tell YOUR dead passengers families.

Forgive me if I restated already given info...I did not read all posts.

By Jeff (socalwakepunk) on Sunday, September 07, 2003 - 9:18 am:    Edit Post Delete Post
I think the real question behind Matt's post is adding the subwoofer worth the risk of having the vent hoses disconnected?

Personally, I would say no. I would change the box before I changed the vent system.

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