Blower vent tubing question

[GMTK]

2004 Hurricane SD 187 with a Volvo 4.3. I've had the boat a year. It's my first I/O as I spent my early years on a bass boat.

First - love this site, lots of great info and contributors. Took the boat to the ramp yesterday to start it up and check everything (we don't have to winterize where I live). Noticed the hose from the output of the blower to the port vent was torn (already ordered a new one). I noticed another vent tube, also on the port side but in front of the engine, ran to the lower part of the boat, near the thru-hull transducer and then the tube ran up towards the engine and just terminated.

I assume this second tube is to provide some sort of fresh air to the engine, but how? I have no openings on the front of the boat which would allow air to get to that tube. Also, my boat does not have any forced inlet air vents. There are only 4 vents on the back of the boat, one of which is the output from the blower motor. I've attached some photos and once showing the 4 round vents (not my exact boat, found it online). I know the two starboard side vents will provide some fresh air, but it doesn't seem like much. Is my set up ok or should I think about a forced air inlet?

 

[harleyman1975]

That second tube could be to vent the bilge, fuel "bunker" or the ski locker or other storage compartments.

 

[floater212]

i would think the end of that hose should go to one of the rear vents, so when the blower is on it will pull fresh air to the bottom of motor, thus moving gas fumes up and out to stop any explosions when you fire it up. mine has 4 vents in back also, blower goes out to one driver side and one from passenger side goes down to bottom under motor. the other two doesn't have any hoses attached.so it would be more for heat while moving. I have seen where both hoses from vents are in bottom area blower out other fresh air in but almost touching in the middle, my thought is " not so good", need enough room for bad air can be pulled out. probably fell off and previous owner didn't care to fix so he tucked it out of the way.

 

[alldodge]

Vent hoses are placed down low and a bit higher. The blower pushes air into the compartment and the lower hose allows air and any fumes to be expelled out the lower hose (gas fumes are heaver then air) and upper. This is normal

 

[GMTK]

The hose that is not connected does have a zip tie keeping it to the right of the motor, which makes me think it's in the right place; it's just a matter of where it connects. The prior owner replaced the vents so he may have disconnected it without knowing. I'm going to see if there is enough material to reach the vent. Thanks for all the replies.

 

[mr 88]

Every boat I have ever owned with a blower always sucked the fumes out ,never blew air in. Which makes perfect sense, pushing the fumes around in a enclosed area does nothing to make it any safer when starting. The exhaust hose should be as low as possible in the engine compartment as noted..There is enough ways for fresh air to get to your engine without worrying about adding a blower to force air to it. Just a waste of time and money. Most boat will have two vents on each side ,one for exhaust [fumes] and one for intake.

 

[bruceb58]

Every boat I have ever owned with a blower always sucked the fumes out ,never blew air in.

Likewise.

 

[Ned L]

Every boat I have ever owned with a blower always sucked the fumes out ,never blew air in.

YES,.. This is correct. The "blower" sucks air (and potentially explosive fumes) from the lowest part of god bilge and blows them out the vent. The fresh air inlets should simply allow fresh air gently into the upper area of the compartment. You don't want swirling or turbulating that can swirl the fumes around.

 

[mickyryan]

the blower line should be attached to vent outside the blower will pull air through this vent and mix with the air in bilge and expel it out of other side suction side hose should be placed at bottom of bilge because gas puddles there as well as other heavy fumes. air intake can be anywhere as long as it has air to intake. ugh just noticed neds post sorry lol to repeat same things

 

[wrench 3]

No Title

Canadian Coastguard regulations state that the inlet hose should terminate just below the level of the engine air intake/flame arrester.

 

[mickyryan]

Canadian Coastguard regulations state that the inlet hose should terminate just below the level of the engine air intake/flame arrester.

I would imagine if the area is a closed air tight box as the diagram then that would be the case for two reasins one the carb needs air and 2 the rest can flow down that the carb doesn't use, however most boats are built with a open box configuration and the suction vent is the most important in that regard because that's the one evacuating the fumes.
open box meaning the box is open to rear of boat, a boat with a inboard might have a sealed box and then that would be most important as would be how much cfm your carb draws at wot along with how much cfm you blower draws so more then one vent would most likely be required.

 

[Brandon5778]

Well I learned something today. I did not have my suction exhaust hose going to the blower under the engine but around mid level. Glad I read this because I didn't think twice about it being set up wrong..

 

[mr 88]

the blower line should be attached to vent outside the blower will pull air through this vent and mix with the air in bilge and expel it out of other side suction side hose should be placed at bottom of bilge because gas puddles there as well as other heavy fumes. air intake can be anywhere as long as it has air to intake. ugh just noticed neds post sorry lol to repeat same things

You better not have any gas pudding anywhere,period.
Fumes are one thing and that's what usually is more likely to ignite a fire vs raw gas laying in tbe bilge.In any case if you have raw gas ,you have a major leak AND excessive fumes caused by the leak. I have a fume,gas detector that if it senses anything won't even let you turn the engine over. A quick lift of the engine cover and a sniff before even turning on the blower is a good idea for any boater, especially after a fill up.

 

[mickyryan]

when I say gas I meant gasous fumes wether they be exaust partially burnt fuel or raw fuel vapors but yeah if you got a flooded bilge you have bigger problems then a blower