I finished the cold air intake using two inexpensive bilge blowers and it works great. I draw air in from the boats cockpit. At the back of my side storage areas, there is a removeable panel that seperates the cockpit from the engine bay. I cut a four inch hole in each of these and attatched flex tubing between the holes and two bilge blowers mounted at the front of the engine. The blowers direct air onto the flame arrester. I used relays to attach the blowers to my regular blower circuit. When I turn on my blower switch, I have two bringing air into the compartment and one blowing it out. I see 1.5mph gain just like I did lifting the hatch. The second bonus to this was found while sleeping on the boat. My wife said somthing smelled a little gassy (might have been the Burrito). The boat was completely covered and we were in the cuddy. I flipped the blower on and the temp nside the boat dropped 15 degrees. The two blowers sucking air out of the cockpit were drawing in cool air through open hatch in the cuddy. It was like a whole house fan for your boat. I think parts cost me aout $50. I would post pics but I cant resize. I was also thinking of adding the ability to reverse polarity so I could blow warm air from the engine compartment into the cockpit on cold nights.

I would be willing to bet that if you removed the blowers, but kept the hose in place, you would see the same gain, but not have the added bonus of instant burrito fallout removal.

reverseing the fans and directing air from the engine to your sleeping compartment is a bad idea, carbon mon ox, etc. This Is why A/C is never installed in the engine compartment

Great idea and result. I have added 4 additional 4" intake vents ( 2 on each side) to my twin but from the outside. I also moved my discharge vents to the transom. I never though of using cockpit air. I wouldnt reverse them either due to gas/oil fumes.

I was thinking of using only when engine was off but mistakes are easy to make. I think blowing the cool air directly onto the carb will do more than just the holes alone. Even though the blower blades will obsruct somewhat, I see no gain until I turn the blowers on.

Cool!
Blower motors for 50 bucks!
Good idea.

Dangit!!! You stole my reply!!!!!

I already have the double intake grates on the side of my boat. But I never thought of adding any to the transom area for "flow."

Ah.....I don't need any more speed. Yeah right!!!!!!!!!

On my Donzi Classic there are 4 "vents". 2 facing forward to let air in and the two facing backwards have hoses hooked to them and my blower attached. I had often wondered if there was a way to connect the same type of hosing to the front vents and directing them toward the flame arrestor.

Intolerant 1, if you want to e-mail a few pics I can resize them and post them. Email them to:

[email protected]

Apparently someone is already marketing your concept of ram-air bilge blowers - for cars!!

I don't think that this is such a good idea, probably not Coast Guard approved either. There should not be any holes between the cockpit and engine compartment incase there is a fire. Also fumes could be a problem. This could be a safety problem.
Just something to think about.
Caleb