Like Getrdunn said - look EVERYWHERE to see where you can get in air without cutting holes that show. I hate to see a boat cut up with NO thought on how it will look. Panels covered with vinyl are easy to fix - fiberglass is not.

SB - the ratings on those fans is without ANY hose.With 4 ft. of hose the air flow is probably in the area of 50 and 75 respectively.

That was the reason for my single quotes surrounding the airflow ratings . I do not know what the actually move for air when they are hooked up and used in actual conditions, and I can actually assume much less. Just like fuel pumps ratings are at free flow, most of us know this isn't real world.

This is why it is great you are involved in this thread, with your vast experience in your field, you have a better handle on this than 99.9% of us.:Score-101010:

Thanks for all the input guys. Yes I agree, that it is better to make holes that won't be seen and are easily repaired vs in the side of the boat. If I'm remembering correctly the combing vents boxes have only 1 3" exit hole. The actual vents are good sized, so this will be the first place I will dig into. This is going to be the first thing I do next Saturday morning and report back.

Speaking of venting- when I noticed I had this issue, I started to look at every boat I could locate. Some had huge power and only a few vents. As SB posted, Apache and from what I found Cigarette vent fairly well. However, I was shocked at how many boats appeared to be even worse than my Formula.

My 242 has 2 ea. 4" holes in the vent box, each side, with plenty of area for flow improvement.

Is this in the side rear vents or the cowl vents just behind the windshield? It's been a while since I have looked into these.

I'm talking about the rear side vents

Im going to agree with EZstriper on this, you need to look at inlet air temp with temp probe and engine vacuum at wot, a 550 hp engine on dyno flows about 700/800 cfm when measured on dyno, your engine compt prob leaks 5 time that at seams, unless your engine compt is really sealed well I would lean towards air temp vs volume, real easy to test. When you dyno a motor at J607 with 0 humidity at sea level going from 60 degree ambient to 120 is a 6% loss. Goes up from there. If you ran a vacuum gauge to manifold you would know for sure, if motor draws .5" vacuum at wot with hatch open and goes to 2 or 3 inches with hatch closed you have a supply problem, if vacuum stays same you have a temp problem so getting a supply of cooler air will require more effort than just ventilating engine compt, fwiw, Smitty

On a side note a while ago I did a experiment on my Baja 272 thinking air temp was slowing me down, I built the last 540 it had to run blown or NA, I thought what IF I supplied the motor innercooled air when running NA? So I built a inlet venturi to mount on my innercooler and ran it NA with and without air going thru the innercooler. It was slower with the innercooled air, by a mile. So in that case the innercooler posed a restriction and it wasnt air temp slowing it down. Boat would loose 2-3 mph pulling thru innercooler even with a inlet venturi smoothing air. Motor pulled 93/94 map (about 2" vacuum) at wot restricted by innercooler and 98.5 map un-restricted (about .5"), at least I knew, Smitty

I suffice to say, if you have an engine room temp problem, you have an engine room (from outside air) breathing problem too.

Two engines (even one) is a serious air mover in of them selves.