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I was looking at a 31 for sale and it had no vents that I could see.
I know some people use the cockpit and eliminate vents in the hull and deck, how much noise do you think it adds to the cockpit and what is the feeling on the amount of airflow it allows for gas engines?

Raybo Marine NY wrote:I was looking at a 31 for sale and it had no vents that I could see.
I know some people use the cockpit and eliminate vents in the hull and deck, how much noise do you think it adds to the cockpit and what is the feeling on the amount of airflow it allows for gas engines?

A lot.

My Sportsfisherman was a gasser before I converted it to diesels. The intake and exhaust scoops were important venting tools while moving and I never even considered a noise factor. I really wouldn't want a gasoline powered vessel without good bilge venting. The scoops are still on my diesel powered 31 and help get air to the diesels. I really don't think closing them off would lower the noise factor by much. My opinion/experience.

Maybe I'm misunderstanding Raybo, but I thought that this boat has no vents. That is the problem. I was on one gasser that had done a similar set up and I thought that it was load for a gasser.

The scoops and outboard venting are the way to go, in my opinion.

noise ---no more then a gunnel vents ,see and hear for yourself .phoenix will splash next week give me a call and you tell me.the cockpit vents are part of the formula .numbers don`t lie

I've seen many 31 gassers and some diesels with no vents other than scuppers on the deck or none at all.

They count on leakage around the deck and engine boxes. None I've surveyed like this had air issues that hampered performance.

Having had first hand experience with a 31 with cockpit vents the answer is yes its noisey.

Let me clear up the confusion, I had seen a listing for a 31 Monday, diesel powered, had no vents.

I have Craig's buddy's boat and on Saturday we were discussing possibly painting the hull and he was asking about no vents or a custom in-hull vent.

Trying to do some research for him, ideally we would either use Capt. Pat's vents and eliminate the gunwale vents, or custom vents, but he was asking about NO vents.

I dont think I would be comfortable with NO vents on a gasser

I have never seen one without vents.

I have seen boats with no side hull vents that were vented in the cockpit--but have been told they were very loud. No first hand expeirnce.

I did note that Capt Pats project is using his original vent design which I perfer over his second design.

I am very happy with my original Raybo designs, if I was starting from scratch would consider a racer(?) design.

Robbie,

A gas boat must have ventilated bilge spaces. Period. If EFI, maybe a comma... But gas fumes are what they are.

Any vent or space that allows air into the engine space will also let mechanical engine noise to exit. If engine noise is introduced into the cockpit, most of it will be easily heard. If the noise is introduced to the open air via hull side induction, much more of the noise is absorbed overboard. Even gunnel vents are less noisy than cockpit vents, at least to my ear.

The noise level is also dependant on the type of machinery. Diesel engines generally produce more noise than gas engines, especially once the turbos kick in.

Regardless of where the air comes in and sound exits, about 80% of engine noise must be muffled with sound insulation throughout the engine compartments. The more hard surfaces that are exposed, the more sounds will transmitted throughout the boat.

robbie are you talking about a gasser if so they must be vented and blowers by uscc regulations . my post refers to diesels only.the entire engine compartment is sound insulated the air intake forms a ventura like a carburator .air must be cool , salt free and turbulant at non restrictive air cleaner to have maximum effect on performance.

Bob- its for "The Gambler"

vents definitely the way to go

i never turn off the blower if im running. i have blocks that fit in the intake vents because thats where all the foredeck water runs. i occasionally forget to take them out (did it with patrick and bruce on the boat) and the engines run fine......plenty of air gets in there ......not to mention water.

ok -----definitly needs some kind of venting knowing you it will be quite creative!!! in combination with blowers will furfill uscc regs.

just got to come up with something different then Craig, cant upset Craig!

robbie would the new owner be interested in a side vent like the captain has (dorade box on the inside).maybe a air intake similar to 32' phoenix actually on inside of pillars and not very noticeable.

bob lico wrote:robbie would the new owner be interested in a side vent like the captain has (dorade box on the inside).maybe a air intake similar to 32' phoenix actually on inside of pillars and not very noticeable.

On the 31 Express, the intakes "are the side panels". Nice feature if I ever go diesel...just enlarge the holes.