External Air intakes?

[Ironworker]

My boat has a set of Capt. Pat's air intakes that were installed by the previous owner. I added a water deflector on the inside top but I'm still concerned I'll still get seawater inside the engine boxes

I know most of you guys are getting rid of the external intakes at repower time and I'm considering doing the same. I'm reluctant to add more work to my repower jobs but I'd like to keep as much saltwater off my new QSB 5.9s with all electronics.

What to do you guys think?

[bob lico]

extensive testing for seven days and the results are best combustible air is from the forward cockpit adjacent to engine hatch covers and the worst by far would be hull side air boxes. early morning as you go out inlet look in the distance and you will actually see the salt laden air up to 3' above the water ,now i don't have to explain how bad that is the engine compartment nor the damage it does to those beautiful QSB`S .now the boat genius out there are going to say yea but my friends 50" Bertram has them. no kidding Dick Tracy that's because they have no choice with the volume of air needed for 1050 HP Mans but some day you will have to remove those port and starboard injectors--------wait

[bob lico]

[bob lico]

teak louvered doors on either side of engine covers are the air intakes a K&N air filter and 4" ID pipe behind grill goes directly to the turbo intake wrapped in W/P blanket worth about 7HP at cruise and DB level with sound down about 2 points lower then OEM engine compartment with diesels

[Ironworker]

teak louvered doors on either side of engine covers are the air intakes a K&N air filter and 4" ID pipe behind grill goes directly to the turbo intake wrapped in W/P blanket worth about 7HP at cruise and DB level with sound down about 2 points lower then OEM engine compartment with diesels

Bob,

Would you happen to have a photo of the plumbing side of your air intakes along with the filter boxes?

[bob lico]

i am being very modest here on HP increase actually if ambient temperature on the water becomes 60 degrees or less and you are on plane at 2000 rpm and increase the throttle you will feel the difference immediacy.

[Yannis]

Bob,

In my 28, I want to get rid of those air intakes on the side decks where we all destroy our toes.
Do you think that two louvered rectangular intakes, made on the step created by the engine room, facing aft and positioned right at where the air filters are would be ok? (Provided that measures will be taken to stop water - mainly during rinsing the deck - from entering onto the engines)

[Ironworker]

Bob,

In my 28, I want to get rid of those air intakes on the side decks where we all destroy our toes.
Do you think that two louvered rectangular intakes, made on the step created by the engine room, facing aft and positioned right at where the air filters are would be ok? (Provided that measures will be taken to stop water - mainly during rinsing the deck - from entering onto the engines)

My concern with this location is increased cockpit noise.

[Tony Meola]

These boats are so open under the cockpit into the engine room they almost need no external ventilation. I like drawing the air from the cockpit but like it was just said, what about the increase in noise. Bob how loud is it with the engines drawing from the cockpit?

[Yannis]

Rick, Tony,

If it's just for the noise, I couldn't care less.
Very few, if any, are down there during cruising, we're all up at the fb.
I'd make the shift in a flash.

[bob lico]

tony the noise was tested with decibel meter after i completed the job the decibel level was 2 decibels less than OEM diesel.i feel one of the Most important factors in doing the job is to look at the photo you see the black water tank right against the interior hull wall. this is the best place for numerous reason to put the tank obviously you don't want that tank in the cabin floor and the clean out require by law is right next to it and the toilet is almost back to back thru the main bulkhead , a little off subject but you have to weight everything when you built your dream boat with this in mind the vents would not allow a tank here in addition to a generator/invertor on port side . the out side vents are doing far more bad than good in a 31 Bertram.look at the 4" intake routing goes over the engine and turns 45 degrees under the wing and goes about 3" above the cockpit floor (the coolest air possible ) were the K&N filter is placed on the end of the 4" intake pipe.due to the 45 degree angle of the intake going from the top of the engine hatch to the cockpit floor it would be totally impossible for water to go upstream into the engine. now lets get back to the engineering aspect of this innovation
and that is heat rises so the hottest ambient air is at the top 10" of the engine hatch so the engine is using the warmest possible air for combustion so the outside air intakes is putting salt laden air into the engine compartment and this cooler air will go down to the bilge forcing the warm air to rise even more.you can check this out some day by taking the boat to WOT. with the both engine hatches open fully then close them and tell me want you feel and check the RPM increase.i have engine Dyno specs. of cummins diesel engines and the change in fuel temperature and combustible air intake is dramatic.

[Amberjack]

I like drawing the air from the cockpit but like it was just said, what about the increase in noise. Bob how loud is it with the engines drawing from the cockpit?

Tony, I have cockpit air intakes and really didn't notice any change in noise levels. The engines are happier with the improved air flow.

[Ironworker]

Doug,

Thanks for posting this photo. What kind of engines are you running?

[bob lico]

good idea Doug if you take the time and effort of cutting up 30 -8" strips of yellow caution tape (like the police used) and make a fold 1" from bottom and tape 30 different places in the area in back of bridge and the entire cockpit you will find this area as well as the area adjacent to bottom of engine hatches the most turbulent area of air movement . the faster the boat travels the more air movement so this area is much better than side vent and the dumb Dorade box inside vital area of engine compartment.

[Tony Meola]

Doug

I like that idea. I see you eliminated the step completely. Has anyone taken a tumble down that drop? It is a pretty good drop.

[Tony Meola]

Doug

I like that intake idea. They are low so actually the noise is probably above them trapped in the sound down.

I see you took out the step. That is a drop, has anyone taken a tumble?

[Amberjack]

Rick-Yanmar 315's. I've been very happy with them.

Tony-The step was never there, this is how I bought the boat. No one has fallen into the companionway possibly because that area is so well defined. It is almost impossible to stumble into it. If there had been a step and we had gotten used to it I can see that could be an issue, but in this configuration I usually grab eat bridge overhang and swing down, as in the Navy.

Bob-Thank you for the re-inforcement. My decision was made to do it this way because the engines needed the air to function optimally and I really didn't want to put holes in the hull. Nice to know it makes aerodynamic sense.

[scot]

I’ve been away too long, Last time I was active on the site the hull vents were all the shizzle! So.. I spent countless hours fabricating some into the 25 inboard project, now they are NOT the thing to do..
Oh well, they are there now and they will have to stay as I’ve already “undone” way too many things on this 15yr project. Whatever the outcome, I won’t back up any more .

[Carl]

Scot-

No worries, I hear in fashion what's old is new again. I'm sure when you're done, they'll be back in style.

[Tony Meola]

Scott

The answer is not to stay away.