Side Air Intakes

Hyena Love · Post by **Hyena Love** » Sep 2nd, '11, 09:45

I am kind of thinking about painting the Hyena. I know, the horror. Spending money on stuff that don't catch fish or save your arse.

But, if I am going to paint, I need to address my absolutely hideous air intake set up. Currently, I have the air intakes mounted on the gunnels, just back of the house. The vents themselves are those cheap soft PVC things that look like they were intended to be used for a clothes drier or something. They are mounted atop some sort of cheesy dirty starboard piece. All in all, an embarassment to any person that actually cared how their boat looked.

So, I'm planning to change those at minimum. But, if I'm painting, now is the time to do side intakes. Thus, the questions for the Faithful are as follows:

1. Any downsides to side intakes?

2. Who has good molds/pre-formed side intake units that might work for this application?

3. My painter tells about some dude on Lake Buchanan that has some. I think he means Captain Pat. Is that true? Pat, you got some rocking units here?

4. Any lessons learned that the Faithful could share on side intakes?

Thanks.

IRGuy · Post by **IRGuy** » Sep 2nd, '11, 10:10

Drop me an email with a phone number and I will call you and discuss the air boxes I just installed on mmy B33.

Frank B

IRGuy@aol.com

JohnCranston · Post by **JohnCranston** » Sep 2nd, '11, 11:15

Ernest,
Next time you're down in Freeport, go look at my boat which is across the street from Noe's. I have Capt. Pat's air boxes installed.
John.
713-906-0842

Mikey · Post by **Mikey** » Sep 2nd, '11, 14:35

HL
I installed Pat's early side vents which require cutting holes in the side of your love. This was the first major job I tackled when redoing Dreamsicle. Lost my deodorant but they came out great! His new ones are easier to install. No fairing. Look at the regular site under projects. Other than more air for diesels the reason I got rid of the factory units (and the stand-up cleats) on the gunnels was to get rid of anything that would catch a toe or shoe while running up forward. Added disappearing cleats. Very Nice.

bob lico · Post by **bob lico** » Sep 2nd, '11, 21:03

mikey don`t you missed catching the stock cleats between your toes while you have your eyes on the poles to rope up.? uh the cursing and swearing i don`t miss that situation. should be first job on all 31 bertrams remove mid ship cleats and replace with fold down or pop ups and take off those ridiculous gunnel air vents!!!----absolute crap!!

JohnCranston · Post by **JohnCranston** » Sep 3rd, '11, 00:09

Mikeyand Bob,

Amen...clean up that space with pop up cleats.

Mikey · Post by **Mikey** » Sep 4th, '11, 10:36

Broke toes racing blow boats. Not fun!

matt · Post by **matt** » Sep 4th, '11, 20:56

This is what I did on my 28. 6"pvc pipe and elbow to make a mold. I then followed Capt Pat's insructions and recommendations to fab up the baffles. Faired and painted with Sterling two part pu paint.

Capt.Frank · Post by **Capt.Frank** » Sep 6th, '11, 19:25

Any pictures of thr process of making the vents?

bob lico · Post by **bob lico** » Sep 6th, '11, 21:34

about ten years ago i had some time to burn i should say experiment. i took 50 or so pieces of yellow caution tape cut into strips 1/2" by 3" and tape the ends all over the boat to see best place for forced or turbulent air could be use as air intake. i took 31 Bertram fbc. up to 19kns. to observed test strips . the bad news is the worst possible place to take combustion air in is where Bertram place those two bit backward vents on the gunnel. the best would be a scoop at front windshield to deck but that`s not feasible, then i realize if i could utilize the "station wagon effect" coming off the brim of the bridge as well as the pillars hitting the cockpit deck and causing accelerated air to form a forward turning circle . i could then force that air through a giant D shape leading to the turbo`s actually picking up upwards of 3hp free. the rest is reality however trust me the gunnel vents are the worst souse of air and way to small, actually useless in terms off diesel combustion air and in the worst possible place for entry/exit and fishing .

Raybo Marine NY · Post by **Raybo Marine NY** » Sep 7th, '11, 06:12

Bob- I always thought the rear facing cowls were to let air out not in?

Not to step on Capt Pat's toes but we made a set of molds for Pursuits since these particular vents are no longer available from Pursuit and people broke and lost them (due to how they were fastened to the hull not the design )

I got the idea of them working for a B31 after looking at the Pursuit and the B31 side by side figuring its a simple way to get rid of the chrome toe stubbers. They are a drop in for the hull, meaning no fairing or paint/gel work required. They are not as large as some of the ones pictured.

I made the molds after 2 people had called me looking for these vents and of course since I made the molds the calls have stopped coming in for them and I have yet to make a set even though Pursuit knows I have the molds now. Im told the original molds were destroyed in a storm or fire or something along those lines.

If anyone was interested in a set a portion of the sale would of course go to the board.

bob lico · Post by **bob lico** » Sep 7th, '11, 07:23

robbie actually when the 31 bertram was first made it had hoses leading down to bilge with blowers in line to remove possible heavier then air gasoline fumes but the hoses deteriorated after a shot time and no longer were used the way bertram intended however they had to comply with CC regulations .so now we have backward scoops then actually let hot air out of engine compartment rather then cool fresh air in because hoses are cut off flush for the most part. the warm air rising with exceed cool air entry and engine are forced to suck in air thru floorboards and bilge. a reverse scoop only works when facing a 45 degree angle wall such as the 1967 corvette big block air induction hood facing the windshield other then that all scoops face forward on high performance boats so remove scoops and install side air induction or cockpit reverse force air induction. bring cool air for combustion and hot air exits thru rod holder places along side engine box that takes hottest air from top of engine box and holds rod for long rigger.

Carl · Post by **Carl** » Sep 7th, '11, 07:29

I guess this is another "one up" for the Express Cruiser.

The sides of the Express Helm are Air Cowls forcing air down into the Motor Box area. The hole for Air Flow is not big enough for Diesels with any good amount of HP...but for my ol'trusty 440's they are plenty big. When the day comes to convert too Diesel all I have to do is enlarge the holes. Although the side intakes are attractive...

John C · Post by **John C** » Sep 7th, '11, 09:20

Rob do you have a picture of the vents? Looking for a set of side air intakes. Need to get more air in. Pats wont fit for this vessel

In Memory Walter K · Post by **In Memory Walter K** » Sep 7th, '11, 09:42

My boat originally had 440 Chryslers. It came with 4 chrome side scoops (2 on each side) taking air in, and 4 chrome flat clamshells facing backwards connected to hoses and blowers getting fumes out. The scoops on mine are inobtrusive and impossible to replace.

Rawleigh · Post by **Rawleigh** » Sep 7th, '11, 11:04

My '66 (original) has two facing forward and two aft. Forward ones are near the cabin pillar, facing forward with the blower and hose to the bilge attached to them. The rear ones are just forward of the hawse holes, facing aft.

Raybo Marine NY · Post by **Raybo Marine NY** » Sep 7th, '11, 20:06

John C wrote:Rob do you have a picture of the vents? Looking for a set of side air intakes. Need to get more air in. Pats wont fit for this vessel

i have pictures at work, these came on the 30 pursuit, I repaired a set and splashed a mold for them figuring they would be a nice drop in for smaller boats and also hoped to sell at least one more to someone.

Made a pair of molds and of course never made another one, lol

John C · Post by **John C** » Sep 8th, '11, 01:41

post a close up if you have one...also need the dimensions. Thanks

DavidDW · Post by **DavidDW** » Sep 27th, '11, 01:59

Hi Bob - every time I see your boat I am blown away.

With regard to the engine air intake, can you please confirm that the air is being sucked through the teak grilles on the outside of the engine boxes?

If so, how do you avoid saltwater splash and how do the grilles drain out (It looks like there is no way for water to drain out at deck level).

I hope that makes sense.

Thanks for your help.

bob lico · Post by **bob lico** » Sep 27th, '11, 08:35

look at the photo closely , where the end of the engine box meets the side panel is the location of the bulkhead . you cut a backwards capital " D" leaving only 1/2" of material at top and bottom and full width from hull to inside edge of spacer that is the f/g piece between engine cover and gunwale.now you have a giant D shape cut out leading to the turbo intake.the teak panel is for show and is 12" forward of the D cut out.this a completely dry area shielded by engine cover,hull side and gunwale only wash down with hose may let water in this space for that this is a drain. air rolls over bridge brim, over engine cover, and around pillar as boat goes forward air goes thru teak panel and accelerates thru "D" the venturi effect like every high performance aircraft air intake since the P-51 mustang .the teak panel is not needed and i run without it when water conditions allow 32knot running speed.the coolest air and least amount of salt air mist enters engine compartment low and forces hot air out rod holder hole at top rear of engine compartment .

wmachovina · Post by **wmachovina** » Sep 27th, '11, 12:34

Don't have em, don't want em and I know I'll get blasted ,,,, don't need em. 250 cummins no intakes except holes thru rod lockers, and hatch etc. I do have two steps that open a big hole between engine boxes when I run long distances in the heat. At cruis there is no noticeable change in engine performance with the engine box completely open. Now with stbd engine at 1500rpm and above the 3.5 next gen does soot up the exhaust. The upside is no moisture in the engine cmprtments. There is a lot of leakage. The plan was to try itnand if a problem showed to deal with it. I have to say no holes works ok so far. Bill, now let the blasting commence.

Rawleigh · Post by **Rawleigh** » Sep 27th, '11, 16:29

I am going to step into the flames with you Bill. A 6.7 liter diesel is 408+ CI. Does a 408 running at 1800 RPM use more air than a 440 turning at 3000RPM's? Maybe it is a heat issue? Educate me please!

wmachovina · Post by **wmachovina** » Sep 27th, '11, 17:16

I'm sure my 5.9s use more air but when I put them in we canceled the idea of vent on my yard's advice, with the intent of evaluating the performance, no noticeable visual(smoke) or egt difference. A hundred mile leg from Walkers to Stuart with 86 degree water and 90 degree air was no problem. Bruce chime in. We are reevaluating as I did see blackened sooty generator exhaust with the port engine at 15-2000rpm,the engine was hogging air. I have some ideas for more air but it really doesn' t seem necessary at MYOPERATING PACE emphasis mine. Usually 20 -21 kt cruise at 2000rpm. Offshore here I don't/can't run 32 so the air requirements are met. With no water /mist ingestion,dry engine room. Your performance may vary :-D

wmachovina · Post by **wmachovina** » Sep 27th, '11, 17:24

Kind of given the thought of some flapper vents on the aft side of the engine boxes for high air demand cruise, hinged vent/ door would open under high demand/as opposed to haven the Mrs open my step vent ( keep it simple)

Pete Fallon · Post by **Pete Fallon** » Sep 27th, '11, 22:17

Bill,
I wouldn't add any side vents, don't you have a blower set up on the generator intake box already, why don't you add a higher capacity blower motor or a scoop under the port gunwale to get more aif flow into that engine box. Just an idea.
You sound like your pretty happy with the 5.9's. Met a friend of yours last week, I was doing a survey on a house boat at Stuart Yacht& C.C. and the owner's son Jim Ford was running the boat for his dad. He said to say hello to you and the mrs. Going in for more knee work in Friday morning.
Pete Fallon

AndreF · Post by **AndreF** » Sep 28th, '11, 13:41

Damn, Pete, how many is that now? Must be a record.

Hyena Love · Post by **Hyena Love** » Sep 29th, '11, 12:30

I was operating under the impression (perhaps mistaken impression) that a significant noise source for a diesel boat is at the air intake location. Thus, placing them out board - like with side air intakes - would tend to reduce the noise levels in the cockpit. Similarly, moving them off the gunnels and into the cockpit itself would tend to increase the noise level in the cockpit. Open a flapper in the cockpit to allow airflow to my turbos, and you are going to hear some real loud turbo whine.

Looking at Capt. Pat's units, I'm thinking they might not be plug and play for a B28. Under my gunnels immediately next to the engines, I have a "shelf" (for lack of a better word) which is then divided about 2/3's of the way towards the rear with a short vert. bunkhead. Admittedly, I have yet to call Pat to discuss it in detail.

Good ideas all. Thanks for the input and the discussion.

JP Dalik · Post by **JP Dalik** » Sep 29th, '11, 14:26

Most of the noise from the B series engines comes from the front and top of the engine when below planing speed. At speed its mostly high pitch turbo whine.

Intaking air through the cockpit as Bob has done or for that matter as we have done is from a source a foot or so behind the engine and creating an air duct.

In our case there is more engine noise from not having gasketed the engine boxes from the repaint than there is from the air intake grills in the cockpit.

I would tend to believe that Capt. Pats have the best airflow through the complartments and would be the most quiet. We chose to pull air through the cockpit because we had the boat completely stripped and could build whatever we wanted, for others the cut ins may be the best choice.

Regardless of what you decide the engines need to breathe.

bob lico · Post by **bob lico** » Sep 29th, '11, 17:37

i just want to say i have taken 30 or more 31 bertram people for test rides at 5 rendezvous and so many visits at her home dock at oakdale yacth. one discussion that always comes up is how quiet the cockpit area is ,as a point of information it is quieter then 454 Mercruisers in a 1979 fbc. i don`t need the hull rendezvous crew to chine in so you just have to trust me on this one.i second jp`s statement they have to breath and if they don`t it will cost you in fuel economy.

bob lico · Post by **bob lico** » Sep 29th, '11, 17:48

this is at 34knots with about 11 adults,nobody with ear protection on having conversation notice where the water is breaking off the port and starboard ----------------31 bertram very dry boat compare to cabo express!!!!!!!!!!!!!!!!!!!!

wmachovina · Post by **wmachovina** » Sep 29th, '11, 18:22

Noise is not a problem with my engines. A little gear rattle at idle, like two fedex trucks in your driveway. They are much quieter than the 454 at all speeds. At cruise a nice unstrained conversation can be held in the pit. Just sayin the airflow seems adequate without holes in the side. I hate holes

DavidDW · Post by **DavidDW** » Sep 29th, '11, 18:41

Thanks Bob - I get it now!

Neat setup.

wmachovina · Post by **wmachovina** » Sep 29th, '11, 18:55

To track back, what a fabulous boat, you can fine tune performance to the max which is impressive, or just build the boat to do what you want. 230 gal diesel, 100 gal water, generator ,ac, hot water , 300 lbs of the mrs clothes, well maybe not that much.three weeks of food for two, three weeks of beer for me, three weeks of rum,tonic, 200# Of ice, run 600 miles in paradise, burn 300 gal of fuel, never get scared , catch fish eat conch, party in the biggest cockpitnin the marina, hey we are all lucky sobs!!!! Oh I took a bathing suit. The guy with the 41Viking didn't want To go because it burned too much fuel. Heh heh, awesome, enjoy your ride guys!

bob lico · Post by **bob lico** » Sep 29th, '11, 19:20

wmachovina i have no gear rattle because there is no drive plate with springs i have Vulcun drives with zf irm gears. what i don`t understand is rum and tonic, that is a unusual combination !!!

wmachovina · Post by **wmachovina** » Sep 29th, '11, 19:30

Well Bob, all those years stayin at the Sunrise motor in in Lyndhurst? And I never met ya, Mount Gay, tonic and a whole key lime, kind a drowns out the gear rattle

bob lico · Post by **bob lico** » Sep 29th, '11, 19:44

now i gotcha. i will have to try it. s&k was on route 109 lindenhurst but absolutely no was allow thru the secret passage into the the zul and bill meese experimental room/engine assembly. like a operating room in a hospital. when you became tired at night you breath in a little nitrous oxide!!!

DavidDW · Post by **DavidDW** » Sep 29th, '11, 20:29

Firstly, I need to apologise for my horrendous artistic ability.

Initially I was going to fit intakes in the sides of the hull much like Capt. Patricks but I preferred not to cut holes in the hull if I didnâ€™t need to.

The diagram below shows what I ended up doing for air induction when installing a pair of 6.354T 240hp Perkins.

2 x everything below.

Intake side:

The intake side was handled by installing rearward facing cowlings vents that are mounted up under the combings. The system is fabricated out of 9â€ fibreglass pipe. I cut the end of the 90 degree bend at 45 degrees and put a shield on the exposed section of the pipe to prevent water entering the system. I have mounted Delta-T 9â€ DC fans on the pipe in the engine room. Air is sucked/blown straight onto the turbos.

On the air out side, I fabricated a shroud and have mounted this to the cabin side to prevent water splashing into the engine room.

â€¢ Inside the shroud is a 6â€ piece of fibreglass pipe which goes through the deck.
â€¢ Iâ€™ve connected this to 6â€ exhaust hose that is in turn connected to a 6â€ fibreglass gooseneck I fabricated. If any water does come in, it drains out through the bottom of a gooseneck.
â€¢ From the gooseneck, the system goes through the front of the engine room bulkhead.

bertram31.com

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