bilge blowers

Bertramp · Post by **Bertramp** » Oct 30th, '13, 12:41

Well...finaly the deck is up and new supports and bulkheads being installed with a new forward deck (bahia mar) being made from COOSA.
Deck aft of engine boxes will be a Glasstech (B.Lico version)
Question ... for you gassers out there (like me) ... how do you have your bilge blowers set up and what brand and size are you using ?
Thanks

Rawleigh · Post by **Rawleigh** » Oct 30th, '13, 13:11

I still have the originals that screw to a pad epoxied to the side of the hull over the outlet! LOL! I like that style if you can still get it.

PeterPalmieri · Post by **PeterPalmieri** » Oct 30th, '13, 13:35

Mine are same as well with dryer vent type hose going into the bilge

Pete Fallon · Post by **Pete Fallon** » Oct 30th, '13, 21:05

Steve,
I used Attwood 4" blowers that are mounted under the side deck near the stainless steel scoops (one facing forward and one facing aft). Used 4" plastic and wire flex hose I got at Chapman's Marine Supply here in Stuart. Forward facing scoop is for fresh air that leads all the way down under the engines, the aft has the blower attached and discharges aft. The 4" Attwood's are 4000 CFM air flow. I also still have the original vent in the middle of the transom, that's the one that comes up from the aft bilge area and natural flow out thru the vent screen in the middle of the transom, a sort of natural venturii set up. It is a 6'' x 1" fiberglass vent glassed into the inner transom it starts just below the wooden shelf that holds the cockpit sole in place , it's only a thin section of glass.
Pete Fallon

Craig G · Post by **Craig G** » Oct 30th, '13, 21:58

Hi Steve, mine are screwed into bulkheads next to engines inside the cockpit panels. They are mounted vertically with the inlet (suction) facing down and outlet (blowing) up. There is a hose under the engine attached to the bottom of the blower, and the hose attached to the top of the blower goes aft to the square looking chrome bezel that faces aft. I have two chrome intake scoops on each side, but there are no hoses attached to them. I think those are just for the engines to breathe air for adequate combustion. I think my blowers are 4" and I got them at BOW or Sailorman. I am doing a cockpit restoration, so I have the panels removed now and can take pictures and text them to you. I would like to stop over and check out your progress. Maybe I'll swing buy in the boat and we can compare notes.

Bertramp · Post by **Bertramp** » Oct 31st, '13, 07:51

Thanks for the input guys.
Craig ... I'm around this weekend
BERTRAMP1@aol.com

Stephan · Post by **Stephan** » Oct 31st, '13, 09:26

Steve-
The group helped me with thinking about ventilation issues here http://bertram31.com/newbb/viewtopic.ph ... wer#p87394
The Jabsco flange mount blower is what I have. http://www.jamestowndistributors.com/us ... co+Blowers I bought a spare just so I would not have the pressure of deciding if I should use the boat with a blower inop. Of course, with that protection they have never failed me. The biggest Jabsco model I am aware of is 250 CFM and I note that the draw is 12 amps so you may consider sizing up your fuse and wiring if you step up to the higher flow models.
Best,
S

PeterPalmieri · Post by **PeterPalmieri** » Oct 31st, '13, 12:40

If I had to replace my blowers I would go with the quietest ones I could find. First off if you are out fishing the noise will drive you crazy. Second of all if your out and leaving the motors idle you can't really hear how the motors are running. I've actually jumped up on the bridge to move the boat only to find that one of the motors stalled out.

I used to only run the blowers before I started the boat, at the suggestion of a few folks on here I was convinced that it is a good idea to keep them running all day if the motors are running. I've followed that advice but I used to enjoy listening to the motors now all I hear are the annoying fans...

CaptPatrick · Post by **CaptPatrick** » Oct 31st, '13, 12:57

The quietest fans are generally axial fans...

Bruce · Post by **Bruce** » Oct 31st, '13, 13:53

blower noise other than actual air flow noise is from mounting without using an insulating rubber matte between the blower and wood and not using rubber grommets with the screws.

It won't take long for the unlubed sleeve bearings in those motors to wear and introduce a slight unbalance which transfers to the hull.

PeterPalmieri · Post by **PeterPalmieri** » Nov 1st, '13, 05:35

Thanks Bruce I will add it to my list.

Bertramp · Post by **Bertramp** » Nov 1st, '13, 10:35

The original that mounts on a block on the port side is shot. A makeshift has been in place and is what I have been using, but I want to replace with the orignal. I notice that you folks are saying "blowers" (plural) ....are you running one on each side ? ... is the original single not up to current code or level of "smartness"?
thanks

CaptPatrick · Post by **CaptPatrick** » Nov 1st, '13, 10:41

Steve,

OEM was a blower each side....

Craig G · Post by **Craig G** » Nov 1st, '13, 13:16

Steve, I would put one on each side. Maybe Sunday I will stop by in my Bahia Mar and show you how mine are. I think you will like that set up. Late morning/early afternoon will work for me with the tide to get under Federal Hwy bridge. I will call you before heading over. Got cold beer?

Peter · Post by **Peter** » Nov 2nd, '13, 00:23

Gasoline fumes sink in still air. If there was a gas leak or a source of fuel vapor into your bilge as the boat was sitting, the bilge would fill up with gas fumes from the bottom. If it filled to the level of the starter motors and you hit the starter switch...KA-BOOM!

So the blower is supposed to clear any fumes from the BOTTOM of the bilge before you start the engine.

But of course the blower has an electric motor and so could also be a source of ignition of itself.

Therfore blowers should always mounted as high as practical above the bottom of the bilge, so they would be out of any fuel vapors trapped down there. And it BLOWS air INTO the bottom of the bilge through a vent hose that leads to the bottom of the bilge area, or at least somewhere below the starter motor level.

Blowers never suck air out of the bottom of the bilge. Never ever... they BLOW air into the BOTTOM of the bilge.

The displaced air leaves via another duct which runs to the bottom of the bilge itself and exits through a deck vent facing aft. You do not want the fresh air being blown in to force any dangerous vapors up to get out, because this forces them to go up from the bottom of the bilge past things like the blower itself which supposedly could ignite them. The aft facing vent set up on this low outlet vent keeps this exit path from being a ram induction port when the boat is moving forward or anchored with its bow into the wind. It is also better to have this vent face aft because when the boat is moving or the bow into the wind this vent has a passive source of low pressure to help clear the bilge of fuel vapors that may have collected there.

There should be other vents which do not necessarily have any duct work attached to them which ventillate the upper areas of the engine compartment and provide intake air for the engines. These can face forward so as to also serve as ram intakes when the boat is moving forward or anchored so that the bow is facing into the wind.

Separate battery compartments are supposed to have thier own separate vents. CG reg, but I do not know of anyone who has ever been busted on this. However most boats which were built with separate battery compartments were originally built to comply and have separate vents.

It's all pretty crude and inefficient, but that is the throught behind the process.

DO NOT SUCK AIR OUT OF THE BILGE THROUGH THE BLOWER. BLOWERS BLOW. THEY DON'T SUCK

Much of this is just me stating the obvious to fellows who already know, but search engines on the 'net find this stuff and someday someone might find my comments to be useful.

Peter

PeterPalmieri · Post by **PeterPalmieri** » Nov 2nd, '13, 06:48

Interesting Peter I will admit I assumed my blowers sucked air up and out.

Bertramp · Post by **Bertramp** » Nov 2nd, '13, 12:57

CaptPatrick wrote:Steve,

OEM was a blower each side....

I have a "cutout" on port side that had a PAR 3" blower that was flange mounted. There is nothing on the starboard side.
Was mine a Friday afternoon boat or was the starboard side a different set-up ? Just curious ....

CaptPatrick · Post by **CaptPatrick** » Nov 2nd, '13, 17:52

Steve,

All I've seen are mirrow images port to starboard... Yup, you've got a FAB! ;)

Pete Fallon · Post by **Pete Fallon** » Nov 3rd, '13, 00:46

Peter P.
I beg to differ with you on blowers blowing air in. If you read the ABYC standards (AVAILIBLE ON LINE) H-2 Ventilation of boats using gasoline (section 2.6.3.2.4) ,"As installed the blower system shall EXHAUST air from the boat at a rate in accordance with the blowers system performance curve." The blower hoses should be in the bottom 1/3 of the engine compartment and intake and discharge hoses should be at least 15" apart. The hoses do not share the same phloem and should be no less than 2-1/2" in size. There can be more than 1 blower in each compartment but they must operate together when the switch is turned on. And there is supposed to be a label near the helm stating the operation of the blowers and how long the should be turned on for. The blower have to have a Underwriters Lab compliance sticker on them. Correct me if I am reading the code wrong.
Pete Fallon

CaptPatrick · Post by **CaptPatrick** » Nov 3rd, '13, 03:36

Pete,

You are reading correctly... The potential gasoline fumes must be EXHAUSTED, (i.e. sucked out of low lying bilge spaces and discharged outboard). Pumping fresh air in and depending on passive outflow of explosive vapors through a deck vent is marginal assurance of vapor removal at best. Also, "There shall be at least one powered blower for each gasoline engine used for propulsion" (ABYC 11-2.5.4.1)

UL rated fume exhaust blowers, properly fitted, will not pose a spark hazard. All vapors are collected through the hose(s), transported through the squirrel cage fan and exhausted outboard without contact to the space around the blower motor.

Navatech · Post by **Navatech** » Nov 3rd, '13, 03:39

Not to hijack the thread but what do the ABYC standards say about bilge blowers on diesel powered boats?!…

Never mind, I found it myself: http://www.abycinc.org/standards/purpose.cfm#H32" onclick="window.open(this.href);return false;. Actually, that's where you can purchase the standard. This is the actual standard: http://www.marinesurveyorschool.org/sem ... 0Boats.pdf" onclick="window.open(this.href);return false;

CaptPatrick · Post by **CaptPatrick** » Nov 3rd, '13, 03:54

ABYC recommends exhaust blowers for diesel powered boats to help remove carbon monoxide. However, the problem with CO is that it is just about the same weight as air and therefore doesn't concentrate in low spaces like gasoline fumes. What would be more effective would be a CO detector and keeping enclosed spaces well ventilated when engines are running, (including generator engine).

Craig G · Post by **Craig G** » Nov 3rd, '13, 10:09

I agree with Pete F. and Patrick. What is there not to believe as it is quoted from the regs. Blowing air in would increase the oxygen available for combustion and just spread the vapors around the bilge except for the small amount that would find its way out the exhaust hose without a fan. I'm keeping mine just like they are and will be in Bertramp's back yard later to show him my installation since my cockpit panels are removed.

Bertramp · Post by **Bertramp** » Nov 3rd, '13, 17:11

Just a note .... Craig and I met up and looked at the blowers.
His present set up is simple and seems quite effective.
My plan is to duplicate it.
On a seperate note, his boat also has only the port side 3" exhaust, but his present installation (not original) does not use it.

PeterPalmieri · Post by **PeterPalmieri** » Nov 4th, '13, 10:44

I'm glad this was clarified, First thing I did on Saturday when I went down to the boat was check the blowers.

TailhookTom · Post by **TailhookTom** » Nov 4th, '13, 10:47

Back in the old days when I had my 24 Albemarle with a single gasser, the first thing I did when I got on the boat was open the engine hatch all the way, the second thing I did was get on my knees and sniff around the engine, if it didn't smell like gas, then I would flip on the blower and after a bit of time start the engine.

Tom

Bertramp · Post by **Bertramp** » Nov 4th, '13, 13:31

Rawleigh wrote:I still have the originals that screw to a pad epoxied to the side of the hull over the outlet! LOL! I like that style if you can still get it.

That style is still available.
My question, what style 31 do you have ?
Do you have an epoxied pad and the vent hole one on each side.
Maybe they only did the one side install on Bahias ....

Peter · Post by **Peter** » Nov 4th, '13, 22:29

I am not sure where "exhaust" has to mean "suction."

As far as I know all "exhaust" means is that it forces the air or vapors out.

Exhaust on cars and steam engines do not suck. The spent steam or burned fuel vapors are blown out the exhaust.

It doesn't make sense to pull a cumbustable mix of air and fuel vapor through an electric motor.

Go ahead if you want to, but I'm sticking with my setup.

The rest of the reg is in agreement with what I stated.

Peter

CaptPatrick · Post by **CaptPatrick** » Nov 4th, '13, 23:10

It doesn't make sense to pull a combustible mix of air and fuel vapor through an electric motor.

The fuel vapors do not pass through the motor... on a squirrel cage exhaust fan all of the vapors are sucked into the fan body and forced out the exhaust port. The motor drives the shaft attached to the fan, but the shaft enters the fan body through a seal so no vapor escapes other than through the exhaust port.

The exhaust blower is mounted as high on the hull as possible and well above low bilge areas where gasoline fumes would accumulate. The suction hose lays in the bilge area and the fan draws the fumes into the fan body and directly overboard.

The only type of blower that could be said to pass the fumes over the electrical segment of the unit would be a axial inline fan, in which case the fan motor must be a UL rated ignition protected fan...

Peter · Post by **Peter** » Nov 5th, '13, 11:53

I'm not being a wise ass here, but if you read the regulation and mentally think of "Exhaust" as meaning "force the air and vapors out" instead of jumping to the conclusion that it has to mean "Suck the air out" my interpretation is 100% valid. Go ahead and look up the reg and see.

And my way you don't deliberately bring dangerous gasoline vapors straight to the known source of ignition.

Boats have pretty specific vocabulary. It isn't good enough to say "Left" or Right" we have to be unambiguous so we say "Port" and "Starboard." Why, when these regs were written in the first half of the last century, when it was difficult to get sealed electric motors, did they dub this thing a "blower" and not a "vapor extractor fan," or "bilge scavenger." It is because it is better if it blows fresh air in and forces dangerous vapors out.

If you had a gas tank that you had to cut open that FOR CERTAIN had explosive fumes in the bottom, and you only had two holes in the top of the tank and a shop vac, would you suck the air out or blow it out?

Just because most people would use the vac to suck the vaors out doesn't make it the smart thing to do.

Anyway, do as you please. If someone tells you to look for fuel leaks with a zippo lighter, or check for obstructions in the barrel of a gun by peering down the muzzle, and you are afraid people will laugh at you for doing otherwise, by all means, be my guest.

Anyway we can all agree that most people disagree with my version. I contend that just because they disagree with me it doesn't make me wrong.

Peter

CaptPatrick · Post by **CaptPatrick** » Nov 5th, '13, 12:06

Good description from another post, by another guy, on another forum...

Think of it as an exhaust hood over your stove/oven...it PULLS. You don't positively pressurize your kitchen to PUSH the smoke out...you directly remove it. As stated before...the fumes are heavier than air and will sit at the lowest point in the bilge. You MUST have the ability to draw them against gravity...up and out.

Rawleigh · Post by **Rawleigh** » Nov 5th, '13, 13:08

Bertramp wrote: That style is still available.
My question, what style 31 do you have ?
Do you have an epoxied pad and the vent hole one on each side.
Maybe they only did the one side install on Bahias ....

Steve: FBC. I know there is one on the starboard side, but I cannot remember about the port. I will have to check.

PeterPalmieri · Post by **PeterPalmieri** » Nov 5th, '13, 14:36

Peter,

I am not going to argue with you as I am just observing and learning. I took some time to browse the instruction manual on a number of bilge blower models. Each one clearly states that air is sucked from the lowest point in the bilge. In addition the mounting hardware is set up in the same manner. Seems pretty cut and dry.

Pete

Navatech · Post by **Navatech** » Nov 5th, '13, 15:43

Peter wrote:check for obstructions in the barrel of a gun by peering down the muzzle

Actually, that's a bad example as soldiers, hunters & gun owners around the world do EXACTLY that… Albeit AFTER making doubly sure the weapon is NOT loaded…

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