Bilge blower
 

Guys,

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Bilge blower

I’ve got one of these bilge blowers on the port side, and only the one duct leading to the area outside the engine stringer on that side. It’s always kinda bugged me that it didn’t seem that it would adequately vent the bilge in a reasonable amount of time in the event we had a fuel vapor issue. In light of the recent catastrophic explosion in Florida, it’s been more on my mind. So I bought another one and intend to mount it on the starboard side and duct it from the same area on the starboard side and out the starboard vent, mirroring the port side. My question is, do we suppose it will be OK to just splice the wiring from the other side? Or should I run dedicated wires from the switch? It only draws 2.5 amps.

As a side question…. What’s the purpose of the other vent hose? It is connected to the vent port above the swim platform and hangs next to the bilge blower duct hose (there are two port holes on either side). The only “purpose” I can come up with is a supply of fresh air for the bilge blower to pull back out of the bilge, which is obviously not the purpose. Otherwise, I can’t really see why you’d want to direct fresh air almost below the engine.

Thanks. Brad.

I had a single blower on my Laser as you described. I added another and just spliced into the wiring. One switch turns on both blowers. Been a few years and no issues with switch/breaker/fuse.

Brad, most systems are designed to circulate air when under way. Using a feed and draw process.

The outgoing air is sourced in the lowest bilge area. Thr inlet air enters in the upper portion of the engine bay. The engine(s) will be drawaing a lot of CFM in the engine bay.

I like to use the 3" race car brake ducting hose. Same concept as the marine wire plastic style, just more resistant and reliable. It isn't that expensive.

Generally, the bilge blower fans are not very high quality. Chenge them often. Same with the bilge pumps.

The blower should have voltage and amperage draw on the tag. Check what size your wiring is. If it's not sufficient, you can use it as a feed to a relay, that switches fused power from the batts.

Something like that.

Tartilla,

So the second duct hose is for outgoing air? Fair enough. But I’m thinking of the Checkmate that Saris built the engine for, where they had the sundeck propped up on a block of some sort and ratchet strapped down, trying to feed more air to the engine at WOT.

What’s there now is 4” ducting. I bought a length of the same for the other side.

That bilge blower seems to be pretty durable. It appears to be the original unit, 22 years and counting. I ordered the same one. Hoping it’s still the same quality. Specs show it draws 2.5A.

Thanks. Brad.

Liberator221,

Did you just splice into the wiring at the existing blower? What I’ve currently got is a stalk of wiring, with about 2” of exposed wiring branches off, leading to the bilge blower. It may actually be easier to just run a tandem 12v from the switch at the dash, and ground it to the strap at the transom. Just curious how you did your wiring, specifically.

Thanks. Brad.

Don't remember for sure Brad, and the boat is not home right now. I think the blower was just wired with butt connectors, so I cut it out and jumped in there with another set of wires to feed the addditional blower then went back with butt connectors.

Your oem second hose that goes from the swim platform to the bilge area is there so if water gets splashed into the vent, it will drain down into the bilge and not get water on anything you wouldn't want it to be. They gotta make it ready for salt water use.

Mirage,

I would LOVE to agree with that, but there are two wide open vent ports mirrored on the starboard side with no hose at all. I'd think that, if PQ was going to go to that effort (they cut a hole in the inner gunwale for it), they'd have probably done so on the starboard side, as well. Also.... While you might be right, it would appear it was unnecessary to have gone to the trouble. To my knowledge, we've never gotten washed over enough to get water in the bilge; we literally NEVER have water in the bilge unless we get caught out in the rain (or some dumbazz forgets the drain plug.... again:picard1::faint2:).

Thanks. Brad.

I have two blowers in my boat with one switch, 12awg. But like Tortilla said get a relay and then you do not have to worry. I Used these on my little boat and they seem to work great, much better √outage to the accessory, why run current through a small switch.

While at it change to some good blower hose, those factory ones suck, you can see where yours has tears.

I`ve had vented hatches and would use the blower wiring for underwayter lights at 2 amps x 2 = 4 amps .
No issues.

I don`t understand your vent tube routing so.. you don`t have one IN (under engine generally) and another OUT to outside the boat?

Dan,

Pardon the mess. It’s a construction site, after all.

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There are two of these on either side. The two on the port side have vent hoses connected on the underside of the gunwale, the outer one going to the bilge blower, and the other going to the bilge, outside the engine mount stringer. The two on the starboard side are just open to the engine well. I plan on venting the new, second bilge blower through the outer vent port on the starboard side. The inner one will remain open, I guess, as I don’t intend to blow another 4” hole through the inner gunwale like it is on the port side, and it’s a bit tight between the outer hull and the inner gunwale (I’d assume that’s why they cut the hole in the port side.

I will have to do something about those wires, though. Don’t think I ever noticed them before. I must have unsettled them during all the rummaging around redoing things in the engine well.

Thanks. Brad.

I've added a 2nd blower to both my Bajas and after reviewing the amperage draw (less than 4 amps each) I too just spliced into the existing wiring. No problems on either boat. I also like the fact it is pulling in twice the air now, from a CFM perspective, for the times when I am idling around. IMHO it definitely keeps the engine bay cooler.

Bajaman,

Looking at all my options, I think I am going to splice in at the output of the switch and run a 12v to the new blower, then ground to the strap at the transom. It will still be a total 5A through the switch (well below threshold), but I won't have to dismount the old blower or cut into its wiring.

I also like the idea of increased evac during idling, helping to cool the engine well after running. Bonus! :cool:

Thanks. Brad.

Those 4" blower are 235 cfm, even with two running that`s not cooling off a big block after a hard run one bit or cooling off a bilge. That big block is consuming 850cfm and it has to pull that from the outside, and extra 470CFM isn`t doing much.
I wouldn`t bother but if it makes you sleep at night go for it .. can`t hurt I suppose.
I raise both hatches when I fill , you don`t?
That boat in florida had to be FILLED with gas somewhere , that explosion isnt fumes.
Someone must have smelled that and did nothing about it imop

Dan,

My primary interest is in evacuating the bilge more thoroughly without exceeding a reasonable amount of time. The additional, even if minimal, cooling of the engine well is only a bonus.

No. I don’t lift any hatches when I fill. I’ve never once smelled fuel vapors. The beauty of fuel injection over carbs. If I start smelling gas, I’m gonna start looking for leaks.

Oh, no. That was absolutely fumes. Fuel burns. Vapors explode. A full propane tank will burn your house down. An empty one will blow it off the foundation and scatter it across the neighborhood. You are not wrong, though. Somebody had to have smelled fuel vapors. Or maybe they didn’t. It was a pretty good sized boat. There’s at least a halfway decent chance it was what they considered normal. I’ve smelled gas from literally every carbed engine boat I’ve ever been on or near. Never seen one go off like a grenade like that, though I’ve heard some stories. My bet is they either neglected to run the bilge blower or didn’t realize it wasn’t working. And it’s an almost certainty at least one of the electrical components either wasn’t a marine-ready unit or had gone sideways. Something acted as an ignition source. There’s undoubtedly a pile of lessons to be learned from the forensics of that incident. My takeaway was to ensure I am adequately evacuating my bilge by adding a second bilge blower and drawing from both sides.

Thanks. Brad.

fuel fill hoses are supposed to be changed after 10 years i,m shocked at how many leak or are cracked on bends the hose has a date on it

Boost,

Scary thought.... I'm 100% certain the hoses in our boat are OEM. Same for the '90 Rinker we sold to some friends when we bought the PQ.

I'm not concerned with the hoses. They appear to be in great shape. Would be an opportunity to convert to a tank return for the fuel delivery system, though.

Thanks. Brad.

There was a gas leak somewhere is my point .. a lot of gas fumes require a lot of gas but I`m not a fire fighter .
Fuel injection or carbs if you have a fuel leak doesnt matter .. I make it a habit to have hatches open when filling. also after a hard run., also before leaving .. pretty much the hatches are open a lot lol

The nose is the #1 defence for many marine issues. Gas fumes being top of the list.

I'm looking into bilge fume monitors, but that is only a backup to good drills and procedures.

I prefer the 3" ducting hose. It keeps air velocity higher. The brake ducting is fairly smooth inside as well as being heat resistant.

How many guys have removed their old fuel tanks and found all the old foam was fuel saturated?

A leaking gas tank filled up the bilge and then the ac sucked it into the cabin while we were sleeping . was so bad it woke us up , felt like we swallowed a gallon of gas.
Thinking back , we got lucky .

Yup. I keep a pretty keen nose. All I smell is something that reminds me of my time at a fiberglass injection molding plant almost four decades ago.

The fact that we have FI keeps me from becoming anesthetized to the smell of gas fumes like I was prone to with the Rinker. The carb just emitted a constant smell of gas. Still does. If I let myself get freaked out by the smell of gas while we owned that boat, we’d have never used it. That’s why I pointed the FI out. If I smell gas now, I know we have an issue, and I’m not gonna blow it off as “normal”.

i don’t believe the velocity in the vent hose makes a difference. It’s just a matter of CFM, and that’s determined by the blower. I would agree with the smooth ID thing, though. But it’s not as flexible, is it?

Thanks. Brad.

The lines are too short to affect velocity.. over a longer length it would become an issue.
The smaller line may actually create more back pressure straining the motor but then again I believe the lines are too short for it to matter .