Jump to content

Creating positive air pressure inside the boat


blackrose

Featured Posts

How about an upturned bowl resting on blocks over your vents Blackrose?

In theory it will trap warm air before it escapes under the gap and sort of doing what you are trying to. May even help divert smoky air around also. Or maybe not.

Just a thought..

Link to comment
Share on other sites

Switch to an all baked bean diet, the smell of smoke will be the least of your odour problems.

 

Joking aside, are you sure it’s fumes from neighbours boats and not your own fire?

If your chimney isn’t that tall it could be wafting from there straight to your mushrooms.

Link to comment
Share on other sites

2 minutes ago, Hudds Lad said:

Switch to an all baked bean diet, the smell of smoke will be the least of your odour problems.

 

Joking aside, are you sure it’s fumes from neighbours boats and not your own fire?

If your chimney isn’t that tall it could be wafting from there straight to your mushrooms.

All this talk about baked  beans and mushrooms is making me hungry. Off to make a bacon butty now.😜😜

  • Greenie 1
Link to comment
Share on other sites

5 hours ago, blackrose said:

I'm getting quite a bit of smoke from neighbours' boats coming through my vents - well, not so much smoke, just the smell of it.

 

I know it doesn't bother some people but I really don't like it, so I was wondering whether I could create positive air pressure inside the boat by using a 12v bilge blower inside the boat attached to ducting, going through a sealed porthole which hangs down the downwind side of the boat outside about 6" from the water where the smoke never goes?

 

Would that positive air pressure inside the boat prevent smoke from outside from entering through my vents? 

I've been here, it was most unpleasant.

It might work and I think it is well worth trying.

My worry would be that you could end up with two air current loops, one in the front of the boat with smokey air coming in one of your vents and out of another further down the boat, and a second in from your blower and out of a stern vent.

I'd block off all the vents except one (gas, stove, etc permitting) and have a blower, but there would be a concern about the effect on your stove, and if your blower stopped for any reason.

Then there is the blower noise...

Link to comment
Share on other sites

1 hour ago, Hudds Lad said:

 

Joking aside, are you sure it’s fumes from neighbours boats and not your own fire?

 

 

Yes, I've been living on this boat with the same stove over the last 17 winters. I know when I'm at a mooring with smoke coming in from neighbours' boats

  • Greenie 1
Link to comment
Share on other sites

5 hours ago, blackrose said:

 

They're not causing displeasure or problems, it's just the nature of living on a boat in winter in a marina, in proximity to other boats.

Spot on its  a way of life 

Edited by Feeby100
Link to comment
Share on other sites

2 hours ago, system 4-50 said:

I've been here, it was most unpleasant.

It might work and I think it is well worth trying.

 

 

Thanks. I've ordered a couple of metres of flexible ducting so I'll give it a go and report back in a couple of weeks.

Link to comment
Share on other sites

6 hours ago, TheBiscuits said:

Having said that, if you have the bits just try it.  Can you temporarily tape the blower to a low level vent just to see what happens without buying ducting?

 

Could have done but then I wouldn't be drawing clean air. I need the ducting to get it down near the water under the pontoon on the downwind side of the boat. I sat down on the pontoon yesterday and the air was fine compared to when I stood up.

  • Greenie 1
Link to comment
Share on other sites

1 minute ago, blackrose said:

 

Could have done but then I wouldn't be drawing clean air. I need the ducting to get it down near the water under the pontoon on the downwind side of the boat. I sat down on the pontoon yesterday and the air was fine compared to when I stood up.

 

That sounds promising then.  Would something used as a wind deflector near some of the vents help in the meantime?

Link to comment
Share on other sites

2 minutes ago, TheBiscuits said:

 

That sounds promising then.  Would something used as a wind deflector near some of the vents help in the meantime?

 

I hate to admit it on here but I've already used duct tape to seal off the upwind side of the mushrooms leaving only the downwind side open. It's certainly helped, but when someone upwind chucks a load of coal on with the best will in the world it's not going to keep the smell out.

Link to comment
Share on other sites

What about using your bilge blower drawing air through an activated carbon filter to remove any smells...?  Might also work well in the summer to remove pollen...

 

I'm interested in your experiments, let us know how you get on....

Edited by Quattrodave
Link to comment
Share on other sites

I think this blower might be a bit too powerful. Can I use some sort of 12v load resistor to halve the fan speed? The blower takes a 6A fuse. Can anyone recommend were i should be looking for?

Edited by blackrose
Link to comment
Share on other sites

I wouldn't use a resistor to drop a fans speed, it will use the same amount of electricity, just turn the excess power into heat... a PWM (pulse width modulation) controller will turn on and off rapidly lowering the fan speed and also be adjustable! Will a computer fan be powerful enough?

Link to comment
Share on other sites

2 hours ago, Quattrodave said:

I wouldn't use a resistor to drop a fans speed, it will use the same amount of electricity, just turn the excess power into heat... a PWM (pulse width modulation) controller will turn on and off rapidly lowering the fan speed and also be adjustable! Will a computer fan be powerful enough?

Depends which computer fan you use and how much noise you can put up with. This one moves 270m3/hr or 160cfm at full speed which is quite a lot...

 

https://noctua.at/en/nf-a14-industrialppc-3000-pwm/specification

 

If the noise/airflow is too much, it can always be slower down by a PWM controller like this...

 

https://noctua.at/en/products/accessories/na-fc1

Link to comment
Share on other sites

2 hours ago, Quattrodave said:

I wouldn't use a resistor to drop a fans speed, it will use the same amount of electricity, just turn the excess power into heat... a PWM (pulse width modulation) controller will turn on and off rapidly lowering the fan speed and also be adjustable! Will a computer fan be powerful enough?

Twice the resistance half the current/Ah

Link to comment
Share on other sites

18 minutes ago, IanD said:

Depends which computer fan you use and how much noise you can put up with. This one moves 270m3/hr or 160cfm at full speed which is quite a lot...

 

https://noctua.at/en/nf-a14-industrialppc-3000-pwm/specification

 

If the noise/airflow is too much, it can always be slower down by a PWM controller like this...

 

https://noctua.at/en/products/accessories/na-fc1

Its going to need to be a lot to create a positive pressure with half a dozen 4" diameter holes in the roof and a couple of big louver vents near the deck  its going to need to be big, and don't consider opening a door. How much air goes up a chimney with the fire going, it has to supply that as well

Link to comment
Share on other sites

1 minute ago, ditchcrawler said:

Its going to need to be a lot to create a positive pressure with half a dozen 4" diameter holes in the roof and a couple of big louver vents near the deck  its going to need to be big, and don't consider opening a door. How much air goes up a chimney with the fire going, it has to supply that as well

All it needs to do is make sure that the net airflow everywhere except the fan is outwards, which needs very little pressure but it does need flow. 160cfm is -- as I said -- quite a lot, almost 3 cubic feet per second which is *way* bigger than what goes up a chimney.

Link to comment
Share on other sites

Well this is what I've done using a 12v computer fan (drawing 0.3A). I've sealed the pothole using kingspan and duct tape and also used masking tape over the low level vents at both ends of the boat as the fan is bringing in plenty of cold air from outside. The 4 mushrooms on the roof are still half open but I've taped over the sides facing the prevailing wind. 

 

I've used a 1amp fuse for the fan as that's the smallest I've got. Is that ok for a 0.3A fan? I know the position of the fuse isn't ideal but the 12v socket is fused. I'll figure out a better position for the fan, probably just hang it down from the window.

 

I don't know the volume of air moved by the fan but it's a lot more than is normally drawn in through the vents. Good job I changed my mind about using the bilge blower!

 

I got the 3" dia polyurethane ducting from eBay. I was surprised at the quality. It's very tough indeed. The end of the ducting outside sits about 5" above the water on the downwind side of the boat. There's no smoke down there.

 

IMG_20220114_134054.jpg

 

IMG_20220114_134100.jpg

 

IMG_20220114_134129.jpg

 

IMG_20220114_134146.jpg

Edited by blackrose
Link to comment
Share on other sites

4 minutes ago, blackrose said:

Well this is what I've done

 

I hope the water level doesn't rise ;)

 

 

 

 

 

 

 

(Joke, obviously)

 

 

 

 

Actually, do you need the fan?  If warm air is leaving via the mushrooms you might get the clean air drawn into the tube anyway.

 

I suppose the fan stops rats climbing up the tube so it's all good!

Link to comment
Share on other sites

3 minutes ago, TheBiscuits said:

 

I hope the water level doesn't rise ;)

 

 

On floating pontoons so everything will rise together.

 

Tonight should be a good test of the system. All 4 upwind boats will have their stoves going once they all get home from work. I'll report back with results.

Edited by blackrose
Link to comment
Share on other sites

Just now, blackrose said:

Tonight should be a good test of the system. All 4 upwind boats will have their stoves going once they all get home from work.

 

So what happens when they run their engines?  Put a CO alarm near the inboard tube end just in case ...

Link to comment
Share on other sites

35 minutes ago, TheBiscuits said:

 

So what happens when they run their engines?  Put a CO alarm near the inboard tube end just in case ...

 

That's true, hadn't thought of that. The only time anyone starts their engine in winter is on Saturday mornings when some go for pump outs. The boat on the other side of my pontoon isn't a liveaboard and they don't come very often in winter. I've got a CO alarm in the saloon but I'll put another one in proximity to the fan.

Edited by blackrose
  • Greenie 1
Link to comment
Share on other sites

1 hour ago, TheBiscuits said:

 

Actually, do you need the fan?  If warm air is leaving via the mushrooms you might get the clean air drawn into the tube anyway.

 

I suppose the fan stops rats climbing up the tube so it's all good!

 

Rats climbing up the tube! WTF? 😱 Perhaps I'll raise the end by a few inches!

 

Since I no longer have low level vents and have effectively halved the area of the mushroom vents I need to make up for the decrease in vent area somehow, so I don't think it would be very safe once my stove is going without the fan.

Edited by blackrose
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.