Bilge ventilation

[boots]

Hi,

 

we have just acquired our first boat (3 year old, 57' narrowboat), and one of the 'issues' we have is that there does not appear to be any ventilation into the cabin bilge.

 

Was going to address this by

 

i) cutting a hole (and fitting a vent cover) in the bottom of a cupboard towards the rear of the boat (as well as similar where-ever I can elsewhere on the boat, albeit out-of-site)

 

ii) cutting a hole behind the fridge and fitting a fan to draw air from within the bilge (powered from the fridge)

 

Was just wondering what do other people have? How much ventilation is adequate?

[soldthehouse]

Hi,

 

we have just acquired our first boat (3 year old, 57' narrowboat), and one of the 'issues' we have is that there does not appear to be any ventilation into the cabin bilge.

 

Was going to address this by

 

i) cutting a hole (and fitting a vent cover) in the bottom of a cupboard towards the rear of the boat (as well as similar where-ever I can elsewhere on the boat, albeit out-of-site)

 

ii) cutting a hole behind the fridge and fitting a fan to draw air from within the bilge (powered from the fridge)

 

Was just wondering what do other people have? How much ventilation is adequate?

Any ventilation no matter how small will provde circulation which will move air 24/7 and youd be amazed how much difference even the smallest amount of airflow does...

[Keeping Up]

cutting a hole behind the fridge and fitting a fan to draw air from within the bilge (powered from the fridge)

This will make your fridge a lot more efficient; I fitted a small computer fan to mine last year.

 

If it's a Shoreline fridge there is a terminal provided specifically for that purpose, which will drive the fan only when the fridge motor is running. I do have a slight issue with the noise level though; even though ir's the quietest computer fan I could buy in Maplins, it is still quite audible - and because I made the mistake of getting a brushless fan, it is not easy to reduce the voltage to it which would make it quieter, so with hindsight I'd say get two 12v fans with brushes, and connect them in series behind the fridge.

[RLWP]

Hi,

 

we have just acquired our first boat (3 year old, 57' narrowboat), and one of the 'issues' we have is that there does not appear to be any ventilation into the cabin bilge.

 

Was going to address this by

 

i) cutting a hole (and fitting a vent cover) in the bottom of a cupboard towards the rear of the boat (as well as similar where-ever I can elsewhere on the boat, albeit out-of-site)

 

ii) cutting a hole behind the fridge and fitting a fan to draw air from within the bilge (powered from the fridge)

 

Was just wondering what do other people have? How much ventilation is adequate?

 

To give the other extreme.

 

Our 20 year old boat has no bilge ventilation and a dry bilge. Based on that "none-at-all" is adequate

 

Richard

 

However, it can't hurt if you want to provide some

[barge sara]

ii) cutting a hole behind the fridge and fitting a fan to draw air from within the bilge (powered from the fridge)

 

If you cut a fair sized hole or drill several say 2" diameter in the floor and provide sufficient space at the top of the frdge for airflow to escape, the warmth from the fridge radiator will drive a convection current without fitting a fan.

 

Edited to add:

You could do the same behind other heat sources such as the SF Stove and the cooker.

Edited March 2, 2010 by barge sara

[XAlan W]

This will make your fridge a lot more efficient; I fitted a small computer fan to mine last year.

 

If it's a Shoreline fridge there is a terminal provided specifically for that purpose, which will drive the fan only when the fridge motor is running. I do have a slight issue with the noise level though; even though ir's the quietest computer fan I could buy in Maplins, it is still quite audible - and because I made the mistake of getting a brushless fan, it is not easy to reduce the voltage to it which would make it quieter, so with hindsight I'd say get two 12v fans with brushes, and connect them in series behind the fridge.

 

Motor caravan dealers should stock or be able to get a kit that fits behind a 3 way fridge. it`s a 2 fan affair with a small control unit +thermostat, You can have it running all the time or cutting in/out via thermostat but you could rig it differently with an electric fridge, it can be had in either 12 or 24 volt.Over here in France all the camping car dealers carry them, in summer it`s a must to keep the fridge working properly when using gas

[luctor et emergo]

You might want to invest in one of those 'drill depth limiter doodats' that stop you accidentially ventilating your bottom plate...

 

 

[boots]

You might want to invest in one of those 'drill depth limiter doodats' that stop you accidentially ventilating your bottom plate...

 

 

oops! a water cooled fridge wouldn't be the best approach. - Guess proceed with caution will have to be the order of the day. thanks for the reminder - that is one lesson I wouldn't want to learn through hindsight.

 

Thanks for the comments everyone,

[capnthommo]

oops! a water cooled fridge wouldn't be the best approach. - Guess proceed with caution will have to be the order of the day. thanks for the reminder - that is one lesson I wouldn't want to learn through hindsight.

 

Thanks for the comments everyone,

 

maybe a good idea to get a 'forstner' bit. use on low speed (battery drill would be good) only. they are very short in length and are used for eg drilling out for kitchen cabinet door hinges. they go up to quite large diameters.

here's one Link to forstner bits

they are pretty controllable at low speed. but still maybe a depth stop would be useful.

cheers

nigel

Edited March 2, 2010 by capnthommo

[luctor et emergo]

You may laugh, (no, you will.... ), but in my misspend youf I messed about with mopeds. As you do. A local fad was the addition of a winged eagle ornament for the front mudguard (ala Jaguar' ehh jaguar) I mounted one of these in a hurry, and remember distinctly thinking that I 'should be carefull, less I drill through the mudguard, into the tyre...'

 

 

yes, I did.... :lol:

 

 

still, it was easier to patch a punctured tyre than a holed baseplate...

[blackrose]

To give the other extreme.

 

Our 20 year old boat has no bilge ventilation and a dry bilge. Based on that "none-at-all" is adequate

 

Richard

 

However, it can't hurt if you want to provide some

 

I agree. Could the OP please tell us the state of their bilges - is it damp down there?

 

 

 

You might want to invest in one of those 'drill depth limiter doodats' that stop you accidentially ventilating your bottom plate...

 

 

 

A 3 year old boat probably has a 10mm baseplate. If your drill goes through the wood floor and happens to hit the baseplate you don't even need to worry about it.

 

Anyway, you've probably got a couple of inches of concrete slab between the floor and baseplate.

Edited March 3, 2010 by blackrose

[luctor et emergo]

I agree. Could the OP please tell us the state of their bilges - is it damp down there?

 

 

 

 

 

A 3 year old boat probably has a 10mm baseplate. If your drill goes through the wood floor and happens to hit the baseplate you don't even need to worry about it.

 

Anyway, you've probably got a couple of inches of concrete slab between the floor and baseplate.

 

 

Probably... that is an excellent margin to count on... drill away...

 

[blackrose]

Probably... that is an excellent margin to count on... drill away...

 

 

Drill away indeed. We are talking about a boat made of steel aren't we - not one made of cheese? Even if the boat only has a 6mm basplate (highly unlikely for a 3 year old boat), you're not going to risk putting a hole through it by accidentally hitting it with a wood bit on a drill!

 

I've cut holes for all my skin-fittings, chimeys & vents and I know it takes a fair bit of effort even with good quality drill bits.

 

Likewise, most boats have ballast under the floorboards - it would be a bit uusual not to have any. I had to smash mine with a lump hammer and cold chisel to break up the ballast in order to get it out of the hatch I'd cut in the floor. Even then wasn't worried about the baseplate

Edited March 3, 2010 by blackrose

[boots]

Hi,

 

you guessed correctly - our base plate is 10mm, and as for the state under the floor - don't know yet until I cut that first hole - that's part of my incentive, just to check what the condition is like.

 

To be honesst, I am expecting to find some water - no real reason. Thoughts were to 'drain' any water - probably by soaking it with a mop (if volumes allow), and then introducing the ventalation.

 

At one point, was thinking about intoducing something like waxoil down there, but then gave up on the idea - condisdering the lack of access I would have, and the obstruction from the ballast etc. can't see would be able to do anything that could make any difference.

[Old Son]

I dont see how a computer fan can circulate air throughout a dry bilge when it is probably full of ballast. I doubt it would have much chance if the bilge was empty! It might help in the 'local' area but moisture will be laying on the bottom plate (if there is any) so how will the air movement reach it? You are talking about a space 30+ foot long and 6 foot wide. Sounds like a bit of a waste of time to me.

[blackrose]

I dont see how a computer fan can circulate air throughout a dry bilge when it is probably full of ballast. I doubt it would have much chance if the bilge was empty! It might help in the 'local' area but moisture will be laying on the bottom plate (if there is any) so how will the air movement reach it? You are talking about a space 30+ foot long and 6 foot wide. Sounds like a bit of a waste of time to me.

 

You're kind of right. If the ballast is laying directly on the baseplate (or on bitumen soaked cloth on the baseplate), any water which gets down there invariably becomes trapped under it. Broken concrete slabs tend to act a bit like sponges - at least on their surfaces. However, if the majority of water is removed the rest will eventually dry out, but it can take a long time. After my bathroom sink overflowed I cut a number of inspection hatches along that side of the boat and removed the ballast to dry it all out (pig of a job!). The second time it happened I couldn't be bothered and just got most of the water out with a wet/dry vac. I inspected it about a year later and it was bone dry down there. A limited amount of water will contain limited amounts of oxygen and so corrosion of the baseplate will also be limited.

 

I'm sure ventilation would help, but as you say the effects will be local and so i don't think it's as critical as many seem to think.

 

I cut hole for a bigger skin fitting since then and used a bigger hose for that sink waste, so it can't overflow again when I have another early onset of a senior moment and forget to turn the tap off!

Edited March 3, 2010 by blackrose

[blackrose]

Hi,

 

you guessed correctly - our base plate is 10mm, and as for the state under the floor - don't know yet until I cut that first hole - that's part of my incentive, just to check what the condition is like.

 

To be honesst, I am expecting to find some water - no real reason. Thoughts were to 'drain' any water - probably by soaking it with a mop (if volumes allow), and then introducing the ventalation.

 

At one point, was thinking about intoducing something like waxoil down there, but then gave up on the idea - condisdering the lack of access I would have, and the obstruction from the ballast etc. can't see would be able to do anything that could make any difference.

 

The way I cut my inspection hatches was drilling 4 holes (say 8-10mm dia) in the corners of where you want the hatch and then just connecting them with a jigsaw. Make sure that your hatch isn't crossing any bearers which are generally 2ft apart. So your hatch goes between the bearers. Look for where they've screwed the floor down to see where your bearers are.

 

If you have a good gap between the underside of the floorboards and the ballast you can just use a regular wood cutting jigsaw blade. If not, then the jigsaw blade will hit the ballast underneath and it's not a very nice feeling when you're trying to hold the jigsaw and it jumps out of your hands! In that case you're going to have to either find a short blade or use a couple of pairs of pliers to snap a blade short. PROTECT YOUR EYES - USE GOGGLES TO DO THIS.

 

If you can cut the connecting lines at an angle you will be able to use the bit of floor you've cut out as a hatch cover by just putting it back in place. If not then you'll have to use a few wooden or plastic spacers to rest it on.

 

If it's anything like mine sods law means the hole you've cut will not be big enough to get the ballast out and you'll need a lump hammer and a cold chisel to smash the large slabs of ballast to get it out. In the end I was just using the hammer directly on the ballast, but mine was 2 layers of broken slabs. Again use goggles for this.

 

A wet/dry vac is the best way to get the water out.

Edited March 3, 2010 by blackrose