UFH - Sprayfoam Bilge

[system 4-50]

In the light of a recent topic on wet floors I thought I would report back as promised in April last year on my ambition to never get any water in my sprayfoamed bilge.

 

I have been completely successful. Apart from:

1. 2 pints via the rear hatch owing to my lining the hatch in such a way that rainwater could defy gravity and get in. Truly amazing to watch!

2. Condensation from the edges of windows that I haven't got around to lining yet. This was expected, I can only do so much immediately. I hadn't allowed for not noticing when it dripped on a stack of cabin lining materials and stained them.

3. Rainwater coming in through the end of hopper windows when closed! This only occurs when there is a strong wind coming at the window at a very specific angle and is due to the random nature of the foam that is meant to stop it. This is as the windows were supplied and though a tiny task, I have never got around to fixing it as I couldn't find the exact foam originally used. Now I have used whatever came to hand so no longer a problem.

4. Condensation on the underfloor crossmembers, whatever they are called. The sprayfoamers, though contracted to spray all the surfaces, skipped the difficult to get-at bits.

5. Condensation where these members rise up the cabin sides as I have removed foam to get the floor down.

6. Condensation on cabin side reinforcing members as per (4). The volume of this is truly amazing, as is its path. It can travel 12 feet or more with no trouble at all, finally making a puddle miles away from where it starts.

7. Rainwater coming in via the hatch runners. I don't have a banana boat (with an upturned stern) so this was also expected and requires special measures which I haven't got to yet.

8. Rainwaters coming in through the screw holes holding the screws that keep the windows on. I didn't seal them so it is not a surprise, and they do seem to work loose. This became much less of a problem after I drilled drain holes on the outside for the channels containing the rubber screw-covering piping to drain. They used to fill up with water right up to the top!

 

The total volume in the bilge has been small as far as I can tell. I can't inspect all of it.

 

None of my plumbing has failed but that is in part due to none of it having been commissioned yet.

 

Condensation is not a continuous problem and only occurs occasionally when weather conditions are right and probably when I am not aboard to take corrective action.

 

My next boat will have no hatch, no windows of any kind, and people will not be allowed to breathe once inside.

 

PS The primary reason for the sprayfoaming of the bilge was to support UFH (under floor heating) on which I have spent a great deal of effort and time, before concluding that my highly effective centrally mounted Puffin stove made it completely unnecessary, so I have abandoned it.

 

 

[Robbo]

 

PS The primary reason for the sprayfoaming of the bilge was to support UFH (under floor heating) on which I have spent a great deal of effort and time, before concluding that my highly effective centrally mounted Puffin stove made it completely unnecessary, so I have abandoned it.

 

 

I'm looking at using UFH, so I'll be interested in knowing what systems you've looked at.

[smileypete]

 

I'm looking at using UFH, so I'll be interested in knowing what systems you've looked at.

 

Spreader plates and Celotex type sheets might be worth a look:

 

 

cheers, Pete.

~smpt~

[system 4-50]

I decided that spreader plates etc were over-egging the cake and just looped a single length of JG bendy stuff up and down a total of 6 lengths of the cabin and brought the ends up in the bathroom.

On reflection I concluded that heating the pipework for short periods of time would increase condensation in parts not immediately adjacent to the pipework and that it was only suitable for steady prolonged heating. i had intended to heat it from an Alde 2928 and it appears that prolonged use of this device would use up gas too fast. I therefore decided it was not worth proceeding, particularly as the Puffin worked so much better than expected.

I had intended to look at converting a JG blending system (as the pipework temp shouldn't go above 50deg) to 12V or finding a way to provide 240V but I didn't get very far into that. See the JG website.

If in 2050, I am still around, (aged over 100), and I have not managed to sell my 2928, then I will come back to this but just for fun.

[RubyTuesday]

Hi, do you have any pictures of your spray foam flooring?

Did you spray directly to the metal, working on the basis that if the spray foam is bonded to the metal the condensation can't form against the metal?

 

All the best,

Chris

[blackrose]

In the light of a recent topic on wet floors I thought I would report back as promised in April last year on my ambition to never get any water in my sprayfoamed bilge.

 

Never? That's a long time... How long have you had your boat?

 

I've been living on mine for about 9 years and do my best to keep the cabin bilges dry, but there are always going to be times when water gets down there.

 

When it does happen then I certainly wouldn't want sprayfoamed bilges which will just trap the water rather than allowing it to flow back to a pump and be drained. I don't think I'd want UFH either.

Edited November 4, 2013 by blackrose

[George94]

Agree with Blackrose. The only thing you should put on the inside of your hull is bilge paint or barge grease - preferably the latter. And ensure you have good access to check it is dry. Boats rust from the inside, not from the outside.

[Robbo]

Agree with Blackrose. The only thing you should put on the inside of your hull is bilge paint or barge grease - preferably the latter. And ensure you have good access to check it is dry. Boats rust from the inside, not from the outside.

 

So spraying it with sprayfoam will stop water and condensation getting to the hull. If water happens to get into the bilge it will be on top of the spray foam! The only down side is that the foam tends to be rough, so may hold pools of water instead of it running to the back. A solution to this would be too sand the foam back to make it flatter.

[blackrose]

 

So spraying it with sprayfoam will stop water and condensation getting to the hull. If water happens to get into the bilge it will be on top of the spray foam! The only down side is that the foam tends to be rough, so may hold pools of water instead of it running to the back. A solution to this would be too sand the foam back to make it flatter.

 

Some of the ideas that people come out with on this forum... I'm afraid that's wrong. Polyurethane sprayfoam consists of a mixture of closed and open cells and is not completely waterproof. Sand it back and you make the surface more porus.

 

Have you ever seen a leaking calorifier? Ok, the water in a calorifier is under pressure but the PU foam all around the leak is completely saturated. I don't know about you, but I don't want a big wet sponge lining my bilges. It's never going to dry out that way.

Edited November 7, 2013 by blackrose

[ditchcrawler]

 

I'm afraid that's wrong. Polyurethane sprayfoam consists of a mixture of closed and open cells and is not waterproof. Even if the foam were made only of closed cells, the thin cell walls are permeable to water to some degree.

 

Have you ever seen a leaking calorifier? Ok, the water in a calorifier is under pressure but the PU foam all around the leak is completely saturated. I don't know about you, but I don't want a big wet sponge laying in my bilges.

Glad now I scraped the foam of the cabin sides to the level of the underside of the floor.

[blackrose]

Glad now I scraped the foam of the cabin sides to the level of the underside of the floor.

 

Well I don't think the sides matter that much because if the foam gets wet from above it's not going to soak up the water, it's just going to drip off. But if the foam is laying in the bilges with water on top, eventually some of that water will be absorbed by the foam and it can't drain away or evaporate easily.

Edited November 7, 2013 by blackrose

[Robbo]

 

Some of the ideas that people come out with on this forum... I'm afraid that's wrong. Polyurethane sprayfoam consists of a mixture of closed and open cells and is not completely waterproof. Sand it back and you make the surface more porus.

 

Have you ever seen a leaking calorifier? Ok, the water in a calorifier is under pressure but the PU foam all around the leak is completely saturated. I don't know about you, but I don't want a big wet sponge lining my bilges. It's never going to dry out that way.

 

Some of the comments people make on this forum about an idea. One foam may be wrong another may not be.

[RubyTuesday]

Here is my thought on this from an engineering point of view.

 

The bilge can get wet for two main reasons

1. Water spillage (be it a pipe leak or petulant rain)

2. Condensation

 

Now no matter what you have in the bilge, spilt water is spilt water. However, when the bilge is un insulated this water ends up on a cold surface which meens that it will take a long time to evaporate.

 

With regards to condensation, this will only form on a cold surface (such as bare steel with one side cooling it such as the canal or cold weather conditions. If the metal is closely covered by foam, such as spray foam the water in the air can not get to the cold surface to then condense and pool. The reason that a lack of breath ability can be bad in buildings is that very few are made or lined on a surface that does not absorb water, again however, this issue does not happen with steel.

 

So if the water content does not come in contact with the cold metal then the water will not condense and pool like in a non insulated bilge and so you would not have the same problems with water collection and the open or closed cell nature of the insulation is of no concern. The only area and argument for open cell more breathable insulation is because of the struts that you mount the floor on probably will be metal and not covered (this could be designed out though) so this is an area that water could condense and potentially get behind the foam. But for foam to get sodden is not possible as in its nature and the reason for it being so effective us that it is made from tiny bubbles that stop air movement thus water could only truly penetrate if the foam compound material can absorb water which it can't.

 

Of course decent ventilation should still be included in any design.

 

Ps spray foam is used for waterproofing!

Edited November 9, 2013 by RubyTuesday

[DHutch]

I certainly think the insulation and or draft proofing of the floor or a narrowboat from the bilge is an interesting topic and something not normally given enough consideration. Not really an issue on a boat used during summer, or even infrequently, but if you where planning to live on worth looking into.

On our boat in winter month you do get a really noticeable foot or so of cold air at the bottom of the room even two days into heating it consistently with the stove. Enough to make sitting with you feet on the floor fairly unpleasant. It might get better with time but it might not.

The argument the 'the canal doesnt get that cold 2ft under the surface' doesnt really hold much water (sorry) , last winter we have a pipe which runs 15mm off the base plate freeze and split, so its not warm down there!

 

While people do use sprayfoam to waterproof clapped out roofs, its far from 100% closed cell and I must say that while the idea of two inchs of closed cell foam sprayed on the the base plate around the scantlings is ver appealling, I would not be happy spray foaming my bilge. If you had wet underfloor heating that might help in terms of allowing you to heat it to dry it if it became saturated, still far from convinced!

 

At which point I would be aiming to have the 1inchs start at the top of the scantlings, making a suitable air tight joint from that to the wall insulation, and then having passive ventilation to the bilge void, with optional mechanical assistance. Most well maintained boats rust from the inside out!

 

Underfloor heating on the other hand, is an excellent idea, although as said, perhaps not required with a stove, and does require a pump unlike our radiators.

 

Daniel

[smileypete]

The argument the 'the canal doesnt get that cold 2ft under the surface' doesnt really hold much water (sorry) , last winter we have a pipe which runs 15mm off the base plate freeze and split, so its not warm down there!

 

That's interesting, where was the pipe running, under the cabin floor, though the engine room space, under the deck?

 

cheers, Pete.

~smpt~

[Ex- Member]

My take on this is to insulate with 50mm Celotex or alike between the wooden joists set on the bearers, this insulation is then directly under the ply floor and above the ballast and does not interfere with air flow through the lower bilge. I really wish we did this now as I believe it would make quite a difference to the overall efficiency of insulation, but I'm not going to rip up flooring to do it now.

 

I agree with Daniel there's definitely quite a chill that is noticeable, especially through our natural Cherrywood floorboards in the saloon, even though the floor board gaps close pretty tight in the colder weather there's still a draught. We now fit a large sisal rug for the winter period to negate this cold, it's not carpet but a natural fibre which is very hard wearing with a rubber back which stops any draught. It does work well, but insulation would be much better.

 

The rest of the boat is floored in ply with 15mm T&G bamboo flooring, so no draught problems but a quite cold floor.

[Arducius]

My take on this is to insulate with 50mm Celotex or alike between the wooden joists set on the bearers, this insulation is then directly under the ply floor and above the ballast and does not interfere with air flow through the lower bilge. I really wish we did this now as I believe it would make quite a difference to the overall efficiency of insulation, but I'm not going to rip up flooring to do it now.

This is exactly what we did. There is some detail on my blog post about our floor build up.

[Neil2]

This is all very interesting. It's strange how, until quite recently, insulating the floor of a NB seems to have been given little attention. Our last boat had underlay and Axminster carpet (not my choice) yet the floor was so cold, when I walked on it in bare feet it felt wet. This is ok in the hot weather but most of the time especially up north you'd like a "warm" floor.

 

Having got to the stage where I'm considering either buying new or getting a boat to refit, I'm very interested in these ideas and the Celotex/Kingspan approach seems to make a lot of sense unless someone can spot any real disadvantages.

[DHutch]

That's interesting, where was the pipe running, under the cabin floor, though the engine room space, under the deck?

 

It was a 15mm copper water pipe, in the engine room in the middle of the boat, partially covered in bilge water, partially under the removable wooden floor section, u-shaped pipe vented at both ends.

 

20 years with no issue, but the cold that year got to it, and a plastic hep20 fitting behind the kitchen sink.

 

 

Daniel

[system 4-50]

I am happily walking around my boat in bare feet without feeling cold, but then, it is not very cold outside yet.

[RubyTuesday]

I am happily walking around my boat in bare feet without feeling cold, but then, it is not very cold outside yet.

I am likening the smugness :-) long may it stand.

[system 4-50]

I am likening the smugness :-) long may it stand.

Is there a smug smiley?