Damp hatch and holes in the floor

[MartinW]

As I dig further into my 2007-built boat and 'Miss Marple' its history - I threw away 23 bin-bags today - food out of date in 2009 etc etc I am coming across several interesting areas including a couple of roughly jigsawed-out holes in the floor inside cupboards at the rear of the boat to give access to the ballast/bilge (My guess is for inspection/drainage as I also found a couple of home-made 12v sump-pumps). This explains why those cupboards have a lovely layer of white mould inside. I aim to fill these holes but wondered if a layer of carpet tile on top would help prevent the cold striking up into the air above and mouldying it up again? Similarly, directly above this area the rear hatch is completely uninsulated and constantly covered in condensation. I wondered about removing and inverting it and making some formwork inside so I can 'cast' spray foam without affecting the operation. Much of the condensation/mould is a result of the almost complete lack of use the boat has seen but I'd also like to do whatever I can to prevent it in future. What should I do?

PS, there were a couple of sets of very well-insulated 'overalls' which might be a fishing thing but would be ideal for winter-cruising. U

nfortunately I am not a size M...

[Tony Brooks]

Cold air sinks, not rises. For a lot of winter the canal and thus the hull and bilge will be warmer than the air outside.

 

I would remove a little ballast below each hatch and dry the base plate. The watch for a few days drying any water that appears. Then leave the traps open and cupboard doors open to ventilate the bilge as best as you can and monitor for any water. If you get a build up of water you need to sort out the plumbing/window/vent leaks.

 

I think your bilge has probably been full of water and has soaked the floor not so long ago.

 

In the long term try to organise through bilge ventilation, preferably drawing air from outside.

 

 

 

 

 

 

[blackrose]

I don't think covering damp wood with carpet tiles is going to cure the damp. You need to ventilate those areas not cover them up.

Edited January 26, 2021 by blackrose

[MartinW]

Thank you both. I guess ventilation is the key, then. I agree that the bilge has probably been wet or at least damp for a while at some point as it is very rusty (Though surveyed with lots of thickness remaining) There was some vague talk of a leaking hatch having been 'sorted' so that might be where the water was originally from) The carpet idea was from something I read about not having smooth surfaces for the water to condense-on. It is really useful to have real knowledge as opposed to speculation - thanks

 

[blackrose]

Drain the area and ventilate. Most importantly make sure the source of the water is stopped, so once it's dry keep checking to make sure it doesn't become wet again. 

 

If your boat is on shore power point a fan on that area. When I had wet bilges I laid a big fan right over the inspection hatch for a couple of days to dry it out.

 

If you don't have shore power it might be difficult to get it bone dry in this weather but at least get the boat warm and you'll be able to get it really dry it out come spring and summer.

[MartinW]

I think that ventilation grilles top and bottom in the cupboards/wardrobes will help. I have also considered covering the hatches in the floors with some kind of perforated mesh. Ultimately, I suppose, the solution is, as Tony suggests, a dedicated whole-boat active ventilation system with heat-recovery but that would require a level of scientific skill (and possibly small-scale hardware) in an area that I don't possess. I bet there is such in the mega-yacht market but I'm not really there, just yet!

[BWM]

If the underside of the hatch isn't too rusted or flakey you may be able to stick cork tiles or similar underneath to stop the condensation for now, and you can revisit it in the future with a more permanent solution. 

[MartinW]

That's a good idea because every time I open this hatch it starts to rain. I understand it's called a Schaffenaker Hatch

 

[Tony Brooks]

1 hour ago, MartinW said:

I think that ventilation grilles top and bottom in the cupboards/wardrobes will help. I have also considered covering the hatches in the floors with some kind of perforated mesh. Ultimately, I suppose, the solution is, as Tony suggests, a dedicated whole-boat active ventilation system with heat-recovery but that would require a level of scientific skill (and possibly small-scale hardware) in an area that I don't possess. I bet there is such in the mega-yacht market but I'm not really there, just yet!

 

I don't get the need for a heat recovery system. We are not talking about a gale, just a very gentle change of air in the bilge area. many of us do this by utilising the cooler air down there and blow it up over the radiators mesh at the back of electric fridges to improve efficiency. All people use is one or two cheap 12V DC computer fans. Often wired to the fridge thermostat  so they only run when the fridge compressor is running. If two fans the are usually wired in series so the run slower and quieter.

 

Ideally one would fit a vent from outside to allow air to be drawn in but its not vital, a discrete grill front and back from the cabin would suffice although many don't bother.

 

I agree high and low level vents in the cupboards may be a good idea but is to ventilate the cupboard and contents, not the bilge.

 

Do nothing for now apart from what I and Blackrose said about water and monitoring it. Then when you are sure there is no water build up think about the next step BUT you do need easy access traps to allow you to remove an water from the accommodation bilge so don't make them hard to remove.

 

 

[MartinW]

Brilliant. Thanks Tony

[Tony Brooks]

You could wire such fans located elsewhere to only run when the batteries are being charged so no load on the batteries.

[MartinW]

Following your advice I have bought a couple of 12v computer fans and mounted them in holes cut in the floor below and behind the fridge. I have seen the instructions for the fridge which notes the terminals to connect -to. I have fitted ventilation grilles above the holes in the floor above the bilge which is dry except where a leaky heating pipe has rotted through the floor. I fixed the pipe and will patch in the floor when it has dried. I insulated the hatch by turning-it upside down and casting a foam slab onto the bottom inside a treated-timber formwork, cutting the foam-off level and covering the result with a carpet tile. I will continue to find and fix leaks and  damp and take it from there. The engine-bilge contains a broken bilge pump so replacing that is next when the rain stops. Thanks for all your help.

 

[MartinW]

This is the plate at the back of the fridge. It is a Beko that was subject to a recall I assume, as all the workings are Danfoss and a new registration is marked on the body at the rear. My question is, which of these terminals do I connect the + and - from the fans to? I think that it did say on the paperwork for the fridge but I can't find that any more.

[Sitesurfer]

I’m thinking F and +

 

 

Edited February 7, 2021 by Sitesurfer
Correct part number

[MartinW]

fantastic, thanks very much.