Here is a very depressing experience: sitting in a damp boat in mid-winter, with a gale blowing, it’s getting dark, it’s raining hard and the deck-head lining has been removed to see if we can find where the water is coming through.
So, a couple of weeks ago, when I find a book entitled “A Warm, Dry Boat”, you can bet I will leap at it
I found it by Googling ‘heating for yachts’. This was the wrong topic to search on. It should have been ‘ventilation in boats’, but I only know that now because I’ve read the book.
So, is it to be A Cold, Damp Boat or A Warm,Dry Boat?
As you can tell, I highly recommend “A Warm, Dry Boat” by Roger McAfee. It took a little while to cross te Atlantic, but it has been well worth it.
Mr McAfee is Canadian and lives on the Pacific coast where it is colder and damper than the UK. So it’s “put your pride aside, admit you haven’t got all the answers, find out from the people with experience.”
What have I learnt?
The refit was planned because various deck fittings were leaking and needed reseating. It was decided, because of the age of the boat and the distances that we might sail in her, it would be better to do the job properly and not skimp it.
I now know that merely replacing fittings is not enough to solve the problem. Moisture will still build up in the air inside this now water-tight (as far as possible) hull – moisture from body heat, moisture from any water in the bilges, moisture from damp clothing, mositure from the air – moisture that then condenses into droplets on cold surfaces and starts the process all over again.
If all that is done to alleviate this is to add a heater to give warmth, the first thing that will happen is that more moisture will be absorbed into the air, the greater will be the difference in temperature between the outside of the boat and the inside and the more condensation will occur. (How much moisture will depend on the heating system). This problem can be greatly reduced by moving the air that is high in moisture out of the boat and replacing it with fresh air, i.e. it is movement of air we are looking for.
In other words, a boat needs to breathe.
So we have to find ways of moving air, and, initially, because of the size of the boat, we will try to do this passively.
The fore hatch, which previously (as in the image above) hinged with the leading edge opening forward, is being refitted with the hinges forward.
Two reasons: a) It is safer – an unlocked hatch cover facing forward on the foredeck can scoop water into the boat at an alarming rate.
b) On the mooring, with the hatch propped open (the exact opening will depend on wind strength), the flow of wind from forward lifting over the hatch should create a potential vacuum at the opening, dragging air out of the forecabin. This should create a flow of air from the main cabin forward. By controlling the air into the boat from further aft, the movement can be maintained and the air exchanged.
In Blue Mistress, the companionway is fairly small, so we are dividing the drop boards into two so that the air intake through the companionway can be controlled by varying the combination of drop boards and the position of the sliding hatch.
Also, a large fuel tank that occupied the starboard quarter berths has been removed and both quarter berths are now open. There are further plans for these for next year, but, in the meantime, two small hatches in the sides of the cockpit aft can be opened and, with the companionway shut, air can now flow the full length of the boat.
It is also possible to have a spare drop board with a fan fitted to it (perhaps run by a solar panel). During the winter, this could be installed with a hose led to the bilge so that the air is ventilated directly from the dampest part of the boat, rather than allowing this moisture to flow into the cabin first.
That’s the theory. Now we need to get the boat back in the water to see whether the plan works. More of this later.