What type of heat?

[mastreb]

I still really like 12v RV style electric blankets used as a bottom pad for heat. Does drain the battery a bit, but if you get one with an hour timer it's not going to kill your battery, warms up the berth well and long enough for your natural body heat to kick in.

But we live in San Diego, so I'm no expert on cold. We just use sleeping bags and forgo heat.

[bugman]

I have a propex heater. It is mounted above the rear berth and vents the exhaust outside. Thermostat with a auto start, so you set it and forget about it. The blower helps keep the moisture down in the cabin. I have spent a few nights on the boat in the winter when the temp has been around freezing with 5 of us on the boat. The boat stayed warm and dry all night. http://www.macgregorsailors.com/modt/in ... ?view=1575

[Mikex]

Thanks everyone for your help regarding the heat. We`ve decided to go ahead with installing an Espar - I`ve had one before on a different boat and the price was right. We are about to start on our boat projects (now that the admiral said that I can take a break from our house renovations! lol)
Our projects include: Espar heat, new windows, autohelm, a full dodger and bimini enclosure, and a solar panel with new batteries. Hope I have time to go sailing!
Terry, thanks for the information about the MacGregor club - we have joined and we plan to take in some of the cruises. It would really be interesting to meet up with other MacGregor sailors and talk about their boats (especially the ones closer to home here on Vancouver Island).

Cheers,
Mike

[kevinnem]

I tend to come up with some off-the wall sort of ideas at times. I am always looking for a better , but unconventional way of doing things, and ways of useing equipment is ways that it was never envisioned to be used. I don't feel this is always helpfull........


but according to my calcs, you might be able to keep the cabin warn, buy warming up a pool of water to a higher level of heat, and then drawing heat form it all night. I think it could be done with about 3 gallons of water. My idea would be to heat up the water, VIA the stove - or buy using one of the hot water camping systems (there are a few).

So you start by making a ton of hot water, then you use hot water to make warm air. I like this idea because it also gives a means of making hot water, and that is something useful. I like it because you can use any method to make the hot water.

I don't know if the "big tank" we have have would be approreate for this use- it is maybe TOO big, and also not "clean" so you couldn't use the water for other uses. I was thinking taht the best solution would be a number of the colapsible water bags under the sink/bunks, in a stryofoam enclosure.

[mastreb]

according to my calcs, you might be able to keep the cabin warn, buy warming up a pool of water to a higher level of heat, and then drawing heat form it all night. I think it could be done with about 3 gallons of water.

Water does have the highest heat capacity of any common substance. It can store about 4 joules of heat per cc per degree celsius. There are 1000cc per liter, and about 12 liters in 3 gallons, and you've got about 30 degrees C you can safely warm water on your boat, so 30 * 12 * 1000 * 4 = 1.5MJ heat capacity.

A watt is one joule per second, so to have the heating capacity of a 1000 watt electric header, you're dissipating 1000 joules per second, so this tank and heat capacity (presuming you have a heat exchanger that has this speed capacity) would give you 25 minutes of 1000 watt heat.

Seems like not enough. Might want to be heating the ballast tank?

[seahouse]

Yup – it takes more energy to heat water than any other substance. So you have chosen an ideal medium to transfer and store your heat, kevinnem. Mankind has borrowed this idea of using water for this purpose from mother nature. But using unconventional thinking is what has moved society forward so fast. So don't stop thinking that way, anybody!

My present house (of my design) uses a similar method to heat in the winter – (hydronic in-floor radiant) water tubes encased in concrete in the floors. The sun's heat goes into the thermal mass of water and concrete which prevents the temperature from rising uncomfortably too high in the house, and the heat is then radiated into the house at night. Without digressing farther than needed, it is a very comfortable, healthy, efficient way to heat a house in our climate.

So, as I understand it, you would heat the thermal mass of water up on shore power, or however other method you have available at the time, so that when you are away from your energy source at night, (say anchored) you have a stored energy source of heat? I like it. Like a thermal storage battery. And around here, shore power is all-you-can-use for one price.

Using mastreb's numbers (thanks mastreb!), you'd need more volume of water, and 3 gallons does seem like a small amount, especially since your temperature range is limited from ambient up to the boiling point of the water.

The floor in my basement is insulated from the ground (as is my swimming pool) so that stored heat is not lost to it as quickly. I mention this because it illustrates the shortcoming of using the ballast tank for heat storage – loss of heat to the environment. It is not practical to insulate your hull and ballast tank from its surroundings. The loss of heat to the (very thermally conductive) water outside the hull will bring the ballast tank back to the outside water temperature very quickly.

But I could see a stand-alone water (say with radiating fins) heat-transfer unit that has removable insulation that could be heated up (solar convective, electricity, etc) and then placed in the middle of the cabin and the insulation removed from it, making it a radiator. That just might be enough to make the difference between being comfortable or not, depending on the conditions at the time.

- Brian.

[dlandersson]

So, use shore power to heat the water in the ballast tank, then consider how to draw on that stored heat when away from shore?

[kurz]

very interesting thoughts about heating.

Actually I think, the CHEAPEST way to heat would be to buy an generator an heat with 220V/110V inside the cabin.

Negaviv is the nois, and the handling: I think you cannot store the generator outside or in a fix position in the boat. So anytime you want to heat you have to carry the 20kg-thing out...

But: Why not put a big "hut" over the kitchen burner? And bring the the exhaust in a pipe outside the boat? For just seldom use ok to install?

To have it comfortable and save the fix-install of a heatsystem (benzin/gaz) looks the only solution. Costs much, takes hours to install... But givs comfort and savety...

[Catigale]

We fall sail in our down to 32F with no external heat and just sleeping bags. Below 32 F, it's time to lay the boat up for winter....

[Whipsyjac]

32F! Let's see Interstates are designated with an "I" eg I5, so are you heading down the #32 Floodway? 32F Or was Florida the 32nd state to join? Does your anchor roller double as an icebreaker

Seriously though I get the sleeping bag thing, my kids all have good ones and are quite comfortable in that respect. How do you deal with the condensation though? Just ignore it? Things get musty pretty fast and they don't dry out quick at 32F on the water. In Canada we regard 32F as 0C or 0 chance of getting the kids to go sailing Have you heard of Shackleton?

Good for you to keep at it until the bitter(cold) end. A couple weeks ago we had a chance sunny day and as we walked to the beach all bundled up there were a couple sloops out with full sails in the glorious sun and bitter cold and yeah, I was jealous

Willy

[yukonbob]

The problem I end up with is the overnight temps vs the daytime temps. In early and late season it easily can go from -15C (5F) to 15C above (59F) in the daytime. I've been out this time of year and have had the temp go down to -50C (-58F) overnight to 5C (41F) in the afternoon. Good sleeping bags are a given, but heat makes it a lot easier to get out of bed and make coffee and breakfast with give the cabin a big boost first thing in the morning.