Heating

[thinwater]

A lot of posts on AC. What about heat while away from the dock? I am one that believe a sailing season is 12 months, unless some freak winter actually brings ice to the middle of the Chesapeake Bay. Then, only rarely, are we shut in for more than a few weeks.

Fresh water systems remain winterized. Outboards do not require it. The cabin is awfully cold.

Ideas?

Does anyone know the rated output of the hot water heater? I wonder if circulating hot water to a few key areas might do the trick without demanding much instalation; a pump or 2 and some switches. A thermostat if I felt fancy. Perhaps it would be enough to knock the chill off.

[SecondWind]

When we were in Baltimore, we purchased two oil filled 1500 watt heaters which we left on the boat, one in each hull. When we left the boat we turned them down to 600w, and adjusted them up as needed when onboard. They never caused us any problem, were absolutely silent, and had no exposed elements which could cause a fire. We were in the water at the time, so if you are on the hard you may need to use a higher setting.

[SecondWind]

BTW,

They will run off of the inverter or genset on lower power settings, especially if you have perwarmed the boat at the dock.

[MagicDragon]

We're on Lake Erie and often sail in April and November, when less hardy souls are still on the hard. KISS (Keep It Simple, Silly) SOLUTION? We simply used a red clay flower pot and put that on the stove with the burner on underneath it. It is amazing how much heat is released, and how long it lasts if the doors and windows are closed. Of course, you never want to do this while sleeping, but it is a simple solution for those 40/50 degree days when an extra sweater is not enough.

[thinwater]

Thanks for the replies.

If I use the inverter, my math says the batteries will be flattened in 30 minutes to 1 hour, depending on charge batteries, and setting. Not good for long trips or even long days. Preheating the boat is a good idea, though. I gather it would hold for a few hours.

I could use a gen set, true enough. I hate listening to a gen set.

The flower pot idea does work - I have used it. Of course, all the flower pot does is increase the portion of radiant heat released very near the stove; it does not increase the BTUs going into the room. Non-vented heaters make me very nervous, and the poster clearly and correctly stated that this practice is not for sleeping.

My thought is that the propane hot water heater puts out about the same energy as a 1500w heater, so why couldn't that firing capacity be enlisted as a fairly simple hot water heating system? If the water leaves the heater at 110F and returns at 90F, then each gpm carries 10,000 BTUs of heat - there is probably not much more than 6000 BTUs available, so the required pump flow is quite low. The batteries could carry this for many hours. To transfer 6000 BTUs, about 50ft2 of passive surface are needed (a rather impractical 600 ft of tubing), but more than 50x less if a fan blows over it and the surface is finned - something equivalent to the heater core of a car in each hull, or 1 larger AC core. A room AC unit rejects about that much heat with similar operating temperature differentials.

Food for thought. Is there any practical reason where by running the heater hard and continuously would damage anything or constitute a danger? Improving the ventilation to the starboard bow compartment might be prudent. The load doesn't seem much different to me than the evening shower rush.

[James Power]

We installed heaters on a couple of mv34's. They used engine coolant as a heat source that was piped to a small " radiator" with a built in fan. Another alternative are the propane heaters, force 10, dickinson, sig marine, espar etc.. Hope this helps. James

[SecondWind]

I see your dilemma. We have twin diesels with 100 amp alternators and freshwater cooling, so we have plentiful electrical power and circulating hot water. You have outboards. Your hot water heater idea could work, but there are propane heaters designed just for what you want to do. I would research that direction, since you'll probably spend less money and have less trouble than trying to design a system yourself. Please be careful and don't give yourself carbon monoxide poisoning.

[thinwater]

For example, a pair of rv heaters such as this:

http://www.jcwhitney.com/autoparts/Item ... 0000165023

Because only the existing hot water heaters is used, safely vented outside, there is no monoxide risk, no additional fired equipment, little wieght, and little installation space. Each heater would only put out ~30% of their rated capacity, because the water temperature is less than engine coolant (105F vs 200+F).

[maxicrom]

Thinwater,

Sounds like you have propane - for the water heater and range. Demand water heaters are not designed to circulate - nor run on a constant duty cycle: My bet is that within few minutes an overheat sensor would probably shut the unit down. Install a propane cabin heater if you don't have one - much easier than diesel or other types - our 36 came standard with a Force 10 cozy cabin heater. We are upgrading to the larger Force 10 double element unit (more heat). It will require a little modification since it has a larger foot print and requires a 2" stove pipe - the standard mounting location is on the bulkhead next to the Stbd cabin door (outboard). If you are looking for full time central heat away from the dock then you need to look at a diesel heat system - but with outboards you are looking at separate diesel fuel supply system. The small Force 10 warms our cabin in about 15 minutes - the lower areas of the hulls stay a little chilly but the settee area gets balmy (a small fan helps with circulation).

We will be doing the DC \ Alexandria Parade of lights in two weeks and our cabin will be warm - hoping for mild evening because the cockpit is no joy on a cold night.

Good luck,

MB

[Bob]

Mike and Linda,
Where is your force 10 mounted? Those little heaters work fine but for the life of me I haven't been able to see an out of the way place to mount it. Maybe a photo post?

[thinwater]

Finding a mounting location on a 32 was a primary factor in my exploring other options; nice boat, but it doesn't need clutter.

The water heater is a tank-type, not an on-demand. Recirculation should be valid.

I should add that I am a chemical engineer by training, and designing hydronic heating systems for chemical plants is common in my work. The difference is a typical industrial project is $500,000 and I was hoping to do a little better than that.

[Tanah-Keeta]

On Tanah-Keeta we used a simple propane ceramic heater made by coleman. With the enclosure, we could enjoy the outside at anchor and be warm. We also used it in the salon with ventilation... but never when we were in bed... a good sleeping bag was enough.

[Bob]

The Coleman is what we are using presently and it performs quite well. Being in Maine in the summer calls for frequent heat to take the damp chill out so I was looking for a more permanent solution.

[maxicrom]

Bob,

Here is an image of our heater mount on a 36 - http://www.2hulls.com/usedcatamaran-200 ... heater.jpg ( I still haven't figured out how to get images in the blog, but luckily this old entry is still online). It looks to me that on a 32 you have more room inboard on this bulkhead and you might have to create a guard to protect anyone from rubbing against the heater while entering the cabin.

Good luck,

MB

[thinwater]

I like that. Simple, small, vented, very low electric use, about $390.

Thanks.