Friday, October 14, 2011

Heat & Moisture

Keeping a boat warm and dry is very important when you are living aboard.  

Heating aboard Ma'alahi has evolved over the last four months.

We have experimented with forced air electric space heaters (too noisy), a radiant heater (only heats objects in its path (not warm enough)), electric oil heaters, and our centrally installed hydronic diesel heating system.

Electric Oil Heater
Up until early September, we were able to keep the family comfortable with three electric oil heaters.  We keep the temperature in the main living area (where M sleeps) between 68 and 70 degrees (the recommended temperature for a newborn).

Since we have made the transition from Summer to Fall, our hydrometer has gone from 50-60% humidty to 80% humidity.  We did not see any visible signs of condensation in the main living area.  HOWEVER, when T inspected the hull, bellow the waterline and under the settees, he found that we had a slight moisture/condensation issue.  We were able to remedy this issue by switching from the electric oil heaters to our centrally installed hydronic diesel heating system.

The oil heaters were keeping the air in the living areas warm and relatively dry.  They were not powerful enough to warm the space between the settees and the hull, thus resulting in a moisture problem.

T and I carefully cleaned and dried all of the areas of the hull (bellow the waterline), that we could reach, in about 3 hours (using white vinegar).  Once these areas were clean and dry we started up the centrally installed hydronic diesel heating system.

Hydronic Diesel Thermostat
Since we started using the central system, the humidity has decreased substantially to between 55 to 70% (depending on the weather) and the hull has stayed dry.

Here is a brief description of how our heating system works: (from
"The circulation of hot water to provide heat is known as a “Hydronic” System. It is a closed system continually circulating the same coolant. It begins with a furnace or boiler, usually fueled by diesel, or electric elements that heat the coolant up to 180 F degrees. A water pump circulates the hot coolant through a domestic water heater and then to the various fan units located throughout the interior of the yacht..."
My understanding is that these systems are very expensive (labor intensive) to install.  Ma'alahi came with this system.  The prior (and only) owners had the system installed when they purchased the boat in 2001.  

T estimates that we use about four to five gallons of diesel per week.  This means approximately $80-$100 per month in fuel.  We will see what happens (as far as expenses go) as it gets colder.  We are happy that we are warm and the boat is dry.

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