Cost for onboard heating

[REBrueckner]

So you are going to live aboard in a cold climate...or use heat regularly for extended periods...What's the cost comparison between diesel (oil burner) heat and electric heat?

SUMARY: Electric heat at $.22 KWH is about two times as expensive as diesel at $4.00 per gallon. If your costs are different or you'd like to use different assumptions from mine, you can recalculate from data below.

A big difference in cost structure is that while electric heaters are rather inexpensive initially, (maybe $20 each for four 1500 watt heaters), the cost of daily operation of electric heat is very high; with diesel heat, initial equipment cost is high but this initial cost is offset by much lower direct heating (fuel) costs.

Note that the total heat output supplied for your comfort will be the same for all systems…In other words, if you have a large enough source to keep you, say, at 68 degrees in freezing outside temperatures, then all systems will be required to produce the same amount of total heat output over a given period of time. I used a daily comparison below, weekly or monthly or six month period would all yield the same comparison.

Say you need heat for 6 months annually and you estimate your diesel heater will actually run 40% of the time: 6 mos x 30 days/mo x 24 hours/day x 40% is about 1700 hours annually. (I think that’s in the ballpark for my 48 ft YF in NY.)

Total Cost Comparison

If the diesel heating system costs, say, $7,000 to install yourself, and the heater runs the above estimated 1700 hours per year (about six months use in the NE) for 15 years, a prorated first cost equates to about $7,000/25,500 hours or $0.27/hour which is 27 cents per hour of run time.

Daily heat for diesel is 40,000 BTU/hr x 40% x 24hrs run is 384,000 BTU/day required. Total daily Diesel cost (0.2GPH at $4.00/ gal) is $.8/hr x 40% x 24 is about $7.68. plus prorated first cost ($.27 x .4 x 24 daily) or $2.59….about $10.27 daily….

For electric, this 384,000BTU /3,412 BTU/KWH requires 113KWH at $.22/KWHor about $25 daily. (But you would need more than one 1500 watt heater for colder portions of the heating day.)

Total daily cost ($25 vs $10.27) means electric is about 2.5 times as expensiove as diesel with electric at $.22 KWH is and diesel at $4.00 per gallon.

Note: (1) you can add some estimated maintenance costs for a diesel system: At 20 cents hourly, for example, about .2 x 1700 hours annually or about $340 annually daily cost increase by $.2 x (40% x 24) or $1.92...bringing daily diesel cost from $10.27 to about $12.19 vs $25 for electric...about 2 to 1.

Note (2)
If these figures seem high, it's because the boat in NY sits in relatively cold water which chills the fiberglass bottom and hull topsides...hence heat losses are significantly greater than in a well insulated house. Only on sub zero winter nights does the boat benefit a bit from warmer water temperastures underneath. I insulated most of my inide hull and especially the engine room and use 40 mil thick eisenglass as storm windows inside the otherwise frosty aluminum window frames...they make a BIG difference. My salon suffers from a lack of roof insulation as the roof is, I think, solid glass (no coring)...anyway, its cold.

Note (3) If you are going to heat a 53ft or 58 ft Hatt, you'll need a Webasto 2020 or equivalent, about 90,000 BTU, in a NY/CT/ RI type climate, since interiior volume and hence heat losses will be substantially greater.