Saturday, December 13, 2014

MOSTLY ABOUT ENVOY'S AC POWER SYSTEM AND REFRIGERATION

Envoy is currently in Lefkas marina for the Med winter.
This posting is nearly all technical.
During this year’s cruising the main Lugger engine ran 346 hours and the Yanmar wing engine just 3.2 hours. Next year we’ll make a point of running the Yanmar for much longer periods, using it for passages on some calm days when the stabilisers are not needed (the stabilisers being driven from the Lugger).
Engines need to be used both regularly and for periods long enough to bring them up to normal working temperature to keep injectors and other components clean. Although Envoy only cruises at about 3.5 knots using the Yanmar, time is not an issue for us and most days our cruising distances are short.
Our biggest technical issue this year was the failure of our ancient Lugger-driven SeaPower 120 volt AC generator, which provided power for refrigeration anytime the Lugger was running (our AC refrigeration being powered only by 120 volts on board or 220 volts shorepower). The SeaPower was beyond repair and replacement would have cost about NZ$9,000, so we decided to cruise this year using the generator as our sole means of powering refrigeration while at sea (in fact very few vessels use engine-driven AC generators as most use inverters for low AC loads and generators for higher loads). This worked extremely well and interestingly we ran the generator for 334 hours, only 25 hours more than in 2013 and in fact 70 hours less than in 2012 - many less hours than we expected, so why?
1. Our cold plate, R12-based refrigerator and separate freezer are very efficient and typically only need to run about two hours per day – a little longer up to three hours in mid summer or with visitors aboard, and a little less – down to 90 minutes in cooler weather or with just two of us aboard.
2. It’s harder to keep the fridge cold than the freezer because the fridge is opened much more frequently. Many days the freezer isn't opened at all! Our freezer is rarely more than half-full of food so this year we regularly froze large bottles of water and put those in the refrigerator to help keep it cold, changing bottles around every couple of days.
3. This year we spent more time than usual in marinas on shorepower, particularly in parts of Sicily where safe anchorages were limited.
4. At anchor we generally run the generator for about 45 minutes in the morning and the same in the evening EVEN WHEN the SeaPower was working, so in reality we only need to run the generator for an additional half hour or so daily without the SeaPower.
5. We always have to run the generator when using the water maker and therefore run refrigeration at the same time. Water making takes several hours and this gives the refrigeration system temperatures a good chance to pull down.
So we now have no plans to change this system of using the generator to power refrigeration.

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