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Old 02-25-2016, 06:18 PM   #21
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You guys must have huge electrical draws if your engine's alternator isn't sufficient when underway, necessitating simultaneous use of the genset.
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Old 02-25-2016, 06:30 PM   #22
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You guys must have huge electrical draws if your engine's alternator isn't sufficient when underway, necessitating simultaneous use of the genset.
Yes, we do.
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Old 02-25-2016, 07:14 PM   #23
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I had that discussion with the marina manager just recently. Not about my boat, but about a friend's boat. He maintained that the scoop should face forward, my argument was that it shouldn't for the reason you mention.
It depends on the type of "scoop" you both are talking about. There are those designed for engine use that can face forward while underway. And there are those that are not designed for engine use while underway and should only be used on say an air con raw water intake thruhull.
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Old 02-25-2016, 07:54 PM   #24
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I just spoke with a friend who's #3 cylinder was seized on his genset. Turns out he was in some nasty weather and seawater worked its way up through the exhaust into his generator. I figured running his genset (or closing the seackocks) would have prevented this.

I'm a fair weather boater for the most part, but I think I would feel more secure if i ran my genset along with my main when the weather was got a little nautical. Im not afraid to put hours in my genny.
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Old 02-25-2016, 09:14 PM   #25
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i dont think that the water can get by the raw water pump impellers that much with a front facing scoop when the genny is shut down.they are pretty tight aganist the housing unlessthey are worn out?
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Old 02-25-2016, 09:50 PM   #26
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yes water can get by an impellor.


front facing scoops for a genset are often considered a no no for planning vessels, maybe semi displacement vessels and probably no big deal on 8 knots and below displacement (but why take a chance)


Sunchaser....yep...4:1 is not out of line at all...probably the 20:1 main(s) to genny that raises some eyebrows....thought that's more along the lines we were talking when saying grossly different...
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Old 02-25-2016, 10:42 PM   #27
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You do not want a fwd facing scoop on a gennie. Water can and will push past the impeller. Aft facing scoop almost as bad as it can suck water from water lift muffler into exhaust manifold. Best no scoop and a siphon break.

Water getting into gennies paid for the construction of my boat. So trust me, it happens. And water won't get into it with it running. On some boats with marginally safe installs, I told them to run the gennie if underway whether they need it or not, at least the running engine keeps water out of itself.

Regarding hrs, I almost never run my gennie while underway, the ME alt and inverter do the job. But anchored out, gennie might run all night. Interesting that ME now has 2280hrs, gennie has 2040hrs, not too far apart considering they don't run together.
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Old 02-25-2016, 10:59 PM   #28
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Many vessels start it before their main and leave it running till plugged in....or longer if having to anchor/moor away from power.
Same here. It is important to adequately load your generator. Depending on your electrical demands relative to the output of your alternators, you may be better off running the genny only after the batteries have run down a bit.
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Old 02-26-2016, 12:09 AM   #29
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Originally Posted by drb1025;
I run mine while underway usually when I need heat from the reverse cycle units.
Does your reverse cycle produce adequate heat here on the coast for winter cruising?
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Old 02-26-2016, 01:22 AM   #30
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Does your reverse cycle produce adequate heat here on the coast for winter cruising?

Yes, they produce good heat all winter. I was a little concerned about the water temps when I bought the boat, as the units become inefficient and stop working as water temp reaches around 40 degrees, but I have never had an issue. The water here is generally mid-40s in the winter. I was recently talking with a local boater that was getting ready for his fourth Alaska trip and his heat source was also reverse cycle. He said he has never had an issue with heat even in SE Alaska. That surprised me, although I am planning to install a Wallas diesel heater for a supplemental heat source before we make that trip.
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Old 02-26-2016, 01:31 AM   #31
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Same here. It is important to adequately load your generator. Depending on your electrical demands relative to the output of your alternators, you may be better off running the genny only after the batteries have run down a bit.
Let's be careful too to know what adequate loading is. I've heard all these stories about never loading under 50%. Northern Lights, however, states the following: "A generator should never run with less than a 25% load. 35% to 70% is optimal." One needs to check their owners manual and/or with the manufacturer. And don't go to a field representative at a boat show or elsewhere. Get the official recommendation.
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Old 02-26-2016, 01:34 AM   #32
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Yes, they produce good heat all winter.
Thank you. Always wondered and you are the first I have thought to ask. Should have asked, what size unit(s) do you have?
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Old 02-26-2016, 01:54 AM   #33
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Thank you. Always wondered and you are the first I have thought to ask. Should have asked, what size unit(s) do you have?

I have three marine air units, two 16k btu and a 12k btu.
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Old 02-26-2016, 01:58 AM   #34
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I have three marine air units, two 16k btu and a 12k btu.
Thanks.
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Old 02-26-2016, 05:47 AM   #35
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You guys must have huge electrical draws if your engine's alternator isn't sufficient when underway, necessitating simultaneous use of the genset.
Two radars, autopilot, computer, monitor and all sorts of lights after pulling up 150 feet of chain knocks the heck out of the standard alternator (75 amp) on a single engine running at 1600 rpm. Not that it isn't charging but it is charging slowly and I prefer a full charge when I anchor the next morning.
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Old 02-26-2016, 06:55 AM   #36
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Does your reverse cycle produce adequate heat here on the coast for winter cruising?
I have 3 Webasto heat pumps on my boat. They worked down to about 35 degrees. The efficiency of the units drops as the water temperature drops. Below 35 degrees in brackish water, there needs to be more water flow through the condenser as the refrigeration effect starts to generate ice inside the condenser. I'm running 3 units off one water pump. If I planned to use them below 40 degrees, each unit would have it's own water pump.

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Old 02-26-2016, 08:03 AM   #37
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I always figure the all up cost of a noisemaker is about $10. per hour.

Purchase , install, feed, maintain, repair and eventually replace.

A Good rebuilt DN 50 alt with a 4KW sine wave inverter might cost 5 boat bucks to get operational, but would save big if the boat main engine were used much.

4KW will start 2 normal boat air cond.

OF course the best saving would be to put HYD pump on the main engine and a 6KW power head,,, is half the cost of the big buck inverter.
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Old 02-26-2016, 11:08 AM   #38
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"4 KW will start 2 normal boat air cons". Have to be very small units, our 5 KW NL runs two 16,000 BTU units with the help of a "Smart Start". Two units start amps if they start at the same time can trip your breakers.
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Old 02-26-2016, 11:14 AM   #39
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Since we are dock queens and do not leave the dock often, we leave the gen set run. We also have a cruise gen powered by the main engine that we switch to for longer cruises. So we have a generator running from the time we leave the dock to we are tied to a dock.
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Old 02-26-2016, 12:40 PM   #40
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Originally Posted by drb1025 View Post
Yes, they produce good heat all winter. I was a little concerned about the water temps when I bought the boat, as the units become inefficient and stop working as water temp reaches around 40 degrees, but I have never had an issue. The water here is generally mid-40s in the winter. I was recently talking with a local boater that was getting ready for his fourth Alaska trip and his heat source was also reverse cycle. He said he has never had an issue with heat even in SE Alaska. That surprised me, although I am planning to install a Wallas diesel heater for a supplemental heat source before we make that trip.
That is a great question Hawg asked. Am I to assume that your reverse cycle heater uses raw water for a heat sink/source as opposed to air? I was on a newish boat the other day that had a reverse cycle (heat pump essentially) that used air as the heat sink/source. I know they would not serve my purposes, but a system that used raw water would work pretty well most of the time. I can get ice in my harbor during really cold spells (fresh water streams feed into the harbor near my moorage) but most places the water temps stay in the high 40s in the winter.
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