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Old 02-08-2012, 20:40   #1
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Do I need a genset and if so what size?

I have been looking at diesel gensets thinking I will need one but I am not 100% sure if I will or not.

Main power users will be this household 240v fridge/freezer (because I just bought a new one for home)
and when required a 240v single split system air conditioner.

Roof of boat has space for around 2000 watts of solar panel

Space to cool will be about the same as your average 40ft cat, all running in 35deg C + outside temps

IF I decided to get a genny I can get one of these second hand and in good condition
which I can disassemble and soft mount in the engine room with larger exhaust running over the side or under bridge deck with the electric start and tank mounted separately.

The question is, do I need one or is the vast bank of panels going to be enough?
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Old 02-08-2012, 20:49   #2
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Re: Do I need a genset and if so what size?

If you don't get the gennie how are you going to power the 240V refer/freezer and air con system?
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Old 02-08-2012, 20:54   #3
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Re: Do I need a genset and if so what size?

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If you don't get the gennie how are you going to power the 240V refer/freezer and air con system?
I was thinking the shitpile of panels, batteries and an inverter. No?

44ftcc runs 240 volt fridges on his cat, admittedly smaller sized, but also less panel and battery and I am not aware of a gennie being used.
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Old 02-08-2012, 21:06   #4
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Re: Do I need a genset and if so what size?

Well do the math. Without looking it up I think a marine AC would draw as much as 1.5-2.0 KW. If you are feeding that from an inverter powered by a 12V battery system that would be about 125-166 amps 12 V DC. It would take a really, really big battery bank to feed that and a lot of solar panels to recharge.
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Old 02-08-2012, 21:17   #5
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Re: Do I need a genset and if so what size?

Nordhavn has some information on decisions like this on their website. Might be worth a look.
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Old 02-08-2012, 21:35   #6
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Re: Do I need a genset and if so what size?

With all the great design of your boats, I'm a little taken back about your rather mastodon genset idea.

My 33' Dragonfly needs no genset.
320 watts of solar (2 Aurinco 100 watt and 1 solarblvd rigid 120 ) with Aerogel insulation on a "from scratch" apartment sized fridge and hot water tank, almost all lighting LED and we're golden.
I even make hot water using the inverter.
Genset?? NO WAY !!!
We went on vacation for a month using the above and didn't even bring along a shorepower cord. Who needs it?
We also used our sine wave inverter to plug in a new friend's catamaran which was having alternator problems. We gave him an hour of shorepower while we were at anchor.

Some people may not believe the above, but it's their loss....
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Old 02-08-2012, 21:40   #7
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Re: Do I need a genset and if so what size?

How many AH in your house bank ?
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Old 02-08-2012, 21:43   #8
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Re: Do I need a genset and if so what size?

And... Is THAT generator going to be happy in an enclosed lazarette?

Anyway, to answer the question, with that fridge and AC, yes, you absolutely need a generator.
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Old 02-08-2012, 21:46   #9
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Re: Do I need a genset and if so what size?

It would all depend on the size of your battery bank. 2kw of solar would be overkill with only 800amps of batteries. Are you going with Li PO4 ?
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Old 02-08-2012, 21:48   #10
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Re: Do I need a genset and if so what size?

senormechanico: Air conditioner?
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Old 02-08-2012, 21:59   #11
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Re: Do I need a genset and if so what size?

Quote:
Originally Posted by senormechanico View Post
With all the great design of your boats, I'm a little taken back about your rather mastodon genset idea.
Its a $$$ and weight thing
$700 vs several thousand for a "marine" genset
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Old 02-08-2012, 22:05   #12
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Re: Do I need a genset and if so what size?

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It would all depend on the size of your battery bank. 2kw of solar would be overkill with only 800amps of batteries.
I have "space" for 2kw of solar
But yes, I had only planned on around 800 amp of batts.
Quote:
Are you going with Li PO4 ?
No idea
all very much in the infancy stage and really, just want a basic system that'll get me to thailand/malaysia where I can get a real system installed by someone who's not gouging me at $70 an hour .
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Old 02-08-2012, 22:15   #13
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Re: Do I need a genset and if so what size?

Quote:
Originally Posted by xymotic View Post
And... Is THAT generator going to be happy in an enclosed lazarette?
Large ventilated engine-room

It would probably be happier than this style enclosed in a box, I would have thought

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Old 02-08-2012, 22:18   #14
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Re: Do I need a genset and if so what size?

Quote:
Originally Posted by senormechanico View Post
"from scratch" apartment sized fridge
How big is an appartment sized fridge?
300l fridge +100l freeze?
I will not be compromising on the availability of cold beer and ice
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Old 02-08-2012, 23:03   #15
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Re: Do I need a genset and if so what size?

Cat man do ... I run a genset with two iverter chargers pushing a combined charge rate of 240AH. Honestly ... if I had to do it again I would have settled for my solar panels (no genset) and the 2 Balmar 150 AH alternators wired through a center fielder and smart regulator. The alternators would be a 'just in case' and good back up. Nice thing is that when you need to motor you are getting 'kick ass' charge ...
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