Diesel generator

I have a 34 foot chb trawler someone is taking the generator out I was wondering what size generator normally comes in those prefer a diesel would anybody have any recommendations

Welcome aboard. It depends what electrical loads you have in your boat. For a 34’ boat something around 6kw plus or minus. If you have A/C then something about 6kw. If no A/C then something less. You do want to load the genset so it isn’t idling all the time.

What Dave says above. I have a 40 Eagle with a 6 kw. Cannot run all 110v appliances, hot water and 3 a/c at he same time but load management is not inconvenient. This helps keep a load on the generator when running. Also I am a big fan of the Northern Lights gen. Well everything but the price.

Mine came with a westerbeke 4.4kw

Its really simple to select the noisemaker size by using your dockside power hose .

If you live comfortably at 120v 30a , that's the size you need.

If you require 240V 50a , there is your answer.

My 38 footer has 2x 50A 125V dock inlets (enough to run everything) and a 6.5kw genset (not enough to run everything). That size genset is easy enough to keep adequate load on, but big enough that load management is easy and it's rare that I have any reason or desire to run more than it can power. The only time I would want a bigger unit is if I were to regularly use the electric stove on generator power in very hot weather where I want to keep all 3 A/Cs on.

What electrical loads do you have?
What shore power do you have?
What came out? Was that enough or too much?

My Marine Trader 34 has a 8kw westerbeke generator that was installed by one of the previous owners. It runs everything on the boat without issue.

Well, there are three types of generators you could install depending on use and loads:

Small, single cylinder, high rpm 3.5-4.0 KW- NextGen, Phasor, Fischer-Panda. These are fine (except for the F-P, a POS IMO) for light loads and a low usage profile. They are noisier than the 3 cylinder ones below and are better suited for limited usage, ie < 30 days a year. Bare genset cost is $6K with soundshield.

3 cylinder, 1,800 rpm, 4.5-6 KW- Northern Lights, Westerbeke, Onan,etc. This category is the workhouse of the 34-38' boat size that needs a robust generator to run A/C a lot and an electric stove with a high usage rate, ie 30+ days a year. $7-8K.

3 cylinder, 1,800 rpm, 8-10 KW- same manufacturers. Higher wattage is needed for two or more A/C systems. Not likely on your boat. $8K+.

So think about how you will use a generator and what you will use it for. If light and you can stand a little more noise then go with the first, otherwise the second category.

David

djmarchand said:

Well, there are three types of generators you could install depending on use and loads:

Small, single cylinder, high rpm 3.5-4.0 KW- NextGen, Phasor, Fischer-Panda. These are fine (except for the F-P, a POS IMO) for light loads and a low usage profile. They are noisier than the 3 cylinder ones below and are better suited for limited usage, ie < 30 days a year.

3 cylinder, 1,800 rpm, 4.5-6 KW- Northern Lights, Westerbeke, Onan,etc. This catagory is the workhouse of the 34-38' boat size that needs a robust generator to run A/C a lot and an electric stove with a high usage rate, ie 30+ days a year.

3 cylinder, 1,800 rpm, 8-10 KW- same manufacturers. Higher wattage is needed for two or more A/C systems. Not likely on your boat.

So think about how you will use a generator and what you will use it for. If light and you can stand a little more noise then go with the first, otherwise the second category.

David

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Unless we're talking about very large A/C systems, 2 A/Cs doesn't need an 8+ kw generator. My 6.5kw will happily run all of my A/Cs (2x 10k BTU, 1x 16k BTU). All 3 running is a little over 35 amps. So with the battery charger on, etc. it's about 70 - 75% load to run all 3 A/Cs. There's enough capacity left to allow the water heater to cycle on (another 10 amps), but that brings it very close to full load (about 90% or just over).

I have a 5.5kw NL and runs A/C, HW, Frig and other incidentals, but keep in mind when I need the gen is when I'm on the hook or mooring and at least in the northeast I'm not running a gen for AC. As others have said match to your needs and location.

I have a 38' with a 12k and a 8k btu AC units. Also a 1500w water heater and a 1000w air compressor. All of that can run on my old 3-cyl 5kW, but it is right at the limit. Water heater and air comp are not normally on, so I pick one or the other. The AC's keep genny loaded enough to stay happy.

My boat could run fine on a 3.5kW, with just a little more load management. But as Dave posted, the 1 (and 2) cylinder machines are not as polite as a 1800rpm 3cyl.

If a bit of noise and vibe does not bother you, then the 3.5 class might be ok. Need to add up all your loads to decide well.

Consider upgrading to an inverter that can automatically augment the genset when the occasional peak loads are greater than the genset (or shore power) can supply. Doing this allows you to downsize the genset which makes it less expensive, lighter, and smaller; and it allows the genset to run close to fully loaded most of the time, which is good for it. I have not done the math, but I bet a 4 kW genset + a 3 kW true sine wave inverter costs less than a 7 kW genset. Just a thought... I strongly recommend a genset that runs at 1800 RPM, not 3600 RPM.

RCAN, when you have taken all the sage advice offered above into account, remember if you have air conditioner(s) aboard, you can mitigate the high starting load those things require and actually lower the wattage specification of the generator you buy by installing Micro-Air Easy Start or Dometic Soft Start microprocessors on them. I would be happy to tell you about my success with them if you elect to go that way.

8K if you want to run both A/C's plus the water heater, battery charger and stove/oven, plus maybe a few outlets at the same time.

6K if you don't have A/C or can manually regulate load (or simply dont't think you'll run everything at once).

Manually regulating load typically leads to longer run times IMHO.

I have a bit of a different outlook. What generator will give you the least trouble?
The nature of a generator is to make your season miserable. For that reason I would not own anything other then Next-Gen. there are no circuit cards or complicated electrical systems. All parts can be bought from the open market. Yes a bit noisy and the output power is a bit dirty but they run flawless and burn very little fuel. I have a 3.5. It runs everything my 30 amp plug runs.