How big of a Genset do I REALLY need? Your advice appreciated...

[jrmccoy]

Gents,

I'm in the unenviable position of needing a new genset. Situation is I have a Norpro 21kw which is dead....and I could get another engine setup for it to cobble onto the still good generator, but I'm going to be in the $8k range for that, which is of course less than a replacement FOR THAT SIZE of genset, BUT for the same money, I could drop down to something way smaller, and go new. I am not convinced that I would have to give up that much because I have a whole boat inverter (outback 3232).

So, looking at specs for like a 5.5kw Kubota Marine unit, it provides almost 42 running amps at 120V or half that, 21 amps at 240v. Maggie Mae has a LOAD of electrical stuff, but really, the only thing that I can't run off the inverter are the AC's, and that's with NO genset (main alternators charge inverter batteries underway)


I note in the marina that everything on the boat plus one AC running is in that range of amperage pull, so maybe I could even run one AC on this little genset, which would honestly work for me, but it could also charge the batteries on the inverter which, outside the AC's is all I actually need to have happen.

So, I don't want to trip over myself to save a couple of grand and have a way undersized genny which becomes a functional problem, but the idea of a small little 250 pound, easy to get in, quiet, fuel sipping kubota is awefully appealing.

So, how big of a genset do I REALLY need?

 

[davidwigler]

At least 15k.

 

[Scarlett]

I don’t know what your cooking situation is but if you have electric stove top and oven running with the water heater and the battery charger at full output you are probably pushing about 10 k right there, add an AC unit and you will be over 10 k. Unless you are really good at energy management like turning off the water heater until the battery charger ramps down etc. you will definitely require more than 5 k, min. Of 10k. John

 

[miboatnutz]

I think you'll find answers to be a somewhat subjective.

We had a Northern lights 16KW genset in our Hatt and without going into great detail in terms of what happened, that eight year old unit which was working perfectly prior to an unfortunate "incident" was replaced with a new NL 20kw unit a year and a half ago.

The reason why we went up in size was because sister wanted to have the ability to run all the AC units all the time if/when necessary plus ancillaries. PO actually replaced the original 20KW unit (can't remember if it was Onan or Kohler but one of those two) with the smaller 16kw NL unit because he didn't think he needed as much capacity.

On our Chris Craft we've got a 6.5kw Onan, however it's capacity is marginal in terms of being able to run both AC units and anything else. Genset is original and have looked at replacing with something larger if we decide to keep the boat.

The other thing to keep in mind is resale value. We bought our Hatt because engine hours were relatively low, genset reasonably new and sized somewhat adequately. If you install a much smaller genset that may work against you if/when you try and sell.

 

[racclarkson@gmail.com]

5K--no way. What was the NORPRO? One day you'll sell that boat. Think ahead.

 

[jrmccoy]

5K--no way. What was the NORPRO? One day you'll sell that boat. Think ahead.

The Norpro was a big old honking 21K. But Maggie Mae didn't have an inverter when it was installed...practically everything on the boat runs (while underway) on the inverter without any genset at all. Main alternators keep inverter bank charged.

So, thought I could drop down in size, but the consistent advice on this subject is to go big or go home. Based on everything I'm reading, I'll go 15k or larger.

 

[carolinacoast]

I got lucky and bought a boat with 2. 12.5 and 20kw. With family aboard the 12.5 can't keep up without me switching things off. . Uses 1/2 the fuel so great on delivery or with just the guys.
As stated, less than 20kw is likely a discount when you sell.

 

[racclarkson@gmail.com]

The Norpro was a big old honking 21K. But Maggie Mae didn't have an inverter when it was installed...practically everything on the boat runs (while underway) on the inverter without any genset at all. Main alternators keep inverter bank charged.

So, thought I could drop down in size, but the consistent advice on this subject is to go big or go home. Based on everything I'm reading, I'll go 15k or larger.

Aslan can trip the dock (at multiple marinas) with not everything running. I could sell extra juice with all on with my NL20KW. I don't currently invert, but hard to imagine running much while also recharging on a small unit.

I'll be passing you on Saturday about 1300 headed up to refuel in McClellanville. Listen for the long blast.

 

[dcate]

personally, I'd rather have a fixed 21 than a new 6. But, that's me.


(And I don't believe I'm alone. There's a *very* nice '53 not far from me. Price isn't too far off. Been on the market for a long time. very small genny. People don't wanna have to deal with that when they buy a boat. I think that's why that boat hasn't sold. could be wrong)

 

[Cricket]

Get the the big generator for when you need it, especially if you have inverter issues, etc.
I always recommend Phasor but NL is good too. Not a fan of Onan, Kohler, and especially Westerbeke.

 

[SEVEN]

Consider it’s hot and humid in South Carolina (which it always is in the summer)and you have a small new gen set. You might be lucky to run one air conditioner and the hot water heater and a few minor other items. Either go big or use it in cooler weather. Good luck.

 

[racclarkson@gmail.com]

Rusty,You know better. We just leave the hose on the dock for hot water.

 

[Pascal]

On a 53, if you re fine with a single 50amp shore power that’s about 12kw... so 15kw is fine. Your 21kw can’t put out more than the 50amp breaker on your panel will allow...

Less than 12kw and you re going to be tripping the breaker on the genset

Installation will be the same regardless of size so going under 12kw isn’t going to save you that much money.

The inverter Isn’t going to hell because at some point you ll have to recharge the batteries using even more power.

If the electrical end of your norpro is good, I’d try to find a new or rebuild engine for it. Doesn’t have to be an Isuzu, maybe a Kubota would work.

 

[SEVEN]

Rusty,You know better. We just leave the hose on the dock for hot water.

Lol, your right Robert I wasn’t thinking

 

[miboatnutz]

Other than going out of business I read mostly positive things about Norpro.

Cheapest alternative might be to just replace the engine on existing unit. There are a couple of guys on eBay who sell used Kubota, Isuzu and Yanmar Diesels that come out of reefer units. They're dirt cheap and some are relatively low hours as a whole bunch of them had to be replaced years back to meet current emmission standards.

Most of them have SAE bolt patterns on bell housing so should be compatible to what you've got now.

Might be able to find a used engine there, do a rebuild if it needs it and install as a replacement.

I bought a three cylinder Yanmar to power an ST16 generator head for back up power at home. Paid $900.00 for it and free shipping.

 

[Hatteras58]

About 4 years ago, we replaced the original 15kW generator in our boat ago with an Onan 13.5 kW. We've been very happy with the performance and fuel consumption and I cannot think of a single time when this unit did not deliver enough to power for all of the ACs, stove, water heater, etc. It's about 300 lbs lighter than the old Onan and opened up a lot of space in the gen room.

Southern Comfort, 1977 Hatteras 58 YF