Gas vs Diesel generators.. Help? (Little Hondas vs Fisher Panda Style)

[CaptainShack]

Ok. Seems most tend to agree the safety issues are major and the noise is considerable.

While two of those Honda's seems great. If one breaks, always having a backup would be nice. Not thrilled with the idea of dragging twin honda's out of a bin onto the deck then deafening all my neighbors including us.

Now that I have a bunch of company names that make gen's I'm going start looking into pricing. Hoping they are a bit more reasonable than 12k.

Thinking a 6-9KW gen would give us decent range and keep the weight resonable for my little 33ft cat. Anyone have any specific suggestions on models available in the US? Gonna call Next-Gen tomorrow and see what prices are looking like.

[rslifkin]

Another generator brand to look at is Phasor. They use Kubota engines like Northern Lights, but the units tend to be a bit cheaper (still with a good reputation). There's also Onan, Kohler and Westerbeke, although I've heard some support related grumbling about Westerbeke and I wouldn't recommend Kohler. Westerbeke is the only game in town these days if you need an inboard gasoline generator though. Everyone else dumped that market.

[SailingHarmonie]

Originally Posted by Jammer

Generators are an expensive way to make power. You're looking at over $1 a kwh all up with any of them.

This^^^^

We make about half our power with solar and half with generator. After 6 years the cost of our solar electricity is down to about $0.35/kW-hr, and as long as the system keeps working will keep getting lower. It will be quite a long time yet before it drops below the cost of grid power, however.

Our generator, when operating at full load (its most efficient setting), makes about 3.6kW at full load and burns about 0.65 gallons per hour. So 5.5kW-hours per gallon of fuel burned. So at $5/gallon a kW-hr of energy costs about a $1.10 just in fuel. Add in maintenance and depreciation, and the total costs for a kW-hr of energy are pushing $1.80.

I just can not understand the economics of a "hybrid" powered boat. A plug-in electric boat can make great sense for those people that can use one for day sailing. Once you want to charge from onboard sources to motor for longer than one battery charge can take you, either the economics or the practicality, I just can not make work in my calculations.

[SailingHarmonie]

Originally Posted by CaptainShack

Ok. Seems most tend to agree the safety issues are major and the noise is considerable.

While two of those Honda's seems great. If one breaks, always having a backup would be nice. Not thrilled with the idea of dragging twin honda's out of a bin onto the deck then deafening all my neighbors including us.

Now that I have a bunch of company names that make gen's I'm going start looking into pricing. Hoping they are a bit more reasonable than 12k.

Thinking a 6-9KW gen would give us decent range and keep the weight resonable for my little 33ft cat. Anyone have any specific suggestions on models available in the US? Gonna call Next-Gen tomorrow and see what prices are looking like.

Do you want a generator to supply enough power to run indefinitely? The only number you need to know is how much power you ACTUALLY use at cruising speed. I assume you know that number?

Would you be happy with a slower speed? Power rises with the CUBE of the speed so even a little drop in boat speed makes a HUGE difference in power consumption. As an electric boater I am sure you know this.

Do not just pick a size because it "feels right" you need to run the numbers. The difference between a 6 and a 9 kW genset is quite large. Maybe you could be by with a three? I mean you started off thinking you could do what you want with a 2kW Honda...

What voltage does your system run at? Do you have the existing equipment on board to convert 120 or 220 to your battery charging voltage?

[Pizzazz]

It is not clear what the mission is. It looks as if you are trying to extend the range of your electric pod/battery setup. In this case, only a diesel generator makes sense (better efficiency, safer, more reliable). Then you will have a diesel-electric cat, which may or may not make sense.

If you are just looking to recharge for house needs, then a kludge like the Honda will do for a season or two but eventually you will get tired of the noise and the trouble of moving the generator on deck to use, then stowing it below deck (which is not safe anyway). Also, on your cat, it may be more efficient to get solar panels for that job.

[malbert73]

Originally Posted by sailorboy1

I have a small inboard diesel generator, but got a Honda EU2200 for running smaller loads. Shortly after that the diesel generator broke AGAIN. By that time I was already liking the Honda better so didn't repair the diesel that had already broke down 4 times in 2 years. Yes the Honda wouldn't runa run as many things at once, but is quieter and uses the same or less fuel as the diesel. It has been 4 years and the Honda now has twice the hours of the inboard diesel and the only things have been replacing the pull cord and cleaning the carburetor a couple times. The cost of that is about $10.

The next maintenance I do to the diesel generator is to remove it.

You mind sharing your brand of diesel genset? My money is FP

[CaptainShack]

SailingHarmonie
You basically nailed it. I didn't want to talk size because we're not sure yet what size we're going to need till we start testing. We're in Boat prep, other refit projects and Research phase at the moment. I never mentioned a 2Kw honda. Just the 3200i which just recently released as an example so others could help me understand the Gas vs Diesel generator. Which worked well and gave me the main issues + a bunch of brands to start getting my head around pricing and reputation of said brands. My boats going to be rigged for 24v. Actual hardware pending. Most of what I have currently is getting yanked.

As for the "economics" your not wrong. We're 33ft. So small as cats go. Power generation I'm researching is to help extend that range ONLY when its needed for the examples given. Heading down the ICW or doing canals, and rivers for fun. Or an emergency need for more power. Not a daily driver to top up the batteries. My solar handles that fine as is and an upgrade will make it even better! We've got solar and plan to add more. Most of the time we're just getting off the dock so we can sail around the NC coast for fun.

Thank you everyone for your replays its been super helpful.

[valhalla360]

Originally Posted by Searles

Be carefull of getting petrol exhaust fumes into your cabins and sleeping areas ,they will kill you verry silently and quickly.⚓️⛵️��

Same with diesel engines (and yes, even diesel exhaust in the cabin can be dangerous before you say it).

[valhalla360]

Assuming you are just supplementing for longer range runs:
- Noise is a non-issue. The modern portable inverter generators are quieter than your current diesel propulsion engine.
- Assuming your fuel tanks are on the bridge deck and bottom vented to the water (not into the hulls), the fire issues largely go away.
- Yes, they need lots of air because they are air cooled.
- Diesels are generally 20-30% more efficient but with current fuel prices, that's largely negated with higher priced diesel.
- I think a pair of 2200w generators would make a nice backup. Just plan your routes and expected range. If you will need the generators, get them started early, so if you have to run at high output, you aren't limited to 3-4kw at the prop.

Biggest issue is where will you place it while running. We had a 2400w Yamaha we used at anchor on our Gemini and it was placed on the aft deck outside the cockpit with the exhaust facing overboard and tied down, so a stray wake wouldn't send it overboard (we still ran a CO detector and kept the rear cabin windows closed when running...would do similar with a built in diesel). When not in use, it was in the bottom vented cockpit with a wood box covering it, to protect it from weather.

Only time we ever had a complaint, someone saw the generator sitting on the back deck and went off on us. Turns out they heard a nearby boat with a built in generator, since ours wasn't running while he was pointing out the "horrid" noise. Didn't do it a lot but when it's stinking hot and no breeze, sure is nice to crank up the aircon.

[malbert73]

Btw- Nextgen 5.5 has been troublefree for me. Kubota 2 cylinder diesel, runs at 2800. NL is overkill IMO for most recreational boats as we don’t run 24-7, though I have run the Nextgen overnight for AC a few times (most of time like most folks just turn it off after sunset when things cool down)

[Tupaia]

I can't help thinking that 2 Yamaha 9.9's @ circa $2500 each would be a cheaper and dare I say better solution.

[mvweebles]

While most NL generators use Kubota engines, the 6kw uses a Shibaura 3-cylinder engine, also used in small tractors.

OP really needs to figure out how much power is needed and for what duration which of course is balanced by battery capacity. OP mentions "long periods of motoring." Does this mean all day, or just a few hours? Is the generator a defacto propulsion engine or a super beefy battery charger? To run two large electric motors for many hours,, may need a large 3-phase diesel generator which would be overkill for all other applications on a 33 foot boat.

[CaptainShack]

Tupaia
If your suggesting twin outboards they wouldn't solve the fun factor of ghosting out of slips like some kind of nautical ninja. I'd also have to build a place for them to mount that would be more effort than our current plan. It would disappoint my other half who's very keen to go for electric for leaving the slip then focus on out sailing skills and planning. I will say 2500 per so 5k +mount and hull modification to support it. + the new fuel system for gas wouldn't be much cheaper than you'd think. But cost isn't the primary motivator for the project. Also loosing the maneuverability of twin pods would be a bummer. I wanna drive this thing like a tank

Malbert
Just got off phone with NextGen for the 5.5Kw is 11.6k$ so thats an option if an $$$ one. Could be worth it for the long hall and I do already have a tank and fuel cleaning system for it.

valhalla360
Seems the real trick is how often do we find the batteries to be overly limiting factor. I'm thinking the back deck has plenty of room for a little grab and go generator. Phase 1. We get the drives installed with the twin E175's 8960Wh batteries and see how that feels. Do some testing. Then shore up the issues with our style of sailing around the Neuse River and the NC coast. I'm not against a 2kW honda or a 3.2kW honda if it can be used safely. Which running it during waking hours on the back, or front of the cat should be fairly safe.

Genset would be super nice having a remote start. Larger tank. Don't have to pull it out. Just flip and go.

These prouts originally had a 15HP diesel . Prior owner put a 20HP Yanmar in.. and cut a chunk of the fiberglass out to gain access for maintaince. Bit of a mess with water intrusion. Twins 9.9hp pods should be more than enough go juice to push my little cat. Fun project.

[Jammer]

9.9 hp pods will typically draw 8.2 kw each at WOT. Not sure quite how you have this engineered but the maximum rated continuous output from the battery banks you have is 7.2 kw per bank which will support a maximum of around 90% throttle.


The 9.9 hp pods are already downsized from the OEM 15 hp engine. I would think just as a guess based on other similar size boats I've been on that you will have to run 80% to get close to hull speed under favorable conditions and you will have to run at WOT to maintain control in difficult conditions.


At 80% throttle you will need 13 kw.


I am not sure what a 3200i (which has a rated output of 2.600 kw and will deliver around 2.4 kw to your drives at 48v after conversion losses) accomplishes for you. It will take six hours to charge a flat bank which will then be good for around an hour of motoring.


This does not serve your stated goal: Provide extra power when we want to run the electric drives for extended periods of time, pushing how long the batteries last when sailing isn't an option. ICW-work, heading through Okeechobee again.. ect

Okeechobee is, what, a 100 mile run? It will take over a week with that setup.


Northern lights make a 12kw diesel genset that is $18,000. I would see this as the minimum that is likely to fulfill your stated mission. 600 pound machine that would likely fit in one of your existing engine compartments. You would be able to run the pods at 70% average throttle would probably be enough for a typical day of motoring if you start with full batteries.


The next size up from Northern Lights is 20kw and you won't have room.


On the gasoline side the closest you can come in portable units is the Honda EB10000 which is a 400 pound machine that delivers 9 kw rated. They are $5,500 street. This would still be too small but serves as a discussion point. There are various non-portable gasoline generators in the 12 kw size range. Though cheaper than the Northern Lights machine they are of similar size and weight and are not marinized.


These are the sort of size ranges you should be comparing, because you cannot move your boat with a suitcase generator.


Now if you want to experiment and see whether I'm bad at math, godspeed, it's your boat and your money. Don't get me wrong, I like electric propulsion, I drive an electric car every day, I'm putting solar panels on my boat this spring, etc etc -- I'm a fan of the technology. I'm just pointing out the obvious-to-me inconvenient facts.

[CaptainShack]

Okeechobee took us about a week with the diesel. So not a big stretch there. Longer actually because of weather. We almost got stuck behind the last Lock for 3 months because of maintance! But we made it. Only so many hours in the day at 5 knots. Particularly in the winter. Running the 20hp at around 2200RPM leisurely. No 50 mile days for us.

The Twin 9.9HP "equivalent" drives I'm looking at are direct to the prop 6kW. No gearing system. At half those drives power output they should last about 6 hours with the bats if you max it out use every last bit of juice. of course we wouldn't. Add a generator if for whatever reason we're motoring 6 hours and you just kicked that up another few hours or more depending on the genset setup. Counting whatever the solar will put in during the day as a bonus.

"obvious-to-me inconvenient facts" thats one way to put it.

That 80% estimated throttle is interesting assumption. Could be. That would shorten the time available for motoring for sure. Depends on the drag on my boat, hull shape and I'd imagine displacement.