2 Generators

"What are people's thoughts? Any reason not to go electric for the get home?"

It would really depend on the boe thruster setup, as it will be used hundreds of times more than emergency propulsion.

Only a Hyd bow thruster can be used for long periods of time, so a noisemaker that can feed the thruster with the main engine at idle is really nice.

FF; said:

Only a Hyd bow thruster can be used for long periods of time, so a noisemaker that can feed the thruster with the main engine at idle is really nice.

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That leads me to another question.
I thought most thrusters shut down from over heat so what would the advantage of a generator feed other than doing away with batteries?

Hawgwash said:

That leads me to another question.
I thought most thrusters shut down from over heat so what would the advantage of a generator feed other than doing away with batteries?

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The generator has a hydraulic pump on it for the bow thruster. Since the generator is at a constant rpm, the performance remains the same with a 100% duty cycle.

Ted

O C Diver said:

The generator has a hydraulic pump on it for the bow thruster. Since the generator is at a constant rpm, the performance remains the same with a 100% duty cycle.

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Thanks again, Ted. I was stuck on electric and didn't connect the hydraulic dots.



Too early in the morning on the west coast for me to try thinking.

Hawgwash said:

That leads me to another question.
I thought most thrusters shut down from over heat so what would the advantage of a generator feed other than doing away with batteries?

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There is a bit of urban myth regarding electric thrusters kicking out due to overheat. Often the kick out is due to wiring, batteries or switchgear being the issue. My bow thruster will stay engaged for over 30 seconds without a kick out, the longest I have ever needed it. The better electric thrusters made today will run for a very long time, purportedly they are designed to do this.

Hydraulic systems have a shelf life as hoses, O rings and fittings age. Not trouble free at all. Some builders hide this plumbing in the darnedest of places

sunchaser; said:

There is a bit of urban myth regarding electric thrusters kicking out due to overheat...Hydraulic systems have a shelf life as hoses, O rings and fittings age. Not trouble free at all. Some builders hide this plumbing in the darnedest of places.

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Having spent some time around heavy equipment and seeing the frequency of hydraulic line failure, I have looked at hydraulic thrusters a bit askance. It's a lot easier to deal with oil on a dozer than a DeFever.

THD said:

Hawg-we have a 20KW and a 12KW. We normally use the 12KW almost exclusively. We only have to use the 20KW if we use the AC

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seriously? You are burning upto 12KW without ac? wow.

Hawgwash said:

Having spent some time around heavy equipment and seeing the frequency of hydraulic line failure, I have looked at hydraulic thrusters a bit askance. It's a lot easier to deal with oil on a dozer than a DeFever.

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Yeah and no. Lines on a dozer take FAR more abuse then some lines clamped to a bulkhead or in a PVC chase. Most of what I've heard and seen hydraulically failing on boats are seals.

High Wire said:

3 Blue Sea MEGA fuses, 2 Blue Sea 6 fuse blocks and 2 circuit breakers.

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Thanks Archie. Gave me something to look up and now I know.

N4712 said:

Yeah and no. Lines on a dozer take FAR more abuse then some lines clamped to a bulkhead or in a PVC chase. Most of what I've heard and seen hydraulically failing on boats are seals.

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Still messy though huh?

Hawgwash said:

Having spent some time around heavy equipment and seeing the frequency of hydraulic line failure, I have looked at hydraulic thrusters a bit askance. It's a lot easier to deal with oil on a dozer than a DeFever.

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Many maybe most hydraulic thrusters and anchor windlass systems on recreational boats utilize an electric clutch to engage the pump as needed. You would probably wear out the engine (s) in the boat before you had 100 hours on the hydraulic system. Also, from the research I did on converting my bow thruster to hydraulic, it's common for fluid pressures to be below 2, 000 psi and with short use periods, oil temperatures are very low compared to systems that run continously. If it hadn't been for the substantial cost of converting mine, I would have a hydraulic bow thruster in my boat.

Ted

Folks that prefer hyd will usually select it for most apps.

Steering , windlass , bow & stern thruster ,stabilizers underway generation of 120/240AC and perhaps the boat hoist.

Most any high motor load like a water maker or scuba compressor can be hyd operated.

And of course a get home , either spinning the existing shaft or a second prop on the stern quarter can be hyd.

Happily the noisemakers powering a hyd generator head can be operated at a speed just to create the power , no fixed RPM as with a mechanical generator head.This allows better low speed loading , so longer life.

Before you consider hydraulic off the generator for a get home engine talk to a couple of owners who have that set up. From what I have been told the "emergency only" nature of that set up means it is never used and if needed is difficult to set up and remember how to operate if it will work at all. Also it requires a very large generator.

Over the years I have not met a trawler owner who has been happy with such a system. Two have said they wanted to pull it out and put in a wing engine.

Like anything else in the boating world, this depends on where and how you boat. Most single engine trawlers in the Eastern Caribbean have wing engines, and not just for get home purposes.

The eagle has 3 gens, 12kw main that has hydraulic pump to power bow thruster or get home, a 5 kw cruise gen which is powered by th main 671, and a small portable for misc. Also a 3 kw inverter for inbetween time of running a gen. The hydraulic can be run continue for hours. The eagle is set up to cruise which is the reason for the cruise gen.

The hydraulic pump and the cruise gen have electric clutch, so the free wheel when not used

I was going to ask if you can run both and share the load but it seams that you would have to split feed the AC panel

Pura Vida said:

I was going to ask if you can run both and share the load but it seams that you would have to split feed the AC panel

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Not easy to share the load between two running AC generators. To do so requires synchronizing gear including regulators and engine governors. Tricky stuff.

"Not easy to share the load between two running AC generators. To do so requires synchronizing gear including regulators and engine governors. Tricky stuff."

This is true because the high priced marine noisemakers are 60-70 years behind the times.

A tiny Honda feeds an inverter tech which allows paralleling units with a cheap plug in cord.

When variable speed noisemakers finally get into white boats , gen size and fuel burn will go down and longevity will go up.

Keep asking .

N4712 said:

Yeah and no. Lines on a dozer take FAR more abuse then some lines clamped to a bulkhead or in a PVC chase. Most of what I've heard and seen hydraulically failing on boats are seals.

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"O" rings can fail, especially when they get +10 years and are in a no pressure set more than a pressure set. Some builders do not engineer and utilize long hose runs with subsequent unnecessary fittings being located in the strangest of places. It is not uncommon to see some low cost Chinese fittings and hose installed where Aeroquip or Cat should have been specified.

Two gens make sense on boats that travel long distance, log many hours or travel to remote areas. Gens just seem much more unreliable than the propulsion gear. Not uncommon to see a 30yr old boat with original propulsion gear, but gennie has been replaced. Maybe more than once.

Gennie problems paid for the construction of my boat.

FF said:

"What are people's thoughts? Any reason not to go electric for the get home?"

It would really depend on the boe thruster setup, as it will be used hundreds of times more than emergency propulsion.

Only a Hyd bow thruster can be used for long periods of time, so a noisemaker that can feed the thruster with the main engine at idle is really nice.

Click to expand...

I have a hydraulic bow thruster that is powered from the main engine. The same hydraulics are used for my stabilizers. This would be no use for a get home motor though, since I'd need it when the main was not working. So I see it as a separate decision.

Bay Pelican said:

Before you consider hydraulic off the generator for a get home engine talk to a couple of owners who have that set up. From what I have been told the "emergency only" nature of that set up means it is never used and if needed is difficult to set up and remember how to operate if it will work at all. Also it requires a very large generator.

Over the years I have not met a trawler owner who has been happy with such a system. Two have said they wanted to pull it out and put in a wing engine.

Like anything else in the boating world, this depends on where and how you boat. Most single engine trawlers in the Eastern Caribbean have wing engines, and not just for get home purposes.

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I don't think I have room for a wing engine - at least not without getting rid of the 20kW generator. I am thinking that electric would be the most compact and simplest to install. Motors are still quite expensive but the price and performance is really improving as they are gaining popularity for transportation in general. Maybe in another 5 years or so it will be a no brainer.

Pura Vida said:

I was going to ask if you can run both and share the load but it seams that you would have to split feed the AC panel

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I had a separate 120 volt ac electric panel install for the second leg of the 240 volt? The extra panel for additional electric heaters and the air condition. The boat is wired for 120 volt, and I did not want to change the original panel or wiring. A separate panel and wiring was easier and cheaper.

Have not looked at wiring the gen sets. The original panel and wiring is sized for 75 amp which the 12 kw can out put. 75 amp is plenty.

www.wesmar.com/product/apu-systems

Wesmar hydraulic get home system described in above download

BandB said:

Now, if I was designing a boat, I'd just go with two equal generators 95% of the time. That way you can rotate them and prolong lives.

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That is what I did, and with the additional benefit that one set of spares covers both gensets.

sunchaser said:

www.wesmar.com/product/apu-systems

Wesmar hydraulic get home system described in above download

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Thanks - the question for me is based around whether I want to add a hydraulic PTO to my existing 20kW generator for this kind of get home system. Alternatively I could use the 240V it's already generating to power an electric get home motor. It would seem to be a simpler solution - though I'm not sure if it would be cheaper yet.

Richard

Britannia said:

Thanks - the question for me is based around whether I want to add a hydraulic PTO to my existing 20kW generator for this kind of get home system. Alternatively I could use the 240V it's already generating to power an electric get home motor. It would seem to be a simpler solution - though I'm not sure if it would be cheaper yet.

Richard

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Where are you intending to cruise that you need to get home from?

BandB said:

Where are you intending to cruise that you need to get home from?

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Hawaii.

Britannia said:

Hawaii.

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Makes very good sense now to see your concern. I know many do long cruises with no secondary propulsion, but don't think I could. Have you talked to KK about what they would suggest and/or what they offered in the boat new? Just thinking that perhaps they've worked through the issues previously and could provide you a very good blueprint for a plan.

BandB said:

Makes very good sense now to see your concern. I know many do long cruises with no secondary propulsion, but don't think I could. Have you talked to KK about what they would suggest and/or what they offered in the boat new? Just thinking that perhaps they've worked through the issues previously and could provide you a very good blueprint for a plan.

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I haven't contacted them yet - though I'm sure I will. I'm definitely in the early stages since I won't be able to start all this til I retire. And, as you were no doubt going to point out, if you're just near coastal then have a good towing package and don't fret. I do, and I don't . And maintain the engine well too, of course.

However, the boat was built in 1988 and only 8 were ever made. I suspect that this will affect how much advice Kadey Krogen can give. I read an article on a Krogen 54 crossing to Europe and it made reference to a hydraulic get home. Of course electric motors weren't really a viable option 25 years ago. In the next 5-10 year they might be the best option.

Richard

Ski in NC said:

Not easy to share the load between two running AC generators. To do so requires synchronizing gear including regulators and engine governors. Tricky stuff.

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Sharing is tricky, spitting is not.

And in smaller boats that is about all you need to do.