Why hybrid?

[ItDepends]

Originally Posted by tenchiki

Some additional considerations:
1) Regenerative systems have gotten a LOT better recently. There is also solar and wind for charging the batteries.

What has changed? Propellers are the same... you can get a BIT better using a permanent magnet alternator instead of field coil, but at the cost of a more complex controller. You STILL can not generate 2kW from an 18 inch prop at 8 knots. And even 2 kW is trivial if you are trying to move the boat with it.

If you have actual data otherwise, prove me wrong...

[s/v Jedi]

Originally Posted by ItDepends

So far, nobody, but nobody, has addressed anything with real numbers, just sales talk and changing the premise. I completely understand (and tried to say so) that I completely understand that a plug-in electric can be a good choice for a day sailor. I completely agree with that premise.

I have a cruising sailboat. We travel about 10,000 miles a year, and use our engine about 350 hours of that time, virtually all of it at about 80% of full engine power where we burn about 1 gal/hr to move at 6 knots. Thats about 350 gallons, and we burn another 60 gallons in a small genset to generate house power. So our total fuel cost in a year is about $2300. Let's call it $2500, inflation and all...

How would a hybrid drive reduce our cost? Explain.

Something is off. You use 80% of full engine power for 6 knots but I only use 15% of full engine power for 6 knots. These massive differences cause different outcomes.

[Adelie]

Originally Posted by Pete7

To be useful, the boat speed needs to be quite high for a small yacht. 5 knots or less, it would be better to stick a 50w solar panel on the deck. 7-8 knots is were the power is really generated. Sailing Uma on their way back from Svalbard talked about this. So if you have regular cruising speed in the 7-8 knot range and are willing to have a fixed big prop* then go for it. Prop size matters too, big is better, on an efficient fin keeled hull to maintain hull speed when you select regen and the drag ramps up, no free ride.



Us with 31ft are probably better off not using regen and going for the folding prop to achieve a better average cruising speed in the 5-6 knot range. Note, average not occasional best speed.



However, if you are using the power generated by a hybrid for another purpose like cooking then perhaps there are benefits to hybrid for a cruising yacht. Just not cheap.



*Apparently and it needs to be checked, a Bruntons Prop can be made to work with some quick switching from fwd drive to regen before the prop slows and the blades change. Ocean Volt also have a folding regen sail drive option, but its Euro 40k for the package, unless your a You Tuber.

The original OV regen system used a folding prop.
The current €40k system uses a Controllable Pitch propeller which produces a LOT more power, especially at moderate speeds (5kt or so).

When a cheaper CPP is harnessed to a hybrid drive it will become a lot more economical.

[Adelie]

Originally Posted by s/v Jedi

Something is off. You use 80% of full engine power for 6 knots but I only use 15% of full engine power for 6 knots. These massive differences cause different outcomes.

You have vastly different boat sizes and engines.
ID’s boat is 35-40’ long and the motor is 25-30hp so probably closer to 35’.

[Adelie]

Originally Posted by ItDepends

What has changed? Propellers are the same... you can get a BIT better using a permanent magnet alternator instead of field coil, but at the cost of a more complex controller. You STILL can not generate 2kW from an 18 inch prop at 8 knots. And even 2 kW is trivial if you are trying to move the boat with it.



If you have actual data otherwise, prove me wrong...

Originally Posted by ItDepends

So far, nobody, but nobody, has addressed anything with real numbers, just sales talk and changing the premise. I completely understand (and tried to say so) that I completely understand that a plug-in electric can be a good choice for a day sailor. I completely agree with that premise.

I have a cruising sailboat. We travel about 10,000 miles a year, and use our engine about 350 hours of that time, virtually all of it at about 80% of full engine power where we burn about 1 gal/hr to move at 6 knots. Thats about 350 gallons, and we burn another 60 gallons in a small genset to generate house power. So our total fuel cost in a year is about $2300. Let's call it $2500, inflation and all...

How would a hybrid drive reduce our cost? Explain.

If your preference is to motor long distances at 6kt hybrid isn’t going to work for you.
At 4kt you’ll need something near 2kW, 1kW near 3kt. But range will be limited by the battery capacity and wattage of solar panels you are willing to install.

Hybrid would probably reduce your annual fuel expenditure a bit but not enough to make up for the added cost of the system, even is lifetime return on investment is considered.

[dannc]

Originally Posted by Adelie

If your preference is to motor long distances at 6kt hybrid isn’t going to work for you.
At 4kt you’ll need something near 2kW, 1kW near 3kt. But range will be limited by the battery capacity and wattage of solar panels you are willing to install.

Hybrid would probably reduce your annual fuel expenditure a bit but not enough to make up for the added cost of the system, even is lifetime return on investment is considered.

Exactly, if one expects to motor long distances at any speed, hybrid will not work if one expects to be using electrical power all or most of the time.

We are looking at a boat, not a sail boat, that has 6KW of solar panels. That is a game changer.

What we have done cruising on boats and what we plan to do, is to get to an area, and then stay in that area for awhile, moving a bit here and there, say 1 to 5 miles every once in a while. Or just traveling 25-50 NMs to a new area. The boat in question will allow travel on quite a few European canals, some of which have speed limits. Having a hybrid system for these use cases makes perfect sense. Using diesel to move the boat just would not be done until there was a longer passage to be done, or there was no sun for many, many days and we had to make some miles due to time issues that would almost certainly be visa related.

The question is does it make money sense?

Because the boat has 6KW of solar power, does one need a generator? Does one need a get home engine if there is a hybrid system? I think the answer is no which saves quite a bit of money that can be used for the hybrid system. Certainly, not burning fuel saves money. The question is how often would one travel under electric power? That gets back to the use cases and reality.

The cost issue can't really be decided until one is really close to ordering the system but a big part of the cost is the size of the battery bank(s). Another issue is complexity which does get back to cost and expense. Is it better to have a generator and a get home engine or a hybrid, taking into account the initial cost, ongoing expense, and complexity?

We will look very closely at having a hybrid system if we mange to get a boat. Hybrid has some big advantages for how we want to use the boat. The only question is, does a hybrid make money sense?

Later,
Dan

[Pete7]

Originally Posted by ItDepends

Actually not at all true. The Autoprop works fine to power a propshaft alternator and so dose a MaxiProp.

But they STILL only make 500 watts at 8 knots with an 18 inch prop.

Au contraire, please read the last paragraph in that post. Bruntons supply the Autoprop which can regen.

However, if you are motoring for 350 hours a year at 6 knots then I agree with Adelie, perhaps its not for you. I don't know what you sail but if its 35-40ft then you might be interested in this graph for slightly smaller yachts in calm water giving power and speed likely to be achieved.

The cost of a 25-30hp diesel in the UK is £5000-6000 for a DIY fit. The cost of the Beta hybrid equivalent? Well they don't advertise prices but I would be willing to bet its X2 the plain diesel price. The cost of a 10Kw pure electric alternative from Electric Yachts in the US is, $5000 for the kit less batteries and similar for a Lynch motor kit in the UK, again no batteries. 15Kwh of batteries is likely to be another £6000 in the UK. So not a viable change in my mind with diesel at £1.70 a litre (say $1.35 in the US).

[BAD ORCA]

Originally Posted by Pete7

To be useful, the boat speed needs to be quite high for a small yacht. 5 knots or less, it would be better to stick a 50w solar panel on the deck. 7-8 knots is were the power is really generated. Sailing Uma on their way back from Svalbard talked about this. So if you have regular cruising speed in the 7-8 knot range and are willing to have a fixed big prop* then go for it. Prop size matters too, big is better, on an efficient fin keeled hull to maintain hull speed when you select regen and the drag ramps up, no free ride.

Us with 31ft are probably better off not using regen and going for the folding prop to achieve a better average cruising speed in the 5-6 knot range. Note, average not occasional best speed.

However, if you are using the power generated by a hybrid for another purpose like cooking then perhaps there are benefits to hybrid for a cruising yacht. Just not cheap.

*Apparently and it needs to be checked, a Bruntons Prop can be made to work with some quick switching from fwd drive to regen before the prop slows and the blades change. Ocean Volt also have a folding regen sail drive option, but its Euro 40k for the package, unless your a You Tuber.

Yes i agree. I did not mean to impress that i thought the regenerative power from the freewheeling prop would be enough to charge the batteries quickly and efficiently enough to be 'regularly' useable by the electric portion of the engine. My thinking was more along the lines that that power could be used to supplement the house loads.

I would expect that the BETA hybrids would need the diesel engine running to be able to charge the electric engine batteries or other forms of power generation like solar to create enough power to use the electric engine regularly.

In our experience with my friends electric engine in her 30ft sailboat however, the regenerative ability of the prop is enough to get approx 10% recovered energy back into the batteries on a 3-4 hour day sail, and thats with 5-6knots hull speed, about her boats max. When the batteries are fully charged (shore power) we can use the electric motor for several hours at about 25%+ power output, give or take. Combined with the sails on low wind days this moves us along quite nicely. She has 200Ah of AGM batteries, (4X 12 volt in series). I would imagine that with the energy density of lithium and a larger bank, that could get much better. If one had a decent solar array, combined with a lithium system and maybe something like a Watt and Sea generator plus freewheeling the prop on a hybrid engine, seems like it could actually make the electric portion of a hybrid engine useable way more often.

All of that though is VERY expensive so the argument of if its actually worth it, i suppose probably not. If one's cruising boat already has most or all of these things though, or plans to install them, then when it comes time to replace the diesel engine, maybe the extra cost for the hybrid diesel makes sense?

[NPCampbell]

Originally Posted by s/v Jedi

Something is off. You use 80% of full engine power for 6 knots but I only use 15% of full engine power for 6 knots. These massive differences cause different outcomes.

You have +10ft LWL + ~150HP and he has ~75HP?

[NPCampbell]

Originally Posted by ItDepends

So far, nobody, but nobody, has addressed anything with real numbers, just sales talk and changing the premise. I completely understand (and tried to say so) that I completely understand that a plug-in electric can be a good choice for a day sailor. I completely agree with that premise.

I have a cruising sailboat. We travel about 10,000 miles a year, and use our engine about 350 hours of that time, virtually all of it at about 80% of full engine power where we burn about 1 gal/hr to move at 6 knots. Thats about 350 gallons, and we burn another 60 gallons in a small genset to generate house power. So our total fuel cost in a year is about $2300. Let's call it $2500, inflation and all...

How would a hybrid drive reduce our cost? Explain.

I am ballparking that the regen on a hybrid would save you about 2 hours, or 2 gallons of fuel per year if used for propulsion.

Assuming:
You sail 6,900 nm per year [(10000 - 350x6)/1.15]
You average less speed sailing than motoring, 5.5kts
You get 80 W/hr @5.5 kts (see Beta Marine brochure)
You have an 80hp motor

Then:
You would generate 6900/5.5*80 W/yr = 100kW/yr
Your motor at 80% produces 47kW/hr (80*.8*746)
100kW / 47kW = ~2 hrs or 2 gallons in your case.

To put it in perspective, a single 300W solar panel @5 hours per day de-rated by 50% would be 300x5*.5*365 = 264kW/yr

The hybrid does buy you one important thing, redundancy. If you pull into a marina and your engine dies then you can still maneuver.

[s/v Jedi]

Originally Posted by NPCampbell

You have +10ft LWL + ~150HP and he has ~75HP?

I can’t see a boat needing 60hp to maintain 6 knots. I know my LWL is much more and my hull speed is much more, but I assume 6 knots is well below their hull speed as well, because it would not be right to use math where a boat is pushed into hull speed as a figure for power required for continuous motoring.

Of course they can have a much smaller engine, like 25hp… I simply don’t know, but something isn’t adding up.

[Adelie]

Originally Posted by NPCampbell

I am ballparking that the regen on a hybrid would save you about 2 hours, or 2 gallons of fuel per year if used for propulsion.

Assuming:
You sail 6,900 nm per year [(10000 - 350x6)/1.15]
You average less speed sailing than motoring, 5.5kts
You get 80 W/hr @5.5 kts (see Beta Marine brochure)
You have an 80hp motor

Then:
You would generate 6900/5.5*80 W/yr = 100kW/yr
Your motor at 80% produces 47kW/hr (80*.8*746)
100kW / 47kW = ~2 hrs or 2 gallons in your case.

To put it in perspective, a single 300W solar panel @5 hours per day de-rated by 50% would be 300x5*.5*365 = 264kW/yr

The hybrid does buy you one important thing, redundancy. If you pull into a marina and your engine dies then you can still maneuver.

6900nm / 5.5kt = 1255hr

1255ht * 80W = 100364Whr = 100.4kWhr * 0.746 HP/kW = 135hp-hr

Diesel engines provide about 18hp-hr/gal.

135hp-hr / 18hp-hr/gal = 7.5gal.

I don’t see that it makes economic sense for the OP.

But long distance motoring is not the point of hybrid marine propulsion. The point of The EP portion of HP is to not need to start the ICE for entering and exiting harbors/marinas, setting/retrieving anchors, and short bursts of power when tacking or just getting out of the way of large vessels that might run you over.

For vessels that do a lot of slow maneuvering like commercial fishing vessels hybrid makes a lot more sense. Canal boats in Europe would also be good candidates.

[Adelie]

Originally Posted by NPCampbell

You have +10ft LWL + ~150HP and he has ~75HP?

OP indicates 1gal/hr at 6kt using 80% of power.

Diesels provide about 18hp-hr/gal so they are probably using about 18hp at 6kt.
I’m betting they are not at 80% power but at 80% rpm which is probably about 60-70% power. That means the engine is in the 30-40hp range not 75hp.

[wingssail]

Originally Posted by tenchiki

Some additional considerations:
1) Regenerative systems have gotten a LOT better recently. There is also solar and wind for charging the batteries...

Can you give us some more definitive information on this?

The reason I ask is that prop slippage works against you when you trying to use regen.

Example: While motoring you may absorb 20HP (15Kw) turning a propeller at a theoretical non-slippage rate of 12 knots but due to slippage the boat only goes 6kts (50% slippage)

However: sailing at 6kts in regen mode the propeller turns as if you are going 3kts, (that 50% slippage) and produces less than 7Kw, probably much less because the propeller is not working at its efficient rpm.

If you could turn a large diameter propeller at a slow speed it might be more efficient, or a moderate diameter propeller with very flat blades (low pitch so it turns fast), you might improve the situation, but neither would be practical for powering a normal boat.

Regen is, in my view, primarily a marketing argument.

[s/v Jedi]

Originally Posted by Adelie

OP indicates 1gal/hr at 6kt using 80% of power.

Diesels provide about 18hp-hr/gal so they are probably using about 18hp at 6kt.
I’m betting they are not at 80% power but at 80% rpm which is probably about 60-70% power. That means the engine is in the 30-40hp range not 75hp.

Your math is impressive, but I still don’t get it. As I see it, when he is using 18hp to go 6 knots, while I also use 18hp to go 6 knots, then it means he is powering to close to hull speed because his cruising speed shouldn’t require what, 10hp?