prop choice and hybrid systems

[Aravind]

Hi

I've been wondering about the following:

When you install a nice 6cyl engine in a 55ft sailboat, you might consider adding an in-line electric motor to achieve that nice silence (and no fuel consumption) for small manoeuvres such as going in and out of ports.

It's also nice to have a folding or feathering prop with your sailboat.


But... do these two systems go together? It seems to me that, with anything but a fixed prop, you cannot have hydro generation?
Hydro generation => cost-less topping up the batteries while sailing to use the electric engine when returning to port.

kind regards
Aravind

[SailingHarmonie]

I know for a fact that MaxProps and Autoprops work fine as prop generators. For other brands you would have to look at their manuals.

You might find the amount of power they generate in the real world to be fine for supplying routine house loads, but very anemic for replacing any significant amount of propulsion power.

You are looking at a LOT of money to spend for a few minutes of quiet power.

[Aravind]

ah cool ty, I like maxprop

an 8kw electric engine system to put in line isn't that expensive
you don't need a lot of batteries either to manoeuvre into the port
10kwh lifepo4 battieries is plenty

[wholybee]

Kiwi Props support hydrogeneration with their feathering prop. others might as well.
https://www.kiwiprops.co.nz/cms/inde.../electricdrive

[Matt Johnson]

Some have gotten a folding prop to work, but we found in testing the Gori and other folders that it was erratic - you could get it to stay in reverse for a few seconds, but as soon as the boat shifted in speed, it would fold and not open again without engaging the throttle.

Feathering works a whole lot better. Max Cruise, Antares and (I think) HH are now using Hydralign feathering with their hybrids. Once it goes into reverse orientation, it takes a lot to get it up over the hill and go into feather... Which is what you want for regeneration.

[SV Confianza]

There are a couple of feathering props being made specifically with hydro gen in mind, like this one: https://ewoltech.com/en/energymatic/

[Madehn]

Strikes me as a very expensive complex (relatively) solution looking for a problem.

[Statistical]

Originally Posted by Aravind

Hi

I've been wondering about the following:

When you install a nice 6cyl engine in a 55ft sailboat, you might consider adding an in-line electric motor to achieve that nice silence (and no fuel consumption) for small manoeuvres such as going in and out of ports.

It's also nice to have a folding or feathering prop with your sailboat.


But... do these two systems go together? It seems to me that, with anything but a fixed prop, you cannot have hydro generation?
Hydro generation => cost-less topping up the batteries while sailing to use the electric engine when returning to port.

kind regards
Aravind

You absolutely can get hydrogeneration from feathering props but understand hydrogeneration is likely going to be massively less output than you imagine and if your reason for doing this is hydrogeneration you might as well stop now. Save yourself the not insignificant cost and effort chasing a phantom dream. At most sailing vessel speeds hydrogeneration is very minimal output. Given you are coupling it to a relatively high output motor/controller and it will produce a tiny amount well outside the efficacy band actual generation will be even worse. It is a tiny amount of almost nothing and not worth the cost/effort involved.

Think of hydrogeneration as an unexpected bonus (if any) or a Christmas present on something you were going to do anyways even if hydrogeneration was a guaranteed 0.00 W then you won't be disapointed.

[Aravind]

Originally Posted by Statistical

You absolutely can get hydrogeneration from feathering props but understand hydrogeneration is likely going to be massively less output than you imagine and if your reason for doing this is hydrogeneration you might as well stop now. Save yourself the not insignificant cost and effort chasing a phantom dream. At most sailing vessel speeds hydrogeneration is very minimal output. Given you are coupling it to a relatively high output motor/controller and it will produce a tiny amount well outside the efficacy band actual generation will be even worse. It is a tiny amount of almost nothing and not worth the cost/effort involved.

Think of hydrogeneration as an unexpected bonus (if any) or a Christmas present on something you were going to do anyways even if hydrogeneration was a guaranteed 0.00 W then you won't be disapointed.

cool, ty for the info

well, a hybrid system often has a decent engine, like 100bhp, and a small electric engine, like 10kw, which is only for 'coming home' and 'going out'. It doesn't take much to fill the batteries of these.

However if your electric engine is your main engine, in this example you would require about 35KW... you won't fill that with hydrogeneration...

A realistic hydrogeneration system makes about 500w at nearing hull speed... plenty of examples of that, look at real world experiences with oceanvolt.

[SailingHarmonie]

Originally Posted by Aravind

ah cool ty, I like maxprop

an 8kw electric engine system to put in line isn't that expensive
you don't need a lot of batteries either to manoeuvre into the port
10kwh lifepo4 battieries is plenty

I can't say I have any idea at all about what your particular idea of "not that expensive" is, but it seems to be money that would be way better spent on other things.

Because... why?

Every boat is different, and every use pattern is different. But we move a LOT compared to most boats, sailing 5,000 to 7,000 miles a year. We motor into a port probably about 10 hours a year. Seems silly to spend any money at all just to make that 10 hours "quiet" when our engine is already pretty damn quiet. Maybe you can spend the capital in noise-proofing your engine space so you can have quiet engine running all the time instead of just trying to impress the people standing on the dock?

And hydrogeneration sounds great because it is "free"--except it really is not. Aside from the not insignificant capital cost, putting 1000 extra hours a year on the seals and bearings of our transmission is certainly not "free". And that is assuming you have a transmission that tolerates indefinite free-wheeling, not all do.

I know electric is the latest "cool thing", and if you gotta have the latest cool thing, have fun with it.

[Aravind]

thx for sharing

well imo it is not to impress ppl on the dock, I really don't care for that. I do appreciate some peace and quiet.

A big advantage is that the electric engine can run at much slower rpm (even 1rpm for instance), which makes maneuvering real smooth in silent waters.

Another factor which is huge for me is the following: when you are doing transatlantic crossings, especially from the west of Africa towards south-america/ Caribbean, it is not an exception if you fall without wind. In my experience, no wind usually means lots of sun...
Lots of sun means I'll be able to trawl happily instead of floating or having to run the diesel. Since we're often talking about several days at the time here, it adds up in fuel costs.

P.S. I have about 4.5kw of solar.

[Statistical]

Originally Posted by Aravind

cool, ty for the info

well, a hybrid system often has a decent engine, like 100bhp, and a small electric engine, like 10kw, which is only for 'coming home' and 'going out'. It doesn't take much to fill the batteries of these.

However if your electric engine is your main engine, in this example you would require about 35KW... you won't fill that with hydrogeneration...

A realistic hydrogeneration system makes about 500w at nearing hull speed... plenty of examples of that, look at real world experiences with oceanvolt.

Onceanvolt only does that with incredibly high cost variable pitch propellers. Again not saying don't do this. Plenty of reasons beyond hydrogeneration to consider this but if you are aiming at huge power generations using hydrogeneration based on past experiences of other people you are going to be horrifically disappointed. The energy from hydrogeneration is almost certainly going to come nowhere close to install cost. I would plan on 0 W of hydrogeneration. If it stiill makes sense with that then any hydrogeneration is a bonus.

[Aravind]

Originally Posted by Statistical

Once volt only does that with incredibly high cost variable pitch propellers. Again not saying don't do this. Plenty of reasons beyond hydrogeneration to consider this but if you are aiming at huge power generations using hydrogeneration based on past experiences of other people you are going to be disappointed. I would plan on 0 W of hydrogeneration. If it stiill makes sense with that then any hydrogeneration is a bonus.

as said, I use the 4.5kw of solar to top up the lithiums

or the main engine which is coupled to the DC engine (which can work as a generator)

or the backup generator

[Adelie]

Originally Posted by Aravind

Hi

I've been wondering about the following:

When you install a nice 6cyl engine in a 55ft sailboat, you might consider adding an in-line electric motor to achieve that nice silence (and no fuel consumption) for small manoeuvres such as going in and out of ports.

It's also nice to have a folding or feathering prop with your sailboat.


But... do these two systems go together? It seems to me that, with anything but a fixed prop, you cannot have hydro generation?
Hydro generation => cost-less topping up the batteries while sailing to use the electric engine when returning to port.

kind regards
Aravind

So most folks talk in terms of there being 3 options form props, fixed, feathering and folding.

There is a 4th option, Controllable Pitch Propellor, CPP.

To my knowledge none are made in the US, strictly Europe. This is because they are expensive and require more maintenance than a similarly sized fixed prop and transmission but they confer significant fuel saving which makes them economically worthwhile where fuel is expensive as it has been in Europe for decades, but not in the US which had comparatively cheap fuel except during the 1970s and recently.

With an appropriate CPP the blades can be feathered for very low drag sailing and they can be pitched appropriately for regen.

OceanVolt is using CPP on their latest Electric Propulsion (EP) saildrive. It costs an arm and a leg but it provides more than twice the regen output of their previous system.

In the long run the advantages of marrying CPP to a hybrid drive will vastly improve by hybrid efficiency and regen capability.

If you really want to go hybrid I would suggest talking to Betamarine who have a hybrid range. That would involve getting a new engine but trying to scab electric drive & regen onto an existing system is liable to have a lot of problems.

If you are serious about CPP, I'll dig up the list of European manufacturer's I found.

[SailingHarmonie]

Originally Posted by Aravind

as said, I use the 4.5kw of solar to top up the lithiums

or the main engine which is coupled to the DC engine (which can work as a generator)

or the backup generator

I keep seeing this idea, but somehow never see real numbers to support it...

In my experience, 1000W of solar panels makes about 5000W-hrs of energy per sunny day. Underway, our 53 foot boat consumes about 7,500W-hrs per day for house loads, so I'll assume that as a reasonable base load.

If we had 4,500W of solar capacity, that could potential deliver 22,500W-hrs of energy in a solar day. Gee, that sounds like a lot! Minus our 7,500W-hrs for house loads leave us with 15,000W-hrs left over for propulsion. How far do you think you can move a 55 foot boat with 15kW-hrs of electrical energy? And can you show my how you come up with that number?

I might be missing a conversion factor here, but my engineering text tells me that 1 kW-hr = 1.3 HP-hr. So my figuring is 15kW-hr in 24 hours lets me run a motor of 0.8 horsepower for 24 hours... How far is that moving a 55 foot sailboat out on the ocean? Is that juice worth the squeeze????