Oceanvolt Servoprop regen tested by UMA

[JustMurph]

Originally Posted by P-Dub

You will need two parallel hybrids to make your boat go anywhere in a sea state with some real snot to battle. I just took my Max 5437 nautical miles and the 35HP's were barely enough in some real crud we got into two days north of Manus Island, PNG. If we had anything less we could very well have been in some trouble.

Good info! Appreciated!

In my mind, the asymmetric parallel hybrid only makes sense if you upsize the single diesel. I.e in boat like mine with a pair of 30s, you want a 50 or 60 in that one hull. That way you have the same HP available to claw off that lee shore if you need it.

This does negate some weight advantage and means you need to move other things around to get the trim of the boat right.

Do you see that working?

What are the main reasons that you find the regen doesn't work well in practice?

[GrowleyMonster]

Regen. Meh. That is, for a small displacement hull that makes 6kts on a very, very good day. The most I ever saw was about 150w as I recall. I had the ability to change a lot of "hidden" parameters that affect the performance envelope and return, but I didn't bother.

With a bigger boat, maybe one that routinely sees speeds near 10kts through the water, regen can be significant. No, it still probably won't top up your propulsion bank while handling your house loads at the same time, but it is a way to stretch your storage in the event that you lose solar and you have no genset, or similar situation. To get the best bang for the knot, you need a controllable pitch prop. You can do almost as well by having a selection of pulleys in a belt drive, to change the ratio to one more suited to your prop pitch, electrical load presented to the motor/alternator, and boat's speed through the water. Most efficient propulsion pitch will not necessarily be (actually, probably will not be) the most efficient regen pitch. If you are serious about recouping energy through regen, especially at different water speeds, you want CP.

When is the drag worth the energy harvested? When you are already overpowering the boat with a powerful rig and powerful wind, and the boat is at or near hull speed, at the steep end of the speed curve. You can reach a point where the boat just isn't really wanting to go any faster, and at that point, you can drag a bucket behind the boat and not see a tremendous drop in speed. The sails are producing more energy than the boat can use. In that state, speed lost through regen operation will be negligible, maybe even undetectable.

Worth the cost, in dollars, for the small amount of energy recovered? With a turnkey brand name system, probably not. If you do it smart, LEARN ABOUT EP, understand the various types of motor and their power curves and limitations, understand controllers and user interfaces and reduction gear, understand batteries and their maintenance, understand wiring and high current DC, and understand what works well together, you can put your own system together for a small fraction of the cost. THEN is regen alone reason enough to go EP? Still, nope. But it helps a little, to tip the balance toward EP.

Don't repower electric just because you have dreams, backed up by youtube videos, of sailing around the world and getting all your electrical needs met through prop and motor. Go electric because OVERALL, it seems to be a good fit for you and the way you use your boat. For cruising boats, EP leaves much to be desired unless it is actually a hybrid system operated by a knowledgeable and technically oriented owner/skipper/engineer. You want diesel for the long legs that a tank full of fuel gives you. Day sailers are another thing altogether. When you have easy in/out of harbor and you are just day sailing or overnighting, and have shore charging available, EP is absolutely excellent. Too many benefits to list and I have done it already, anyway. For that sort of use pattern, TBH it is stupid to mess about with a smelly, noisy, thirsty, maintenance-hungry diesel and risk spilling fuel, etc when you can fuel up your clean, easily maintained, quiet EP system with the shore power cord instead. Not every boat and every skipper need even consider EP because it just doesn't work well for everyone. Certainly, don't do it for the regen.

[P-Dub]

Originally Posted by JustMurph

Good info! Appreciated!

In my mind, the asymmetric parallel hybrid only makes sense if you upsize the single diesel. I.e in boat like mine with a pair of 30s, you want a 50 or 60 in that one hull. That way you have the same HP available to claw off that lee shore if you need it.

This does negate some weight advantage and means you need to move other things around to get the trim of the boat right.

Do you see that working?

What are the main reasons that you find the regen doesn't work well in practice?

I think your upsize proposal is a real possibility but an acceptable setup would be dependent on each boat's design and sailing characteristics. You make a good point about the greater weight offsets needed with a larger diesel that can't be overlooked in a cat.

The issue I found with regen, at least for the setup on my boat, is you lose entirely too much speed for the net benefit. We lost, on average between a little over 1/2 and up to 2/3 a knot when in regen mode, conditions dependent. The amps being produced by my system don't even register until you are at over six knots of boat speed while in regen mode. You do not get usable amperage, around 10 and fluctuating all the time, to recharge your battery bank until you are sailing at greater than 9-10 knots. At that point, you need consistent boat speed, from consistent wind for a long time to have a tangible benefit. Keep in mind, this loss of boat speed is per motor. If I have regen running on both port and starboard, I lose approximately 1.25 to 1.75 knots of boat speed. On a "Performance Cat", that's too much of a loss for me, personally. The net gain in this power cost-benefit analysis doesn't pan out, again, for me. Another problem, one that I am battling to try and find a solution for, my props would feather anywhere from immediately entering regen mode to 5 minutes later. This proved a bit useless on top of the other system limitations. If you don't mind losing, in my opinion, a not-so-insignificant amount of speed, have a very long distance to go and have incredibly consistent wind to push you at solid boat speed, then, for me, regen is not practical.

I'll provide another caveat regarding my view on an asymmetrical e-drive system in a cat. We were motoring between Selat Sagawin and Salawati Utara in Raja Ampat, Indo because there was no wind. No wind and strong currents are not at all unusual in those parts. The currents run pretty strong throughout Indo and if you don't time them just right you could be doing what we were, both diesels running at 2200 RPM and going just about .4 knots at the mid-way point. It sure would have been nice to have an additional kick of maybe 10 hp overall to make it a tad less torturous. An asymmetrical setup would have had us flipping a U-turn and going around or stopping and anchoring to wait for the tide change. If you must get anywhere or need that extra bit because of the conditions, two diesels or one well-upsized are minimums. If you had a diesel and the e-motor running hard to push through junk, you had better have an enormous battery bank and even then, those e-drives chew through the available watts, rapidly.

[P-Dub]

Originally Posted by GrowleyMonster

Regen. Meh. That is, for a small displacement hull that makes 6kts on a very, very good day. The most I ever saw was about 150w as I recall. I had the ability to change a lot of "hidden" parameters that affect the performance envelope and return, but I didn't bother.

With a bigger boat, maybe one that routinely sees speeds near 10kts through the water, regen can be significant. No, it still probably won't top up your propulsion bank while handling your house loads at the same time, but it is a way to stretch your storage in the event that you lose solar and you have no genset, or similar situation. To get the best bang for the knot, you need a controllable pitch prop. You can do almost as well by having a selection of pulleys in a belt drive, to change the ratio to one more suited to your prop pitch, electrical load presented to the motor/alternator, and boat's speed through the water. Most efficient propulsion pitch will not necessarily be (actually, probably will not be) the most efficient regen pitch. If you are serious about recouping energy through regen, especially at different water speeds, you want CP.

When is the drag worth the energy harvested? When you are already overpowering the boat with a powerful rig and powerful wind, and the boat is at or near hull speed, at the steep end of the speed curve. You can reach a point where the boat just isn't really wanting to go any faster, and at that point, you can drag a bucket behind the boat and not see a tremendous drop in speed. The sails are producing more energy than the boat can use. In that state, speed lost through regen operation will be negligible, maybe even undetectable.

Worth the cost, in dollars, for the small amount of energy recovered? With a turnkey brand name system, probably not. If you do it smart, LEARN ABOUT EP, understand the various types of motor and their power curves and limitations, understand controllers and user interfaces and reduction gear, understand batteries and their maintenance, understand wiring and high current DC, and understand what works well together, you can put your own system together for a small fraction of the cost. THEN is regen alone reason enough to go EP? Still, nope. But it helps a little, to tip the balance toward EP.

Don't repower electric just because you have dreams, backed up by youtube videos, of sailing around the world and getting all your electrical needs met through prop and motor. Go electric because OVERALL, it seems to be a good fit for you and the way you use your boat. For cruising boats, EP leaves much to be desired unless it is actually a hybrid system operated by a knowledgeable and technically oriented owner/skipper/engineer. You want diesel for the long legs that a tank full of fuel gives you. Day sailers are another thing altogether. When you have easy in/out of harbor and you are just day sailing or overnighting, and have shore charging available, EP is absolutely excellent. Too many benefits to list and I have done it already, anyway. For that sort of use pattern, TBH it is stupid to mess about with a smelly, noisy, thirsty, maintenance-hungry diesel and risk spilling fuel, etc when you can fuel up your clean, easily maintained, quiet EP system with the shore power cord instead. Not every boat and every skipper need even consider EP because it just doesn't work well for everyone. Certainly, don't do it for the regen.

Yup, pretty much all that above...

[Matt Johnson]

Originally Posted by P-Dub

Don't do it, Matt!

Unfortunately, that setup is fine if you only ever plan on sailing in areas where you always have flat water, no storms, abundant wind, have copious amounts of sun, and you never have issues with your solar, your diesel, or one of the e-drives.

You will need two parallel hybrids to make your boat go anywhere in a sea state with some real snot to battle. I just took my Max 5437 nautical miles and the 35HP's were barely enough in some real crud we got into two days north of Manus Island, PNG. If we had anything less we could very well have been in some trouble.

The numbers sound good on paper but reality is an entirely different animal. Further, the hybrid tech Max offers seems nice but is not ready for prime time. It's fine on a canal boat, but until they marinize the system for ocean-going vessels I would steer clear. There were multiple failures with the e-drives and I'm still battling issues. The hybrid marine regen has proven to be functionally useless in the real world, as well.

Just some practical Max life experience, if you like. Don't feel bad about pushing this tech though. MaxCruise filled me a tall glass of the Kool-Aid also, and I drank it. Two parallel hybrids or one parallel and one diesel along with a 3kw small portable generator is what you are going to need. You are then covered for the inevitable eventualities that do come up, as I'm sure you know, on the water.

Thanks for the insight and sharing your experience. It's always difficult being one of the first with something new, but info like what you've shared allows everyone later on to go into it knowing what to expect.

I can't remember if we talked about it when we met in Vietnam, but our original plan had been for 25hp outboard motors on this boat- so that kind of shows what our expectations are for motoring - but we changed the plan to hybrid once WE talked Max Cruise into going with an asymmetrical system as an option.

This allows us to stay within our weight goals while having the larger battery bank, a dual purpose engine/generator and redundancy of both propulsion options. And no gasoline or outboard headaches.

But we came into this knowing that this was an axillary system and not for motoring long distances at high speed. It's a compromise we're happy to make, but it's absolutely not for everyone... And those other people that want more power, they can go with dual diesel hybrids like you did.

Slower motoring has always been okay for us (we always stayed under 5kts on the last few boats). But we are building the engine bed on the electric side for a direct swap to a second diesel just in case we later feel it is needed

[P-Dub]

Originally Posted by Matt Johnson

Thanks for the insight and sharing your experience. It's always difficult being one of the first with something new, but info like what you've shared allows everyone later on to go into it knowing what to expect.

I can't remember if we talked about it when we met in Vietnam, but our original plan had been for 25hp outboard motors on this boat- so that kind of shows what our expectations are for motoring - but we changed the plan to hybrid once WE talked Max Cruise into going with an asymmetrical system as an option.

This allows us to stay within our weight goals while having the larger battery bank, a dual purpose engine/generator and redundancy of both propulsion options. And no gasoline or outboard headaches.

But we came into this knowing that this was an axillary system and not for motoring long distances at high speed. It's a compromise we're happy to make, but it's absolutely not for everyone... And those other people that want more power, they can go with dual diesel hybrids like you did.

Slower motoring has always been okay for us (we always stayed under 5kts on the last few boats). But we are building the engine bed on the electric side for a direct swap to a second diesel just in case we later feel it is needed

We did speak about your propulsion needs at that time and if memory serves me correctly you already had two Yanmars that Max was seeing if they could retrofit with the Hybrid Drives or something to that effect. It is interesting that you sold Max on the asymmetrical system as Terry insisted that his research on his idea of the asymmetrical setup was the way to go, why he was setting it up on his boat, and that I should do the same.

I would hope no one purchasing a "Performance Cruising Cat" is looking to motor long distances at any speed. I, personally abhor the iron genoa. Unfortunately, conditions often exist that necessitate the use of our diesels. This is a cat and not a monohull and this is a lot of boat with a lot of windage to push through the water and when things are hitting the fan, you will absolutely need two diesels in certain circumstances and at certain times. It's not a matter of wanting more power but rather needing more power. It's a safety issue, not a sailing-style issue. That is the takeaway.

I am thankful I did go the asymmetrical route and consequently, I did not have to make some really tough decisions that could have exposed me to some potentially dangerous situations because I lacked sufficient power. Eventually, a situation will arise in which you'll need that margin of safety appropriate power affords. Perhaps I am a little more risk-adverse as I get older but I want to be able to sail and spearfish another day.

[JustMurph]

Here's my thoughts on the value of parallel hybrids. Would you guys agree?

- Go big on solar, this is your primary power source. 3kW +
- You don't do this to save money, diesel or the environment (especially on a performance cat, where we can sail in most conditions, so don't burn much fuel in a season)
- Your motors double as big generators, so when you do need them to charge, you get it done fast
- There is a significant comfort/convenience/maintenance factor to not needing to start diesels for the 5 or 10 min to get on and off the anchor/dock, in most situations.
- Regen is a bonus (if it works)
- Additional redundancy is a bonus (having 2 engines is enough for most), but comes at the cost of complexity


It seems regen needs a lot more work in both hardware and software. Folding props can work, but aren't reliable or efficient. Actuated feathering props (like servoprop) seems to be a better solution, but at the cost of a little more parasitic drag when not regenerating. You can do this on shafts, but I don't think anyone has incorporated this into a regen system yet.

Then there's the software (control). It seems most of the systems can't respond to the fluctuations in boat speed anywhere near quickly enough. Add the actuation of a feathering prop and this does turn into quite a dynamic system.

Anything you add or disagree with?

[Rorke Miller]

Matt Johnson,

What is your set up? Is there dedicated post about it?

In my experience, one engine is sufficient for powering in almost all conditions. Propulsion in the second hull is undeniably helpful for maneuvering.

Rorke

[CaptainRivet]

Originally Posted by P-Dub

I think your upsize proposal is a real possibility but an acceptable setup would be dependent on each boat's design and sailing characteristics. You make a good point about the greater weight offsets needed with a larger diesel that can't be overlooked in a cat.

The issue I found with regen, at least for the setup on my boat, is you lose entirely too much speed for the net benefit. We lost, on average between a little over 1/2 and up to 2/3 a knot when in regen mode, conditions dependent. The amps being produced by my system don't even register until you are at over six knots of boat speed while in regen mode. You do not get usable amperage, around 10 and fluctuating all the time, to recharge your battery bank until you are sailing at greater than 9-10 knots. At that point, you need consistent boat speed, from consistent wind for a long time to have a tangible benefit. Keep in mind, this loss of boat speed is per motor. If I have regen running on both port and starboard, I lose approximately 1.25 to 1.75 knots of boat speed. On a "Performance Cat", that's too much of a loss for me, personally. The net gain in this power cost-benefit analysis doesn't pan out, again, for me. Another problem, one that I am battling to try and find a solution for, my props would feather anywhere from immediately entering regen mode to 5 minutes later. This proved a bit useless on top of the other system limitations. If you don't mind losing, in my opinion, a not-so-insignificant amount of speed, have a very long distance to go and have incredibly consistent wind to push you at solid boat speed, then, for me, regen is not practical.

I'll provide another caveat regarding my view on an asymmetrical e-drive system in a cat. We were motoring between Selat Sagawin and Salawati Utara in Raja Ampat, Indo because there was no wind. No wind and strong currents are not at all unusual in those parts. The currents run pretty strong throughout Indo and if you don't time them just right you could be doing what we were, both diesels running at 2200 RPM and going just about .4 knots at the mid-way point. It sure would have been nice to have an additional kick of maybe 10 hp overall to make it a tad less torturous. An asymmetrical setup would have had us flipping a U-turn and going around or stopping and anchoring to wait for the tide change. If you must get anywhere or need that extra bit because of the conditions, two diesels or one well-upsized are minimums. If you had a diesel and the e-motor running hard to push through junk, you had better have an enormous battery bank and even then, those e-drives chew through the available watts, rapidly.

So you basically saying that 35hp in one hull and other hull the 10kw driven with 5kw is not enough if conditions are really bad. Because thats what this setup can do for a max cruise 44. Correct?
You have the 35hp betas or the yanmars?
That would suck asvthis asym setup is really sexy, not because i like epropulsion but less maintenance and less diesel as most you use both e to get in/out habour/ anchor spot and then sail.
And if diesel then motorsailing+generator or the emotor innthe other hull. Would be interesting how much diesel more if you run the emotor additional on 3 and 5kw compare to just the diesel only.

[CaptainRivet]

Sounds really its better get the 38hp yanmars, stick on each a beefy alternator plus put on Flex-o-folds and get seperate hydro regens like watt&sea for each hull.
Thats actually what the guys at Asia catamaran did on their Stealth 14 that sailed around the world and it worked like a charm.
I had a slow Vilm2 motorsailor and had a "motor" of a windgen as DIY shaft generator as my prop was free spinning...that was a slow longkeeler but between 4 and 5kn sailing i got constant 30A@13V and lost 0.25kn.

[GrowleyMonster]

Originally Posted by CaptainRivet

Sounds really its better get the 38hp yanmars, stick on each a beefy alternator plus put on Flex-o-folds and get seperate hydro regens like watt&sea for each hull.
Thats actually what the guys at Asia catamaran did on their Stealth 14 that sailed around the world and it worked like a charm.
I had a slow Vilm2 motorsailor and had a "motor" of a windgen as DIY shaft generator as my prop was free spinning...that was a slow longkeeler but between 4 and 5kn sailing i got constant 30A@13V and lost 0.25kn.

390w? That's actually very very good for only a quarter knot speed penalty, at 4 to 5kts. Nice going.

[CaptainRivet]

Originally Posted by GrowleyMonster

390w? That's actually very very good for only a quarter knot speed penalty, at 4 to 5kts. Nice going.

Yes was not too bad, used actually a timing belt to drive it and had space for quite a big pulley on the shaft. also additional charge when motoring, was a big diesel...
Well its the pure mass 12t longkeeler, when it was moving it was moving means 15kn wind sailing 5kn SOG then 30A, 3kn was still around 10A and motorsailor means a big 4 blade fixed prop on the shaft.
Now the opposite 6.3t lightship, fully loaded 8.3t 40ft cat. Will upgrade in around 3 years to a real performance one and the asym hybrid + emotor was my favorite too but sounds like back to original plan.

[CaptainRivet]

Who is looking for a hydrogen:
https://sailnsea.company.site/SailingGen-Hydrogenerator-p577098024

Quite cheap with 1700Euro and really working well, know 2 who have it. German guy who developing that since >15years as its his passion.
Reasonable price, super service.