Oceanvolt Servoprop regen tested by UMA

[donradcliffe]

Originally Posted by Dirk01

Please help me. I know from wind turbines that they have systems to adjust the pitch (in older systems with spring loaded hydraulic cylinders, because it is safety relevant too. In newer systems they use electric drives with a battery backup). But I've never heard of camber-adjustment. How does it work? Can you describe the effect? Or even better you can post a scetch?
Or do I have to understand it as a compensation of the drag-angle? And if my assumption is correct - how big would that effect be in reality? Is it nearly not measurable or would it increase the efficiency by 10%? So at a regen-rate of 300W-500W it is roughly 30-50W? Would that justify the mechanical effort? Or isn't it easier to compensate it with a slight windward ruder angle (sacrificing maybe 0.01kt)?

Cheers
Dirk

Dirk, you need to keep up with the times. According to my son, they are tinkering with piezo-electric panels on fighter jet wings to actively warp the winds while flying. Think about a carbon fiber prop that bends from forward to reverse, or a big wind generator blade that dectects and responds to turbulence.

Actually, a look at prop cambers tells my engineering mind that the effects are small. The max prop is basically flat blades, and people are willing to put up with a little less efficiency in forward and more in reverse. The pitch adjustment is an order of magnitude more important.

[Dirk01]

Originally Posted by Adelie

That’s wrong.

Regen does NOT harvest speed from the boat moving thru the water, it harvests energy which is converted into electricity stored in the battery. Harvesting energy reduces speed. The speed-power relationship is not linear which means that when the boat is going faster you can harvest more energy with less impact on speed.

The Cal-34 I want uses about 7680W to go 6.3kt and 9120W to go 6.8kt. If the boat was going 6.8kt before turning on regen and 6.3kt after then regen is soaking up about 1440W from the boat. Let’s assume that all the losses account for 2/3 of the power harvested, so I will only get back out 500W.

If I sail like this for 10hr then I will have available 10hr * 500W = 5,000Whr or 5kWhr of energy. And I will have advanced 5nm less than I would have.

If The next day the wind goes calm I can use that stored energy to propel the boat. Let’s say I wanted to use the energy at the same rate I harvested it, 500W. That 500w would propel the same boat at about 2.5kt. 10hr at 2.5kt is 25nm. Accounting for 5nm I “lost” while generating the energy I’m still 20nm ahead.

If I went 2kt I would use 250-300W. Let’s assume 300W. 5kWhr would supply 300W for 16.7hr. At 2kt I would go about 33.3nm and would net 28nm accounting for the lost 5nm.

What if I went 5kt? Boat uses 3840W to go that speed. With 5kWhr I can motor at 5kt for 1.3hr which would move me forward 6.5nm. Accounting for the 5nm “lost” I’m still 1.5nm ahead.

You get more distance out of regen by using the fact that the power-speed relationship is non-linear and accepting that when you use the energy you need to go slower than when you harvested it.

If you can’t accept the slower speeds when using the stored energy then stick with an ICE.

Finally, I don’t have to use the energy to propel the boat, I can use to make light, cook, make or heat water. This is an apples to oranges tradeoff with different math than discussed above.

Adelie - well said. Totally agreed
Most of the naysayers don't understand the sense nor do they know what they are talking about. It's the same with BVEs. They only would buy a BVE if it can drive 1.000km in one go, pulling a heavy trailer of about 2.5to. Any discussion with such people is senseless. Just walk away and let them stick with an ICE.
Let us find the advantages and look forward. I definitively will design two elctric engines into my cat. 42ft@8to with 2x12kW retractable electric propulsion systems (so called direct drives mounted at the sterns) in combination with 2x15kWh Battery banks (gros), added by about 1,8kWp solar. And a 10kW Fischer-Panda genset as a backup for the long run and to extend emergency situations for up to 90mins at 100% power (thrust is 2x2500N!) (should be enough time and thrust, because I'm still a sailboat and not a motor yacht). But, and that wil be much more important, I will enjoy my "electric living". So the side effect is probably more important than a relaxing and reliable electric propulsion system. I'm convinced I have to start the genny from time to time to prevent internal rust only.

Cheers
Dirk

Edited: I forgot to mention, that my planning is to retract two of my six panels when I'm underway (stability reasons). To harvest 2x300W would compensate that loss most of the times surely. And if it is only the half it's o.k. too. I do not plan to operate my wash-dryer underway.

[Dirk01]

Originally Posted by mglonnro

It can't be used to engine exactly the way we are used to with diesel, I guess.

So I need to update my ways of using the engine, if I go 100% electric. I can live with that

YEAH - that's the way it works.
Driving a BEV is different. Much much mor fun, cost effective and mmmh relaxing (I know what I'm talking about! I drove abot 1.5 Miokm Diesel ICE and changed since a year to BEV (but with much less km per day).
Driving 300-400km day per day and often unpredictable some 250km more or less - stick with an ICE.
Electric drive is different. If you can change your mind and living - do it and enjoy it. If you don't want to change anything - stick with diesel ICE.
It's an attitude to life - not a technical question.

Just my 5ct.

Cheers
Dirk

[Dirk01]

Originally Posted by Adelie

The speed going up when they turned on the regen was a function of more wind and/or moving into a tail current. They don't have a speedo on the boat, only the gps readout.

Adelie - do you mismatch something? Regen is related to the drag thru water. Not SOG.

Or didn't I got you correctly?

Cheers
Dirk

[Dirk01]

Originally Posted by Tupaia

4300W is roughly 6hp, I can relate to hp easier than W as I have better experience of ICE.

So 6hp (a small outboard) will drive Uma at 5 knots in flat calm sea, yes no problem.

About the only times I have been completely "dependent" on my engines is when beating against wind and a current or tide in an entrance or river where sailing and tacking would be impossible. 6hp would not provide either the speed or in the case of electric propulsion the duration for such circumstances.

My current ICE setup gives 8.5 knots flat out or 5 knots for 140 hours. I have been in conditions, checking into NZ and Aus are both examples where river navigation is needed. Entering NZ I was down to 1 knot SOG against a 45 knot headwind and strong current. The 7Nm journey took 4 hours with engines running pretty near WOT the whole time. I had made record "sailing" time from Tonga, not suffering a 1 knot speed penalty for regen and was able to avoid being caught at sea trying to make landfall with a rather nasty approaching weather front.

The point I am making is if your current boat is fitted with a 30hp ICE that's 22000W why does anyone think 4300W is going to cut it. The reason it has 30hp is because experience has shown this to be the best size for all conditions.

Now if your approach is not consistent with this then why not remove the engine completely it can certainly be done. Living with inadequate power does not sound like a solution to a problem.

I also know a lot of long term cruisers, with poor performing sailing boats or who are overloaded that relay heavily on motor-sailing an option that is virtually impossible with such a reliance on regen. I have yet to meet a sailor who would rather sail slower.

Tupaia - maybe your approach is different.
You're relying on power. Others on weather (better and better) forecast and navigation aids. Times are changing. Minds should / could also.
That relates not to everyone. And that's absolutely o.k..

Take your path - and let others early adopters try other things. I'm thankful to them. And I'm learning. All day...

[Dirk01]

Originally Posted by malbert73

Exactly. If you want to sail and have an “auxiliary” engine it could work. Other posters who try to reason between diesels and electric forget that electric is not designed to motor upwind against waves. You must be prepared to sail in that instance.
UMA is a very nice sailing boat and moves easily in light air. Their vulnerability is no breeze and adverse current- and it seems now they usually stop and anchor unless they will be docking at the end and can recharge

For mainstream sailors, I think electric could be great in the tradewind/tropical areas where solar, regen, and wind can keep batteries topped off and there’s nearly always breeze to sail in.
For me in a notoriously fickle breeze region with land ties and kids, I need the opportunity to motor for 20-30nm which you can’t do with electric

Yes, you're right! Stick with ICE (commenly diesel). That's the way it works for YOUR needs.

Cheers
Dirk

[bergius]

Originally Posted by noelex 77

The issue that needs to be mentioned is that, judging from many of their videos, their electric propulsion demands require frequent connection to shore power. There is nothing wrong with visiting marinas or docks with power, but this is not everyone's preference.

The fact of high latitude sailing is that there simply isn’t enough sunlight outside of summer months for pretty much anything.

We’re seeing a drastic drop in solar production here now that it is September. And Uma is some 19° more north than we are (Berlin vs. Tromsø).

Summer months are another story of course. Nights are short, and batteries are often full by 8am…

But, the power for the boat systems has to come from somewhere (remember, they make their living by producing videos. That requires running some power-hungry hardware that most boats wouldn’t have). They have solar, regen when sailing, and now a generator when they aren’t. That sounds like a decent amount of redundancy.

[Dirk01]

Originally Posted by s/v Jedi

We’re talking about sailboats; they use sails for propulsion. If conditions don’t allow sailing, you anchor or heave to and wait for the tide to turn or the wind to come down. Going at it for 4 hours at wide open throttle is how motorboats do it

Yes! Absolutely agreed!
Most of sailors forget their engine (Sails) or weather. They want to be at point B at a certain time. Regardless anything.

Cheers and
Dirk

[wingssail]

Originally Posted by malbert73

...For mainstream sailors, I think electric could be great in the tradewind/tropical areas where solar, regen, and wind can keep batteries topped off and there’s nearly always breeze to sail in...

Mainstream sailors? What mainstream are you talking about? The main stream of cruisers motor almost everywhere. And aside from ocean crossings, even in tradewind/tropical areas (like the Caribbean) that I've been I rarely see people sailing entirely from one destination to the next.

They may start off with sails up on a broad reach but when they need to beat to make port, or the day starts getting long, the motor comes on, invariably,

[Dirk01]

Originally Posted by wingssail

Physics tell you that the electricity gained from regen is very low compared to the electricity required to move the boat and that the drag which results is not huge. But those are not the germane fact.

What is germane is that for most cruisers (and boaters in general) it is impractical to depend on the power gained through regeneration to drive your boat whenever you might want to. That is the fact that we need to keep in mind, not the physics of what percentage of the speed is lost to provide what amount of electricity.

Of course it is possible to have and enjoy a boat powered by an electric motor, and though regeneration you can obtain some usable power. With a big enough unit and plenty of good wind, you can get quite a lot, but not enough to run your motor for very long.

And even that requires a change in the way that most people use their boats, which I don't think is practical.

Most people motor much of the time, and almost all people simply turn on the motor whenever the sailing conditions are bad (light wind, strong wind, any wind on the nose) or when they just feel like it. I am a prime example: I am a sailor, first and foremost, yet I motor about 25% of the time during normal cruising. I could not do this with electric, it just isn't possible to collect enough watts to drive my boat 20-50 miles on electric power, mileage under power which I do from time to time. So I'd have to change my cruising habits. I admire those people who make this choice and can do it. Few people would.

My boat uses about 7,000 watts to motor at 5 knots. A 20mile trip under power would require 140,000 watts (or 280 hours of regen). Or 23 days of solar if I had 1000 watts of solar, which I don't have. I have less than 300 watts of solar. If I am coastal cruising where there are no marinas or recharge stations, anchoring each night, and where the winds are often light, electric just isn't going to work. I have to change my cruising habits.

So regen or hydrogeneration may be a good thing, but electrical power for cruising boats will only be practical and appeal to very few boat owners and regen won't change that. That is the fact that is important, not the physics of regen vs drag.

And if you add a genset? For the 50nm run. Would that be a way? A way for you?

Cheers
Dirk

[donradcliffe]

Rather than have an ICE genset, just oversize it a bit for emergency situations, and you can throw away the electric motor and batteries.

One other consideration, if you do put in a 9kw genset, be sure to have it heat your shower water with its free waste heat.

[Dirk01]

Originally Posted by seandepagnier

Somehow I sailed all over NZ and did not have an engine in the boat. Also captain cook did.

I don't believe you. A lot of people say 45 knot headwind but it's really only 25 knots. Did you sail to the south island?

Almost all the currents in NZ are tidal and reverse after a few hours.

Completely idiotic thing to do and easily avoidable.

What "record" ? I sailed from vavau (northern tonga) to NZ in 9 days (1200 miles) on a 27ft monohull. I didn't make any records I doubt you did either.

The regen is adjustable so there is no penalty: you can turn the regen off. The drag is no where near 1 knot.

You have no concept for how inefficient your 30hp is. It is equal to far less than 22000W electric power. Something diesel junkies (addicts) fail to acknowledge is that their inboard drive system is a pathetic 20% efficient at best on top of 25% engine because your propeller is too small. Same with the uma prop, it is just too small to be efficient.

So until you correct this, you cannot even speak about horsepower with any sense of honest figure or calculation. Like trying to row your boat with a stick instead of a paddle and talking about calories burned.

You said "can certainly be done" which implies it is adequate then contradict yourself in the next sentence saying it is inadequate.

Well said. Nothing to add

[noelex 77]

Originally Posted by bergius

The fact of high latitude sailing is that there simply isn’t enough sunlight outside of summer months for pretty much anything.

I am sure there are others more familiar with their videos, but my understanding is that their only power generation until recently was 480w of solar and an ineffectual regen system. With a rather comprehensive suite of electronics (they are sponsored by B&G) a water-maker and computer use, this leaves little energy for electric propulsion. Without plugging in regularly to shore power they will only have a very small amount of energy for electric propulsion even in areas of very good solar insolation. They will struggle to have enough to cover their house needs in areas of poor solar insolation.

They have recently added a petrol generator, a new regen system and are toying with a wind turbine. It will be interesting to see how successful these systems are in allowing them more time away from shore power in the future, assuming that is something they aspire too.

There is no perfect way to go cruising. Regularly plugging into shore power suits many skippers, but when setting up a cruising boat it is important to understand the limitations of your equipment choices.

[wingssail]

Originally Posted by Dirk01

And if you add a genset? For the 50nm run. Would that be a way? A way for you?

Cheers
Dirk

Dirk1, No, I do not think that makes sense for us. We are a simple boat. Our philosophy is that we don't "add" things to solve problems. More likely we are looking to take things off, not add them. We want to keep the boat light, fast and as simple as possible without diminishing its livability and comfort. We have achieved that without lithium, electric drive, or regen.

So, removing an ICE, installing electric drive, installing lithium batteries and all the falderal to support them, then adding back an ICE as a generator makes no sense to me. Cost and complexity, and to what advantage? I have no problem with my diesel engine, not smells, smoke, whatever. It gives excellent utility. It charges my batteries, it gets me where I need to be if I can't sail. It is reliable. I've had it for 28 years.

And one thing I have learned from this thread: The management of Lithium, charging, alternator protection, safety, dc to dc, buffer FLA, multiple nppt, etc etc isn't all sorted out yet. Look at the number of opinions on this thread. Add to that the fact that you'd have about 3 times as many little electronic devices as before and eventually some are going to fail, which brings up the concern, how do you diagnose problems with a more complex system? Or fix it in Papua New Guinea?

So I am Lithium/ED/regen hesitant.

[Dirk01]

Originally Posted by Adelie

The number of recreational boats with no engines is not miniscule, I started out on the lakes of Minnesota which has a lot of canoes and now am in California which has at least as many surferboards and kayaks as boats with engines. Lets ignore those boats and ignore the myriad of small power boats, sailboats and dingies that would not be appropriate in most cases to take offshore if for no other reason than they don't have built in berths. And let's skip the power boats.
So we are looking at 30-50' sailboats. Almost all of the boats in this category are designed as coastal cruisers or marina queens. The intended use is for people with limited to moderate experience to go play on the water for a limited time of days to weeks with a need to return to home and work on a schedule. That need for limited experience users to meet a schedule drive the engine and fuel tank sizes that are installed.

This forum is intended for cruisers and people that want to be cruisers. That is a different use case than the typical recreational vessel so drawing conclusions for cruising vessels from the design of recreations vessels is suspect at best. The biggest issue is that there is no externally imposed schedule except that imposed by weather and season. Any other schedule is driven by the preferences of the cruiser.

You have the preference to be able to motor at full power for extended periods and you are content with the use of an ICE. That's fine.
That doesn't mean that everybody should share your preferences and values. There are plenty of us that would happily accept the tradeoffs of electric propulsion, the limited range at full power and moderate range at low power, the need to recharge for extended periods in order to use that limited storage and adjusting schedule and destination in exchange for not paying for fuel, not dealing with fuel smells and in helping society to move away from fossil fuels.

Nothing to add

Cheers
Dirk