Oceanvolt Servoprop regen tested by UMA

[Adelie]

Originally Posted by wingssail

By the Way adelie, the assumptions you put in your example about UMA are not valid, in my view.



UMA needs go go 6.4 knots to make 300 watts. In your example you spoke of doing that for 24 hours. I doubt that UMA's average speed under sail is 6.4 knots (or 153nm/per 24 hour day). More likely, if you look at 36' cruising boats, you'd find that they plan on 100-125 nm per day, about 5kts on the average. Far less than 300 watts I'd say. When evaluating something it is best to use a conservative figure not the most optimistic.

The most optimistic calculations are common in justification of electric boats using regen. People talk of 15 knots with a cruising catamaran. But I think it is rare that cruising cats average those kinds of speeds over long periods of time.

Further, to generate all that power that some people think is possible I think a lot more drag will be produced.

What UMA is doing is possible and admirable. It is not cruising their boat using regen to fully recharge their motor's batteries. Their passages will be too short for that unless they dramatically restrict their hours of motoring (which they obviously do). They aren't even crossing oceans.

Yeah, I didn't look at what speed they are averaging, I was pointing out that they can bank significant energy when wind speeds are good for use when wind speeds are pretty much nil. Looking at the average is misleading but let's do it anyway.

Based on stock LWL, displacement and sail area the boat should make about 127nm/d in cruising trim (I used E.Starzinger's formula). That's 5.3kt average. From Uma's testing 5.3kt would produce about 165W. 24hr * 165W = 3.96kWhr.
At 3kt they use 1.2kW so they could motor 10nm in 3.3hr.. Or they could go 26.4nm in 13.2hr at 2kt using 300W. Or they could use some of the energy for house and the rest for traction. Or they could use some of the power for house, save the rest for a special jaunt or emergency uses and just sit idle when the wind is calm. OV.s chart indicates they should be able to produce 275W at 5.3kt.

I said the average is misleading. Here's why. Boat speed on passage has a non-gaussian distribution and the max speed for the boat is only 2kt or a bit more than the average. That means the boat spends more time above the average speed than it does below for any likely speed distribution. Also energy production is non-linear so time somewhat above average speed produces a lot more power. See the graphic for various distributions for 125 and 100nm/d averages and how much energy is produced using the Uma production numbers.
If you sailed at 5.3kt all day (127nm/d) the production would be 3.96kWhr.
At 4.25kt (102nm/d) the production would be 2.04kWhr.

And because somebody is going to point out that there is not going to be that much variation in a single day's speed, I have reproduced the same distributions for a 24d passage which gave the same daily average as you can see.

Any speed distribution other than all day right at the average is going to produce at least as much as energy.

OK in real life that is probably not the case, but it's probably not that far from the truth. As Cornell's Elcano boat discovered the varying speeds have weird effect on production, but there is a whole bunch of info not known about that little fiasco so probably not a good source of info except as a cautionary tale to load up on solar and treat the regen as an ancillary source of power.

What I expect is that at some point Uma will make a trans-Atlantic passage and then they may be able to provide real life data. It would be very nice if they had a way to log speed and production on a minute, by minute or hour by hour basis but that would probably require something from OV. Given their relationship with OV, OV may want the data and be willing to set up the logging. It would require adding a knotmeter to their boat which I don't believe they have.

[Adelie]

Originally Posted by Tupaia

No, we are not, we are talking about replacing ICE with electric. Like I said if you want to "sail" take out the engine altogether.
If the issue is that black and white to you why do you have a sailboat at all? There is a lot of spectrum between engineless sailboat and motorboat.

In the instance I cited NZ do not allow anchoring prior to checking in under any circumstances dangerous or not. A fellow sailor unable to motor against the conditions ran aground and spent a miserable and stressful night on their side in the mud. He was refused permission to anchor or call for assistance.


Here are a couple of other examples where inadequate power or duration would be restrictive.


The Panama Canal.
Most EP boats could do the Panama canal by adding a small (2kw) genset or mounting the dinghy's outboard on the mother ship. I've done the math 3 times for boats 30' to 54'. Doing the Suez might not work. Haven't done the math and don't know the particulars.


I have been pinned against a dock unable to get off or out of the harbour without using full power.... in order to "sail" around to the other side of the island and anchor.
With an electric motor of sufficient power, you could get off of a dock you were pinned to just like using the ICE. It would just use a moderate amount of your battery capacity getting off and then there would be issues with how far did you need to motor to an anchorage.


Have you ever tried "sailing" out over a bar against standing waves? The best time to do this is when there is little or no wind and it requires a lot of sustained power.
No experience with this. How long would power need to be sustained? How much power? You are going with the current so doesn't seem like sustained power would be needed so much as judicious bursts. As I said before, no experience.


Have you ever entered a lagoon through a pass requiring full power and then having to motor for 10's of miles to avoid coral heads?
I'm curious what lagoon that is. Once inside how much current was there? Not trying to say it doesn't exist, just curious. Are most lagoons like this or is this an edge case?


The Kinabatangan river requires 2 days motoring up and 2 days motoring back down, through the jungle no chance of sailing at all and nowhere to recharge. You could of course row.
If it takes 2 days to motor each way then that means there isn't much current to overcome. Just because a boat can't regen on a river doesn't mean that they don't have solar and/or wind to recharge with.
It just takes time to wait for the recharging to accumulate and battery capacity to hold the energy.


Friends motored hard for close to on a day in order to reach Richards Bay in SA to beat an impending storm where many boats were damaged. I turned round and beat back to La Reunion under "sail".
So your friends motored hard to get somewhere a lot of boats were damaged, and you sailed away unscathed. Seems like a good argument for ignoring the engine, whatever it is fueled by, to stay at sea sailing. This was the practice in centuries past.


The number of recreational boats that don't have motors is miniscule as are cruising boats with only auxiliary power. You just have to look at the engine hours on second hand boats and the size of fuel tanks on monohulls in particular to get a handle on how much the majority of sailors depend on their engines.

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.

[Adelie]

Originally Posted by NaClyDog

This is an interesting point but I'm still doubtful it would be possible. Everything required would also be bigger. Maybe you could achieve greater efficiency as you increase the sizes of everything but I am doubtful.

Scaling has a lot of affects, mostly towards to good for waterborne vessels.

[StuM]

Originally Posted by Adelie

Y It would be very nice if they had a way to log speed and production on a minute, by minute or hour by hour basis but that would probably require something from OV. Given their relationship with OV, OV may want the data and be willing to set up the logging. It would require adding a knotmeter to their boat which I don't believe they have.

Based on claims to date, do you really think that OV would make that data public?

[Adelie]

Originally Posted by StuM

Based on claims to date, do you really think that OV would make that data public?

No, but I bet Uma would. If there was data logging on my boat, I would want a copy.

[seandepagnier]

It is possible to sail on and off a dock regardless of wind direction or wind speed. An engine or motor is not needed.

The only exception to this is strong currents combined with nearby obstructions. In this case usually still fine because I sailed on and off docks in 3-4 knots of current. It is rare that you need to wait and if you do not for very long.

As for coral atolls. I also tacked through passes. You can get into almost every atoll in the pacific without an engine but apparently there are just 2 in the whole pacific that are difficult. It is just people believe it can't be done, but it's proven otherwise because I know other boats without engines that also entered lots of different atols. As for coral heads inside the atoll I didn't have any problem sailing around them either.

[donradcliffe]

I'm impressed with UMA's daily house load--making videos must be very power intensive. I am also not impressed with how small their prop is. You would think that with a variable pitch prop that can feather they would have gone for about a 50% larger diameter.

I used a trolling generator on passages as part of my alternative energy system. It was rated at 200 watts, but could be relied on for about 100 watts at my average cruising speed of 7-7.5 knots. I didn't notice much boat speed difference with vs without the trolling generator when I was reaching or running with 18+ knots of wind, but pulling it back to the boat it had a drag of 40-50 lbs. With less than 8 knots of wind it dropped my boat speed from 5.5 to 5 knots and only put out 2 amps, so it came out of the water. The trolling line was a royal PITA, with problems with seaweed, chafe, leaping out of waves and kinking, etc. However, I ended long passages with full batteries, but I burned a lot of diesel in the doldrums.

I also had a 200 watt wind generator and 240 watts of solar, but today I think I would go for 1000 watts of solar and forget the mechanical maintenance and noise. If you want to see some real world data on boat speed penalty vs power output, take a look at the Watt and Sea generators. They are used by almost all the single-handed distance racers

Jimmy Cornell admitted that his attempt to collaborate with Ocean Volt for an electric only cruising cat was a total bust. I think they overthought the variable pitch prop and its control system.

On the other hand the Pacific Voyaging Canoes seemed pretty successful with electric drive pods and house loads powered by 4kw of solar and a primitive battery setup.

[seandepagnier]

Originally Posted by Tupaia

In the instance I cited NZ do not allow anchoring prior to checking in under any circumstances dangerous or not. A fellow sailor unable to motor against the conditions ran aground and spent a miserable and stressful night on their side in the mud. He was refused permission to anchor or call for assistance.

I know people who ran aground because they had an engine... oh wait no it's because they navigated into shallow water which had nothing to do with having an engine or not.

You continue to post foolish remarks, but consider this: your engine is harming me. So any justification you have for using it will not be considered valid. It doesn't matter how convenient it is for you: it does nothing but cause pollution for me. It sure also makes cruising less legitimate, and justifies more and more restrictions for the future if most of the people doing it are extremely privileged people who have the means to cause no pollution quite easily but instead are selfish excessive polluters who are spoiling their own cruising grounds for all future generations in a world currently on the brink of complete chaos.

If you must use diesel engine, just use vegetable oil: you can sure afford it, it's cheap, and you can buy it anywhere. Even if not good enough, electric propulsion with huge lithium battery banks isn't good either, but at least these people are trying something and it's better than nothing.

If you use fossil diesel you are trying nothing and using no imagination: lazy and part of the biggest problem of humanity: the enemy of good and the root and seed of the demise of a future, a robbery of the youth of tomorrow and an oppressive perverse hegemony to be recorded and remembered as pillagers who cause devastation and disgrace.

[mglonnro]

Originally Posted by StuM

Based on claims to date, do you really think that OV would make that data public?

I assume it would be possible to log all the relevant stuff (power generated, power used, speed, environmental conditions etc) just using standard sensors on an NMEA network?

[Tupaia]

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.

Just looked at my log.

Tonga to NZ was 6 days and 18 hours 3.5 hours was motoring from Whangarei heads to the immigration berth. Customs had already contacted us and were waiting for us. The low of 986 that we avoided subsequently produced winds of 50+knots between 30 and 35 degrees S.

An average speed of 6.7knots which on reflection is pretty poor for us.
A max boat speed of 19.3 knots, max sustained speed of 16knots.
We were at one point making 3.8knots in 4.3knots of wind.
A min wind of zero, complete calm for 18 hours centre of High at 29 d S
Min "sailing" speed before motoring was 2 knots.
A max sustained wind was 37 knots (williwaws of 45knots) Whangarei.
Fuel used 38 litres.

[seandepagnier]

Originally Posted by Tupaia

An average speed of 6.7knots which on reflection is pretty poor for us.
A max boat speed of 19.3 knots, max sustained speed of 16knots.
We were at one point making 3.8knots in 4.3knots of wind.
A min wind of zero, complete calm for 18 hours centre of High at 29 d S
Min "sailing" speed before motoring was 2 knots.
A max sustained wind was 37 knots (williwaws of 45knots) Whangarei.
Fuel used 38 litres.

Thanks for the data, more convincing evidence of your behavior.

Average boat speed 6.7 knots on a boat capable of 19 knots is definitely no record.

wind is now "37 knots" instead of 45.

My average speed for 9 days from vavau 5.5 knots
Max speed for 24 hours 144 miles: 6 knots (27 ft monohull hull speed limited)
I was also using spinnaker at times, and sailed in and out of minerva reef
Was not becalmed but sailing 2 knots is not becalmed so you were not either. There is technically no such thing as "zero" wind.
Max wind speed sustained 30 knots (gusts a bit higher)
Fuel used: none

38 liters seems an absurdly large for only a few days. Perfect example of why diesel power like this should be limited to renewable fuels which you have the option (38 liters of vegetable oil is not very expensive) of but choose to spend the money on a larger boat than needed instead. People abuse this and cause more emissions than the vast majority of people on the world for purely leisure/recreational purposes. Had you used the engine few minutes for on and off the dock the total would be <1 liter. Had you produced the coconut oil consumed yourself you should mention that.

Now we know the river whanagarei... This is not even a difficult one such as greymouth or some of the others. I tacked up and down this river also know someone with 45ft boat who tacked it a few times against strong contrary winds as well so it's fine to do in large cruising boats as well. So perfectly fine to navigate without engine there and just a waste of fuel to use engine anywhere on that river until you are past the bridge and even then most of the time you can sail all the way.

I sailed also around the north island and experienced much higher winds especially on wairapa near castle point. At times beating in 40 knots (with spray) and sailing downwind in such lows you avoided with 50+ knots. So you could make it without engine, and if needed, it's no problem to hove to for a day or two, certainly not worth the cost to humanity to burn a bunch of fuel when there are so many options available to avoid it.

This is more convincing evidence for why a complete ban against diesel fuel at docks is in order and strongly needed. In the transition period over the next 10 years we can offer you bio-diesel with the associated trade off such as 2-3x the price (still super cheap, 38 liters would only cost about $200 nzd) but with an ultimate complete phase-out in 10-15 years (fuel docks will offer only charge ports at this point) giving you ample time to convert to electric propulsion. This is really a bare minimal to show respect with no really disadvantage or loss of function, otherwise to use fossil diesel you are disrespecting all of the people (numbering in billions) in the world who oppose for your privileged (cruising) lifestyle and disregarding their fate as well as your own.. in the meantime.. just use vegetable oil you can buy it at pak-n-save, and your own exhaust will cause you less harm as a direct benefit.

[Tupaia]

Originally Posted by seandepagnier

Thanks for the data, more convincing evidence of your behavior.

Average boat speed 6.7 knots on a boat capable of 19 knots is definitely no record.

wind is now "37 knots" instead of 45.

My average speed for 9 days from vavau 5.5 knots
Max speed for 24 hours 144 miles: 6 knots (27 ft monohull hull speed limited)
I was also using spinnaker at times, and sailed in and out of minerva reef
Was not becalmed but sailing 2 knots is not becalmed so you were not either. There is technically no such thing as "zero" wind.
Max wind speed sustained 30 knots (gusts a bit higher)
Fuel used: none

38 liters seems an absurdly large for only a few days.



Snip



This is more convincing evidence for why a complete ban against diesel fuel at docks is in order and strongly needed. In the transition period over the next 10 years we can offer you bio-diesel with the associated trade off such as 2-3x the price (still super cheap, 38 liters would only cost about $200 nzd) but with an ultimate complete phase-out in 10-15 years (fuel docks will offer only charge ports at this point) giving you ample time to convert to electric propulsion. This is really a bare minimal to show respect with no really disadvantage or loss of function, otherwise to use fossil diesel you are disrespecting all of the people (numbering in billions) in the world who oppose for your privileged (cruising) lifestyle and disregarding their fate as well as your own.. in the meantime.. just use vegetable oil you can buy it at pak-n-save, and your own exhaust will cause you less harm as a direct benefit.

I agree 38 litres is a lot for me for such a short trip. Over 22 years of ownership and 17 years full time live a board, based on engine hours I averaged 209 litres per year.

I would suggest that this is relatively small compared to the fuel consumption of most sailing boats out there cruising.

It would be interesting to see what the engine hours and fuel consumption is for a typical full time cruiser.

As an example check out the ARC results pages
https://www.worldcruising.com/conten...0A%20&%20B.pdf

Group A - 13 Boats 771 hours or average of 59 hours each
on the same passage



Multihulls - 13 Boats used 380 hours or average 30 hours each
https://www.worldcruising.com/conten...lti%20Hull.pdf


I was astounded that many boats exceeded 100 engine hours the max being 137 hours. ONE HUNDRED AND THIRTY SEVEN hours.

My last E-W Atlantic crossing was 3.3 engine hours.

Multihulls Fiji to Vanautu
https://www.worldcruising.com/conten...%20Fij-Van.pdf

6 Boats used 174 engine hours or average 29 hours each.

I didn't stop at Vanuatu the first time but my trip from Fiji to New Cal used engine 5.7 hours.

I am not saying engines are good and I am not of a mind to remove mine but to expect pure electric propulsion and regen to meet the usage requirements of the majority of "sailing" boats as it stands today is pie in the sky.

I admire your dedication and perseverance by going without and I am not dismissing the efforts of those trying out new technologies.

But the above is the reality and is what applies in the real world to the majority of cruising boats.

Compare this to the school run in an SUV and even the heavy cruisers fuel usage displayed above pales into insignificance. If you really want to make an impact - Tax kids and make it illegal to transport them in a motor vehicle.

[Tupaia]

Just been discussing this with a friend. Big Yacht Captain. He recently put $238,000 of fuel in a super yacht that would get them from Gibraltar to Turkey and cruise a bit but not sufficient to get back. The generators run 24/7.

I did some checking and found a 71mtr yacht with a tankage of 209000 litres and a fuel burn of 600 litres per hour from 2 x 2600 hp engines about 43 litres / mile at 14 knots. This about twice the fuel per mile of a 747.



Assam has a fuel capacity of 1 million litres


There are currently 8500 super yachts 267 were built last year 2020.

Food for thought.


I also know of a Sky Dive Club owner who is into electric aeroplanes. Short flight times large fuel burn during take off. Not dissimilar usage from a marina based sailor.



So I am not saying there is not a place for electric propulsion, just where it is appropriate.

[Jamme]

Apparently UMA just bought a Honda EU22 generator to reach Svalbard:

https://m.youtube.com/watch?v=M8ZJlzSA6mU

[tkeithlu]

Muaddib1116, notice the "at the same distance/time." You can take the energy out again at a high rate while having put it in at a slow rate, but you still get less than 100% efficiency. The pod has drag, the gears have friction, the battery does not function at 100% out of what you put in, and so forth.