Oceanvolt Servoprop regen tested by UMA

[Bullshooter]

In that recent video, he clearly explains why he is purchasing the generator, and adds that he already has gas cans for his dingy outboard. He also mentions that his initial trials with the regen have not provided enough information yet to be safely prepared to go to remote wilderness without fuel-driven generator. Duh, right? I don't think that the video from the installation and initial test were presented as any more than a "Let's see what this regen can do!" first look.

I don't know why some suggest he does not have a knot meter. I thought he showed the decrease in speed when the regen was on. ???

He strikes me as a very intelligent and resourceful person, exploring the possibilities with electric in sailing/cruising. I don't distrust him inherently as a sneaky salesman trying to fool us into thinking OceanVolt is going to save the planet. Then again, it's just a YouTube video so I have nothing to lose if he is. I wish him the best. I've only watched about 5 of their videos so i'm not a fanboy who idolizes him.

Those who love to bash the use of electricity on sailboats often bring up the fact that when you need power to motor, a diesel engine is a necessity. Hard to dispute that. Then when UMA gets a gas generator, they are accused of hypocrisy. Ironic.

[mglonnro]

Originally Posted by s/v Jedi

Hot water has been used for cabin heating even longer than cold water for cabin cooling.

Yes, absolutely, but I think Dirk01 was sizing his system to heat the shower water. I will gladly use it for the rest as well!

[Adelie]

Originally Posted by Bullshooter

...

I don't know why some suggest he does not have a knot meter. I thought he showed the decrease in speed when the regen was on. ???

He strikes me as a very intelligent and resourceful person, exploring the possibilities with electric in sailing/cruising. ....

I was the one that suggested they don't have a knotmeter. I checked the first video in the thread closely. Just when they started in-water testing Dan indicated they the GPS speed readout and they DO have a knotmeter that they haven't calibrated in a while.

From watching the rest of the testing it appears they used the GPS readout for speed rather than the knotmeter. This would be a significant weakness in their testing if they used the GPS speed.

I agree that he AND Kiki are intelligent, but testing is not their background so it would not be surprising if they made this mistake.

[Bullshooter]

OK thanks for clarifying and catching that.

Another point here is that he didn't claim that it was any kind of scientifically valid test, if I remember correctly. He just wanted to quickly check what kind of watts he would get and how much his speed might decrease. I could be wrong - I was just watching casually and missed where he got that bar chart from.

[Adelie]

I'm not trying to knock them, just point out the limitation of their data currently.

Uma & Sailing Wisdom are the only people I've found that have published real world data for regen. Other than manufacturers but I don't trust their numbers.

[NaClyDog]

Originally Posted by Adelie

Uma & Sailing Wisdom are the only people I've found that have published real world data for regen. Other than manufacturers but I don't trust their numbers.

This I find quite amusing.

[Adelie]

Why??

[NaClyDog]

Originally Posted by Adelie

Why??

You don't trust the manufacturer's numbers but you will trust the numbers of someone paid by the manufacturer. You don't think that may be a wee bit of a problem?

[Ericson38]

The amount of usable (converted to mechanical rotation) energy provided by 100 gallons of diesel fuel example (20 hp from a 4 cylinder Kubota):

(20*746) * 100 = 1,492,000 watt hours. This is consuming it at 1 gallon per hour.

If this 1.5 MW-hr were in a battery of exactly that capacity and could be discharged to 0v, it would take (with 600 watts charging via continual solar panel output) at least 2486 hours to recharge.

Scaling up a 88kwHr 1200 lb Tesla model S (88 kWHr) battery for weight, this marine storage battery would weigh ~ 20,300 lbs (drain to zero).

A Telsa model S has a 88kW/hr (1200 lb) battery, so this amount of energy represents just under 17 Telsa packs from full charge drained down to 0 capacity.

The energy density of diesel is very high, as you can see.

[senormechanico]

Originally Posted by Muaddib1116

Dan was obviously not being very scientific, but if I recall, I think he was seeing 300W+ at around 6.5kts SOG. He then turned the system off and went up to 6.6/6.7, and turned the system back on and stayed the same and then went up to 6.8, so the wind was picking up a bit. It would be very hard to be scientific about it outside of a lab. Start watching the video at around 24min for his "testing".

What bugs me about his testing is he ignores the speed thru the water.
The water's current and direction could be a very significant part of this.
Where I live (North part of Puget Sound , Admiralty Inlet) currents can approach 6 knots during a big tide and barometric change.

[Adelie]

Originally Posted by NaClyDog

You don't trust the manufacturer's numbers but you will trust the numbers of someone paid by the manufacturer. You don't think that may be a wee bit of a problem?

There are different levels of trust.
Manufacturers have an obvious vested interest. Their results have to have some basis in reality or no amount of sales hype will get them continuing business.
Sponsored users would be step up from there.
Uma are sponsored users for whom the vendors are a secondary or even tertiary money stream. This is at least a step up from a regular sponsored user.

I’m a professional skeptic, I check the things that people tell me as much as possible and am very careful about how much I trust people at work. My job affects whether people live or die in years to come and being judicious about who to trust is part of that. I think Uma’s numbers are in the ballpark for this product.

[Adelie]

Originally Posted by Ericson38

The amount of usable (converted to mechanical rotation) energy provided by 100 gallons of diesel fuel example (20 hp from a 4 cylinder Kubota):

(20*746) * 100 = 1,492,000 watt hours. This is consuming it at 1 gallon per hour.

If this 1.5 MW-hr were in a battery of exactly that capacity and could be discharged to 0v, it would take (with 600 watts charging via continual solar panel output) at least 2486 hours to recharge.

Scaling up a 88kwHr 1200 lb Tesla model S (88 kWHr) battery for weight, this marine storage battery would weigh ~ 20,300 lbs (drain to zero).

A Telsa model S has a 88kW/hr (1200 lb) battery, so this amount of energy represents just under 17 Telsa packs from full charge drained down to 0 capacity.

The energy density of diesel is very high, as you can see.

The point of EP isn’t to match diesel performance exactly but to do something different.

EP doesn’t work on power cruisers, except multihulls.

EP is good as slow intermittent propulsion on sailboats, for short periods of calm between more extended periods of being propelled by sails which offer time to recharge by whatever method is available. I exchange the “fuel” is free and ever accumulating, if rather slow about it.

Your numbers for diesel Diesel engines are about 11% high, they deliver about 18hp/gal/hr, not 20.

Also, you were discussing specific energy (energy/weight) of diesel not energy density (energy/volume).

[Ericson38]

Originally Posted by Adelie

The point of EP isn’t to match diesel performance exactly but to do something different.

EP doesn’t work on power cruisers, except multihulls.

EP is good as slow intermittent propulsion on sailboats, for short periods of calm between more extended periods of being propelled by sails which offer time to recharge by whatever method is available. I exchange the “fuel” is free and ever accumulating, if rather slow about it.

Your numbers for diesel Diesel engines are about 11% high, they deliver about 18hp/gal/hr, not 20.

Also, you were discussing specific energy (energy/weight) of diesel not energy density (energy/volume).

Energy density and specify energy are both high, correct.

With 100 gallons of fuel weighing about 7 pounds per gallon, about a 700 pound mass. Having 1.5 Mw-Hhr of energy inside 700 pounds mass gives 2.13 KWhr per pound, after thermal and mechanical losses of the engine are considered in the conversion.

And takes up 13 cu ft of space. So close to 114,700 watt-hours per cubic foot.

I don't think EP works in very many auxillary sailing applications, but it certainly can be shown to work within limits.

If you can pull 300W out of the water with a free running propellor as a drive source, it essentiall becomes another single solar panel to recharge the bank.

Thats less than 1/2 hp though, so to really extract energy from the water flowing past the boat, a much much larger diameter prop with large surface area, is required.

To drive a 40 foot sailboat at hull speed should take in the 30 hp range (7 kts). Pulling 3 hp out of it with a free running prop (2100 watts) gets us to 27 hp remaining for thrust forward, neglecting that 3 hp worth of resulting drag is not completely converted to rotational mechanical energy.

[s/v Jedi]

Originally Posted by Ericson38

The amount of usable (converted to mechanical rotation) energy provided by 100 gallons of diesel fuel example (20 hp from a 4 cylinder Kubota):

(20*746) * 100 = 1,492,000 watt hours. This is consuming it at 1 gallon per hour.

If this 1.5 MW-hr were in a battery of exactly that capacity and could be discharged to 0v, it would take (with 600 watts charging via continual solar panel output) at least 2486 hours to recharge.

Scaling up a 88kwHr 1200 lb Tesla model S (88 kWHr) battery for weight, this marine storage battery would weigh ~ 20,300 lbs (drain to zero).

A Telsa model S has a 88kW/hr (1200 lb) battery, so this amount of energy represents just under 17 Telsa packs from full charge drained down to 0 capacity.

The energy density of diesel is very high, as you can see.

I think these numbers are accurate enough, the problem is that the comparison is flawed. You can’t make diesel fuel while out sailing (used cooking oil?) but can generate electric energy using solar, wind and regen.

This means that you need to take a large amount of diesel fuel with you, but not that you need a battery of the size to store an equal amount of energy.

The portable generator that Uma got is a perfect setup for them because their solar production is going down the further into the arctic they go. Also, it would allow them extended motoring as they could run it while underway.

[Bullshooter]

Remember that improvement in batteries, even efficiencies in electric propulsion (see https://electrek.co/2021/08/19/cande...ited-lifetime/ continue to happen, and such improvements will allow for EP to become more useful, possibly useful enough to replace deisel in some sailing applications.