Oceanvolt Servoprop regen tested by UMA

[Adelie]

Originally Posted by NaClyDog

Good on you. I would like to see someone actually produce some evidence of what is being claimed in this thread.


At the risk of sounding like a broken record, a youtube video is not evidence.


I think if reality matched the claims, there would be many many more people doing this and we would have ample proof.

Video of speed read outs and nervy production is evidence. Not rigorous evidence but evidence none the less.

[donradcliffe]

I have to say that the abandonment of the fast cat regeneration project by Jimmy Cornell is not rigorous evidence, but its evidence enough for me.

The laws of physics say if you harvest energy out of the propulsion system, it will slow the boat. If you are harvesting 5 kw, the effect on boat speed should be the same order of magnitude as having an 8 hp outboard at full throttle pointing forward. That 8 hp outboard would produce about 160 lbs of thrust in the wrong direction, ie drag.

Another way of measuring the effect would be to run the electric boat from its batteries in a flat calm, and see what speed difference reducing the power by 5 kw would make.

[JustMurph]

I don't think anyone is claiming that there is NO difference, just that it's not as huge as some people claim it is, or that it's some massive problem.

I completely agree with Adelie that the cost is the main barrier, as is complexity. You're spending more than double a diesel repower while adding a lot of complexity, and potentially weight if you have enough generation for continuous full output motoring.

The biggest problem and the main downfall with jimmy's setup is that he had no IC generator of any kind and only a fairly modest solar setup (1.3kw IIRC). I personally think you'd be mad to try that. It might work in ideal conditions, but it won't when the weather is **** or you're in the high latitudes as jimmy likes to.

NaClyDog: Of course a youtube video is evidence, even if not rigorous testing. That's just a silly statement. I haven't seen anyone present any evidence of any kind showing ~20% losses.

[NaClyDog]

Originally Posted by JustMurph

NaClyDog: Of course a youtube video is evidence, even if not rigorous testing. That's just a silly statement. I haven't seen anyone present any evidence of any kind showing ~20% losses.

Hey, you are entitled to believe whatever you like but I also have a bridge for sale, cheap. I'll have the youtube video up of it in no time, I'll make you a great deal, I swear... it will all be in the video!

[JustMurph]

Lots of talk. Show me the substance mate! Anything!

[NaClyDog]

Originally Posted by JustMurph

Lots of talk. Show me the substance mate! Anything!

My point exactly. All those videos have no substance. They are glossy magazine ads. No more, no less.

[JustMurph]

https://www.sailmagazine.com/diy/kno...dro-generators

This article on hydro-generators (which are making similar power to a servoprop equiped SD15 at lower speeds) notes performance drop of 0.1-0.4 knots.

[PaulBartomioli]

Originally Posted by BigBeakie

In past long discussions about whether there is speed robbing drag caused by the Oceanvolt regen system, what has been missing is visual confirmation, one way or the other, with a working system.

It got quite tedious trying to explain why the resultant drag is very minimal ( perhaps tenths of a knot), as members kept up the old "physics is physics" justification for their opinions on some technology they had no first hand experience with.

So, although it seems to have taken a very,very long time for a user to film the Oceanvolt regen system in operation, finally Dan of Sailing UMA YT channel has tested his new SD15 Servoprop regen systen and recorded the result, and whadayouknow? there is no appreciable drag that slows a boat down. Of course it DOES slow a boat down ( because yes, physics is physics), but as several of us have maintained from the beginning, NOT to any significant degree. Here it is at about the 25:35 point in the TY video below if you want to skip ahead:

To put it mildly, the owners of Sailing Uma have more cred than your comment. You get points for admitting your ignorance and YouTube bias, however well-deserved it may be. IF anyone has ANY questions about using solar on a sailboat, they were sailing NORTH of the Arctic Circle with a 100% solar-powered rig. They do have a small Honda Generator to provide battery charging due to the lack of sunlight. Bottom line, if Dan says it is true, it is true.

[Adelie]

Originally Posted by PaulBartomioli

To put it mildly, the owners of Sailing Uma have more cred than your comment. You get points for admitting your ignorance and YouTube bias, however well-deserved it may be. IF anyone has ANY questions about using solar on a sailboat, they were sailing NORTH of the Arctic Circle with a 100% solar-powered rig. They do have a small Honda Generator to provide battery charging due to the lack of sunlight. Bottom line, if Dan says it is true, it is true.

On what basis do you assess the relative credibility of BIgB vs Uma?

Uma is not 100% solar powered.
It is powered by batteries recharged by solar, regen, shore power and a Honda generator.

[PaulBartomioli]

I mentioned the Honda Generator. ANY Solar-powered unit has storage batteries. The regen is part of the electric system. Have you seen the series where each of these changes was added?

As I stated, BigB used the standard internet/YouTube bias to base his comments, as evidenced by his statement that he had not seen the video. Therefore, he has zero knowledge of the thoroughness of what Uma has done over the years.

[noelex 77]

Originally Posted by PaulBartomioli

IF anyone has ANY questions about using solar on a sailboat, they were sailing NORTH of the Arctic Circle with a 100% solar-powered rig.

I don't think they are 100% solar powered. Much of their energy comes from shore power.

This would be OK for many users, but duplicating their set up and expecting to power 100% from solar, especially in areas of less than great solar insolation, would be a mistake.

[PaulBartomioli]

you are wrong. watch the videos. WHY do you think they have a small honda generator?? It has limitations, but it is not a mistake. They have been sailing this way for years. Provide the proof for your "shore power" statement.

[Adelie]

Originally Posted by PaulBartomioli

I mentioned the Honda Generator. ANY Solar-powered unit has storage batteries. The regen is part of the electric system. Have you seen the series where each of these changes was added?

As I stated, BigB used the standard internet/YouTube bias to base his comments, as evidenced by his statement that he had not seen the video. Therefore, he has zero knowledge of the thoroughness of what Uma has done over the years.

Uma has never been 100% solar powered except when on passage. Even at the very beginning they were using shore power.

[noelex 77]

Originally Posted by PaulBartomioli

you are wrong. watch the videos.

Many of their videos show their efforts to track down shore power.

Originally Posted by PaulBartomioli

WHY do you think they have a small honda generator??

Primarily because they are venturing into a cruising area (around Svalbard) where the opportunity to plug into shore power is limited. I think their videos make this clear.

I am strong supporter of solar power. The house loads on our boat are supplied 95+% by the solar array, but it is important to have realistic expectations. It easy to dream of a small solar array powering all loads including EP, but the reality is different.

[Adelie]

Wintering in GB & Norway they were highly dependent on shore power for heat among other things.
They have previously indicated that when not on passage they fly the drone, shoot film and edit the videos which leaves them at a slight power deficit that they usually make with shore power from time to time.

Their early interest in regen and more recent interest in wind power is a result of wanting to both diversify power sources and to make up that deficit.