Oceanvolt Hybrid Motor

[harlem24]

The question is, what do you want? Run the engines or the genset regulary or not?
If not regen, solar or a Watt&Sea or a wind gen is the thing for you.
If you do still want to use diesel then we can stop this discussion, because it does not lead anywhere...

[transmitterdan]

What would be nice is some actual data measured by some semblance of scientific rigor. The fact there isn’t any tells a lot. It doesn’t take much in the way of test equipment.

It doesn’t matter what we “want”. The question is what can we “get”?

[BigBeakie]

Originally Posted by transmitterdan

What would be nice is some actual data measured by some semblance of scientific rigor. The fact there isn’t any tells a lot. It doesn’t take much in the way of test equipment.

It doesn’t matter what we “want”. The question is what can we “get”?

Well you can get 1kW per motor at 10 knots, so if you have both motors in regen mode, and why wouldn't you, that's the 2kW that was mentioned as being in a "dream" state. That's with the standard OV saildrive the SD15. It's considerably more if you choose the OV Servoprop model, and the output starts further down the curve at lower boatspeeds.

But you knew that, didn't you?

FYI, the data on the Servoprop shown on the OV site is, from my understanding, the results from tank testing ( you know... controlled conditions, repeat testing of variables, accurate speed/resistance/RPM measurements, data logging and analysis) and on water boat testing on their Swan 50, from memory.

Some visual evidence for you > Here is video of a Slyder 47 sailing using an OV SD15 saildrive for regen where the SOG is about 10 knots and the kW regen output are shown at about 1kW on each motor. You'll find it searching Slyder 47 Oceanvolt on Youtube:

https://www.youtube.com/watch?v=aP9gasAKDHM&t=9s

As to your assertion that regen slows the boat down significantly, and I think you used 10% as a "guess", just have a think about why Alex Thomson would have chosen an Oceanvolt for regen if it was going to slow him down on Hugo Boss??? Those guys in the Vendee Globe teams are chasing tenths of a knot improvements in boatspeed, so your concern of the resistance effect of OV regen really seem unfounded.

[transmitterdan]

Vendee Globe boats have large power requirements. They have limited fuel. And they sail long distances where solar is limited. So regen is their power source of last resort.

And do I need to point out that a high percentage of Vendee Globe boats break? Why?

[BigBeakie]

Gee, I don't know why the VG boats break so much stuff. Maybe they're just careless or don't maintain their boats well? Why don't you enlighten us?

Let me take a guess. Could it be that perhaps it is the toughest ocean yacht race in the most dangerous seas on the planet and it is single handed non-stop?

But anyway, what's you're point?

[transmitterdan]

They break because they drive them hard 24/7. Regen means they drive them even harder.

[cj88]

Originally Posted by transmitterdan

They break because they drive them hard 24/7. Regen means they drive them even harder.

Do you honestly think that having regen or not would make any real world difference to how hard they drive those boats and how much they break. They will always drive them to their limits and even beyond with or without regen, that's racing.

[transmitterdan]

Originally Posted by cj88

Do you honestly think that having regen or not would make any real world difference to how hard they drive those boats and how much they break. They will always drive them to their limits and even beyond with or without regen, that's racing.

So we agree racing has little bearing on cruising strategies. Q.E.D.

[Adelie]

Originally Posted by yvest

1) Don't think regen would put more stress on the boat and rig than a non folding propeller, which is "some", but ...



2) Not necessarily, an electric motor is inherently also a generator



3) key point is regen works at night or cloudy day on a passage, and if the batteries are full, you can heat your water for a shower or something

1. Regen puts opposite direction loads on the thrust bearing. If the bearing is designed for or is able to handle long term loads in that direction no problem.

2. DC motors sure, not so AC motors. Many commercial systems seem to be going AC for efficiency benefits. Doesn’t mean you can’t generate from an AC motor, means that it will cost you for the capability.

3. True as long as the boat is sailing somewhere near hull speed. You ain’t going to get much out at 3kt or even 4kt.

Understand I’m a supporter of electric propulsion, but I want people to know what they’re getting into going that route.

[BigBeakie]

Oh quite right! What were we all thinking! Why would a cruiser be interested in a silent, lighter, extremely low maintenance propulsion solution that also generated the fuel that it runs on when arriving at the anchorage?

Yep, definitely only for those crazy racers out there

[Adelie]

Originally Posted by transmitterdan

That’s a good reason. But what we have seen in this thread is people thinking that regen will let them propel the boat for miles during calm days. A 500W power source won’t move a cruising boat very far.

Maybe you could get 1 hour of ocean propulsion from 24 hours of hard regen sailing with huge batteries. And regen for propulsion use is only useful for propulsion if drag of regen does not slow the boat. Thus the “hard sailing” phrase.

For a Cal 34 each hour of regen at 500w will get you get about 1.0-1.3nm of range at 3.0kt. That assumes you are losing about 1/3 of the power in charging and discharging the batteries and using the power.

Not stunning but not to be dismissed out of hand.

[Adelie]

Originally Posted by transmitterdan

If the wind is right you don’t have to give up any boat speed. That’s when regen helps the most. I would say any loss of boat speed due to regen makes regen close to useless for propulsion purposes on a cruising boat because you can’t reach your destination faster (most likely you will lose time).

Let’s agree not to drag “magic horsepower” into the discussion. It’s pointless to debate whether a 3hp motor can push a cruising boat at 6 knots...because it can’t. Yes, maybe some ultralight trimaran but not a fully laden boat for 2+ people interested in comforts of home.

If they are all that interested in the comforts of home why didn't they fly? Or just stay home?

[Adelie]

Originally Posted by harlem24

I don't know if you follow Sailing Uma on YT, but they state that they need 3kW to push the boat to 4kt, they have a 76 34" Pearson.
Atm they just finished a sail from the Netherlands to Norway where they most likely tested the regen capability of their OV saildrive.
And as also stated before La Vanagbond wants to go almost fossil free, so let's wait with what they come up.

1.2kW got Uma 3.0kt.
https://www.cruisersforum.com/forums...ml#post3172120

[Adelie]

The point of electrical propulsion on an ocean going boat is not to motor thru the doldrums, or to maintain 6-10kt of boat speed when the wind drops or to get anywhere near hull speed powering into 20kt of wind which seems to be the point of ICE engines as they are currently being sized and installed.

On an ocean going boat electrical propulsion will get you in and out of harbors and anchorages, get you out of the way of a vessel that might otherwise run you down, it will get you across a VTS channel and it will help you power thru tacks in heavy winds. Generally if you need to make some distance it will push you along at a modest 3kt or so. If you can't live with the above list of compromises then don't choose electrical propulsion for your own boat. And don't tell others that's not a choice they should make either.

Regen, like solar, wind turbines and hydro generators are different ways of recharging batteries to store power until you need it. They all have different advantages and disadvantages. Solar seems to be the low hanging fruit, after that it depends on your circumstances such as boat size, sailing venue and season.

[Jim Cate]

depends on your circumstances such as boat size, sailing venue and season.

Well, you have hit upon a factor not often mentioned in these discussions about solar:season!

The yields quoted for PV somehow are always at high noon in a low latitude area with no cloud cover. My observation is that when you venture into mid latitudes reality is not as good to you. For instance, here in Tassie, lat ~43 S, in summer the days are pretty long, and that almost makes up for the low sun angle, and our mere 400 watts is quite adequate. Around the equinox things deteriorate rather rapidly, what with lower angles and shorter days. Now in the pit of winter, on sunny days we were getting peaks of 400 Whrs a day with <100 all too often as compared to our 1500+ Whr/day in summer, and more than that back in the Sydney area (lat ~33 S) and doubtless greater than that in the tropics (we've not had these panels in the tropics yet). Having the ability to tilt the panels would certainly help, but that is not possible in many installations, and ours is one of them. And for those who only cruise in the summer, and in temperate latitudes, not so much of a worry for sure. For long term and far ranging cruisers, it matters.

I post this not to refute any claims but perhaps to temper the expectations expressed in many threads here on CF. They often seem hopelessly optimistic to me.

Jim