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Old 30-07-2020, 07:43   #2041
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Re: Oceanvolt Hybrid Motor

500W isn’t a significant amount of power. But still I think solar and Li batteries is the way for most cruisers. Works just as well at anchor as on passage.

Our power usage is less on passage than at anchor. Every boat is different obviously.

I have heard of claims like 2+kW for hydro regen. That will put significant extra stress on the boat. I agree that 500W is not so bad for the rig. It will be horribly inefficient to turn a 10+kW motor to only generate 500W to 1kW. Lots of heavy moving parts for such a small amount of power.
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Old 30-07-2020, 09:59   #2042
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Re: Oceanvolt Hybrid Motor

Don't mistake an electric motor with a diesel engine...
More output power does not mean more heavy parts.
If you look at how small an 75kW motor of let's say a BMW i3 is, peak power is 125kW, regen is about 65kW.
So the 10kW, 12kW peak, motor is not really big and heavy.
OV claims they get up to 1,5kW regen per motor. But that is under ideal conditions.
And we are still talking about a multihull, so two motors. So between 1 and 2kW depending on the boat speed and the conditions.
Interesstingly La Vagabonde just announced that their next boat will be as fossil free as possible. I suspect they are doing some sort of hybrid, hopefully serial with only a genset and no diesel engines. But we'll see.
Still waiting on the numbers of Sailing Uma, they just finished their first long passage from the Netherlands to Norway after switching to OV.
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Old 30-07-2020, 10:12   #2043
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Re: Oceanvolt Hybrid Motor

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Because the first law of cruising says, “There is no free lunch.”

1) Regen puts more stress on the boat and rig.
I don't understand how regen can put more stress on the boat, than a fixed and locked prop?
If any boat and rig has any trouble from that "stress" then there is a whole other ton of problems on that boat.
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Old 30-07-2020, 10:43   #2044
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Re: Oceanvolt Hybrid Motor

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I don't understand how regen can put more stress on the boat, than a fixed and locked prop?
If any boat and rig has any trouble from that "stress" then there is a whole other ton of problems on that boat.

For tiny power generation (500W) you are right. But for significant power, say 2kW, it is more complicated. Almost all regen systems use variable pitch props though. A fixed prop is a terrible idea for a regen system.

At significant power like 2kW the efficiency of the system comes into play. Let’s say the system is 50% efficient (that would be a very high estimate) then it needs 4kW of power from the sails. For a moderate cruising boat that means significant drag and that requires more canvas than you would otherwise need. It is akin to trying to get a displacement hull to climb up its own bow wave. More drag means more opportunities to break something.

But if all you want is 500W then fine. But solar can do that with almost no drag. So what is the benefit of regen except when on 24 hour per day passages? That represents what, maybe 0.1% of a cruising boat’s life?
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Old 30-07-2020, 11:07   #2045
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Re: Oceanvolt Hybrid Motor

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But if all you want is 500W then fine. But solar can do that with almost no drag. So what is the benefit of regen except when on 24 hour per day passages? That represents what, maybe 0.1% of a cruising boat’s life?
because you have already maxed out the solar that will fit? I agree solar is the place to start. It would make no sense to have a boat with hydrogeneration and no/minimal solar.
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Old 30-07-2020, 12:40   #2046
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Re: Oceanvolt Hybrid Motor

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For tiny power generation (500W) you are right. But for significant power, say 2kW, it is more complicated. Almost all regen systems use variable pitch props though. A fixed prop is a terrible idea for a regen system.

At significant power like 2kW the efficiency of the system comes into play. Let’s say the system is 50% efficient (that would be a very high estimate) then it needs 4kW of power from the sails. For a moderate cruising boat that means significant drag and that requires more canvas than you would otherwise need. It is akin to trying to get a displacement hull to climb up its own bow wave. More drag means more opportunities to break something.

But if all you want is 500W then fine. But solar can do that with almost no drag. So what is the benefit of regen except when on 24 hour per day passages? That represents what, maybe 0.1% of a cruising boat’s life?
500W is way above tiny, as far as I know, considering that PV gives you around 4 times the power installed per day in Wh, and that these 500 are constant on a passage, these 500w are equivalent to 2kW installed solar array.
Which again, is very far from tiny.
(and I have nothing against PV, of course)
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Old 30-07-2020, 14:02   #2047
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Re: Oceanvolt Hybrid Motor

@transmitterdan 2kW solar array is 20 100W panels, if you prefer (numbers do not seem to be your friends )
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Old 30-07-2020, 14:22   #2048
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Re: Oceanvolt Hybrid Motor

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@transmitterdan 2kW solar array is 20 100W panels, if you prefer (numbers do not seem to be your friends )
If you don't use flexible but hard panels, the number can go down to 5.
400Wp is available for a decent price.
But that are residential ones.
If I look at what is mounted on some boats that you find on the interwebs then those seem to work well...
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Old 30-07-2020, 16:51   #2049
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Re: Oceanvolt Hybrid Motor

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500W is way above tiny, as far as I know, considering that PV gives you around 4 times the power installed per day in Wh, and that these 500 are constant on a passage, these 500w are equivalent to 2kW installed solar array.
Which again, is very far from tiny.
(and I have nothing against PV, of course)

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.
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Old 30-07-2020, 16:54   #2050
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Re: Oceanvolt Hybrid Motor

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@transmitterdan 2kW solar array is 20 100W panels, if you prefer (numbers do not seem to be your friends )

There are 350W panels available and even more power if you stoop to using commercial roof panels.
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Old 31-07-2020, 01:08   #2051
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Re: Oceanvolt Hybrid Motor

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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.
Hm, 24h regen equals 12kWh. Propulsion on a passage, if becalmed, would mean 4-5kt witch would equal about 3kW output. So 24h regen while sailing gives you 4h of motoring in calm conditions.
Since regen is not your only power source, the batterie will be topped up already by solar.
And for sure, regen slows the boat down. OV states that you lose about a kt of boat speed.
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Old 31-07-2020, 05:51   #2052
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Re: Oceanvolt Hybrid Motor

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Hm, 24h regen equals 12kWh. Propulsion on a passage, if becalmed, would mean 4-5kt witch would equal about 3kW output. So 24h regen while sailing gives you 4h of motoring in calm conditions.
Since regen is not your only power source, the batterie will be topped up already by solar.
And for sure, regen slows the boat down. OV states that you lose about a kt of boat speed.

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.
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Old 31-07-2020, 08:23   #2053
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Re: Oceanvolt Hybrid Motor

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.
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Old 31-07-2020, 23:23   #2054
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Re: Oceanvolt Hybrid Motor

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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.
Would not be suprised that La Vagabond ends up with anohter Outremer as Jimmy Cornell is getting a fully electric one based on a 4x (to do the Magellan route), and Outremer is planning to have it on their catalog as a 4E, and also one with a diesel gen to be called 4H (ptobably the one lavag would get)
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Old 01-08-2020, 14:28   #2055
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Re: Oceanvolt Hybrid Motor

https://www.multihulls-world.com/mag...ulls-world-173
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