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Old 09-05-2017, 02:46   #916
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Re: Oceanvolt Hybrid Motor

If I read all this stuff correctly the numbers for Kato are

8.4kW (Generator) 7knots
30KW (All power sources) 10Kn

From this one assumes a couple of things.

Firstly, you would not want to run the boat at 10Kn for any great period of time as you would quickly drain the battery banks, so we can assume that in reality the cruising speed with generator running is nominally 7kn. Now this is with a lightweight boat so lets assume 6kn with full fuel and water and everything else on board.

Secondly, one would assume that you could translate this result in ratio of Kato Boat metrics to any other boat. So lets say for a boat like the Free Flow you would expect around 4kn cruising speed PROVIDED you have a 8.5KVA rated generator.

This raises the question of what Kato's performance would be should it be equipped with a generator rated to 15Kw. Hard to say but interpolating these results probably about 8.5kn less the one knot for loading so 7.5Kn. Translated to the FF this would be around 5.5Kn.

Further, it appears from all of the data that Claude has provided, (as well as previous data for Oram 44C that OV 15Kw translates to 30KW diesels. Indeed see the last couple of posts. I am somewhat sceptical of this data and as I said previously I suspect the equivalence number is around 25Kw.

This would mean that SD15 EP is definitely not applicable to production boats as the performance would not be adequate and certainly explains the OV marketing strategy of targeting very quick large cats and smaller monos. Having said that it seems like a very good product. Once hopes that in the fullness of time they will introduce a 30KW model with 30Kw batteries and 20-30Kw generator. I would think this would have to be priced below U$100K for it to gain traction.
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Old 09-05-2017, 02:48   #917
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Seaslug Caravan View Post
Now this is where it gets a bit murky. I know in conversations I had with Neel that any sort of wind action and he was so hopelessly under powered he was reluctant to leave the marina.

As for schools out they were so "HAPPY" with their instalation they replaced it with conventional petrol outboards.

Mr D are your pants on fire?

Just askin.

This is crystal clear!

The fact is twin 4kw electric is the same as twin 9,9 Yamaha. And yes it is a little light for a 44ft catamaran.

And yes Neil would like to have fitter larger ELECTRIC motors. More like 8 or 10kW per side. (And still would like too) Have you chatted with him lately?

I will guess this is why C44 does not have twin Yanmar 9.9 on his boat but twin 20hp (or is it twin 25hp?)

Likewise, do you actually know why School's Out swapped their motors? Or are you just throwing mud and hoping that it will stick...

So stick to the point here! Which is: A twin 9.9 Yamaha installation would give you exactly the same result as a twin 4kW electric installation on an Oram C44
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Old 09-05-2017, 03:25   #918
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Re: Oceanvolt Hybrid Motor

No, it doesn't.
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Old 09-05-2017, 04:43   #919
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Claude-D View Post
The fact is twin 4kw electric is the same as twin 9,9 Yamaha.
Here we go again. Magic EP horsepower.

With the same prop and geared for the same prop RPM at full power?
In all sea/weather conditions?
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Old 09-05-2017, 04:49   #920
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Re: Oceanvolt Hybrid Motor

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Originally Posted by cwjohm View Post
I do not necessarily think that the laws of physics are violated. I think it is simply testament to the incredible job that Julien has done in building this boat. I think it is entirely possible that this performance is generated by as little as 25Hp equivalent propulsive force from the motors. I would be interested in a comparison of 44Cs boat to Kato in terms of ratios of Kg/m and motor HP.
Except the discussion has been getting something on the order of 8-10kts on 8-10hp, not 25hp.

It both are run flat out....oops, the generator is only putting out 8-11kw (depending on when they are commenting), so getting the higher claimed speeds are not possible except for short bursts and certainly not under generator alone as was previously claimed.

So yeah, there's either a profound lack of understanding of basic physics or an attempt to confuse and mislead.
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Old 09-05-2017, 04:59   #921
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ranchero76 View Post
2.silent propulsion,
I see this all the time and it baffles me why so much emphasis is made on it.

Last time I was out, cruising along a around 6kts and started paying attention. I could hear the wind noise, the water rushing around the hull and occasionally a creak or halyard slap as we hit a wave. I really had to pay attention to hear the motors running and it was a small background to the other noises.

Tried the same experiment yesterday with my F250 doing 70mph down the freeway. Wind noise, tire on pavement noise but unless I gunned the engine, I literally couldn't pick out the engine noise.

There just isn't a lot of noise with modern engines.
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Old 09-05-2017, 05:06   #922
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Re: Oceanvolt Hybrid Motor

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I know there are systems out there, but it would still be scary in the middle of the ocean. This is why I prefer the concept of parallel hybrid systems.
Unless you are fitting a 20yr old mechanical diesel, there's really no difference if hit by lightning. If a strike burns out everything electrical, you aren't starting the electronically controlled diesel either.

The bigger issue is getting parts and repairs done in remote areas compared to a common engine which the local repair places will be familiar with. And before someone claims electrics never fail, better than 90% of the repair and maintenance on my boats and cars over the last 30yrs have been primarily electrical in nature.
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Old 09-05-2017, 05:19   #923
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Claude-D View Post

The fact is twin 4kw electric is the same as twin 9,9 Yamaha. And yes it is a little light for a 44ft catamaran.
9.9hp is approximately 7.4kw.

Please share the math explaining how 4.0kw = 7.4kw.

I'm an engineer so feel free to use equations and proper unit conversions rather than analogies.
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Old 09-05-2017, 05:28   #924
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Claude-D View Post
Yes, you are correct... The Oceanvolt SD15 in Hydro-generation mode is not as efficient as it could be. This is because we are using the Gori propellers, which are optimised to push the boat forward. These Gori propellers are designed without any consideration for Hydro-generation.

However, the SD15 in Hydro-generation mode are able to generate significant amount of power, but not so much as to affect the speed of the boat too much. So, if you are traveling at 12 knots and generating 1.5-1.8kw the speed drops and will be barely noticeable, and not subjected to a large sail increase. Because after all the important point is propulsion. The hydro-regeneration is just an added bonus that you will not have with a diesel motor....

The new Servoprop is totally different and does not rely on a Gori propeller (or other) but is as you suggested feathering propellers.
Please tell the whole truth! As an example, a boat sailing at 12kts in 15kts of wind will certainly notice the drag of 2.5-3hp taken to produce 1.8kw of electricity. The same boat sailing at 12kts in 20kts+ of wind, not so much. Sensible regen should only happen when the sails are overpowering the boat. Stop making the claim regen can happen without notice at all times. When all power produced by the sails is needed to move the boat, there is nothing left for power generation, regardless of how efficient your system. All the discussion about the prop connecting with the water does not erase the fact that every 745w requires 1hp in a 100% efficient system, which you do not have.
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Old 09-05-2017, 14:12   #925
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Re: Oceanvolt Hybrid Motor

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Originally Posted by valhalla360 View Post
Except the discussion has been getting something on the order of 8-10kts on 8-10hp, not 25hp.

It both are run flat out....oops, the generator is only putting out 8-11kw (depending on when they are commenting), so getting the higher claimed speeds are not possible except for short bursts and certainly not under generator alone as was previously claimed.

So yeah, there's either a profound lack of understanding of basic physics or an attempt to confuse and mislead.
Well, more correctly they are saying that a 15HP EP motor will generate the same thrust as a 45HP diesel.

What the EP supporters (driven by the marketing hype of OV) are saying is that given the different torque curves of EP vs diesel they can upgrade the prop to generate more thrust per energy input. There is certainly some merit in this argument. However, they destroy their credibility by over extending this argument to make unsupportable claims. Of course they do this in order to make the financial equation seem even moderately viable.

Hyped up marketing claims are a part of our life as every second television advertisement demonstrates, and you just need to attend any boat show and listen to the sales people spruiking boats to hear the crazy performance claims that are trotted out.

It is really a matter of buyer beware. Personally, I think the OV product is a pretty good one. If your boat cruises pretty well on a 25Hp diesel then the 15KW OV motor will do a good job. Of course you will pay 75K Euro for the pleasures that EP offer.

I guess the real problem is that in order for people to make EP remotely financially viable they are installing underpowered propulsion sytems and this at best severely limits boat handling and at worst creates unsafe situations.
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Old 09-05-2017, 14:44   #926
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Claude-D View Post
This is crystal clear!

The fact is twin 4kw electric is the same as twin 9,9 Yamaha. And yes it is a little light for a 44ft catamaran.

And yes Neil would like to have fitter larger ELECTRIC motors. More like 8 or 10kW per side. (And still would like too) Have you chatted with him lately?

I will guess this is why C44 does not have twin Yanmar 9.9 on his boat but twin 20hp (or is it twin 25hp?)

Likewise, do you actually know why School's Out swapped their motors? Or are you just throwing mud and hoping that it will stick...

So stick to the point here! Which is: A twin 9.9 Yamaha installation would give you exactly the same result as a twin 4kW electric installation on an Oram C44
I have 20 hp motors. This was made clear, why are you questioning it?

The 4kw Torqueedo motor doesn't give the same result as a Yamaha 9.9.

It's less powerful in forward, and MUCH less powerful in reverse.
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Old 09-05-2017, 14:52   #927
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Re: Oceanvolt Hybrid Motor

What's the rationale behind fitting these boats with inadequate generators?

The boats equipped with 2 X 4 kw motors had 5 kw genset. Kato has 2 X15, yet only a 10 kw genset.

For that boat 30 kw might be adequate, but for any length of time it can only use 10, which is unlikely to be enough.

Why not match the genset output to the motors?
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Old 09-05-2017, 15:05   #928
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by cwjohm View Post
It is really a matter of buyer beware. Personally, I think the OV product is a pretty good one. If your boat cruises pretty well on a 25Hp diesel then the 15KW OV motor will do a good job.
I agree - under reasonable conditions. It's when the SHTF and you need that last 5HP that the 15kW OV will let you down.
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Old 09-05-2017, 15:17   #929
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Re: Oceanvolt Hybrid Motor

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Originally Posted by 44'cruisingcat View Post
What's the rationale behind fitting these boats with inadequate generators?
Weight/Space requirements of genset and fuel storage after you've put in huge battery banks?
Quote:
The boats equipped with 2 X 4 kw motors had 5 kw genset. Kato has 2 X15, yet only a 10 kw genset.

For that boat 30 kw might be adequate, but for any length of time it can only use 10, which is unlikely to be enough.

Why not match the genset output to the motors?
The assumption apparently is that the batteries will provide the extra 20kW when needed - and that exposes the major drawback of all EP - the limited time that full power will be available given any reasonable size battery bank.
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Old 09-05-2017, 16:57   #930
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Re: Oceanvolt Hybrid Motor

[QUOTE=cwjohm;2389041]If I read all this stuff correctly the numbers for Kato are

8.4kW (Generator) 7knots
30KW (All power sources) 10Kn That is on Batteries,
not batteries + genset


From this one assumes a couple of things.

Firstly, you would not want to run the boat at 10Kn for any great period of time as you would quickly drain the battery banks, so we can assume that in reality the cruising speed with generator running is nominally 7kn. Now this is with a lightweight boat so lets assume 6kn with full fuel and water and everything else on board. My understanding from Tony is Kato II was 9.6 Ton at launch with obviously no mast, chain, water etc and only a bit of diesel for the Genset. The sea trial was with all the above plus half water & diesel AND provisions AND 9 people on board. So, not exactly racing trim. Claude was there, instead of making stuff up, why not ask him?

Secondly, one would assume that you could translate this result in ratio of Kato Boat metrics to any other boat. So lets say for a boat like the Free Flow you would expect around 4kn cruising speed PROVIDED you have a 8.5KVA rated generator.You're just making stuff up now.
We have the OV predictive model which has shown, over several catamans not just Kato II, to be accurate. We will get much better results than your made up values. And we are getting the Eniquest 16kW DC Genset because it is a helluva unit for the weight and cost.


This raises the question of what Kato's performance would be should it be equipped with a generator rated to 15Kw. Hard to say but interpolating these results probably about 8.5kn less the one knot for loading so 7.5Kn. Translated to the FF this would be around 5.5Kn.Kato II gets 7 knots using 4kW to each 15kW motor, and we will get 8kW to each motor.FF50 is 15Lwl, cruising displacement 12.5 Ton, Lwl/Bh is 12.5:1
What will our speed be in flat water on the genset, Chris?


Further, it appears from all of the data that Claude has provided, (as well as previous data for Oram 44C that OV 15Kw translates to 30KW diesels. Indeed see the last couple of posts. I am somewhat sceptical of this data and as I said previously I suspect the equivalence number is around 25Kw.I know you don't believe anything I say because I am a "zealot" without any respect for the scientific method ( despite my background) but believe this. Claude has a massive amunt of data on EP from actual boat installations gathered over many years. If he says an Oram 44 get 6.5 knots with a 4kW electric and the same speed with a 9.9HP Yamaha, it is because he has measured it several times on several boats.
But again, ask him if you actually want to know what is real.



This would mean that SD15 EP is definitely not applicable to production boats as the performance would not be adequate and certainly explains the OV marketing strategy of targeting very quick large cats and smaller monos. Having said that it seems like a very good product. Once hopes that in the fullness of time they will introduce a 30KW model with 30Kw batteries and 20-30Kw generator. I would think this would have to be priced below U$100K for it to gain traction.

This remains to be seen. There are Leopard 40 or 44 installation with happy owner. But I understand what you are saying re heavy fat boats, it's not ideal. But so be it. We are trying to find a very acceptable balance between Gunboats and Lagoons with the FreeFlow, so we'll see how it goes.

/QUOTE]
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