Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 20-09-2016, 09:22   #106
Marine Service Provider

Join Date: May 2012
Location: New Orleans
Boat: We have a problem... A serious addiction issue.
Posts: 3,940
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by exMaggieDrum View Post
I have always wondered if pushing a cat with only one engine is less efficient since rudder would have to be used to counteract the push to one side or the other. I'm sure it must some but not sure how that compares to the savings of only one motor running. Talking about long distance offshore here.
A cat with just one engine one is going to be slightly less efficient that a cat with the prop down the center line, but it's a pretty trivial amount. Probably just the drag induced by 1-3 degrees of rudder applied. Not zero, but not a whole lot either.

The goal with a well designed diesel is to have it operate at around 75% of max load. This is the fuel efficency peak in kw/h/grams fuel.

So let's assume our cruising cat is operating one engine at 75% max load and is making 6kn. If we crank up the other engine and set it to the same rpm you would expect the boat to now be doing around 9kn (rule of thumb... Double the HP increase speed by 50%).

But what happens if we turn on both engines BUT lower the rpm to maintain the same speed of 6kn... It's easy enough to do, but fuel efficency drops by about 10% PER ENGINE. The net result is an increase in fuel burn of about 20% total. See the right hand fuel burn graph below (dropping from 75% load to 37.5% load).

It would take a lot of rudder deflection to make up for all that excess fuel burn.

As a note, this ignores two things

1) ancillary systems like alternators and pumps that take up some engine power. Adding these in makes running one engine more efficent.
2) it also assumes that the boat is operating at <75% of hull speed. Why for a cruising cat is almost guaranteed.
Attached Thumbnails
Click image for larger version

Name:	image.png
Views:	57
Size:	125.1 KB
ID:	131457  
__________________

__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.
Stumble is offline   Reply With Quote
Old 20-09-2016, 09:42   #107
Registered User

Join Date: Apr 2016
Posts: 110
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Stumble View Post
A cat with just one engine one is going to be slightly less efficient that a cat with the prop down the center line, but it's a pretty trivial amount. Probably just the drag induced by 1-3 degrees of rudder applied. Not zero, but not a whole lot either.

The goal with a well designed diesel is to have it operate at around 75% of max load. This is the fuel efficency peak in kw/h/grams fuel.

So let's assume our cruising cat is operating one engine at 75% max load and is making 6kn. If we crank up the other engine and set it to the same rpm you would expect the boat to now be doing around 9kn (rule of thumb... Double the HP increase speed by 50%).

But what happens if we turn on both engines BUT lower the rpm to maintain the same speed of 6kn... It's easy enough to do, but fuel efficency drops by about 10% PER ENGINE. The net result is an increase in fuel burn of about 20% total. See the right hand fuel burn graph below (dropping from 75% load to 37.5% load).

It would take a lot of rudder deflection to make up for all that excess fuel burn.

As a note, this ignores two things

1) ancillary systems like alternators and pumps that take up some engine power. Adding these in makes running one engine more efficent.
2) it also assumes that the boat is operating at <75% of hull speed. Why for a cruising cat is almost guaranteed.
So based on this information, once one gets beyond the mental uneasiness of asymmetrical power (electric on one side and diesel on the other), perhaps that is the best of both worlds???
__________________

__________________
SDChristian is online now   Reply With Quote
Old 20-09-2016, 10:22   #108
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Oceanvolt Hybrid Motor

One of the most attractive aspects of sailing is the lack of engine noise. Simplicity is another but that starts slipping out the window as boats get larger.

Cost is a major factor for all but the financially elite and $ per mile keeps many a fine vessel tied to the dock or forever on the drawing board.

Electrically propelled ships have been around for many years. They are not simple or cheap. The diesel gen sets make plenty of noise.

The perfect hydrogen generator may be perfected tomorrow. Solar radiation has enormous potential.

Who knows? A sweet potato may power communities someday.

None of my research indicates that electric propulsion is a viable option for my sailboat and I made a comfortable living off of knowing a bit about electricity.

Build a better mouse trap and the world will beat a path to your door, is an old and accurate saying. Easy to understand. I would not mind following a well worn path to an aux engine but have no time for smoke and mirrors.
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 20-09-2016, 11:55   #109
Marine Service Provider

Join Date: May 2012
Location: New Orleans
Boat: We have a problem... A serious addiction issue.
Posts: 3,940
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by SDChristian View Post
So based on this information, once one gets beyond the mental uneasiness of asymmetrical power (electric on one side and diesel on the other), perhaps that is the best of both worlds???
Maybe, but not really in my world for two reasons...

1) the time when you really need both engines on is for low speed maneuverability. Inside an anchorage, or in a marine or threading your way up a narrow channel. In these circumstances you need the second motor on anyway, so you would have one electric motor, and one diesel motor going... It's going to be very difficult to rev match the props when the throttles are so different.

2) What happens when you need a lot of power a very small percentage of the time?

Generally speeds and efficiency are assuming flat water, no wind, a clean bottom, and lightly loaded. But what happens when you are dragging anchor in a 50kn squall with a bottom that was last done 18 months ago, and into a 2kn surface current wth 6' waves? This is a rare but realistic situation in my world, and the answer is enough HP at the prop to make headway even under less than ideal circumstances. This requirement can't be met without a large EP motor and a generator sized to match... But I don't think I want to rely on a large generator that never gets turned on to save my boat in a bad situation.

The only way I could see an electric on one side and a diesel on the other is if the size of the diesel were increased to make up for the missing HP on the other side and the EP was just for manuvering. The problem here is that then when running at our nominal 6kn you are outside the efficency band of the motor. Worse, you would need a larger prop (or different pitch) to apply all that HP when you really need it. This kills your efficency at all other speeds.
__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.
Stumble is offline   Reply With Quote
Old 20-09-2016, 12:53   #110
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,374
Images: 69
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by GaryJones View Post
This is what you are saying and it is totally correct:
You are sailing at speed x (let's say 15 knots -- you do have a nice fast cat)
You turn on regeneration and the friction causes you to reduce speed to 14 knots.
Then either immediately using the other engine or at another time when you are doing 14 knots you use the same power drawn at the same rate to get you back to 15 knots.

As you rightly point out this is only possible in an ideal world with zero losses and hence not happening.

But this isn't what Stumble is saying.

Engine power to boat speed on a boat isn't linear.
Install 2x 5hp engines on your fast cat and run at full throttle you'll probably get 5 knots.
Install 2x 10hp engines and you'll probably get 7 knots.
Install 2x 20hp and 9 knots.
Install 2x 40hp and 10 knots.
You got me thinking. As it happens, a lot of different engines have been used on our sisterships.

2 x 10 gets 7.5 kts.
2 x 20 gets 9.5 kts.
2 x 25 gets 10.5 kts
1 x 60 got 12 kts.

It's actually surprisingly linear.

But I do see your point. However the ability to, in light wind, use power stored when sailing fast is going to be limited by the size of the battery bank. And any useful sized battery bank is going to impact on sailing performance...
__________________
"You CANNOT be serious!"


John McEnroe
44'cruisingcat is offline   Reply With Quote
Old 20-09-2016, 13:00   #111
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,374
Images: 69
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by exMaggieDrum View Post
I have always wondered if pushing a cat with only one engine is less efficient since rudder would have to be used to counteract the push to one side or the other. I'm sure it must some but not sure how that compares to the savings of only one motor running. Talking about long distance offshore here.
It doesn't take much rudder. On our boat usually 1 - 2 degrees. Our most fuel efficient way to motor is with one engine and fairly slowly.
__________________
"You CANNOT be serious!"


John McEnroe
44'cruisingcat is offline   Reply With Quote
Old 20-09-2016, 15:34   #112
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,516
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Stumble View Post
1) the time when you really need both engines on is for low speed maneuverability. Inside an anchorage, or in a marine or threading your way up a narrow channel. In these circumstances you need the second motor on anyway, so you would have one electric motor, and one diesel motor going... It's going to be very difficult to rev match the props when the throttles are so different.
This would be a biggy. The completely different torque characteristics of the two types of engine ( ) would make balancing thrusts when manouvering a real PITA.
__________________
StuM is offline   Reply With Quote
Old 20-09-2016, 15:43   #113
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,516
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Stumble View Post
So let's assume our cruising cat is operating one engine at 75% max load and is making 6kn. If we crank up the other engine and set it to the same rpm you would expect the boat to now be doing around 9kn (rule of thumb... Double the HP increase speed by 50%).

But what happens if we turn on both engines BUT lower the rpm to maintain the same speed of 6kn... It's easy enough to do, but fuel efficency drops by about 10% PER ENGINE. The net result is an increase in fuel burn of about 20% total. See the right hand fuel burn graph below (dropping from 75% load to 37.5% load).
Spot on. To put this into a real world example. For my boat:

One engine 2800rpm = 6.2 knots @ 3.7lph total
Both engines 2200rpm = 6.2 knots @ 4lph total
(and twice the engine hours so twice the maintenance cost )
__________________
StuM is offline   Reply With Quote
Old 20-09-2016, 16:25   #114
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Posts: 637
Re: Oceanvolt Hybrid Motor

exMaggieDrum,

Thanks for that summary of Calders article, very interesting. But a couple of your comments seemed off the mark from what I know about Nigel Calder.

"My thought - of course, Calder will have significant sponsorship from the vendors to promote them to his wide audience. "

I think Mr. Calder has established enough credibility and professionalism in the industry to warrant some respect. Questioning his credibility by inferring he is "on the take" from vendors to give a good review, says more about your cynicism than his ethics.

Also, he has "ripped out a few systems in the past" because his boat is a test bed for electric propulsion and he has tried many, many motors and other components of EP. He has written extensively on EP for several years, in case you were not aware.
__________________
BigBeakie is offline   Reply With Quote
Old 20-09-2016, 16:30   #115
Marine Service Provider

Join Date: May 2012
Location: New Orleans
Boat: We have a problem... A serious addiction issue.
Posts: 3,940
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by BigBeakie View Post
exMaggieDrum,

Thanks for that summary of Calders article, very interesting. But a couple of your comments seemed off the mark from what I know about Nigel Calder.

"My thought - of course, Calder will have significant sponsorship from the vendors to promote them to his wide audience. "

I think Mr. Calder has established enough credibility and professionalism in the industry to warrant some respect. Questioning his credibility by inferring he is "on the take" from vendors to give a good review, says more about your cynicism than his ethics.

Also, he has "ripped out a few systems in the past" because his boat is a test bed for electric propulsion and he has tried many, many motors and other components of EP. He has written extensively on EP for several years, in case you were not aware.
Calder also headed up the EU sponsored hybrid drive research project. I have zero doubt about his facts.

There is a legitimate debate about what the model usage profile should look like. How many hours at what speed, range require, etc. where I would disagree with him, but that's just a priority issue not one of honesty.
__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.
Stumble is offline   Reply With Quote
Old 20-09-2016, 17:50   #116
Registered User
 
leftbrainstuff's Avatar

Join Date: May 2011
Location: San Francisco and Australia
Boat: Liberty 458
Posts: 1,973
Re: Oceanvolt Hybrid Motor

The energy density of diesel is significantly more than a magnitude better than lion batteries.

No matter how you spec or package your hybrid / elec drive the math kills it for range and recharge time.

Arguing about fuel consumption variances is insignificant.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
__________________
leftbrainstuff is offline   Reply With Quote
Old 21-09-2016, 03:10   #117
Registered User

Join Date: Aug 2016
Posts: 4
Re: Oceanvolt Hybrid Motor

We're busy constructing two Schionnings that are getting full oceanvolt shaft driven systems, a Gforce 15C and a moulded bilge Arrow 1360. The conservative performance numbers we've been given for the OV systems are actually quite good and they are based on lower hull beam to length ratios. Its true that there is not much weight saving compared to the same boat using twin diesels, provided the diesel boat also has no genset. If she has a genset with her diesels then the OV system is lighter by approx the weight of the genset, so 160 to 220 kg. In the OV setup though the weight can be far better distributed as the shaft drive units only weigh around 28kg each.
I do think that these systems in their current form are better suited to the lighter, more easily driven hull forms found in the performance cat sector. We also have a shaft drive twin diesel GForce 15C in the shed, so we'll be able to directly compare the two propulsion systems between the exact same boats, both of which are pretty slippery.
Ash D
__________________
Northstarmulti is offline   Reply With Quote
Old 21-09-2016, 03:16   #118
Registered User

Join Date: Aug 2016
Posts: 4
Re: Oceanvolt Hybrid Motor

Forgot to mention that my weight comparison is based on lighter diesels in the 30-40 hp range (yanmar 3ym30 and Nanni 38hp). If using Yanmar 45hp (which is very heavy @ 220+ kg) then the OV is approx another 140+ kg lighter.
__________________
Northstarmulti is offline   Reply With Quote
Old 21-09-2016, 03:26   #119
Registered User

Join Date: Mar 2016
Location: London
Boat: Dreaming
Posts: 25
Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Northstarmulti View Post
Forgot to mention that my weight comparison is based on lighter diesels in the 30-40 hp range (yanmar 3ym30 and Nanni 38hp). If using Yanmar 45hp (which is very heavy @ 220+ kg) then the OV is approx another 140+ kg lighter.
Hey Ash,

I have been following your progress on facebook with these builds for a while. They are really starting to take shape.

If I am not mistaken, the OceanVolt system you are installing is 2x 8.3kW engines? Do you feel this is going to be enough to replace the Yanmar / Nanni you are putting in her sistership? I guess they were selected as they are the largest shaft drive model that OceanVolt sell?

What size generator are you installing to run with the electric engines?
What size battery bank?

I am really looking forward to seeing the whole thing complete and in the water. Exciting times!

Gary
__________________
GaryJones is offline   Reply With Quote
Old 21-09-2016, 04:50   #120
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: Oceanvolt Hybrid Motor

http://oceanvolt.com/

Am able to access various distributor sites but not OV.
__________________

__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Reply

Tags
motor

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Toyama Hybrid Batteries BlueSovereign Electrical: Batteries, Generators & Solar 4 29-01-2014 14:37
For Sale: '07 Lagoon 420 Hybrid Catamaran 250,000 Octopus Classifieds Archive 9 08-11-2009 08:03
Hybrid vs Diesel - Pros and Cons capcook Engines and Propulsion Systems 17 10-06-2009 14:49
Hybrid Engines libellula Product or Service Reviews & Evaluations 78 12-09-2008 19:34
diesel/electric hybrid sailorboy1 Electrical: Batteries, Generators & Solar 91 18-06-2008 18:03



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:59.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.