Cruisers Forum
 


Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 30-05-2018, 05:12   #61
Registered User

Join Date: Apr 2013
Posts: 11,002
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by Corvidae View Post
Fun little thread going on here. Since I'm about to convert my boat to electric tomorrow, it should be fun to see how it pans out in reality. It's not the usual use case though, seeing as I'll be running dual 10kw motors to replace the twin diesels. So in my case I'll be going from 3 down to the 1 diesel in the 13kw generator. So a lot of moving parts are going away, and being replaced by almost their weight in batteries. 200ah per motor, with room to double that on each side, plus the range extension of the generator. Given the latest quotes on replacement engines in Ft. Lauderdale, it's also costing me about $3k less than diesel replacements, including upsizing the generator.

It should be interesting in that the original diesels were way more power than the boat really needed. One motor at less than half throttle was easily able to maintain 6.5 knots with twice that in head winds. The electrics will have to work considerably harder to match that, but should be up to the task. The real questions are going to come down to longevity and range. I'll check back in after I've had a chance to compare.
Just curious if you priced up a pair of 10kw diesel propulsion motors and a smaller 5-6kw generator to cover house loads.

Is most of your savings really due to drastically lower overall HP you are putting in since the boat comes with motors that are 5 times the output of what you are replacing them with?
valhalla360 is offline   Reply With Quote
Old 30-05-2018, 05:19   #62
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by Dockhead View Post
Well, I think there are two issues with electric propulsion.

One is how do you store the energy.

The other is how do you produce it.
Exactly. All the issues with range, power, cost, etc distill down to these two basic points.

Current technology for energy storage, to come even close to matching that of a tank full of fossil fuel, will entail lots of weight and high cost.

Producing the energy will require a generator or lots of solar or frequent stops to plug in. The first you're back to having an engine on board eliminating one of the goals of many electric power fans.

The second, with current panel efficiencies requires more sq ft than is available on most boats.

The last one the issues are obvious.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
skipmac is offline   Reply With Quote
Old 30-05-2018, 05:41   #63
Registered User

Join Date: Aug 2009
Location: oriental
Boat: crowther trimaran 33
Posts: 4,414
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by valhalla360 View Post
Give us the assumptions as your numbers don't add up.

10kw of power (even under good conditions would presume a small boat that wouldn't have room for 1000w of solar.
I had a motor that used 150 watts to push me 2 knots. I used to have 850 watts solar on my boat.

Your assumption of needing 10kw and not being able to have 1000w is off by a factor of about 60 times.

I would combine this 2 knot speed with 2-3 knot tidal currents in the south island of new zealand, and motor all night in winter on golfcart batteries making 4-5 knots


Now I realize electric and solar works fine, but it's boring, so I got rid of all that. It's more efficient to use a sculling oar, and also a lot of other advantages. For larger boats, try long oars with sliding seats.

All these arguments about "getting off the dock" or "motoring against wind" are pointless. If you are a good sailor you can sail on and off the dock and you tack against the wind. Every time someone claims otherwise for whatever reason, I found out they were wrong.
seandepagnier is offline   Reply With Quote
Old 30-05-2018, 06:03   #64
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43 and OPBs
Posts: 12,888
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by boat_alexandra View Post
I would combine this 2 knot speed with 2-3 knot tidal currents in the south island of new zealand, and motor all night in winter on golfcart batteries making 4-5 knots

2-3 knots tidal current in one direction all night in winter in the South Island (14 - 15 hours?)? Where would that be?


Lucky you didn't need to go the other way
StuM is offline   Reply With Quote
Old 30-05-2018, 06:41   #65
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by boat_alexandra View Post
I had a motor that used 150 watts to push me 2 knots.
This is for a 27' boat in favorable conditions. Extrapolate this to a 37' boat with current or headwinds and you will need kWatts to get anywhere at all.

Quote:
Originally Posted by boat_alexandra View Post
I used to have 850 watts solar on my boat.
That 850 Watts would need 45-50 sq ft of panels. Divided up on a boat with typical size panels that would be 15-20 ft of panels 2.5-3' wide. That's a lot of room even on a larger boat. I don't know where I would put that much on my 42' boat unless I built a large, hard topped cockpit cover which isn't an option.

Quote:
Originally Posted by boat_alexandra View Post
Your assumption of needing 10kw and not being able to have 1000w is off by a factor of about 60 times.
Not off by a factor of 60 if you consider even a slightly larger boat and anything but a dead calm or a following wind/current.

Quote:
Originally Posted by boat_alexandra View Post
I would combine this 2 knot speed with 2-3 knot tidal currents in the south island of new zealand, and motor all night in winter on golfcart batteries making 4-5 knots
Based on this logic I can take a rubber raft off the coast of Florida with no motor or sails and follow the Gulf Stream all the way to Europe at about 1.5 kts. However, one cannot always bank on a favorable current and that really isn't a realistic part of calculating speed and range with electric.

Quote:
Originally Posted by boat_alexandra View Post
All these arguments about "getting off the dock" or "motoring against wind" are pointless. If you are a good sailor you can sail on and off the dock and you tack against the wind. Every time someone claims otherwise for whatever reason, I found out they were wrong.
How well does sailing off the dock work when you have a 10-12 kt wind or a 2-3 kt current pushing up against the dock?

There is no denying for your boat and your boating style that electric or no power at all is workable. The argument is whether or not electric is practical for larger boats that want or need to motor more than a few miles.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
skipmac is offline   Reply With Quote
Old 30-05-2018, 07:06   #66
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
Re: Electric Drive: Who uses it?

I have followed every electric boat thread for years on this and other forums. In that time I have read adamant claims for what electric can do by a number of proponents who argued against the facts and calculations posted by numerous others with technical expertise. Many of the advocates left the threads angry that the naysayers were not listening and went off to build their boat and prove the naysayers wrong. To date I don't recall a single one ever returning to report their success.

Bottom line, for all practical purposes IE not overly expensive, not overly complex and available commercially, electric can be a very good option for boats that need power only to reach open water and/or for small boats that don't need to motor long distances in variable conditions.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
skipmac is offline   Reply With Quote
Old 30-05-2018, 07:13   #67
Registered User

Join Date: Mar 2017
Location: Indian Harbour Beach
Boat: Gallart 13.50 MS
Posts: 131
Re: Electric Drive: Who uses it?

The engines, Volvo Penta MD21A, were rated at 75 hp at 4500 rpm, 50 hp at 3000 rpm and reached peak torque at 95 ft.lbs at 2000 rpm. One motor was able to keep the boat at 6.5 knots at about 900 rpm against steady headwinds with no problem. Both engines were governor limited to 1700 rpm which put the boat at 8.5 knots (hull speed) in just about any conditions. There was a lot more engine there than the boat was using. Especially with the 22 inch props it's running.

With the electrics I expect the batteries to last about 20-40 minutes at full throttle, at near hull speed, or a couple hours at 5 knots. The generator should also be able to push a continuous 5 knots in clear seas. At least that's what the engineers tell me.

The price comparison was for a pair of 40hp Yanmars was ~$13.5k with two year warranties. There's nothing available at the same size without adding in freight shipping. I found smaller diesels at a lower price, but at that point I'd be getting diesels for about the same price as electrics. And at equal price points, I'd go electric every time. What makes the electrics work out to be cheaper is also that I'm assembling kit parts rather than buying a complete unit, and I'm going with AGM rather than LiON batteries. Extra cost on the diesel is that I would have to pay someone to install them. I carried the electric motor on board yesterday myself, for free.

The trade off overall, is that instead of a motor sailor that would go wherever, whenever, almost entirely regardless of the weather, it's going to be a sailboat that has to pick and choose good tide and weather windows. And given the use I'm intending, that's just fine. The only reason I went with a MS is the space, the motoring ability wasn't important. Having two motors just negated the need for a bow thruster more than it gave any navigational advantage. Honestly I expect the only time I'll be using full throttle is trying to escape from shoals.
Corvidae is offline   Reply With Quote
Old 30-05-2018, 07:32   #68
Registered User

Join Date: Apr 2013
Posts: 11,002
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by boat_alexandra View Post
I had a motor that used 150 watts to push me 2 knots. I used to have 850 watts solar on my boat.

Your assumption of needing 10kw and not being able to have 1000w is off by a factor of about 60 times.

I would combine this 2 knot speed with 2-3 knot tidal currents in the south island of new zealand, and motor all night in winter on golfcart batteries making 4-5 knots


Now I realize electric and solar works fine, but it's boring, so I got rid of all that. It's more efficient to use a sculling oar, and also a lot of other advantages. For larger boats, try long oars with sliding seats.

All these arguments about "getting off the dock" or "motoring against wind" are pointless. If you are a good sailor you can sail on and off the dock and you tack against the wind. Every time someone claims otherwise for whatever reason, I found out they were wrong.
Might want to go back and look at the boat figures he came back with.

I believe you are talking about a drastically smaller boat going 50% slower than the already very slow addumptions. I also assume the 2kts at 150w was in ideal conditions.

If you want the challenge of living like the sailors from the 1800's more power to you but then it's not really relevant to this topic.
valhalla360 is offline   Reply With Quote
Old 30-05-2018, 07:54   #69
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Electric Drive: Who uses it?

All you guys arguing against Boat Alexandra I have a few thoughts for you.

1. He isn’t arguing theory, he actually did it.
2. He abandoned electric propulsion and went with a sculling oar, and again, he isn’t talking theory here, he is actually doing it. My assumption is he did so because the sculling oar works better for him.
3. Everywhere he goes, he does so by sailing or sculling, to include some parts of the ICW if memory serves.

Who was it who said that the people who say something can’t be done, ought not get in the way of people doing it?

Not many would like electric propulsion than I, I despise the noisy Diesel engine in my Salon, would much prefer a little whiff of an electric motor. But I’m not willing to put up with the shortcomings. I do think a small outboard would accomplish the same thing with a fraction of the expense and work.
Maybe my children will get to have one
a64pilot is offline   Reply With Quote
Old 30-05-2018, 08:01   #70
Registered User

Join Date: Apr 2013
Posts: 11,002
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by skipmac View Post
I have followed every electric boat thread for years on this and other forums. In that time I have read adamant claims for what electric can do by a number of proponents who argued against the facts and calculations posted by numerous others with technical expertise. Many of the advocates left the threads angry that the naysayers were not listening and went off to build their boat and prove the naysayers wrong. To date I don't recall a single one ever returning to report their success.
Growleymonster has done it and posted but he doesn't go on about magic electric HP. In his posts he readily admits both the pros and the cons and for the typical cruiser there are substantial trade offs.
valhalla360 is offline   Reply With Quote
Old 30-05-2018, 08:12   #71
Registered User
 
Colin A's Avatar

Join Date: Mar 2013
Location: East of the river CT
Boat: Oday Mariner 19 , Four Winns Marquis 16 OB, Kingfisher III
Posts: 657
Send a message via Skype™ to Colin A
Re: Electric Drive: Who uses it?

There are a few boats that actually use solar to provide a decent bit of propulsion but practicality is not really there.
https://en.wikipedia.org/wiki/T%C3%BBranor_PlanetSolar
https://www.powerandmotoryacht.com/b...dse-12m-hybrid


The Tesla battery packs and other battery development help with the weight and space issue but it's still a big issue.



As mentioned before some of the effects that make electric cars more efficient don;t exist in boats (regen braking and low power consumption at highway cruising speed)


Nigel Calder did a bunch of testing on this 6-7 years ago. For cruising boats he came away with the concept that strictly for propulsion hybrid (diesel gen electric drive) boats were not that practical, but in theory a parralel hybrid system that also charged the house loads might be.

https://cordis.europa.eu/result/rcn/57677_en.html




The other advantage of electric to me is all the different sources available, solar wind, dockside gen. Of course I don't think it's very practical yet for most applications.
__________________
mysite: Colinism.com
Colin A is offline   Reply With Quote
Old 30-05-2018, 08:22   #72
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by valhalla360 View Post
Growleymonster has done it and posted but he doesn't go on about magic electric HP. In his posts he readily admits both the pros and the cons and for the typical cruiser there are substantial trade offs.
No argument at all.

Since I don't seem to be clear on my position re electric drive.

1. It can be a very good option.

2. It can offer a number of benefits.

3. I am personally interested in going electric.

4. A number of forum members have very successfully gone electric, most prominently Boat Alexandra, whose sailing accomplishments I respect and admire. There are also at least three others I can think of that have successfully gone electric; Growley Monster, Kalinowski and mbianka.

BUT

I have yet to see any electric system that will replace diesel for a similar cost with comparable range and comparable power. Until battery technology improves I don't think it is possible.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
skipmac is offline   Reply With Quote
Old 30-05-2018, 08:54   #73
Registered User

Join Date: Jul 2011
Location: Maryland, Right Now
Boat: Morgan 452
Posts: 150
Re: Electric Drive: Who uses it?

At the risk of going WAY OFF TOPIC, I would point out that there were "boats" that used a hybrid electric/diesel system going back more than 100 years. They were submarines and used a diesel generator on the surface, batteries while submerged to get places.

Similarly, there are (I believe) catamarans that use a diesel in the bow area of one of the amas and electric motors in the stern of the amas for propulsion.

I cycle back to my original point - if the boat is designed for electric propulsion from the get-go, it can be a very effective (not necessarily efficient) propulsion system. The devil is in the details.
CaptFrankM is offline   Reply With Quote
Old 30-05-2018, 09:24   #74
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Electric Drive: Who uses it?

There was a hybrid Cat, my understanding it didn’t do so well.
My bet was the purchasers had unrealistic expectations, then couple that with not many, if any people out there knew how to maintain it, or repair it, and you have a mess.

Porsche for example years ago built what I thought was a very good airplane engine, even went through the hassles to certify it, and shelved the thing. Largely due I believe to not many knowing how or wanting to work on it, they only wanted to work on the same old engines they always had.
a64pilot is offline   Reply With Quote
Old 30-05-2018, 10:30   #75
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
Re: Electric Drive: Who uses it?

Quote:
Originally Posted by Corvidae View Post
The engines, Volvo Penta MD21A, were rated at 75 hp at 4500 rpm, 50 hp at 3000 rpm and reached peak torque at 95 ft.lbs at 2000 rpm. One motor was able to keep the boat at 6.5 knots at about 900 rpm against steady headwinds with no problem. Both engines were governor limited to 1700 rpm which put the boat at 8.5 knots (hull speed) in just about any conditions. There was a lot more engine there than the boat was using. Especially with the 22 inch props it's running.
That definitely sounds like way, way more engine than that boat would ever need. In fact, as your experience indicated, one of those would be plenty of power. Was this some kind of custom installation? How come so much power?

Quote:
Originally Posted by Corvidae View Post
With the electrics I expect the batteries to last about 20-40 minutes at full throttle, at near hull speed, or a couple hours at 5 knots. The generator should also be able to push a continuous 5 knots in clear seas. At least that's what the engineers tell me.
Without having all the specs in front of me that sounds very realistic and achievable.

Quote:
Originally Posted by Corvidae View Post
The price comparison was for a pair of 40hp Yanmars was ~$13.5k with two year warranties. There's nothing available at the same size without adding in freight shipping. I found smaller diesels at a lower price, but at that point I'd be getting diesels for about the same price as electrics. And at equal price points, I'd go electric every time. What makes the electrics work out to be cheaper is also that I'm assembling kit parts rather than buying a complete unit, and I'm going with AGM rather than LiON batteries. Extra cost on the diesel is that I would have to pay someone to install them. I carried the electric motor on board yesterday myself, for free.
This does explain some of the cost savings you mention. You're comparing 40 HP diesel engines to 13 HP electric motors. Kind of apples and oranges. If you compared 40 HP diesels to 30 HP electrics the difference I think would fall in favor of the diesel. Also, I assume there will be some additional costs or personal labor in changing over the mounting for the electric.

I have to say though that 20 kW (about 26 HP) does seem to be underpowered for your boat and may occasionally leave you wanting. However I recall some of the electric motors I researched spec'd a much higher power output in bursts and somewhat higher for short term use. That may answer for maneuvering.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
skipmac is offline   Reply With Quote
Reply

Tags
electric

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Rudder Drive: Superb Electric Drive Innovation - Hanse 315 myocean Engines and Propulsion Systems 6 21-10-2016 06:05
One Thru-Hull - Many Uses? Tspringer Construction, Maintenance & Refit 6 13-06-2009 00:14
WD-40 and it's various uses mmckee1952 Flotsam & Sailing Miscellany 36 23-02-2009 23:57
Ideas for Good, Uses Outboard russellmania Engines and Propulsion Systems 2 15-05-2008 17:23
Pactor Modem Uses Leighton Marine Electronics 3 05-09-2007 08:59

Advertise Here


All times are GMT -7. The time now is 13:15.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.