Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 29-08-2015, 00:08   #1
Registered User

Join Date: Nov 2014
Posts: 17
Solar powered boat

About year ago I've posted a thread here (http://www.cruisersforum.com/forums/f14/solar-battery-load-perfect-balance-136734-2.html) trying to share my experience with others. It was about solar-powered electric propulsion. The question was simple: is it possible to move a vessel on sun-generated power for several hours?

Although the solar power issue seems to be extremely popular among cruisers, the disscussion was rather academic and not supported by field-tested systems. Perhaps because nobody else was ever considering such project viable for many good reasons. Tempted by the challenge, I spent last year developing an experimental solar system to push my 3-ton house boat along the shores of spectacular mountain lakes in Canadian Rockies.

After 6 weeks long voyage this summer I'm very cautious - if not sceptical - about the idea in general. Yes, it is possible to build a vessel powered exclusively by the solar energy, but it will look like anything but the boat. Like the aircraft carrier, perhaps. Hybrid power plants may represents more realistic approach, i.e. diesel generator/PV panels/battery system.

The main challenge is to strike the practical balance between sun energy harvesting surface and the functionality of the vessel. Another words: to find this sweet spot when installed solar panels are delivering just the right amount of energy and the boat didn't loose it's appeal completely.

Let's do some rough calculations with minimalistic approach. Smallest outboard gasoline motors, able to push 2-3 ton sail boat with few knots on calm waters, can deliver some 2HP of power. This translates to 1.5kW, within the range of Torqeedo 2.0 Cruise electric outboard. To run this motor at half throttle 1kW of power need to be supplied, and 24V/200Ah battery will be emptied very fast. Now, if you support the battery by inserting solid stream of sun-harvested energy, the battery discharge current drops dramatically, making much longer trips possible before lo-batt shut off.

The problem lies within limitations of PV technology. Certain average output can be achiewed with certain area of panels, to put it simply. This is usually not a big issue for megawatt installations in Arizona desert or even for off-grid system on the roof of your cottage. But when you need to power an electric vehicle - car, boat, golf cart - the available harvesting surface is usually way too small to render practical, self-sustainable system. To harvest - say - average 1kW of real life output one must install at least twice that much of total Pmax! Assuming that an typical cruiser may offer enough space to install perhaps 300, unlikely 500W of Pmax worthy PV panels, this is dead end already...

Because of limited sun-harvesting area, electric motor must rely mainly on the capacity of on-board battery bank. This is yet another obstacle for the idea of any electric vehicle, because batteries are heavy and must be re-charged. While filling your gas tank may take minutes, battery re-charging is a matter of hours. The most powerfull, commercially available electric motors may deliver 40, even 80 HP, but the boat must carry hundreds kilograms of batteries, good for a hour long sunday afternoon trip around local pond.

When it comes to shop for an electric motor for your boat, the choice is limited actually to one brand, Germany made Torqeedo that is. Torqeedo motors filled self-created marketing niche somewhere around 2005, when strict regulations prohibit the use of gasoline fueled engines on many European waters. In such scenario an average user will consider the electric propulsion as a poor substitute only. When special projects are in focus, however, the electric motor may be much more seriously considered than just as a mediocre equivalent of gas or diesel engine.

I've been able to taylor well balanced system, compromising the look and functionality of my vessel to a reasonable degree. One must realize, however, that what was tested and prooved on fresh waters and with narrowly specialized boat doesn't necessarily applies to all vessels. I hope the numbers mentioned below will be a good starting point for consideration.

So, this is basically an oversized pontoon boat on two 30" diameter tubes and 22' x 8' deck, of approx.2750 L replacement. Not particularly slim or elegant, she was custom designed and build to undergo extended cruising on remote mountain lakes in British Columbia. The supplies there are limited, therefore self-sufficiency was the main culprit and the solar power was a viable option. Mercury 60HP Big Foot engine supply the main propelling force, two Torqeedo Cruise 2.0 motors were choosen for alternative electric propulsion. Although main engine will deliver about 11 knots at full throttle, 3-4 knots I'm considering just fine with electric motors, consuming roughly 1kW at this speed. Pushing the electric throttles full will drain 4kW, but the speed gain isn't really that dramatic or needed in this case.

Carefully tailored array of various PV panels consists 4 separate, independently controlled strings, 2 on each slope of cabin roof and awning. This is accomplished with 2 double channel MPPT chargers (Italian made Western WRM30) to eliminate conflicting current flows between shaded and exposed sides, and to handle different characteristics of panels. This configuration equals 534W of Pmax per side, 1.064kW total. To my amazement the system is able to deliver 650-700W in a good day with both sides exposed to sun equally. The same days at evenings (with one side shaded) 400-450W contribution was typical. In this scenario the 24V lead acid battery bank was delivering remaining 500W or less of power, not really much of abuse for 225Ah capacity. As a result, several hours of peacefull, steady drive against 5-10km/hr wind could render 50km long trip with enough battery energy left for overnight needs. The future replacement for bigger (and much lighter!) LiFePO battery will significantly improve the overall performance.

Personally I've found electric propulsion to be enjoyable almost as much as sailing with light breeze. No polution, no noise, long hours of joyfull ride on secluded, pristine lakes. It may be perfect for canal boating or barges, where speed is no issue and usually huge cabin offers large sun-harvesting surface. Recent developments on lightweight flexible solar panels, lithium batteries and efficient charge controllers may render really nice systems. On the other hand such installation is fairly complex, clumsy, heavy and prohibitevely expensive. Savings on fuel? The cost of suitable solar power plant will cover probably a decade of diesel supply for your Volvo!

To hammer another nail into the coffin of electric propulsion idea, consider the following fact. By comparison of net calorific values, fossil fuel carries roughly 100 times as much energy as mass equivalent of Lithium battery. Another words: 100kg weighting Lithium battery will hold the same amount of energy as 1kg of gasoline (12,200 kWh). Unbelievable, rediculous, but true.
Attached Thumbnails
Click image for larger version

Name:	boat 2015_lo_01.jpg
Views:	174
Size:	424.8 KB
ID:	108076   Click image for larger version

Name:	boat 2015_lo_02.jpg
Views:	145
Size:	441.8 KB
ID:	108077  

__________________

__________________
Matthew Dobrski is offline   Reply With Quote
Old 29-08-2015, 01:25   #2
Registered User
 
goat's Avatar

Join Date: Apr 2013
Location: Everywhere (Sea of Cortez right now)
Boat: PSC Orion 27
Posts: 1,098
Re: Solar powered boat

You need to make sails out of flexible solar panels so you can get double duty out of them. Use the batteries in the bottom of a monohull as ballast. Good luck and check back in next year.
Just kidding, thanks for the update Matthew.

goat

Sent from my SGH-I257M using Cruisers Sailing Forum mobile app
__________________

__________________
goat is offline   Reply With Quote
Old 29-08-2015, 06:37   #3
Registered User
 
ranger42c's Avatar

Join Date: Aug 2012
Location: Maryland, USA
Boat: 42' Sportfish
Posts: 2,984
Re: Solar powered boat

Elco also makes electric motors for boats.

-Chris
__________________
Selby Bay, South River, Chesapeake Bay, USA.
ranger42c is offline   Reply With Quote
Old 29-08-2015, 10:29   #4
Marine Service Provider

Join Date: May 2012
Location: New Orleans
Boat: We have a problem... A serious addiction issue.
Posts: 3,940
Re: Solar powered boat

It sounds like you hit the same wall everyone else does.

If it's any help your 100kg-1kg is actually a little pessimistic on solar. Not that it helps a lot, but I use 50-1 as a rule of thumb for FLA. The difference isn't from storage capacity, but it how each system uses the available power. When you calculate how much available power each system can access, without converting to heat or sound, or driving pumps, electric gets a little better. Still not enough to change the result for most people, but it is better.
__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.
Stumble is offline   Reply With Quote
Old 29-08-2015, 11:12   #5
Sponsoring Vendor
 
OceanPlanet's Avatar

Community Sponsor

Join Date: May 2009
Location: Woolwich, Maine
Boat: Sold it!
Posts: 401
Send a message via Skype™ to OceanPlanet
Re: Solar powered boat

Well done Matthew! Great report. Looks like fun cruising too.
__________________
Twice around was enough for me...
Now I just help others prep for ocean trips...
www.bruceschwab.com
OceanPlanet is online now   Reply With Quote
Old 29-08-2015, 12:10   #6
Registered User
 
Kokanee's Avatar

Join Date: Jan 2013
Location: Adelaide Australia
Boat: Cuddles 30ft Motor Sailer
Posts: 216
Re: Solar powered boat

Congratulations Matthew! on a realistic and successful approach to a solar powered boat. Technology is proceeding rapidly and the possible cruising range will be extended every year.

And what a wonderful place to cruise silently.
Which lake is your cruising ground? I was trying to pick it from the photo's but couldn't. I grew up and learned to sail on Kootenay Lake.
__________________
Kokanee is offline   Reply With Quote
Old 29-08-2015, 12:24   #7
Registered User

Join Date: Jul 2014
Posts: 324
Re: Solar powered boat

I suppose you you had to see for yourself


All the Best
__________________
Arthur Garfield is offline   Reply With Quote
Old 29-08-2015, 13:03   #8
Registered User

Join Date: Mar 2013
Location: sailing south
Boat: Ericson 35-2
Posts: 313
Re: Solar powered boat

I have 3 tons of ballast and a 25 gallon diesel tank on my boat, which gives me about 100 hours of running at economic speed. If that ballast was lithium batteries, I could have a comparable range.

I wonder, what makes this idea unfeasible (something must, since the idea is obvious, but nobody builds battery-ballasted boats).
__________________
RedHerring is online now   Reply With Quote
Old 29-08-2015, 16:13   #9
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,880
Images: 4
Re: Solar powered boat

Quote:
Originally Posted by RedHerring View Post
I have 3 tons of ballast and a 25 gallon diesel tank on my boat, which gives me about 100 hours of running at economic speed. If that ballast was lithium batteries, I could have a comparable range.

I wonder, what makes this idea unfeasible (something must, since the idea is obvious, but nobody builds battery-ballasted boats).
Lithium is lighter than lead, and way more expensive? And they don't like to get wet?

Actually, in my boat the (AGM lead) batteries are under the sole and on centerline, so they probably do count as ballast. Not as much as my lead keel though...
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 29-08-2015, 19:06   #10
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,056
Re: Solar powered boat

Quote:
Originally Posted by RedHerring View Post
I have 3 tons of ballast and a 25 gallon diesel tank on my boat, which gives me about 100 hours of running at economic speed. If that ballast was lithium batteries, I could have a comparable range.

I wonder, what makes this idea unfeasible (something must, since the idea is obvious, but nobody builds battery-ballasted boats).

Two things really,
Money, three tons of lithium batteris, I can't imagine the cost, other problems I feel could be overcome
Second is recharge time, even a large PV array would probably take weeks to full recharge three tons of Lithium battery.

Better I think to have a huge array, like he said make it look like an aircraft carrier and drive the motors pretty much directly, with enough battery bank to get through the night and a small generator to help out, and accept slow cruising.
It is physically possible of course, major drawback is economics.
Currently your motoring for less than $1 an hour, that is awful frugal in my book, and be tough to beat those numbers


Sent from my iPad using Cruisers Sailing Forum
__________________
a64pilot is offline   Reply With Quote
Old 29-08-2015, 21:29   #11
Registered User

Join Date: Nov 2014
Posts: 17
Re: Solar powered boat

Quote:
Originally Posted by Kokanee View Post
Which lake is your cruising ground? I was trying to pick it from the photo's but couldn't. I grew up and learned to sail on Kootenay Lake.
The pics were taken at Arrow Lake Narrows, close to a Burton village...
Oh yes, I've been cruising Kootenay Lake twice already, been on neighbor Arrow Lake (reservoir actually) several seasons, did famous Shuswap Lakes
also. But the most beautiful place in this region I've discovered this year: small Slocan Lake. Crystal-clear water, monumental Valhalla mountains in proximity, nice small communities around and reasonably controlled development. Pure joy.

Matthew.
__________________
Matthew Dobrski is offline   Reply With Quote
Old 29-08-2015, 22:49   #12
Registered User

Join Date: Nov 2014
Posts: 17
Re: Solar powered boat

Quote:
Originally Posted by ranger42c View Post
Elco also makes electric motors for boats.

-Chris
Thank you for the reminder! Indeed, Elco represents significant achievements on electric propulsion field as well. BTW, your reply forced me to re-visit company's website, where I've found an interesting article about the future of electric boating (http://www.elcomotoryachts.com/wp-co...April-2015.pdf).

The article very cleverly and convincingly paints an optimistic picture of electric boats. The optimism is driven by predictions on lithium-based battery technology development, assuming tenfold energy density increase within next decade or so. This may eliminate gasoline powered engines at the rate similar to digital photography revolution...

I'm far from questioning the efficiency and sufficiency of electric propulsion, however. The topic of my thread is about battery charging limitations, away from convenient power outlets at dock.

Matthew.
__________________
Matthew Dobrski is offline   Reply With Quote
Old 30-08-2015, 12:23   #13
Registered User
 
Kokanee's Avatar

Join Date: Jan 2013
Location: Adelaide Australia
Boat: Cuddles 30ft Motor Sailer
Posts: 216
Re: Solar powered boat

Quote:
Originally Posted by Matthew Dobrski View Post
The pics were taken at Arrow Lake Narrows, close to a Burton village...
Oh yes, I've been cruising Kootenay Lake twice already, been on neighbor Arrow Lake (reservoir actually) several seasons, did famous Shuswap Lakes
also. But the most beautiful place in this region I've discovered this year: small Slocan Lake. Crystal-clear water, monumental Valhalla mountains in proximity, nice small communities around and reasonably controlled development. Pure joy.

Matthew.
Yes, Slocan Lake is wonderful. Siverton & New Denver are lovely little towns.

"The topic of my thread is about battery charging limitations, away from convenient power outlets at dock."

Not many marinas to charge up at on most of most of those lakes. None at Slocan, as far as I know. Wind generation isn't a great option in those parts, as it is normally fairly calm in summer, although big blows do occur.

Possibly a dumb idea - but thinking a bit out of the box; have you thought about a lightweight, narrow hulled "trailer boat" covered in PV panels doubling you charging capacity. Possibly collapsible or inflatable for easier transport to the lake. You could either tow it behind your boat, or anchor it at a base location and let it charge; returning at the end of the day to a set of fully charged batteries.
Swap them out for another day's exploring.
__________________
Kokanee is offline   Reply With Quote
Old 30-08-2015, 22:06   #14
Registered User

Join Date: Nov 2014
Posts: 17
Re: Solar powered boat

Quote:
Originally Posted by Kokanee View Post
Possibly a dumb idea - but thinking a bit out of the box; have you thought about a lightweight, narrow hulled "trailer boat" covered in PV panels doubling you charging capacity. Possibly collapsible or inflatable for easier transport to the lake. You could either tow it behind your boat, or anchor it at a base location and let it charge; returning at the end of the day to a set of fully charged batteries.
Swap them out for another day's exploring.
Believe or not, I just start to like you ! See, my dear soul mate, I'm not THAT MUCH desperate to make my boat 100% green. Somehow I must control already insane amount of hassle and money involved. After all, I'm happy with what I've achieved so far, successfully creating so-called "parallel hybrid" propulsion system. This year I've made 300 miles trip around and burned maybe 5gal of gasoline...

Cheers,
Matthew
__________________
Matthew Dobrski is offline   Reply With Quote
Old 31-08-2015, 09:33   #15
Registered User
 
Kokanee's Avatar

Join Date: Jan 2013
Location: Adelaide Australia
Boat: Cuddles 30ft Motor Sailer
Posts: 216
Re: Solar powered boat

Yeah, I can understand drawing a line on the time and money invested. If it gets you out there on the water and back again; just enjoy it as it is.

I seriously considered going all electric when my old Volvo died last year, but after realistically costing things out, it was going to be triple the cost of re-powering with a new diesel if I wanted my desired cruising range. I decided I wasn't quite that green as well. (I might have gone double)
__________________

__________________
Kokanee is offline   Reply With Quote
Reply

Tags
solar

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
100% Solar-Powered Boat - How Would You Build it ? Isara Electrical: Batteries, Generators & Solar 17 13-08-2017 11:04
World's Largest Solar-Powered Boat TaoJones Cruising News & Events 1 07-03-2010 23:09
Powered USB Hub vs Powered USB Cables Bryan Kemler Monohull Sailboats 2 20-01-2010 16:24
solar 21 just about to be first solar/electric powered boat to cross atlantic schoonerdog Multihull Sailboats 2 07-02-2007 10:04



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 05:01.


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.