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Thread: 27 mile solar powered day trip

  1. #1
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    Default 27 mile solar powered day trip

    Since adding an electric outboard with solar charging to my row cruising Walkabout, I've been wanting to test performance on solar alone. The electric motor was intended to supplement rowing, extending my range, but it works better than planned and the 170 W solar panel output matches motor electrical consumption in full sun. Saturday was forecast to be a typical CA summer day in the Suisun Marsh, full sun and strong west wind. I plotted a loop down Suisun Slough, up Montezuma Slough, then back on Cutoff Slough. The plan was to use the motor only with no rowing, which almost succeeded...

    The battery had been left as charged at the finish of the Delta cruise. As I was setting up at the ramp in Suisun Harbor, the battery reached full charge in the 10 am morning sun. So I started out with a full 22 A-h charge on the 26 V LiFePO4 battery. Solar charge current started out at about 4 A at 10 am, increased to 5.5 A at 1-2 pm, then back to 4 A at 4 pm. Motor current of 4 to 5 A will drive the boat at 3.5 to 4 kts, so I adjusted motor current to match the charge current for most of the trip. If speed dropped below 3 kts on some of the straight upwind legs of the slough, I upped the current to 8 A for a few minutes.

    It was near low ebb when I started out, so I got some tidal boost at first, then opposing current for most of Suisun Slough. Current was favorable all the way up Montezuma Slough and neutral on Cutoff Slough. I did the usual tactics of hugging the shore for eddies in opposing current and tucking under the levees to avoid headwind when possible.

    This is my GPS track of the loop:
    Last edited by rgthom; 07-27-2021 at 03:35 PM.

  2. #2
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    Default Re: 27 mile solar powered day trip

    As you can see from the track, I did not make it all the way down Suisun Slough. After passing Hunter Cut the slough gets shallow for a short section. I have passed this way before, but this was a very low tide and I started grounding out. So I had to raise the motor and switch to rowing for a bit. The chart showed the slough getting deeper just past the turn, but I was well into where it should be deeper and it was even shallower. If you have seen the videos of Mudskippers out of the water this is what I looked like. A full stroke of the oars would turn up a pile of mud and move the boat a foot. I made a short video:



    Not knowing where it now got deep again I just turned and went out by Hunter Cut into Montezuma Slough, then out into Grizzly Bay that way. There was about 20 minutes of rowing, when the motor was off but the solar still charging the battery.

  3. #3
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    Default Re: 27 mile solar powered day trip

    An Egret was feeding on the shore of Grizzly Bay, I managed to catch him taking off:


  4. #4
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    Default Re: 27 mile solar powered day trip

    One more video, showing the solar electrics and the rope steering wheel. Mount Diablo is ahead.


  5. #5
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    Default Re: 27 mile solar powered day trip

    At the end of the trip I had covered 23.4 nm (27 miles) in 5:48, averaging 4 kts or 4.7 mph. I left the solar to charge while retrieving the boat, and the battery reached full charge again before I disconnected it. So I am going to claim this was a fully solar powered trip .
    A gas motor such as a Honda 2 hp might have been a little faster, but the Walkabout is a displacement hull and it would not be much different. I think sailing upwind in the narrow sloughs would have been very difficult. I do not see any sailboats in these channels except our band of hardy cruisers, and even they are motoring at times.
    My conclusion is that a small solar powered skiff is now a very viable option for displacement speed cruising in sunny areas, much to my own surprise. I could imagine scaling this up to a 1 kW motor, bigger battery and more solar panels on a bigger boat. Initial cost would be much higher than a gas motor, but for me the quiet, exhaust free operation could be worth it.

    -Rick

  6. #6
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    Default Re: 27 mile solar powered day trip

    What is the length and weight of your boat? Do you know the thrust of your motor and prop? I am interested in the equivalence to an electric OB.

  7. #7
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    Default Re: 27 mile solar powered day trip

    That is a very decent average speed, easily comparable to a cruising sailing dinghy. The solar electric setup may be more expensive than a small gas motor but I bet it is cheaper than many sailing rigs...

  8. #8
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    Default Re: 27 mile solar powered day trip

    Is the case with the electrics your own design?

  9. #9
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    Default Re: 27 mile solar powered day trip

    Looks like you have the perfect setup for the narrow channels of your cruising grounds. Congrats!

  10. #10
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    Default Re: 27 mile solar powered day trip

    Quote Originally Posted by ahp View Post
    What is the length and weight of your boat? Do you know the thrust of your motor and prop? I am interested in the equivalence to an electric OB.
    The boat is John Welsford's Walkabout, stretched by 8% to 17' 8". With me aboard cruising weight was about 600 lb for the trip around the sloughs.

    The motor is an EP Carry outboard: https://www.electricpaddle.com/ Joe Grez does not like to compare static thrust numbers with the trolling motors, but claims his motor provides more boat speed for less electrical power. He is of course biased, but he may be right. It takes less power to drive my boat than I had expected.

  11. #11
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    Default Re: 27 mile solar powered day trip

    Quote Originally Posted by offbelayknife View Post
    Is the case with the electrics your own design?
    The whole setup is an evolution from standard components. There's a (long winded) thread on it here: http://forum.woodenboat.com/showthre...amping-rowboat

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    Default Re: 27 mile solar powered day trip

    Quote Originally Posted by Woody Jones View Post
    Looks like you have the perfect setup for the narrow channels of your cruising grounds. Congrats!
    Thanks Woody. The local fishermen would still say you need a bass boat with 90 hp outboard and a trolling motor, but they look amused as they pass me.

  13. #13
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    Default Re: 27 mile solar powered day trip

    Congratulations - that's a great story to hear. Thanks for sharing.
    Well done!
    T
    It's all fun and games until Darth Vader comes.

  14. #14
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    Default Re: 27 mile solar powered day trip

    Quite impressed. I hate outboard noise.
    be modest, and be proud of it.

  15. #15
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    Default Re: 27 mile solar powered day trip

    That is really a great result to all of your planning and work! I would love to see a future where people chose this type of experience over the grotesque spectacle that "yachting" has become. Smaller boats, slower speeds, electric power, solar charging. But sadly I expect that the size of the boat, and the size of the fuel bill, are too closely tied to the size of the ego for many boaters.
    - Chris

    Life is short. Go boating now!

  16. #16
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    Default Re: 27 mile solar powered day trip

    Very cool. Nice boat, loved the vide clips. great trip. Thank you for sharing this. There are a lot of things you are doing right and where you are doing it seem a perfect fit.
    Last edited by Ted Hoppe; 07-27-2021 at 10:29 AM.
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  17. #17
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    Default Re: 27 mile solar powered day trip

    Your Walkabout is a lovely boat and has supported so much experimentation. If you were to build from scratch again knowing all you do now what do you think the boat would be like?

  18. #18
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    Default Re: 27 mile solar powered day trip

    Electric motors for little boats are great. They're so quiet. I was in an anchorage over the weekend (Spencer Spit) and was really surprised at just how many big cruisers had the crappiest, loudest, tiny outboard motors clamped to RIBS to push the skipper and their dog to the beach. I ended up pulling up my anchor and moving away from the pack. I was trying to read and relax and the noise was unbearable.
    Quote Originally Posted by James McMullen View Post
    Yeadon is right, of course.

  19. #19
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    Default Re: 27 mile solar powered day trip

    Thanks for the encouragement everyone. I am still surprised at the interest in such a low speed boat, which has nothing to do with sailing...

    Chris - My ego can get out of hand at times, but it does not depend on the size of my motor .

    Ted - I'm trying to improve the video clips, at least they are not so jerky, but not in your league.

    Clarkey - I am now seriously thinking of a retirement build, a bigger camp cruiser for two with electric motor. I will post some thoughts later.

    Tim - Yes, that's really the market Joe Grez is targeting for his EP Carry, and I wish him success.

  20. #20
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    Default Re: 27 mile solar powered day trip

    your boat is very interesting with lots of custom improvements. I have been fallowing your postings because of it and because you are not preachy about your environmentally friendly methods of propulsion. I went to the website to check this motor out and I love it! Your trip proves that EP Carry is something to consider for sure. Price wise it's a definitely doable and comparable with gas motors for small boats.
    Now I am VERY interested in your choice for 2 person cruising boat !
    Thank you for sharing.
    "Little Bear" 1955 Fontana 18' - 1958 Atomic 4
    2016 kayak Mill Creek 13

  21. #21
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    Default Re: 27 mile solar powered day trip

    Thanks for sharing, your setup is really intriguing. As a point of comparison, you average 4.7 mph while my 15' sail and oar dinghy has averaged 3.9 mph over 12 trips in various wind conditions from pretty strong to drifting.

  22. #22
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    Default Re: 27 mile solar powered day trip

    When I was only rowing on some of our small boat cruises of 10 to 20 miles per day, I could do the distance but not always as fast as the sailboats. My advantages were I could set off early with no rigging to do, and could sometimes take shortcuts under bridges or through shallows. On this year's trip with the motor, I was way ahead of the sailboats on the first upwind leg and waited 45 minutes. That said, I think sailors go sailing because they want to sail. I mean, the point of doing it is to sail and getting somewhere is just an extra.

    BTW I am not advocating this nor do I work for EP Carry. I learn something from other's posts and since this is a bit unusual thought I would share.

    -Rick

  23. #23
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    Default Re: 27 mile solar powered day trip

    Cool thread, Rick--thanks! I love it when a plan comes together.

    Tom
    You don't have to be prepared as long as you're willing to suffer the consequences.

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  24. #24
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    Default Re: 27 mile solar powered day trip

    Quote Originally Posted by rgthom View Post
    \ If you have seen the videos of Mudskippers out of the water this is what I looked like.
    An underappreciated creature if ever there were.





    Great report, and great results!

    James

  25. #25
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    Default Re: 27 mile solar powered day trip

    Yesterday smoke from the fires to the north drifted down and blanketed the Bay. The marine layer underneath kept ground level air breathable, but the sun was red in the morning and dull all day. So, a great day to see what the solar would do in poor conditions. I launched at Belden's landing on Montezuma Slough and did a 10 mile round trip to Little Honker Bay (one of Canoeyawl's favorite quiet anchorages ).



    Starting at 10 am with full battery and slack tide, the solar current was only 2 A instead of the 4 A full sun level. Not bad considering, the Genasun boost MPPT makes the most of what is available. I decided to motor for a mile at 4 A, then row until the battery recharged. Rowing was at the same 3.5 kt speed, and I found it was just 1/2 mile until the battery was full again. Even in such poor conditions the solar supports 2:1 motoring to rowing.

    At Little Honker Bay the day was getting hotter (about 90 F), and with the muddy colored water and matching muddy colored sky I started getting oddly disoriented. I mean, I knew where I was but it all looked unworldly. The birds did not seem to mind, so here's a short video of pelicans and some others, with a pan of the windmills and Kirby Hill as the grounding landmark, all in muddy sepia tone:



    On the return I was going against both wind and tide, so upped the motor current to 8 A to maintain 3.5 kts. With the sun almost overhead the charge current rose to 4 A, then the 4 A deficit was drawing from the battery. For this 22 Ah battery that would be a 5 hour run time, I made it back in less than 2 hours with plenty to spare.
    Last edited by rgthom; 08-09-2021 at 12:52 PM.

  26. #26
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    Default Re: 27 mile solar powered day trip

    Very interesting. It shows the benefit of selecting a really efficient motor when working with limited amounts of energy. I wonder if a bifacial panel might be of particular benefit to you given your horizontal mounting and normal abundance of reflected light? They do seem heavy though.

  27. #27
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    Default Re: 27 mile solar powered day trip

    The solar panel is reaching its spec output at mid-summer mid-day. If I could put in a multi axis tilt to follow the sun at any angle that would increase output for sure, but if you saw my attempt at 1 axis tilt it is not easy to do. Windage is also a problem anytime the big panel is not horizontal. Since the solar radiance drops anyway toward the horizon through thicker atmosphere I am just going to stick with simple flat horizontal.

  28. #28
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    Default Re: 27 mile solar powered day trip

    I'm just getting ahead of myself and musing on your next boat! I was thinking that one or two of the relatively newfangled bifacial panels (which seem remarkably cheap and have the useful ability to generate power from the back surface of the panel) might be good for a fixed, horizontal, bimini type arrangement able to take advantage of light reflected from the water as well direct sunlight. Lots of weight up high though.

  29. #29
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    Default Re: 27 mile solar powered day trip

    Thanks for sharing.
    I am hoping to build a solar powered trimaran open camp cruiser for inland waters here in Finland. This looks very promising.

    here is another solar cruiser on boatdesign.net that might be of interest.

    https://www.boatdesign.net/threads/current-situation-diy-efficient-solar-electric-powered-newport-17-project.64961/

  30. #30
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    Default Re: 27 mile solar powered day trip

    Here is one I read about yesterday. Bellingham to Juneau, They stopped so the solar power could catch up.
    https://www.soundingsonline.com/news...zNEe5Doh-ckjdc

  31. #31
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    Default Re: 27 mile solar powered day trip

    This is so cool, man. Somesuch like his would be nice to drive around the local lake looking at bald eagles.

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