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Thread: Displacement designs for solar electric river cruiser, 20 - 25 feet

  1. #316
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by John hartmann View Post
    Continuing the brainstorm, this is too small for your requirements, but has a number of traits which might be of interest as you further refine your search for a design with optimum compromises. It is Vivier’s Gabian. Drawn as a lateen rigged sailboat, but without a CB trunk, and with water ballast which could provide room for a battery bank doubling as ballast. Electric outboard, off center in a well.Large deck area for solar panels. Huge storage compartment for gear forward, so cockpit remains uncluttered under way. Set up without the sailing rig, it could be used as a motor and oar set up, if properly dimensioned. This boat is a little over 16’ long, 5’8” beam, so a similar but longer hull would likely be required for your design brief.
    Attachment 100252
    Attachment 100253
    Attachment 100254
    Interesting, very much a Felucca with modern building technique. Vivier says it is built in "plywood carvel", butted narrow strips of ply which depend on precise CAD to fit up properly. So, not much chance of tweaking the length.

    From the SF Maritime Museum:


  2. #317
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Let's see if linking to a FB photo works... This is from Tad Roberts, the twin 4.5 kW motors installed in the recent Timbercoast 22 launch. I have not seen the battery setup yet.


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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Now that things have taken a Mediterranean swing may be the BCA Demco catalogue is worth a look?

    http://www.bcademco.it/EN/piani.html#4


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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by Clarkey View Post
    Now that things have taken a Mediterranean swing may be the BCA Demco catalogue is worth a look?

    http://www.bcademco.it/EN/piani.html#4

    That Rustica 570 looks possible, very close to a Redwing 18. Plans available from our hosts: https://www.woodenboat.com/boat-plans-kits/rustica-570

    It does say semi-displacement, and recommended power is 10 to 15 hp outboard, so not sure about low power electric performance.


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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Paul Gartside took an interest in this when I wrote to ask him about his Wayward design. We have been discussing a new design specifically for solar electric, based on Wayward but lighter weight. With his permission the first rough sketch is posted below. Changes include:

    - Displacement reduced from 3000 lb to 2000 lb, Paul says even lighter if possible.

    - Construction changed from strip plank to light plywood, maybe stitch and glue.

    - Depth reduced to minimum to limit windage.

    - Motor enclosure eliminated, electric outboard to be transom mounted.

    - Roof size increased to support 1 kW solar panels, some kind of folding or lowering mechanism to be determined.

    - Head area changed to simple porta-potti under berth.

    - Stick steering maintained, but only 1 station.

    I pushed a little to get the stern to sweep narrower and a smaller transom, but Paul says the transom is above waterline and some beam is needed to support the solar. He thinks speed will not be affected. As he also says it is hard to predict performance by calculation, mostly one compares to existing designs and there is not one just like this.

    The cabin roof would have a sliding hatch or maybe just a fabric cover as done on some builds of Ninigret. The fabric could include a bug screen option for hot CA summers.

    I like it! Plans would be available if we go ahead. Any thoughts on features or changes?



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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    I’m hella good at laying fillets.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by amish rob View Post
    I’m hella good at laying fillets.
    We have a guest room...

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Dang. If I bring my skiff or punt, we may actually be able to row boats together, finally, too!

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Looking very promising. Any thoughts on battery placement?
    There's the plan, then there's what actually happens.

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  10. #325
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by BBSebens View Post
    Looking very promising. Any thoughts on battery placement?
    Low...

    Not specified yet, but probably midships to trim properly.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Rick , Paul's design looks very nice.

    But I'd keep a strip n glass option: beside lower resistance, someone looking to reduce their carbon footprint with this, might also prefer to have the option to build it from their local softwood.
    Last edited by Edward Pearson; 11-23-2021 at 06:19 PM.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    My favorite thread in years. Thank you, everyone. For myself I'd want a cat or a tri. Lots of beam to support lots of solar panel, narrow, wave piercing hulls, and oodles of stability.
    There is no rational, logical, or physical description of how free will could exist. It therefore makes no sense to praise or condemn anyone on the grounds they are a free willed self that made one choice but could have chosen something else. There is no evidence that such a situation is possible in our Universe. Demonstrate otherwise and I will be thrilled.

  13. #328
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by Edward Pearson View Post
    Rick , Paul's design looks very nice.

    But I'd keep a strip n glass option: beside lower resistance, someone looking to reduce their carbon footprint with this, might also prefer to have the option to build it from their local softwood.

    The boat's ecological virtue would be weakened building it from Gabon's rainforest Occume.
    Thanks Edward, but I will leave that to Mr. Gartside (it may be more marketable, as you say). I just want a quiet river cruiser, and will probably use meranti as it is more available here at consistent quality.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    I read here I think that 80% of the solar energy that strikes the panels gets converted into heat . How hot will they get on a Summer day? The radiant heat from the panels may be a bit much for the crew below . Maybe an aluminum shield would be good in Summer at least . It would be spaced below the panels so they would still be cooled by airflow .

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by Bill Perkins View Post
    I read here I think that 80% of the solar energy that strikes the panels gets converted into heat . How hot will they get on a Summer day? The radiant heat from the panels may be a bit much for the crew below . Maybe an aluminum shield would be good in Summer at least . It would be spaced below the panels so they would still be cooled by airflow .
    Good point. I have checked the temperature of the single panel on the Walkabout, even on a hot summer day it is not much above air temp. It is almost always windy on the Delta, this helps the cooling I am sure.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    Good point. I have checked the temperature of the single panel on the Walkabout, even on a hot summer day it is not much above air temp. It is almost always windy on the Delta, this helps the cooling I am sure.
    Also I think that statistic is misleading since *most* surfaces convert radiant energy from the sun into heat. That's why things get hot in the sun. I've never noticed that the panels on Skookum Maru add significant heat to the deck, and from what information I can find on the Internet (surprisingly not much) it seems like the solar panels block more heat than they produce. From one source:

    ...there is a common misconception that solar panels generate heat amidst converting sunlight into usable electricity. Instead, solar panels absorb heat that otherwise would have been passed onto your roof. The panels block the heat from being absorbed by your roof and eventually your home and actually prevent extra heat from being generated.
    (https://news.energysage.com/keeping-...ool-your-roof/)
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    [QUOTE=cstevens;6556283]
    Quote Originally Posted by leaotis View Post

    ............. I'd love to hear how it performs once you have a chance to get it in the water.......
    Did a brief harbour trial yesterday. 33amps = 4kts. 137amps - 5.8kts. The motor is quiet! I was concerned about cavitation b/c the prop is so close to the surface but it only cavitates under hard back-down. I've load tested the batteries with 33 amps (a old hair dryer set to low). It took 9hrs to drain the batteries. 9hrs x 4kts = a theoretical range of 36 nautical miles. I'm happy.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    [QUOTE=leaotis;6569346]
    Quote Originally Posted by cstevens View Post

    Did a brief harbour trial yesterday. 33amps = 4kts. 137amps - 5.8kts. The motor is quiet! I was concerned about cavitation b/c the prop is so close to the surface but it only cavitates under hard back-down. I've load tested the batteries with 33 amps (a old hair dryer set to low). It took 9hrs to drain the batteries. 9hrs x 4kts = a theoretical range of 36 nautical miles. I'm happy.
    That looks fantastic. I'd be happy too!
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    This is clearly very close to your stated needs. If it were to be my boat, I would give up cockpit space for more sheltered cabin room. Specfically, bring the cabin top back another two feet or even a bit more to make the interior more livable and provide for more dry stowage space. The hatch would then be under the solar panels. A snap or zip-on windscreen would fit neatly for cold windy or rainy days. You could even curtain off the head to starboard if desired.

    -Dave

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    I agree with trading some cockpit space for more cabin, especially if you're mostly traveling with 1-2 people. Otherwise the drawing looks great.

    Tom
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    The Gartside boat is looking very sweet. The only problem with stretching out the cabin is more weight. This will be structure, of course, but also simply more stuff. More room always leads to more stuff to fill it.

    Rick, why would you not want both an inside and outside helm?

    Jeff

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    [QUOTE=leaotis;6569346]
    Quote Originally Posted by cstevens View Post

    Did a brief harbour trial yesterday. 33amps = 4kts. 137amps - 5.8kts. The motor is quiet! I was concerned about cavitation b/c the prop is so close to the surface but it only cavitates under hard back-down. I've load tested the batteries with 33 amps (a old hair dryer set to low). It took 9hrs to drain the batteries. 9hrs x 4kts = a theoretical range of 36 nautical miles. I'm happy.

    That looks great! And thanks for providing the numbers. Is this running on 12 V, so that the 33 A is 33*12 = 396 W electrical power input?

  23. #338
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    That looks great! And thanks for providing the numbers. Is this running on 12 V, so that the 33 A is 33*12 = 396 W electrical power input?
    Rick per an earlier post it's 24V, so ~0.8kW draw at 4kts:

    2.2Kw Aquamot 24v fixed pod installed. Power is supplied by 8, 3.2v 302ah LiFePO4 cells. w/150a BMSs ~50Kgs.s Motor w/ folding prop, wedge, S.S backing plate and cables ~24Kgs. Controller ~ 5.5Kgs. Boat before electric addition weighed 420Kgs.
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    To Dave and Tom and Jeff: I am still not sure if the cabin setup is the most useful. Originally I just asked for the sleeping area V-berth to be in a cabin, cooking to be on a table we could set up in the cockpit and no real galley. Keep it simple. Paul sent the sketch with the windowed raised area included, and added the galley inside. My concerns are that if we now have a real galley it is probably too small, as you guys say. For summers on the Delta it will be hot and no chance of rain, so lots of ventilation for sleeping will be needed. The one option already mentioned is to keep the cabin top open with a fabric cover when needed, as in some Ninigret builds. Like this:



    Melissa is also a bit claustrophobic, so I asked Paul about putting more vertical space in the sleeping area, maybe with raised deck forward as in the original Wayward. He was resistant, partly due to windage.

    Yet another concern is ground tackle handling. After dealing with muddy anchors in the Walkabout cockpit I put a bow roller on and made the forward compartment into a rode locker. This is far cleaner, so I would like to do the same on the new boat. I asked Paul if we could find a way to access the anchor from inside, maybe a hatch or move the cabin forward with the open top. He was resistant to this also, and felt stepping out on the deck should work.

    So, at the moment, the designer and I are not quite in agreement on some of the details. As I am not ready to start building I plan to let this simmer for a while and see if we can come to an understanding.

  25. #340
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    I am finding this a fascinating and very informative thread with information coming in from people who know a hell of a lot more about boat design & electrical stuff than I do (I'm building my 4th boat now). My current build is a Caledonia Yawl which I hope to put and electric outboard in.

    But for my next build I would like a displacement, electric powered, dayboat - say around 18-20 feet LOA. I love the Atkins Ninigret - does anyone know if a shortened version has been designed.

    Please keep going with the thread :-)

    Regards Neil

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    To Dave and Tom and Jeff: I am still not sure if the cabin setup is the most useful. Originally I just asked for the sleeping area V-berth to be in a cabin, cooking to be on a table we could set up in the cockpit and no real galley. Keep it simple. Paul sent the sketch with the windowed raised area included, and added the galley inside. My concerns are that if we now have a real galley it is probably too small, as you guys say. For summers on the Delta it will be hot and no chance of rain, so lots of ventilation for sleeping will be needed. The one option already mentioned is to keep the cabin top open with a fabric cover when needed, as in some Ninigret builds. Like this:



    Melissa is also a bit claustrophobic, so I asked Paul about putting more vertical space in the sleeping area, maybe with raised deck forward as in the original Wayward. He was resistant, partly due to windage.

    Yet another concern is ground tackle handling. After dealing with muddy anchors in the Walkabout cockpit I put a bow roller on and made the forward compartment into a rode locker. This is far cleaner, so I would like to do the same on the new boat. I asked Paul if we could find a way to access the anchor from inside, maybe a hatch or move the cabin forward with the open top. He was resistant to this also, and felt stepping out on the deck should work.

    So, at the moment, the designer and I are not quite in agreement on some of the details. As I am not ready to start building I plan to let this simmer for a while and see if we can come to an understanding.
    The negotiations between designer and client must be fascinating. I can see how seemingly small changes to a design create a ripple effect with many unintentional consequences, and the need for lots of adjustments in other areas, which might not be obvious to non-designers. I'm betting even a small change creates a lot of extra design work. And, of course, the possibility of degrading performance in other areas.

    I'm happy to sail a boat small enough that anchoring means chucking a small anchor overboard from the cockpit.

    Tom
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by neil.henderson View Post
    I am finding this a fascinating and very informative thread with information coming in from people who know a hell of a lot more about boat design & electrical stuff than I do (I'm building my 4th boat now). My current build is a Caledonia Yawl which I hope to put and electric outboard in.

    But for my next build I would like a displacement, electric powered, dayboat - say around 18-20 feet LOA. I love the Atkins Ninigret - does anyone know if a shortened version has been designed.

    Please keep going with the thread :-)

    Regards Neil
    For a smaller version I would suggest you look at the Handy Billy design by Harry Bryan.

    Jeff

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Tad Roberts just posted what looks like a new cruiser for low power on his FB. He says this:

    "Efficiency at very low speed requires fine ends, especially aft where things are apt to get draggy with blunt transom shapes. This 26' x 8'6” plywood cruiser is designed to run efficiently up to “hull speed” of 6.5 knots."



    The boat Paul Gartside sketched does not really have a fine shape aft, but Paul believes it needs the beam here to support the solar. I am still very unsure what the right hull shape should be for low speed electric, and it appears the designers are not fully in agreement either.

  29. #344
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post




    Nice looking boat.

    There has been a lot of discussion about the underwater hull shape, not much about windage, something the boat pictured appears to have a lot of. I know aerodynamic drag is less at low speeds but as anybody who has ridden a bicycle can attest riding in anything forward of the beam is going to slow you down. We all like a salty looking boat, it just might not be the most efficient.
    Steve

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  30. #345
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by jpatrick View Post
    For a smaller version I would suggest you look at the Handy Billy design by Harry Bryan.

    Jeff
    Thanks for the response/suggestion - placing the helm in the middle of the boat would seem to use up a lot of space to me - perhaps a tiller helmed version would be more spacious internally - like David Paynes Snapper design?

    Thanks Neil

  31. #346
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by stromborg View Post
    There has been a lot of discussion about the underwater hull shape, not much about windage, something the boat pictured appears to have a lot of. I know aerodynamic drag is less at low speeds but as anybody who has ridden a bicycle can attest riding in anything forward of the beam is going to slow you down. We all like a salty looking boat, it just might not be the most efficient.
    Thanks, there has been some mention but it is a big issue at low power (and in a windy cruising area). It is part of my struggle with the Gartside design, space in the berth is kept minimal to limit windage (or tophamper, as Paul describes it). It is all a tradeoff, as usual. The Roberts boat is clearly for more power, with slow solar recharge.

  32. #347
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by neil.henderson View Post
    Thanks for the response/suggestion - placing the helm in the middle of the boat would seem to use up a lot of space to me - perhaps a tiller helmed version would be more spacious internally - like David Paynes Snapper design?

    Thanks Neil
    Or stick steering at the side, as in Gartsides' Wayward. The 21 foot Handy Billy is still in my options list of designs.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    Thanks, there has been some mention but it is a big issue at low power (and in a windy cruising area). It is part of my struggle with the Gartside design, space in the berth is kept minimal to limit windage (or tophamper, as Paul describes it). It is all a tradeoff, as usual. The Roberts boat is clearly for more power, with slow solar recharge.
    Have you considered a pop top berth, with canvas sides? The deck could lift vertically as a whole, or lift on a hinge instead. Either way would give more room in the berth when needed, and low windage when moving.

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

    www.tompamperin.com

  34. #349

    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Probably depends where you use the boat. Around here (relativel long fetches, even in the more sheltered areas) the wind generated chop starts slowing you down sooner than the windage does. So may as well have the windage for the extra internal comfort it provides.

    if you use it somewhere sheltered enough there isn't much in the way of wind generated waves, you're right about the windage - just depends on your priorities.

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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    Tad Roberts just posted what looks like a new cruiser for low power on his FB. He says this:

    "Efficiency at very low speed requires fine ends, especially aft where things are apt to get draggy with blunt transom shapes. This 26' x 8'6” plywood cruiser is designed to run efficiently up to “hull speed” of 6.5 knots."



    The boat Paul Gartside sketched does not really have a fine shape aft, but Paul believes it needs the beam here to support the solar. I am still very unsure what the right hull shape should be for low speed electric, and it appears the designers are not fully in agreement either.

    Oh. Wow…

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