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

  1. #351
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post

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


    Moving the windshield forward to the next station line would give you more room above the bunks.
    And having the cabin sides and coamings follow the sheer line, rather than being boxy like they are would look better.

  2. #352
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    The TR design is a beauty. Quite big, too. Maximum trailerable beam without a wide load permit.
    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.

  3. #353
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by WI-Tom View Post
    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
    Thanks, I'm thinking now of another way of doing this. Windage really will be a problem on the Delta, and trying to make a roomy cabin forward without it being added windage or complicated is just not working. So, how about making the solar roof as the pop top cover, ditch the forward cabin, and sleep in the center area with a filler to make the side seats into the berth?

    Start with the Long Steps hull expanded to 22 feet. That keeps the double ended, rowboat type underwater hull shape. Add a sturdy windshield, somewhat in the style of the old Swedish motorboats. The solar roof in lowered position would attach securely to the top of the windshield and an aft support, with sitting room under the roof. The boat could be underway like this with all crew under cover, for minimum windage in rough conditions. This would also be trailering configuration. Fabric (waterproof or bug screen) sides would make a full enclosure when desired. In calm conditions, the roof could be raised to a standing room height. A quick sketch:



    Advantages are:
    - minimum windage
    - minimum weight
    - a big covered cabin area
    - roomy sleeping area

    Disadvantages:
    - need to convert the sleeping area each night
    - some effort to attach the sides for privacy or bug protection

    Any thoughts?
    Last edited by rgthom; 12-02-2021 at 07:46 PM.

  4. #354
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    ...
    Any thoughts?
    Moving the wind catching part of the boat to the middle makes sense. T'were it me I wouldn't want to deal with raising the roof for full headroom throughout. I would be more inclined to see if I could hinge it at the front and raise the back only, for standing room at the back but not the front. Fewer moving parts, less tricky engineering.
    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.

  5. #355
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by JimD View Post
    Moving the wind catching part of the boat to the middle makes sense. T'were it me I wouldn't want to deal with raising the roof for full headroom throughout. I would be more inclined to see if I could hinge it at the front and raise the back only, for standing room at the back but not the front. Fewer moving parts, less tricky engineering.
    Hmm, a bit odd looking but maybe.


  6. #356
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    Hmm, a bit odd looking but maybe.
    Yah, but a great angle for solar charging (provided you're pointing toward the sun, of course.)
    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.

  7. #357
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Do you have an estimate of how much the roof would weigh?
    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.

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    Quote Originally Posted by JimD View Post
    Do you have an estimate of how much the roof would weigh?

    6 of the flex panels would be 40 lb. Total for a light roof probably 80 lb. Easy to lift at one end for sure.

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

    Iíd be awfully tempted to make that awning from glassed foam. A little R value overhead wonít hurt none at all, and it could make a stiff, light top.

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

    Quote Originally Posted by amish rob View Post
    Iíd be awfully tempted to make that awning from glassed foam. A little R value overhead wonít hurt none at all, and it could make a stiff, light top.
    Stiff and light is good, but R value not so much for the solar panels. They work best kept cool, and airflow on both sides is much better than any kind of insulator. Did you see the support for the panel on the Walkabout? It's just an open frame with U-channel supports on each side. I am planning on similar for the big panel array.


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

    The insulation is for the people under the awning, Yo! Seriously, just messing around with some insulation in a canopy I use to camp makes a HUGE difference in perceived temp in the hot times.

    And, if you need a stiff, light hard top, anyway, may as well build one that insulates the boat’s interior, too.

    Our dog’s doghouse is made from rigid foam, and in the summer it’s more comfortable than the treehouse.

    And, you could fasten brackets for the panels to bonded in fasteners, stood off whatever distance.

  12. #362
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by amish rob View Post
    The insulation is for the people under the awning, Yo! Seriously, just messing around with some insulation in a canopy I use to camp makes a HUGE difference in perceived temp in the hot times.

    And, if you need a stiff, light hard top, anyway, may as well build one that insulates the boat’s interior, too.

    Our dog’s doghouse is made from rigid foam, and in the summer it’s more comfortable than the treehouse.

    And, you could fasten brackets for the panels to bonded in fasteners, stood off whatever distance.
    OK! Maybe a hard foam roof with the panels on standoffs above it would work. Melissa does not like heat...

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

    So, are you simply stretching the Long Steps or enlarging it in length AND beam? The standing headroom requirement seems to complicate things. Perhaps leave enough cockpit aft of the panels to allow standing up. The headroom requirement jus adds weight and windage where you don’t really want it, whether at anchor or underway. I know it’s nice to stretch on occasion but that’s why you nuzzle up to the bank and go for a walk.

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

    Quote Originally Posted by Dryfeet View Post
    So, are you simply stretching the Long Steps or enlarging it in length AND beam? The standing headroom requirement seems to complicate things. Perhaps leave enough cockpit aft of the panels to allow standing up. The headroom requirement jus adds weight and windage where you donít really want it, whether at anchor or underway. I know itís nice to stretch on occasion but thatís why you nuzzle up to the bank and go for a walk.
    Full expansion, so a 50% bigger boat. And since you mention it, I was just looking at a fixed seating room roof with standing room aft to reach the motor, forward to handle ground tackle, and in the sketch leaving off one of the 6 solar panels to have standing room at the helm station. Yellow is standing room:


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

    A little skepticism here, but over the years there have been a number of threads proposing ways to squeeze big boat features into a smaller boat that wasn't designed for them, with standing headroom at the top of that list of features. It's fun to brainstorm ideas, but in truth it rarely ends well.
    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.

  16. #366
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by JimD View Post
    A little skepticism here, but over the years there have been a number of threads proposing ways to squeeze big boat features into a smaller boat that wasn't designed for them, with standing headroom at the top of that list of features. It's fun to brainstorm ideas, but in truth it rarely ends well.
    Good point. I hope I'm not asking for too much, and am backing off from the separate cabin. Standing room is important, my back hates sitting for long and even at work I have a standing desk. Paul Gartside was OK with a standing height roof which could be lowered. Here's a tweak to that: deleting the forward cabin, reducing the window area to just a windshield, and making the solar roof as the top of a seating height open cabin. Ability to raise the roof to standing height would be a bonus but it seems reasonable. I might also move the windscreen forward a bit from this.


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

    Rick, I have a few thoughts. Just personal opinions and they may not be relevant to your objective but for whatever it's worth...

    Most of the discussion at this point is about different tradeoffs. Low windage, or cabin space and headroom? Most efficient hull, or bouyancy to support superstructure, solar array, etc? I like Tad's design a lot, aesthetically and as a good cruising boat. It looks a lot like a Timbercoast 22 optimized with a low resistance hull for electric power and solar. (As I understand it, the design brief for the Timbercoast 22 had some specific requirements for visual relationship to the planing Bartenders, hence the hull shape). Honestly I don't love the Paul Gartside boat all that much but that's purely my own aesthetic preference and has nothing to do with the qualities of the design itself. But one thing I've noticed is that, all other considerations aside, all of the designs discussed here fall into two categories: "Camp cruisers", with little or no permanent accommodations, and "pocket cruisers" - small cruising boats with at least some basic level of accommodations (stand up galley, enclosed head, etc.).

    You have expressed several times and in different ways that what you are looking for is something like an enlarged version of your Walkabout. Still essentially a camp cruiser but with a bit more room. Thus the move away from an enclosed cabin, etc. But I wonder if that's really the right direction for a retirement cruising boat for two people? I'd note that all of the designs floated by the professional designers fall more into the pocket cruiser category. Certainly the pros are being influenced by the market - I'm sure there are far more people interested in a trailerable pocket cruiser than in a minimalist camp cruiser - but also I think they have a point, in that camp cruising is all well and nice in an 18' boat, but seems a bit of a starvation exercise in something larger. I love the idea of a little camp cruising sharpie as I posted a while back, but practically speaking that's a weekend boat for one person not a cruising boat for two.

    Looking back at the original design parameters, which were:

    - LOA 22 feet (20 to 25)
    - Beam 6 to 7 feet
    - Hull weight ~1000 lb, cruising displacement ~2000 lb
    - Electric outboard 1 to 3 kW, battery 3 to 5 kWh, solar panels 1 kW
    - Cruising speed 4 kts
    it seems to me that the design brief is certainly able to support pocket cruiser levels of comfort. Maybe not to the extent of stand up headroom below and a fully enclosed head, as with Tad's design, but certainly more than just an enlarged Long Steps with a canopy. I'd want at least what PG's design provides. Galley with a stove, sink, and standup headroom through a hatch (even better with a canvas dodger over it). A place for two people to sit out of the weather. A place to pull on my pants. I don't think PG's design nails it yet but it's closer than the "Giant Steps" concept for me.

    I keep going back to Joe Grez's little boat Sunnyside. It's smaller even than your Walkabout but with almost pocket cruiser levels of accommodation. For a number of reasons that approach might not work for your cruising area but it still seems like a good example of what could be done well within your parameters.

    As I said, just thoughts. Take them as you will. I look forward to seeing things progress as you get closer to selecting a design.
    - Chris

    Any single boat project will always expand to encompass the set of all possible boat projects.

    Life is short. Go boating now!

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

    Sorry, can't quite leave this thought alone it seems... Another example of what I'm talking about. Tad Roberts' Fidler design:



    19' LOA, 2700lbs displacement. The displacement number aside, this design would fit in your parameters. Based on the Gerr power calculation she would do 4kts with 1.39kW and 5kts with 2.72kW. Tad writes about this design:

    With styling and arrangement closely based on BC gillnetters of the 1920-30’s, the Fidler 19 is a minimum BC Coastal displacement cruiser. This is about the smallest boat able to take one or two folks north for an entire summer. She has the displacement and freeboard to handle very large loads without it affecting fuel consumption much. The hull is large volume with good deadrise and hard bilge turn amidships, her ends are fine for best efficiency at low speed. The engine is in a well and intended to be left down thus no transom cutout. If a builder wants the ability to lift the motor the cutout can be enlarged, but aesthetically I greatly prefer the intact transom.


    With more cabin than cockpit she will keep the crew comfortable in the pouring rain or a stiff northwest on the nose. Accommodation is basic, a helm seat, galley counter, and large double berth. But she does boast the luxury of headroom to sit up in the berth. Of course a porta-pottie can be sited under the berth. Fuel is under the cockpit sole and there are large storage lockers either side of the engine well.
    For various reasons you might not like this design approach, but I think it does indicate that you can have a more comfortable experience without exceeding your design brief.
    - Chris

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

    Quote Originally Posted by cstevens View Post
    Rick, I have a few thoughts. Just personal opinions and they may not be relevant to your objective but for whatever it's worth...

    Most of the discussion at this point is about different tradeoffs. Low windage, or cabin space and headroom? Most efficient hull, or bouyancy to support superstructure, solar array, etc? I like Tad's design a lot, aesthetically and as a good cruising boat. It looks a lot like a Timbercoast 22 optimized with a low resistance hull for electric power and solar. (As I understand it, the design brief for the Timbercoast 22 had some specific requirements for visual relationship to the planing Bartenders, hence the hull shape). Honestly I don't love the Paul Gartside boat all that much but that's purely my own aesthetic preference and has nothing to do with the qualities of the design itself. But one thing I've noticed is that, all other considerations aside, all of the designs discussed here fall into two categories: "Camp cruisers", with little or no permanent accommodations, and "pocket cruisers" - small cruising boats with at least some basic level of accommodations (stand up galley, enclosed head, etc.).

    You have expressed several times and in different ways that what you are looking for is something like an enlarged version of your Walkabout. Still essentially a camp cruiser but with a bit more room. Thus the move away from an enclosed cabin, etc. But I wonder if that's really the right direction for a retirement cruising boat for two people? I'd note that all of the designs floated by the professional designers fall more into the pocket cruiser category. Certainly the pros are being influenced by the market - I'm sure there are far more people interested in a trailerable pocket cruiser than in a minimalist camp cruiser - but also I think they have a point, in that camp cruising is all well and nice in an 18' boat, but seems a bit of a starvation exercise in something larger. I love the idea of a little camp cruising sharpie as I posted a while back, but practically speaking that's a weekend boat for one person not a cruising boat for two.

    Looking back at the original design parameters, which were:



    it seems to me that the design brief is certainly able to support pocket cruiser levels of comfort. Maybe not to the extent of stand up headroom below and a fully enclosed head, as with Tad's design, but certainly more than just an enlarged Long Steps with a canopy. I'd want at least what PG's design provides. Galley with a stove, sink, and standup headroom through a hatch (even better with a canvas dodger over it). A place for two people to sit out of the weather. A place to pull on my pants. I don't think PG's design nails it yet but it's closer than the "Giant Steps" concept for me.

    I keep going back to Joe Grez's little boat Sunnyside. It's smaller even than your Walkabout but with almost pocket cruiser levels of accommodation. For a number of reasons that approach might not work for your cruising area but it still seems like a good example of what could be done well within your parameters.

    As I said, just thoughts. Take them as you will. I look forward to seeing things progress as you get closer to selecting a design.
    Thanks Chris, your comments help a lot to refocus the thinking. The original brief really meant camp cruiser, having an area reserved as the berth and under a hard cover was the main layout change. I still think camp cruiser is correct, for a lot of reasons. First, scaling up the electric propulsion gets expensive very quickly. A motor is not bad, similar to same scale gas motor, but batteries and solar panels are the bigger cost and letting those get big blows any reasonable budget. Second, due to the low power, it has become clear that windage is going to be a big factor in managing the size of propulsion system needed. A boat like Sunnyside will do 4 kts in calm, but I bet it would need much more than an EP Carry to cruise the summer Delta. It seems any design that starts adding a cabin with berth and galley needs to be taller or will feel like a coffin. Melissa pretty much has two modes of travel, either roughing it in a tent or a 5 star hotel. She actually thinks the Walkabout is big enough for us, but I have to manage most of the gear shuffling and for me a boat of about twice the size and set up better sounds like something we would use together more often.

    One we get into pocket cruiser territory the expectations rise exponentially. If there is a galley it needs to be large and easy to use. The berth cannot be claustrophobic. If there is an enclosed head it should be comfortable. I keep drifting off into thinking about a bigger boat, but if we did that it would not be primarily solar powered. Something like an Elco 26 with small diesel would be very nice, like Chaser. The cost of fuel in many years of use would not come close to the cost of a full electric system at that size.

    I also have towing to consider. A boat weighing 1000 lb would be near the limit of my 4 cylinder Honda, but should be OK for local towing. A bigger boat means buying a bigger car, it all gets out of control rapidly.

    Anyway, I will keep mulling this over. We just had a meeting with my partner companies, and my big mouth and I may have agreed to keep running my company for 3 more years. So, nothing is happening soon...

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

    Quote Originally Posted by cstevens View Post
    Sorry, can't quite leave this thought alone it seems... Another example of what I'm talking about. Tad Roberts' Fidler design:



    19' LOA, 2700lbs displacement. The displacement number aside, this design would fit in your parameters. Based on the Gerr power calculation she would do 4kts with 1.39kW and 5kts with 2.72kW. Tad writes about this design:



    For various reasons you might not like this design approach, but I think it does indicate that you can have a more comfortable experience without exceeding your design brief.
    Oh I like that boat, but as Tad says these heavy displacement types need more power. The numbers you calculated are much higher than a scaled up rowboat, and windage drives it up farther. As a dayboat with electric drive, a big bank of batteries, and overnight shore power recharge it would be great. Maybe I will give up on being able to run on just solar and do this, but not yet.

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

    Quote Originally Posted by rgthom View Post
    Thanks Chris, your comments help a lot to refocus the thinking. The original brief really meant camp cruiser, having an area reserved as the berth and under a hard cover was the main layout change. I still think camp cruiser is correct, for a lot of reasons. First, scaling up the electric propulsion gets expensive very quickly. A motor is not bad, similar to same scale gas motor, but batteries and solar panels are the bigger cost and letting those get big blows any reasonable budget. Second, due to the low power, it has become clear that windage is going to be a big factor in managing the size of propulsion system needed. A boat like Sunnyside will do 4 kts in calm, but I bet it would need much more than an EP Carry to cruise the summer Delta. It seems any design that starts adding a cabin with berth and galley needs to be taller or will feel like a coffin. Melissa pretty much has two modes of travel, either roughing it in a tent or a 5 star hotel. She actually thinks the Walkabout is big enough for us, but I have to manage most of the gear shuffling and for me a boat of about twice the size and set up better sounds like something we would use together more often.

    One we get into pocket cruiser territory the expectations rise exponentially. If there is a galley it needs to be large and easy to use. The berth cannot be claustrophobic. If there is an enclosed head it should be comfortable. I keep drifting off into thinking about a bigger boat, but if we did that it would not be primarily solar powered. Something like an Elco 26 with small diesel would be very nice, like Chaser. The cost of fuel in many years of use would not come close to the cost of a full electric system at that size.

    I also have towing to consider. A boat weighing 1000 lb would be near the limit of my 4 cylinder Honda, but should be OK for local towing. A bigger boat means buying a bigger car, it all gets out of control rapidly.

    Anyway, I will keep mulling this over. We just had a meeting with my partner companies, and my big mouth and I may have agreed to keep running my company for 3 more years. So, nothing is happening soon...
    All good thoughts, and your wife's expectations would be preeminent in my view. If she is comfortable with, or prefers, the camp cruising experience that would be a deciding factor for me. (My wife, on the other hand, has zero tolerance for tent-style camping, which may be affecting my viewpoint somewhat!)

    As for the small diesel idea, while I love the concept of a solar cruiser given your access to renewable diesel in CA I think that is certainly an alternative that still achieves some level of independence from fossil fuels.
    - Chris

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    Life is short. Go boating now!

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

    Quote Originally Posted by rgthom View Post
    Oh I like that boat, but as Tad says these heavy displacement types need more power. The numbers you calculated are much higher than a scaled up rowboat, and windage drives it up farther. As a dayboat with electric drive, a big bank of batteries, and overnight shore power recharge it would be great. Maybe I will give up on being able to run on just solar and do this, but not yet.
    Maybe? At 3kts Fidler would draw .59kw. The power draw over the range from 3-5kts seems like it could work with a 1kW solar array, adjusting speeds based on actual charging from the array. But there is no question that greater displacement makes everything else bigger and more expensive, from power train to trailer. Everything is a tradeoff!
    - Chris

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    Life is short. Go boating now!

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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 hope I'm not asking for too much, and am backing off from the separate cabin. Standing room is important, my back hates sitting for long and even at work I have a standing desk. Paul Gartside was OK with a standing height roof which could be lowered. Here's a tweak to that: deleting the forward cabin, reducing the window area to just a windshield, and making the solar roof as the top of a seating height open cabin. Ability to raise the roof to standing height would be a bonus but it seems reasonable. I might also move the windscreen forward a bit from this.

    This illustration is probably the most promising way to do it.(which, as with almost everything I say on this forum, is only in my humble opinion)
    Last edited by JimD; 12-03-2021 at 08:59 PM.
    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.

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

    Quote Originally Posted by rgthom View Post
    Thanks, I'm thinking now of another way of doing this. Windage really will be a problem on the Delta, and trying to make a roomy cabin forward without it being added windage or complicated is just not working. So, how about making the solar roof as the pop top cover, ditch the forward cabin, and sleep in the center area with a filler to make the side seats into the berth?

    Start with the Long Steps hull expanded to 22 feet. That keeps the double ended, rowboat type underwater hull shape. Add a sturdy windshield, somewhat in the style of the old Swedish motorboats. The solar roof in lowered position would attach securely to the top of the windshield and an aft support, with sitting room under the roof. The boat could be underway like this with all crew under cover, for minimum windage in rough conditions. This would also be trailering configuration. Fabric (waterproof or bug screen) sides would make a full enclosure when desired. In calm conditions, the roof could be raised to a standing room height. A quick sketch:



    Advantages are:
    - minimum windage
    - minimum weight
    - a big covered cabin area
    - roomy sleeping area

    Disadvantages:
    - need to convert the sleeping area each night
    - some effort to attach the sides for privacy or bug protection

    Any thoughts?
    My boat has an operable windshield through which I can handle lines on the mooring cleat , the anchor being stored and deployed from the cockpit . The operable windshield is also very cooling in the Summer of course .

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    Quote Originally Posted by Bill Perkins View Post
    My boat has an operable windshield through which I can handle lines on the mooring cleat , the anchor being stored and deployed from the cockpit . The operable windshield is also very cooling in the Summer of course .

    That sounds right Bill. Do you have a picture of the windshield?

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

    It's just a simple flat plate with a piano hinge. This does give unimpeded access to the centerline where the mooring cleat is . My boat has a long straight keel and I am launched into a constricted place at the marina . When the wind or tide has me pinned to the dock I routinely use a spring line ,which can be conveniently singlehanded with this setup . I lead a bight of line around a dock cleat and can release it without leaving the helm . With your electric you won't be jacking the boat around with short bursts of power either. There's likely to be some use of the bow spring in your future. Of course the anchor line can be handled through the window as well.

    Last edited by Bill Perkins; 12-04-2021 at 04:42 PM.

  27. #377
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    Default

    Quote Originally Posted by Bill Perkins View Post
    It's just a simple flat plate with a piano hinge. This does give unimpeded access to the centerline where the mooring cleat is . My boat has a long straight keel and I am launched into a constricted place at the marina . When the wind or tide has me pinned to the dock I routinely use a spring line ,which can be conveniently singlehanded with this setup . I lead a bight of line around a dock cleat and can release it without leaving the helm . With your electric you won't be jacking the boat around with short bursts of power either. There's likely to be some use of the bow spring in your future. Of course the anchor line can be handled through the window as well.


    Thanks, perfect for the anchor.

  28. #378
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    https://www.sailrite.com/How-to-Inst...ls-on-a-Bimini

    this video might be helpful for your solar boat top design.

  29. #379
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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 hope I'm not asking for too much, and am backing off from the separate cabin. Standing room is important, my back hates sitting for long and even at work I have a standing desk. Paul Gartside was OK with a standing height roof which could be lowered. Here's a tweak to that: deleting the forward cabin, reducing the window area to just a windshield, and making the solar roof as the top of a seating height open cabin. Ability to raise the roof to standing height would be a bonus but it seems reasonable. I might also move the windscreen forward a bit from this.

    How much of that transom is immersed? I'd be worried about both wetted surface and induced drag. Something closer to a Whitehall stern might serve you better. Maybe something like the Delaware River gill net skiff in American Small Sailing Craft. 20' x 6'2", pretty stable and with good carrying capacity.

  30. #380
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by johnw View Post
    How much of that transom is immersed? I'd be worried about both wetted surface and induced drag. Something closer to a Whitehall stern might serve you better. Maybe something like the Delaware River gill net skiff in American Small Sailing Craft. 20' x 6'2", pretty stable and with good carrying capacity.
    This is still the main question, as keeps coming up. Paul Gartside thinks the boat needs some beam at the transom to support the solar, and that speeds of 4 to 5 kts are semi-displacement in any case. Tad Roberts says "Efficiency at very low speed requires fine ends, especially aft where things are apt to get draggy with blunt transom shapes." It is clear that modeling is not available to predict this accurately, and that boats need to be built and tested if maximum speed at low power is the main goal. It is on the wish list, but I am still concerned about the tradeoffs.

  31. #381
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by timo4352 View Post
    https://www.sailrite.com/How-to-Inst...ls-on-a-Bimini

    this video might be helpful for your solar boat top design.
    Thanks, that was interesting. It was a big sewing project to add the panels to an existing bimini, but I am hopeful a purpose made support can be made that is easier. This is what I'm thinking now:

    - Light open frame, of wood and or aluminum, with a gentle arch to shed water.
    - A fabric cover over the frame to make the roof waterproof. The Shelterite material he used in the video can be bonded with vinyl adhesive, no sewing. That would make a waterproof cover.
    - Solar panels mounted over the Shelterite. I like the snaps he used, very secure yet easy to remove.
    - Some kind of pocket over the forward edge of the panels, to retain them when towing. On the Walkabout single flat panel, I used a small aluminum U-channel to trap the forward edge. That is holding it fine at freeway towing wind speeds. Like this:


  32. #382
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    The David Payne designed Snapper boat (17' LOA) carries hardly any wake at all and is extremely stable - I cruise at about 5.5-6 knots with a 10 hp diesel. The hull shape is very slippery and makes a wonderful day boat.
    298A5510.jpg

  33. #383
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by rgthom View Post
    This is still the main question, as keeps coming up. Paul Gartside thinks the boat needs some beam at the transom to support the solar, and that speeds of 4 to 5 kts are semi-displacement in any case. Tad Roberts says "Efficiency at very low speed requires fine ends, especially aft where things are apt to get draggy with blunt transom shapes." It is clear that modeling is not available to predict this accurately, and that boats need to be built and tested if maximum speed at low power is the main goal. It is on the wish list, but I am still concerned about the tradeoffs.
    hull speed for a 16' waterline is about 5 1/2 knots, so no, for the size of boat you're looking at, that's not a semi-displacement speed.

    More here: http://forum.woodenboat.com/showthre...planing-dinghy

    and here: https://www.amazon.com/Evolution-Pla.../dp/B08HTP4RNV

  34. #384
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by neil.henderson View Post
    The David Payne designed Snapper boat (17' LOA) carries hardly any wake at all and is extremely stable - I cruise at about 5.5-6 knots with a 10 hp diesel. The hull shape is very slippery and makes a wonderful day boat.
    298A5510.jpg
    Looks like a smaller version of the Delaware River gillnetter I mentioned earlier.

  35. #385
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    Default Re: Displacement designs for solar electric river cruiser, 20 - 25 feet

    Quote Originally Posted by neil.henderson View Post
    The David Payne designed Snapper boat (17' LOA) carries hardly any wake at all and is extremely stable - I cruise at about 5.5-6 knots with a 10 hp diesel. The hull shape is very slippery and makes a wonderful day boat.
    298A5510.jpg
    Wow, another pretty design. This one is a little small, and apparently designed for an inboard, but the transom looks like the way to do it for minimum stern drag.


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