SolGato’s Lateen Crab Claw Rig

Discussion in 'Multihulls' started by SolGato, May 12, 2021.

  1. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member

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    As our summer sailing season fast approaches, I’ve started picking up where I left off a few seasons ago on the design of the sail rig for my Solar Electric Catamaran, SolGato.

    Based on the rig I saw on an AquaCat and referred to as a “Flying Lateen” in other posts on this site, the sail will be hung inside a pivoting A frame with the upper spirit acting as the 3rd leg or rigid forestay if you will. The lower sprit is allowed to swivel around the upper at the base which is mounted to the forward cross beam. I am considering mounting the base of the upper sprit to a car that can slide along the beam for further adjustability, my thought being that it might allow for more sailing angles similar to a rear track on a Bermuda type rig, but I don’t really know? I have some extra track and thought I would give it a try.

    To reef or de-power, the lower sprit will be raised up to spill the sail. To strike the rig, the forward base mount can be unpinned and the upper sprit dropped as the A frame is pivoted forward until it rests atop the hulls. The upper sprit mount can then be unpinned and the sail rig removed from the frame to be wrapped up and tied off along one of the hulls.

    For the sail, I have purchased a new SunFish cruising sail that I plan to have cut down with sleeves sewn in for the sprits.

    Not trying to win any races, just cruising in light winds. I already have fast boats, this one is a cruiser. Plus, I don’t want to add any holes to the hulls, so all mounts and positioning is based around existing beam locations, existing structure points, etc.. which means I can’t do a clean sheet design. As always, I am striving to leave as much adjustability in the design as possible since I know weight distribution and positioning of the sail volume will be key to “performance”.

    BTW, my new solar hardtop is lifted by linear actuators, so the front height is now independently adjustable of the rear allowing for a wedge shape which will provide more clearance for the sail with the ability to position the volume further aft and lower if need be. These photos show the sail in the most vertical position.

    Anyway, I’m hoping to be able to do some test sails this season, but I’m still busy updating my Trimaran, and this rig is pretty low on the list, especially since it’s already a working solar electric boat.

    Someday I might start a full build thread on it. Built many years ago using a salvaged Hobie Getaway, its design is continually evolving as I refine and simply various systems. This season in additional to a lighter weight remote controlled linear actuated top, SolGato also received a pair of new LiFePo4 batteries for increased range and power while further reducing weight.
     
    Last edited: May 12, 2021
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  2. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    That is a fascinating project. Can't wait to see her sea trials.
    I'm hardly one to judge these things, but the sail area looks pretty small for light wind sailing. It's good to start conservatively though.

    -Will
     
  3. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member

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    You’d be surprised how little sail area you need in our trades to cruise around our Bay during the Summer. Some of the Hawaiian Sailing canoes around here have very small sails.

    Also these photos were taken with the old hardtop. Here is a photo of the new top. The lower angle at the front will allow for more sail area and hopefully a little less windage.

    In the end it might only putt around, but at least it will still look fast!
     
    Last edited: May 13, 2021
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  4. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    She's a beauty.
     
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  5. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member

    Thanks Will!

    On the surface it doesn’t look like much, which means I’ve done my job.

    Typically Solar Electric builds scream “look at me, I’m Solar electric”. But I prefer to take a more subtle approach by hiding and simplifying the technology as much as possible.

    The biggest challenge thus far was building as light of a bimini top as possible to keep the center of gravity as low as possible, and working out the geometry of the actuators to allow for independent front and rear actuation to allow for tracking of the sun, clearance for the future sail rig, protection of the rear trampoline seating area from rain, and of course trailering.

    In the end I settled on 5/8” Triple Wall Polycarbonate. Very light, very ridged, UV stable, and flexible enough to slightly contour for rain runoff. With the solar panels weighing less than 5lbs each, the new top is far lighter than my old fiberglass version allowing for the use of fast reasonable priced linear actuators. And the aluminum support frame for the top is made from anodized T-Slot, so it can receive all kinds of anchors, even sail slides, etc.. Eventually I plan to build a shower curtain like tent enclosure for camping that will hang from the track to fully enclose the rear trampoline area, and when it comes time to replace the main rear trampoline, I will likely switch to a solid vinyl instead of the mesh to keep from getting splashed occasionally when motoring through swell.

    Here’s a link to the top in action. If you swipe left for the second video it gives a side view. I am most proud of being able to incorporate the raising of the seat backs with the lifting actuation:

    Login • Instagram https://www.instagram.com/p/CH9OSD6lFfT/?igshid=kgkh60ipqjum
     
    Last edited: May 13, 2021
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  6. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    Wow that sounds awesome! Just to share a quick idea: For a light solar Bimini you could take a plexiglass / PMMA or PC sheet and shape it into a slight curvature. Then laminate those maxeon solar cells below it with EVA film. Then stiffen it with ribs.
     
  7. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member

    Hey Dejay.

    Yes, one could certainly do that, but pound for pound, I don’t think there’s a lighter more ridged plastic material than Multiwall polycarbonate.

    Take a look at the specs on products like PolyGal and Tufflite.

    One popular use for Multiwall polycarbonate is for protecting windows during hurricanes. It’s basically a honeycomb like construction, which is what gives it great strength. The 16mm triple wall I used only weighs about .5lbs per square foot and is ridged enough to not deflect in shape under its own weight in a 4’x8’ size sheet.

    For comparison, I purchased a few sheets of 1/2” Thermo-Lite engineered fiberglass board that I originally planned to use, and it weighs nearly 2X that of the polycarbonate.

    With regard to the solar cells, I see a lot of problems with integrating the cells. First it’s a lot of work, and second I prefer to keep things modular. Things like solar panels, chargers and batteries are always improving. If you integrate these components, it’s hard to service them or swap them for an updated version.

    Case in point, SunPower’s latest panels with Maxeon cells deliver 110W of power versus their previous 100W panels with the same footprint. My boat has 6 panels, so the newer versions would provide an extra 60W of power, equating to an extra 2.5A of power for a 24V system. With my panels being modular, removing them is easy and I will likely sell them second hand and upgrade to the newer versions as I became a dealer and have a crate of them in storage.

    As a general rule, you are already at a disadvantage with DC Power in a marine environment with contacts and wiring being far more susceptible to corrosion, so if one did embed cells, you better do a really good job laminating. This is actually one of the main things that sets quality flexible panels apart from the cheap ones. The process and materials they use for a backing, and their lamination process and UV protections, along with the quality of the junction box all play a vital role in how long they will last in a marine environment. A lot of cheap panels suffer from delamination issues which allows for water intrusion ultimately causing cell shorting.

    But the big reason in my opinion not to integrate cells, is because a lot of people don’t realize how much heat they produce, especially back contact. They can easily cause paint and gelcoat discoloration, blistering and cracking when mounted directly to a surface.

    In fact, I would recommended that anyone installing flexible panels directly to the surface of their boat use a backing material placed between them to keep them from damaging the surface.

    Now imagine if those cells were imbedded directly in the top material?

    Between the heat of the sun and the heat generated by the cells, it might be challenging to retain a specific shape with the material heating up and cooling down. Fiberglass is probably a better material. In fact, some of the flexible panel manufacturers are starting to use FRP as a backing material instead of HDPE.

    Anyway, just some food for thought. I’ve seen a few high end boats with integrated cells and have to wonder how those systems will be performing in 5 years and what the boat will look like.

    To me, the concept is sorta like installing batteries in something and then not making them removable.
     
  8. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    Just an idea I wanted to share. Your solution is awesome and modularity is probably better in general.

    But custom sized solar panels are not unheard of, there are some vendors for this. So specifically offering a custom solar Bimini might make sense. A custom solar panel that is a structural element and maximizes the area solar gain.

    The prices I've seen for the sunpower maxeon panels I've found is $3000/kW. Th exorbitant prices for good flexible solar panels is why I got interested in the possibility of DIY for this. The 24% efficient cells themselves should be relatively cheap.

    So that is like 2.5kg/m²?
    From the datasheet I found the flexible maxeon panels have about 3kg/m²

    So theoretically a 3mm PMMA sheet 3.6kg/m² plus with EVA laminated solar cells and a light fiberglass plus ribs could compete.

    From what I understand both PMMA and EVA is UV stable and transparent in the range relevant for the solar cells efficiency.

    The heat problem should be solved because there is no backing so there would be airflow directly behind the cells.
     
  9. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member


    You might want to look into becoming a dealer and buying a crate of panels at wholesale and selling off what you don’t need. If you do this, the panels are free and you might even make a few extra bucks to put toward your build.

    FYI, the 110W panels typically sell for about $225 retail here in the USA.

    With regard to laminating cells and integrating them into the top material, I still think one would run into material stability issues with regard to heat transfer from the cells to the backing material. The heat would be concentrated and I think over time it would cause the plastic backing material to ripple and distort in shape just as the flexible panels do if unsupported. So in the areas between fiberglass support ribs and mounting support areas, the material may distort, especially if only 3MM in thickness.

    I wonder if perhaps you could instead laminate the underside and have the face of cells under the rigid material? This would offer even better protection and cut down on pooling of water and collection of dirt. And the laminating material is much thinner with less mass so heat would dissipate better.

    Anyway, not trying to discourage you but give you a few things to think about that you might not have considered.

    I see lots of flexible panels being installed on beautiful new boats, and when I zoom in on the photos I often do not see any backing material. I think a lot of those owners may be in for a big surprise if and when they remove those panels.

    Here is a photo of what my fiberglass Bimini looked like after having panels installed directly on it for about a little over a year.

    Prior to installation, the top was refinished using a Marine Topside paint, and each cell caused discoloration, cracking and crazing of the finish due to heat.

    Keep in mind these panels are wired in Series not Parallel, so it's not like there’s a bunch of amperage moving through them.
     

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  10. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    Yes this is what I was thinking. Take a 3mm plexiglass as the top "glass" surface. Then thin EVA, solar cell + wires, EVA film. The "laminating" I meant is being done under vacuum and heat. I think 150C is required which should also make the PMMA soft. You can do this with a heat gun.
    Not sure if you'd actually need a backing in that case, but maybe a thin transparent fiberglass or carbon cloth would do.

    Thanks for the price info!
     
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  11. peterAustralia
    Joined: Mar 2006
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    peterAustralia Senior Member

    I am sure the rig will work, I have seen photos of a smallish Wharram cat (approx 30ft) with the same rig, it cruised in Thailand. Over time you may wish to add the ability to move the tack (apex) of the sail fore and aft, this would allow the sail to pivot to higher and lower angles depending on the wind speed. I am aware of at least two boats that initially tried the CC (crab claw ) rig, then reverted to the Bermudan as they were unhappy with upwind performance. One was a 16ft Wharram Melanesia, the plans suggest the CC rig, which was built, the owner then junked that, found a piece of bamboo and used that as the mast for Bermudan mainsail, 80 sqr ft or so. The second was the large Pahi 70ft named Mareva that had an extensive refit in 2020, and went from CC to Bermudan. The CC is OK, simple, cheap, safe, easy to build, fix , easy to get down in a squall etc, etc but is a trade-off between that and upwind performance. Bruce Shell of Shell boats also has a catamaran with a similar CC sail. In the attached diagram notice the inclined bamboo mast, and the three stays, the stays abeam are wire, the forestay is rope and goes through a pulley to the cockpit allowing the rake of the mast to be changed
     

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  12. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member

    Aloha Peter. Yes the CC has its trade offs, but is perfectly suited for our Hawaiian waters and trade winds. It certainly got the job done for the Polynesians. The simplicity and ease of use are probably the best qualities if you want to just putt around without fear of being overpowered in gusts. My boat has so much technology in it, it’s days of flying a hull are over. That’s what my Hot Rodded Hobie Wave is for.

    Your suggestion about repositioning the tack has the same affect of the adjustability I am leaving in the position of where the upper sprit hangs from the A frame. As you push the A frame forward, this rotates the sail into a vertical position moving the sail area up higher and forward like the traditional crab claws did to grab the trades when in swell. Pulling the A frame backward then rotates the sail more horizontal putting the sail area lower and further aft.

    I know how these Hobie Cats behave with main only, jib only, etc.., but because I have two big lumps of brushless motors hanging off the rear where the rudders once hung, and a bimini with a support frame and batteries in the hulls, its going to take some dialing in.

    Hopefully I’ve left enough adjustability in the system to get it to work satisfactorily. I can always add a bow sprit to move the tack forward as you suggested if I find I didn’t leave enough.

    The Holopuni Sailing Canoes which are common around here have one of the simplest and effective sail rigs. The owner of this canoe shown in the photo covered more area than anyone else for many years with his boat. Solo, with passengers, light winds, strong winds, I was always impressed to see him covering so much “ground”. There’s another that flys a head sail sometimes that really moves downwind.

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  13. peterAustralia
    Joined: Mar 2006
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    peterAustralia Senior Member

    OK, always good to experiment, best of luck
     
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  14. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Junior Member

    Forgot to mention that when you buy wholesale, those panels are less than half the cost of retail bringing the cost down to about $1/Watt. Minimum order is a crate. Also some of the former SunPower people have an offshoot company using the Maxeon cells, but making better use of the footprint by adding cells to cover the whole area of the panels, and moving the junction box to the corner in place of one cell. The company is called Sol-Go.

    SOL-GO http://www.sol-go.com/
     
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  15. peterAustralia
    Joined: Mar 2006
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    Location: Melbourne Australia

    peterAustralia Senior Member

    from facebook proasailing group
     
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