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Thread: Pivoting Amas for Sailing Canoes

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    Default Pivoting Amas for Sailing Canoes

    Hello, I am going to attempt building pivoting amas for my sailing canoes, like Meade Gouge used on his Woodwind and ElderlyCare canoes. I don’t have the dimensions that he used for his, just some pictures, below. I will use them on canoes with a length of 14.5’, 15.5’, and 17.5’. With sail areas of 35, 46, and 80 square feet.

    E2CE76D7-6A56-4141-8B0C-9D5C3BFF89A3.jpg BB4ADDAD-519C-47DE-8AC6-F56D171C5E89.jpg

    My first questions are: length, ama beam, over all beam for both amas, depth, and how many pounds do they displace? Trying to guess sizes for the pictures. I have started with amas to the following two different shapes one if fuller than the other. Dimensions are 5”-5.5” beam, 8.5” deep, and 84” long. I’ll work out the volume in a bit. Straight sides down the length. Built of it 4-5mm ply. I only have .5mm on hand now. Drawings below.

    What do you guys think? Has anyon seen this boats of Meade’s?

    7992AFF3-2F96-49C3-B819-549F7EC2EAE5.jpg 1DBB83D1-0187-4FBD-A2B2-985D56F4533E.jpg
    Last edited by Matt young; 04-01-2018 at 11:49 AM.
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    Default Re: Pivoting Amas for Sailing Canoes

    I have a similar interest.
    Haven't been able to find any dimensions or shapes for Meade's boats.

    Right now I have a small Laser sail and mast. So my overall geometry would be limited to the righting moment of a hard sailed laser.
    This is to protect the laser mast which is known to fail with prolonged hard sailing.

    Also, I would make the amas using strip planked cedar. should be an easy quick build of 1/4" cedar and 6oz cloth inside and outside.
    Deciding the shape and making the stations would be the hardest part. You could easily make a much better shape.

    Good luck and please keep posting your progress.

    Just remembered this forum about sailing canoes - there might be some references to ama sizes that have been used. http://www.songofthepaddle.co.uk/for...Sailing-Canoes
    Solway dory has some sailing canoes. Much smaller fixed amas and bigger double cross arm amas - nothing that directly compares.
    There was also a recent contestant in the Ultimate Floridage challenge with this kind of boat. Actually 2016 - http://sailnaway.blogspot.com/

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    Default

    This is a similar design, if you look through the blog you will find a lot of details

    http://sailnaway.blogspot.co.uk/

    There are some good videos which show the movement of the AMA.

    The guy that sailed Elderly care has added anti dive plains to the AMAs this yeabr />

    I am experimenting with inflatable AMAs- see vids below, very crude but an easy way to get the buoyancy right. The one issue I have had is the AMAs toeing in so worth thinking about how you prevent that.


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    Default Re: Pivoting Amas for Sailing Canoes

    Bump, I really hope others interested in this subject will see this and comment.

    Any conclusions, so far?

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    Default Re: Pivoting Amas for Sailing Canoes

    Upchurchmr and Tink,

    Thank you for the replies and suggestions. I have been going through them and thinking.

    Nice picture of Voyageur. And Randy Smyth's trimaran Synergy in the background, for a whole other way to build an outrigger. OK, anti-dive plains, that is a very interesting piece of information. Believable that they would be needed. Do the amas need more buoyancy in their bow or all the way down the hull? In other pictures I have seen a line in theses amas that appears to lead from forward of the pivot points on the ama, around the pivot point and to the cockpit, don't know what that is for. Could this have been to help keep the bow up, automatically or manually? I thought about a stopper pad or flat spring type system that could keep the bow from diving. But then I wondered if the ama would just stay pinned against it, if it didn't have enough natural buoyancy to raise itself.

    If I have my facts right, Meade and Jan built large trimarans with pivoting amas, and they liked them. I wonder how those functioned and preformed.

    You both sent me into the Sailnaway blog. I had followed his work earlier on but hadn't keep up. Thanks for that, its a really good build with some nice details. I haven't had time to go through the whole thing yet. It was really good to see his amas in action, being able to move the way they do really makes sense to me. Yes they are shorter than Meade's. They appear to be 4' long? My first reaction from watching them in the video is that they seam too short, but then I wondered if that might keep them from nosediving. There looked to be a fair bit a turbulence on the trailing edge of them, or maybe that is to be expected. I wonder if some rocker on their run would help that?

    - Yes I have seriously considered the Soloway style ama. I decided against it for now, for a couple of reasons. I want to go with a trimaran vessel, two of my canoes have hull shapes that work much better the flatter they sit. I am not looking to hike out. My long goal is to have an cruising setup, one where I would sit comfortably for many hours, doing this is all wind conditions. I also like the possible higher speeds, more distance, you can get with the trimaran set up. With that said I want amas that are not so big, so I can stand on them and right the vessel if I were to turtle. Not very likely if I stay with lug sails, tested and approved in a very rough condition capsize experience, was able to right, re-enter, and bailnaway.

    This is the pivoting ama I am going to draft up next, while researching some more. At some point I'll have to make one and test it, I am starting to think about doing this in SOF construction.

    - 66" long
    - some rocker to the run
    - a fuller bow, but still trying to keep it lean and efficient
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    Default Re: Pivoting Amas for Sailing Canoes

    Scaling from the picture of Voyager, the ama seems to be ~ 6' 10". Shorter, fatter amas will slow you down and cause more spray. Just the opposite of everything Gougeon designed.
    To me it seems about the same as Gougeon's Elder Care.
    You are naturally going to get turbulence off of a square sterned ama.
    You could put more rocker, or make it double ended to reduce the drag, but on a tri you are always going to depress the leeward ama.
    How much you allow it to depress will depend upon how much you want to get driving force from the sail. A boat like this is intended to depress the ama until you decide to reef / let out the main.
    I believe the intention is to have less total bouyancy in the ama than the weight of the boat, meaning you could "never" get the main hull to rise out of the water - limiting the chance of turning the boat over. In fact, if you want higher speeds, you should increase the size of the ama (also increasing the risk of capsize, and making mast, crossbeam, leeboard, rudder, and hull connections heavier to take the load). That may be too obvious to state - sorry.

    Canoes are really poor shapes for high speed, due to the quick curve in the hull from the bottom to the sides - IMHO. A kayak is much easier to get up to speed than a typical canoe due to this shape difference. I suspect the Gougeon boats are more like a kayak or higher speed sailboat than a canoe.

    Having built a bunch of SOF kayaks, I personally wouldn't use one here. They just don't have the structure (typical design) to take sailing loads if you want to go faster. The skin also distorts from water pressure (caves inward) which will slow you down even worse when sailing. If you really want one, take a look at Dave Gentry's designs. gentrycustomboats.com

    If you want more resistance of the ama to nose diving (without anti-diving planes), the time honored way is to raise the bow deck height rather than making it fatter. See Dicknewickboats.com

    By the way, have you seen Gougeon's book on Epoxy boat building? Free download: https://www.westsystem.com/the-gouge...-construction/
    Lots of information on high speed trimarans.

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    Default Re: Pivoting Amas for Sailing Canoes

    I think the idea of pivoting amas is relatively untried and testing but is the way to go. If you get the design right I think dive plates are not necessary Meade did the Everglades challenge without them, the guy that did it this year has added them for some reason - they look last minute based on not being painted. I did find him on FaceBook, I will see if he will answer a few questions through that.

    One problem with pivoting amas I have thought of is if they leak, if the water ends up in the bow it may cause issues.

    I don’t know if you have been following the inflatable proa link but it went a bit off topic and there are details of a proa made with a simple frame and pallet stretch wrap used as a skin. I was thinking that it would be a great way to make experimental amas for my canoe. You could make them on a frame or cover foam in the stretch wrap to get the design right before covering with glass. I think a wave piercing bow design might be orthodox looking at. I think the stretch wrap construction would allow lots of testing for little money or cost.



    http://forum.woodenboat.com/showthread.php?236562-Inflatable-Proa&p=5526418#post5526418

    Look at posts 50 onwards especially Tom Christie ones.


    The big tri was called Adrenaline, it use a laminated leaf spring at the back, here is a video https://youtu.be/M8pVa4-PQmc
    you can see the leaf spring in the stills at the start of the video but at about 45seconds in there is a shot of the underside which what looks like a ridged mount.

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    Default Re: Pivoting Amas for Sailing Canoes

    Re stopping bow going down, your post 5, there certainly appears to be some sort of stop / limiter in the pictures

    I would imagine that when the ama was to leeward you would be happy it pivoting freely, which would de-stress the whole system - the whole point of pivoting in the first place. You might want to lock the windward ama so it didn’t risk tripping over its self ????

    I think, but it is very open to interpretation, the windward ama is moving a lot less than the leeward in the second video,


    https://youtu.be/XN9R_ee1vEk

    https://youtu.be/SRPOrY-8z1k

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    Default Re: Pivoting Amas for Sailing Canoes

    Quote Originally Posted by upchurchmr View Post
    Scaling from the picture of Voyager, the ama seems to be ~ 6' 10". Shorter, fatter amas will slow you down and cause more spray. Just the opposite of everything Gougeon designed.
    To me it seems about the same as Gougeon's Elder Care.
    You are naturally going to get turbulence off of a square sterned ama.
    You could put more rocker, or make it double ended to reduce the drag, but on a tri you are always going to depress the leeward ama.
    How much you allow it to depress will depend upon how much you want to get driving force from the sail. A boat like this is intended to depress the ama until you decide to reef / let out the main.
    I believe the intention is to have less total bouyancy in the ama than the weight of the boat, meaning you could "never" get the main hull to rise out of the water - limiting the chance of turning the boat over. In fact, if you want higher speeds, you should increase the size of the ama (also increasing the risk of capsize, and making mast, crossbeam, leeboard, rudder, and hull connections heavier to take the load). That may be too obvious to state - sorry.

    Canoes are really poor shapes for high speed, due to the quick curve in the hull from the bottom to the sides - IMHO. A kayak is much easier to get up to speed than a typical canoe due to this shape difference. I suspect the Gougeon boats are more like a kayak or higher speed sailboat than a canoe.

    Having built a bunch of SOF kayaks, I personally wouldn't use one here. They just don't have the structure (typical design) to take sailing loads if you want to go faster. The skin also distorts from water pressure (caves inward) which will slow you down even worse when sailing. If you really want one, take a look at Dave Gentry's designs. gentrycustomboats.com

    If you want more resistance of the ama to nose diving (without anti-diving planes), the time honored way is to raise the bow deck height rather than making it fatter. See Dicknewickboats.com

    By the way, have you seen Gougeon's book on Epoxy boat building? Free download: https://www.westsystem.com/the-gouge...-construction/
    Lots of information on high speed trimarans.
    a very good observation of the design issues, thanks. Less thanks for reminding me the book I paid hard cash for is now free.

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    Default Re: Pivoting Amas for Sailing Canoes

    Tink,

    I also bought the first issue of Gougeon.

    I'm quite puzzled about the control on the ama. One picture looked like it was a rope/cord going aft of the aka. The only thing that could do is pull the stern up and the bow down. This might be useful in light winds reaching. It would be nice if Matt Scharl could offer some comments. I did send a message asking if the design for Voyager would be available. No answer yet.

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    Default Re: Pivoting Amas for Sailing Canoes

    Amas that pitch independently from the main hull are common in traditional Pacific Island canoes. Tahitian canoes use a stiff forward crossbeam and a very flexible light branch for the aft beam, in effect similar to the wooden spring used on Adrenalin. The marshall Island canoes mount their crossbeams quite close together which allows the ama more pitch freedom.

    https://photos.app.goo.gl/BsE0B2z43fmnY1CL2
    https://photos.app.goo.gl/qCwnnNov36rBkFaj1

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    Default Re: Pivoting Amas for Sailing Canoes

    Gary,
    Great information, details, and examples! That certainly shows two more ways do support flexing amas. Thank you.
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    Default

    Probably the most commercial available and proven (certainly seam to be lots used on Everglades Challenge coverage) low volume ama long single aka are the BSD BOSS inflatable amas .
    http://www.baloghsaildesigns.com/ama-extreme.html

    They look odd but seam to work and be popular. Looking at then there are a couple of things that jump out at me
    1 - Lots of volume in a short package forward of the aka and so very little risk of a nose dive / tripping ovebr />
    2 - Similar volume and more weight in the long tail aft of the aka which keeps the nose up and will stop the ama trying to toe in, an issue I have had with my amas.

    I will work on some more hydrodynamic and aesthetically pleasing design on cad with these characteristics to see where it leads

    https://youtu.be/XSnQ0U19OjY





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    Last edited by tink; 04-06-2018 at 03:40 AM.

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    Default Re: Pivoting Amas for Sailing Canoes

    These are the examples Gary referenced.





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    Default Re: Pivoting Amas for Sailing Canoes

    Tink, I like the direction you are going. Below is an image of Adrenaline, it has a larger and finer version of the tappered shape you are talking about. The run does raise up at the stern of the amas. I have also attached an image of the leafspring detail at the stern. I also like the reverse rake of the transom.

    34148BB2-E3F2-47DB-A014-AA0BBD38F318.jpeg 6E667D9C-A672-495F-9342-179102D1D0C9.jpeg
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    Default Re: Pivoting Amas for Sailing Canoes

    Thanks Matt,
    reached the limit of what I can do with Onshape I think, will play on Delftship next time I have enough steam to run my laptop

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    Default Re: Pivoting Amas for Sailing Canoes

    I don't see the connection between short, fat, inflatables compared to the Gougeon boats - Adrenalin, Voyager, Eldercare and compared to Gary's examples which are even more extremely narrow.

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    Default Re: Pivoting Amas for Sailing Canoes

    Quote Originally Posted by upchurchmr View Post
    I don't see the connection between short, fat, inflatables compared to the Gougeon boats - Adrenalin, Voyager, Eldercare and compared to Gary's examples which are even more extremely narrow.
    ignoring shape for the moment the Gougeon style boats and ones fitted with the BSD floats use a small amount of buoyancy on a relatively long aka to achieve the righting force they require. Both types generally mount the aka quite far forward. I would say that both fall into the category of “A boat like this is intended to depress the ama until you decide to reef / let out the main.” - from your post 6.

    It would be a requirement that both types have a centre of buoyancy roughly in line with the aka attachment point.

    The Gougeon type appear to be slightly nose heavy and as such there may be a risk of nose diving, from my experience there may also be a risk of the bow towing in by which I mean the bow of the ama slewing to the main hull.

    The BSD inflatable floats put the centre of gravity aft of the ama attachment and so the ama will fly with the stern down. This type can be made with the same length to breadth ratio as the Gougeon type, it is just a different placement of the volume.

    What I have drawn at the moment is ‘tubby’ as in my first stab at a design I did not go to far from the BSD, this envelope can now be stretched

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    Default Re: Pivoting Amas for Sailing Canoes

    Pardon my ignorance, but have any of you guys tried to call or write the Gougeon boys to ask them if they'l share their thinking on this?
    It never hurts to ask.

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    Default Re: Pivoting Amas for Sailing Canoes

    Both of the Gougeon brothers have passed on.
    "Yeah, well, that's just, like your opinion man"
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    Default Re: Pivoting Amas for Sailing Canoes

    Actually its all three Gougeon Brothers have passed on.

    I have written Gougeon company, there is an article on Meade's sailing canoes, but it is not heavily technical.
    One of his early sailing canoes has been reproduced as a mold by a group in Michigan, but they would not reply about obtaining the design. Apparently it is a local boat building association for training youngsters.
    Hugh Horton drew the lines for the Bufflehead, which was the basis for Meade Gougeons early sailing canoe (no amas). He sells just the basic lines and will talk a little about how the rest of the boat was built. Meade deviated from those lines in his last boats with amas. He had a "respected" Canadian kayak builder make his first boat with amas. I tried to contact him and got no answer. Apparently he works by eye - no formal plans and adjusts the next boat from experience and sailor desires. I haven't found lines for the last boats, nor any other details.

    As I said, I sent a question to Matt Scharl about the Voyager design. He seems to be a very busy sailor and has not replied.

    I desperately hope someone else will have better success and share it.
    Barring that, my latest fantasy is to get the lines for a Flying Dutchman and narrow the boat significantly, since that is a really fast monohull. Of simply take a typical catamaran hull and adapt it to a tri canoe type boat. You really don't need any stability for the main hull by itself.

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    Some CAD ‘sketches’ of different length - ‘buoyancy forward, weight aft pivoting amas’, all with the same buoyancy. Obviously as the L:B ratio increases so does the weight per kg of buoyancy and wetted surface area. I use my current amas for secondary stability and they are not in the water that much so think the convenience of lighter shorter ones suits me.






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    Default Re: Pivoting Amas for Sailing Canoes

    Tink,

    Why do you think your ama shapes are so much different from Meade Gougeon's shapes?
    His design did win the class for the Everglades Challenge.
    I'd think that was a pretty good recommendation.

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    Default Re: Pivoting Amas for Sailing Canoes

    I no way want to discredit his designs but the ama hangs down bow heavy and he appears to have added features to control this. I am wanting to emulate the BSD design which hangs bow up. This requires the centre of buoyancy just infront of the aka attachement and the centre of gravity behind the aka attachment. Hence the funny shapes.

    I am also not after speed, just a safety amas to stop capsizes. My canoe sails fine without floats in a steady wind but I also sail on a river where the wind is unpredictable and could cause a sudden nockdown.

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    I have had another look at the SOS Adventure canoe which completed the UC in 18 1/2 days so a good test

    The adventure canoe had a control but the broke during the challenge but this shows the mechanics



    Also at some point during the race he added dive plates






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    Default Re: Pivoting Amas for Sailing Canoes

    Quote Originally Posted by tink View Post
    ... from my experience there may also be a risk of the bow towing in by which I mean the bow of the ama slewing to the main hull.
    You could resist this by attaching a non stretch line near the stern of the ama to the the support for the aka on the hull, it should not prevent the float from rotating but still keep it parallel to the main hull.
    If there was a tendency to toe out, a similar line at the front of the float would help.

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    Default Re: Pivoting Amas for Sailing Canoes

    You might need to worry more about toe in with an inflatable - no real sideways strength.
    On a rigid ama you should be able to control the toe in by having wide enough attachment brackets at the aka.

    What I see is something to pull the nose of the ama down. Since it's a rope it cannot pull the nose up.

    So it looks like the anti dive planes and the aft rope control are doing two different things.

    Perhaps his slightly reverse raked bows on the amas did not help with nose diving.

    Anyone who spends 3 days in one of these has my sincere admiration, and 18 days is just insane.

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    Default Re: Pivoting Amas for Sailing Canoes

    Quote Originally Posted by oldcodger View Post
    You could resist this by attaching a non stretch line near the stern of the ama to the the support for the aka on the hull, it should not prevent the float from rotating but still keep it parallel to the main hull.
    If there was a tendency to toe out, a similar line at the front of the float would help.
    I’d added bridles as dockside fix achieving what you suggest. My akas/amas telescope in to aid getting in at a jetty these interfer with this. I am also wanting to keep it as simple as I can.

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    Default Re: Pivoting Amas for Sailing Canoes

    Quote Originally Posted by upchurchmr View Post
    You might need to worry more about toe in with an inflatable - no real sideways strength.
    On a rigid ama you should be able to control the toe in by having wide enough attachment brackets at the aka.

    What I see is something to pull the nose of the ama down. Since it's a rope it cannot pull the nose up.

    So it looks like the anti dive planes and the aft rope control are doing two different things.

    Perhaps his slightly reverse raked bows on the amas did not help with nose diving.

    Anyone who spends 3 days in one of these has my sincere admiration, and 18 days is just insane.
    My inflatable has a ridged spine so does not bend sideways, the attachment to the ama was not ideal and the likely contributed to the toe in. Obviously though there is a stress in this area which would be good to understand and reduce.

    Yes fully agree that the control nad the dive planes are doing opposite tasks. I would like to eliminate both however.

    And 18 days does show signs of insanity, might explain why he tried to sell it as soon as he finished.

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    Default Re: Pivoting Amas for Sailing Canoes

    Gary,

    What is your opinion of the different benefits for pivoting amas and more rigidly attached amas?

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    Default Re: Pivoting Amas for Sailing Canoes

    Quote Originally Posted by upchurchmr View Post
    Gary,

    What is your opinion of the different benefits for pivoting amas and more rigidly attached amas?
    They both work and I don't really see much advantage in one or the other. My first priority with an ama is to have a veed deck so that it can come out of the water easier when it becomes submerged into a wave face.

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    Default Re: Pivoting Amas for Sailing Canoes

    My first priority with an ama is to have a veed deck so that it can come out of the water easier when it becomes submerged into a wave face.
    That was exactly my first thought when I saw that wide flat top on the forward part of that new ama drawing.

    One thing about trimarans in particular is that at times, and with chop coming from certain directions, they can develop a very uncomfortable, semi-nauseating wobble that a lot of folks find pretty uncomfortable.The pivoting ama might go a long way toward reducing that effect.

  35. #35
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    Default Re: Pivoting Amas for Sailing Canoes

    The general trend in ama design has been to go with wave piercing hull shapes as opposed to the old-style amas that are intended to stay above the water always. For this reason, they are also designed to pop back up onto the surface very easily. I seem to recall those Adrenaline amas as being described as cigar shaped. This was an innovation at the time (OK, in Western boat development) -- the combination of a wave piercing hull and a pivoting structure so that the ama would provide lift but be otherwise free to move through the waves fishlike with very little drag.

    But keep in mind that the volume and length of any ama will determine how much speed you can get out of a trimaran. When pushed hard, the boat sails on the leeward hull and the other two hulls pretty much go along for the ride. If the ama is short or of low volume, you'll place a real limit on performance. When putting the whole design together, the ama needs to be able to support the full sail plan -- it's not just a secondary support for added stability.

    Also, when it comes to safety, the bigger the amas, the harder it will be to capsize the boat. Not the other way around as suggested high up in this thread. And if ever she does wind up keel in the sunshine, then an easy folding system might help sort things out. But of course it's better to have a boat that wants to stay upright in the first place.
    -Dave

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