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Thread: GIS Yawl

  1. #61
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    Default

    Email is fastest at the moment. I can check it more easily and the lack of images make it download faster.

    My internet connection problem should be resolved soon.

    Michael

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  3. #62
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    Default Yawl tweaked again to fit dory

    I tweaked the mizzen yet again so that it fits into the stern of the dory better. Both plans attached.

    This dory is to be a companion to the Goat, using the same rig as well as able to take a couple more rigs that I will draw for the boat, a trad. dory rig and a standing lug rig.

    The dory will have a centerboard and I'll follow the same foil design but make it a centerboard. A lot of thought has yet to go into its design.

    One of our volunteers commented that the lesser rake of the mizzen in the dory looks more pleasing to the eye. It made me think maybe so. Michael, what do you think of the mizzen rake at this point?

    Cheers,
    Clint

  4. #63
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    Howdy Clint,

    I agree. Probably because the dory has so much rake at the ends. Will be REALLY interesting to compare the sailing capability and performance of the two boats under the same rig. Not to mention the rowing performance with the rig partly up.

    Best wishes
    MIK

  5. #64
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    Hi Clint, would it be ok for me to mention what caught my eye most as a comparison. The two rudders. Lovely deep blade for Goat and what looks a bit shallow depth on the dory? Hope it's ok to say so, I am no dory expert at all, it just caught my eye. Looking again it might be just how you drew the water line.

    Compare with Iain O's dory of a similar size

    http://jordanboats.co.uk/JB/IainO_Ca...ohn%20Dory.pdf

    Brian

  6. #65
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    Brian, Yup good observation...that construction is just a sketch without looking at dimensions. In fact, IO's John Dory, which I have built, will be a useful guide for sizing centerboard, rudder, etc. He drew 7 rigs for his John Dory, one of which is a nice balance lug sail, but not as nice as the Goats. I'll prob. add a little length to his CB.

    It will be interesting to have these two boats with the same rig, Mik. These two boats represent the next 2-3 years of my shop life (less if I lose my job!), so it is fun to see it coming together.

    Clint

  7. #66
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    Speaking of rudders (it looks a little small to me, too, but I ain't a dory expert by a mile!), I'm wondering if the Aussie rudder box could be adapted to a traditional craft like a dory...It sure would be nice to be able to raise and lower the blade Aussie style while keeping the traditional look...?

    If you think about it, the angle of the attachment and the immersed leading edge are perfect for a rudder box. When the blade strikes bottom it would just slide up. It shouldn't be too hard to rig lines that let you pull it back down...

  8. #67
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    Will be a fascinating comparison. You do realise Clint, that you are going to have to make two rigs to really test them side by side, and you will need another helmsman - consider my application for that post as applied for.

    Brian

  9. #68
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    Thanks for thoughts guys. I think the Aussie rudder box is ingenious and saw it for the first time on the GIS.

    But I have to go with tradition and do the dory rudder. It will be mounted on a bronze rod so the rudder slides up the rod rather than popping out of gudgeons so it is practical. And, until I sailed an Alpha-Beachcomber this past summer, I thought the rudders on those boats were way undersized. But somehow the thing digs beautifully and gives great control. That is largely due to the fact that under sail power, especially in a breeze, the stern squats and the rudder sinks and digs even more. This is also why a GIS would whoop even the best sailing dory especially on the wind and on a reach. However, the dory will be used for tandem rowing as much as it is used for sailing, a true sail-and-oar boat.

    Back to the GIS, I will be able to sail the dory next to Dana's GIS which will bear a new sail rig soon. The sail rig is coming together nicely. See pics on my new website.
    www.clintchaseboatbuilder.com



    Cheers,
    Clint

  10. #69
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    Very nice ... a quick explanation of what you are doing might be interesting to go with the photo (remember to put the same text with the photo on your webpage too - it will attract people looking for info on google very effectively.

    Also I did notice this


    I particularly like the antique stool that supports the Goat! You have a very high grade of trestles for your mini goat Island Skiff Model!

    MIK

  11. #70
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    Clint:

    I am looking forward to sailing this Spring and seeing the GIS yawl you are building. Judging by the quality of your work, I'm sure that comparing my GIS to yours will be like comparing the build quality of a Trabant to that of a BMW!

    By the way, I am thinking that a 5 hp gas motor is too heavy and bulky to tote around. I may try a transom-mounted electric motor and another battery, which would allow me to have two batteries under the mid-seat; that would be nice ballast as well as I will be sailing solo 90% of the time. What do you think?

    Dana

  12. #71
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    Default A Carbon Fiber Goat Mast!!!

    As some know I am giving and receiving training in high tech composites technology here in Maine and have access to a remarkable facility. One of my pet projects I am sketching out with the help of a couple composites gurus, is making a half-mold of a mast for a Goat Island Skiff. I would also aim to have this mast useful for other of my designs or other boats that can be potentially retro-fitted for use with a balance lug (with a mizzen of course!).

    The rough procedure is to make a plug -- or perhaps use an actual mast if the same dimensions apply to a CF mast -- and to lay-up a fiberglass mold with flanges around the plug. There is a lot to work out there. With the half-mold the carbon would lay inside the mold and wrap up onto a temporary inside flange. The whole bit would be vacuum bagged and infused with epoxy resin. Two halves would be made and glued together along the inside flange. This is about as far as I've gotten!

    It is clear that an key early decision is what are the ideal dimensions of a carbon mast? That one is for Mik. If the ideal diameters and taper are different, I'd make a separate dedicated plug for the mold, which is preferable anyway.

    By the way, I plan to make the B'mouth first to get sailing. This project is for next winter!

    Clint

  13. #72
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    Clint, I have been using 50% carbon / 50% glass spars on my lug rig for three full seasons.



    It is well worth while. The very light spars are a delight to raise and use. My tubes have no holes in them at all, so good buoyancy can be kept.

    There is one big difference though. Wood and alloy spars can be stiff from first loading, whereas carbon is different. It seams to bend easily at first and then stiffens up as a bend develops, just as a windsurf mast is always set with lots of prebend. This can affect light wind sail setting, then as wind increases the yard works very well. Boom seems to develop a lot of bend, as does the mast in strong winds.

    My sail is smaller than the Goat, and uses 50mm mast and boom tubes, with a 40mm to 20mm tapered yard. The specs can be seen here, which might help,

    http://carbonfibretubes.co.uk/standard.html

    If I were to order again I would probably spec an extra wrap of carbon to stiffen some what.

    They also look cool.

    Brian

  14. #73
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    The new birdsmouth option for the mast will solve many of the issues (as does the hollow square mast option). Both approximately halve the weight of the original solid mast.

    The hollow square mast is in the plan and the birdsmouth option is available free from me.

    Best wishes
    Michael

  15. #74
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    So, is a carbon fiber Goat mast a worthy project to consider with the training, resources, and motivation to make one from scratch? i.e., Mik wouldn't a CF spar still be superior to a b'mouth or square hollow. I'm lifting this square hollow spruce mast for the Goat I am building and thinking it is pretty hefty. A carbon equivalent would be sensationally lighter. So, I will be curious to know how to size it. I noted Brian's thoughts.

  16. #75
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    Howdy Clint,

    I think a carbon stick is a worthy project. Just wanted to make sure that following readers understood it was an option rather than something required.

    MIK

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