Maybe, maybe not

Discussion in 'Boat Design' started by valery gaulin, Oct 23, 2021.

?

Should I build?

  1. Maybe

    90.0%
  2. Maybe not

    10.0%
  1. CT 249
    Joined: Dec 2004
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    Location: Sydney Australia

    CT 249 Senior Member

    Sharpii, I meant the fairly standard modern rig of short overlap fractional jib and "pinhead" main. I agree that square tops/flatheads are not ideal for all boats.

    The main on my 36'er takes less than a minute to reef, singlehanded, from leaving the wheel to getting back to it. It could be lots faster if I just got around to tweaking. The luff on my boats is pulled down by an extra-long Cunningham eye tackle so no winch is required. The halyard is just dumped from the clutch to a marked point and then one winch (near the companionway) is wound down. No leaving the cockpit, no problems, and it can be done on a square run as well.

    With a nice modern rig you don't need to reef or change jibs until 25+ knots if you have the rig tweaked and are sailing well; mast bend, sheet, vang and traveller controls will depower the rig.

    The Dacron main on our boat is 2004 vintage, I think, and still has quite a good shape and no structural issues. It does require more attention to cunningham, vang and mainsheet than a newer sail but that's only when trying to tweak it to far better all-round performance than a JR could come close to according to the JR people themselves. The jib I recently threw away came out all the way from New York on the boat and it would have been about 25 years old at least, I'd say. That's pretty good going and I'm not sure why a junk rig would be significantly better, all else being equal.

    While junks may be easy to reef, that's a lot of weight to pull up every time you go sailing. Even when we lived in a windy part of the world (south coast of NSW, Australia) we didn't reef most days, so it seems odd to have to drag up a heavy sail 10 days just so you can drop it down one panel more easily the other day.
     
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  2. valery gaulin
    Joined: Jan 2017
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    Location: Montréal

    valery gaulin Senior Member

    @Tops @clmanges @CT249 Here is some pictures of the water displcement for 6500 lbs and also at 20 degree heel angle. I calculated the prismatic coefficient to be cp = 0.64, is it too much considering that it is a motrsailer? I don't expect to sail when there is light wind! I intend to motor sail to keep a speed between minimally 3 knots , cruising 6 knots, and probably 7 knots when possible!

    Also attach are pictures of the waterline length as was ask from some of you! View attachment 174086 View attachment 174087 Untitled CC construction side view with waterline v275.png Untitled CC construction with waterline v275.png Untitled CC construction heeling displacement comparison.png View attachment 174091 Untitled CC construction heeling displacement 20 degree.png Untitled CC construction prismatic coefficient 0.64.png
     
    Last edited: Dec 6, 2021
  3. valery gaulin
    Joined: Jan 2017
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    Location: Montréal

    valery gaulin Senior Member

    @sharpii2 @bajansailor

    Here are some section view if interested! And maybe the post above with the waterline at 6500lbs displacement at 20 degree of heel. Untitled CC construction section view fore and aft v275.png Untitled CC construction section view forward cabin v275.png
     
    Last edited: Dec 6, 2021
  4. RogueUK
    Joined: Dec 2021
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    Location: UK

    RogueUK New Member

    Apologies if you've addressed this already but I missed it - how are you planning to transmit the load from the mast down into the keel? A compression post at that location seems like it would get very annoying very quickly in terms of visibility?
     
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  5. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Looks well suited to an A frame/sheerlegs rig- easy to raise and lower.
    Jeff.
     
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  6. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    Good point! But I was expecting to have the steering station exactly at that center bulkhead to starboard. Basically right beside the mast/compression post, I believe it would allow good visibility forward for the pilot.
     
  7. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    Yes, but they look ugly!
     
  8. Tops
    Joined: Aug 2021
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    Location: Minnesota

    Tops Senior Member

    Hello Valery, is this what you are thinking of for helm and mast location? Looking at the link on page 1, does that update with your changes to the model?
    Untitled CC construction_snapshot.png
     
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  9. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    Yes, this is exactly what I have in mind!

    My 3D computer model is not updated with this yet! No time to draw...
     
  10. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    In the eye of the beholder, if lots had them they'd be "normal", if you like simple, strong and versatile for loading heavy things they're pretty cool. Still gotta have a wire down the middle for the luff of the main. There is some weight inefficiency compared to a single stick.

    What I'm not following is the flare in the raised deck portion- seems that the deck edge exposed to wharves/whatever when the sponson/rubrail is on the lower sheerline.

    Jeff
     

  11. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    The flare in the raise deck portion is mainly for deflecting water, also I will put round port hole in this area, therefore less direct sunlight inside the cabin, more deck space, and also for looks to balance the straight sides of the hull.
     
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