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Thread: 4-sided sails on Raid sailboat

  1. #1
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    Default 4-sided sails on Raid sailboat

    Who knows how to setup and trim 4 sided sails for speed, efficiency, pointing ability?

    Clint Chase Deer Isle Koster (KDI is preferred over DIK).
    14 feet, about 250 pounds with gear, and about 100sf sail area. CNC kit with some early design details that were changed such as kick up control of rudder.

    The KDI gets picked up next week and goes immediately to Pocket Yachters Palooza in Port Townsend. The three day cruise that follows is tentative, unknown sailboat, never sailed in area, and not sure about sleeping on board, also tweaked my back while changing brake rotors on truck.

    But , other day sails on way back are under consideration, such as Humboldt Lagoon(s) and maybe coastal rivers to inland.

    Ants
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    Last edited by AntsUiga; 07-10-2021 at 04:01 PM.

  2. #2
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    Default

    I "watched" the development of the Deer Isle Koster on the Wooden Boat forum, it's a gorgeous boat and a wonderful camp-cruiser.

    About balanced lug sail trim...low stretch halyards are your friend. If the downhaul on the front of the boom is not 2:1 already, make it so. 3:1 ....mmmmm. Maybe. 4:1 is probably too much. However, you want that leading edge nice 'n tight. The most common balanced lugsail oopsie looks like this.

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    See the big crease from the back of the boom up forward to the front of the yard? If you get that, try two things...1.) easing off on the boom downhaul and then topping up the yard harder and then...2.) tightening down on the boom downhaul.

    you have a little bit of this going on already in the photo you posted. You can also try making a change so the boom rides an inch or two further forward, relative to the mast.

    Wonderful boat!
    S-2 7.9: "Wildcat of Loch Awe"
    1968 Selmer Series 9 B-flat and A clarinets
    1962Buesher "Aristocrat" tenor saxophone
    Piper One Design 24, Hull #35; "Alpha"

  3. #3
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    I'm still hoping that an SSS "raid" - small boat cruise is in the works for someday. It would be fun to see your Koster out with RoG
    S-2 7.9: "Wildcat of Loch Awe"
    1968 Selmer Series 9 B-flat and A clarinets
    1962Buesher "Aristocrat" tenor saxophone
    Piper One Design 24, Hull #35; "Alpha"

  4. #4
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    Default

    Any interest for the next SSS Raid is always good!

    I have one on the calendar with TSCA on Tomales Bay in September.

    I have been searching for useful ways to improve sail trim. The search has not yielded an overabundance of good information. In general, the sail attachments are not fixed, or are open to many variables. The sail is fixed on the tack of the boom, but the location of the boom relative to the mast can move up or down, forward or aft. Simple - Yes, but subject to lots of options.

    On this boat, there is a fixed fairlead and hook on the yard with a ring to hold yard close to the mast. As for your suggesting to move the yard side of sail, there is a limit (1-3 inches) by adjusting the lashing. If that does not work, the attached fairlead get screwed to another location.

    Ants

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  5. #5
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    Ants,
    Alan suggested: “You can also try making a change so the boom rides an inch or two further forward, relative to the mast.” Wouldn’t moving the yard aft do the same?

    I
    t looks like the eye plate on the yard was moved aft at some time. Which moved the yard forward. If it went back to the original position would that help? Maybe the attachment point on the yard needs to be adjustable? Or you could try using a lashing temporarily to find the right attachment point.
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    Last edited by Dazzler; 07-11-2021 at 10:46 AM. Reason: Added italicized sentence for clarity.
    Tom P.

  6. #6
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    Both excellent suggestion from Alan and Tom.

    My concerns are based on a set of photos without seeing the boat in person. It would be nice to have a general plan when I can move and adjust things.

    Step 1 would be to unlash sail from everything, support it on 4 corners and see what shape gravity gives the sail. How full is the luff? What happens when tension is applied to each corner? All this confirm how well the sailmaker did their craft.

    Step 2 may be to add yard and boom and see how that impacts horizontal sail shape.

    Step 3 would be to use lashings to move checkout to mast. Then the fore and aft attachment point to yard and boom can get scrutiny.

    Step 4 would to take best lashing points and go sailing.

    Then, the set of reef points need to be tested.

    When all seems good, time to go with permanent attachments instead of lashings. There is an abundance of loose blocks, cleats, and multi-part purchases to play with.

    If the hard on the wind performance still seems to suffer, a jib on a furler is an option that should help.

    Just because it is an option, there is also a spinnaker cut to Sabot dinghy size to play with.

    Ants

  7. #7
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    This picture is of a skerry in France...it's not my old skerry, but I rigged the downhaul the same way as 3:1 with smaller blocks... except that the lower block on my setup was affixed to the mast, not to the deck. That way I wasn't going to pull up the deck when I torqued down on that downhaul....all the compression was taken by the spar.

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    You won't beat a Laser or a Banshee to windward in your Koster with a balanced lugsail, so do not despair if more high-tech dinghies point higher. Where that boat will shine is from about ten degrees off of hard-on-the-wind down to a very broad reach. That goes double for when you have 70 pounds of camping gear aboard.
    Last edited by AlanH; 07-12-2021 at 02:46 PM.
    S-2 7.9: "Wildcat of Loch Awe"
    1968 Selmer Series 9 B-flat and A clarinets
    1962Buesher "Aristocrat" tenor saxophone
    Piper One Design 24, Hull #35; "Alpha"

  8. #8
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    Look closely at the sail attachment on your boat. It's loose-footed on the boom. I would suggest having a loop of line that keeps the clew close to the boom, but is loose enough that it will slide back and forth easily.Then put a 2:1 or 3:1 purchase on the outhaul, leading up to a cleat somewhere over the daggerboard.

    The upper edge of the sail is laced to the yard. I'm going to STRONGLY recommend that you lace the sail like this:

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    rather than the "wrapped around the yard" style, which is how it's done in that picture.

    IN fact, Michael Storers page about rigging lugsails is a very good read, check it out.

    https://www.storerboatplans.com/tuni...-and-lug-sail/
    S-2 7.9: "Wildcat of Loch Awe"
    1968 Selmer Series 9 B-flat and A clarinets
    1962Buesher "Aristocrat" tenor saxophone
    Piper One Design 24, Hull #35; "Alpha"

  9. #9
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    Bodfish, CA
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    Thanks! These tips on details are very useful.

    Keep the SSS Raid enthusiasm building!!

    Ants

  10. #10
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    Happy day! Look at that smile.
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    Tom P.

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