Junket Boat

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  • 08 Apr 2021 11:36
    Reply # 10286877 on 10235843

    My mast is approximately 3m in length above the partners and I think I can manage a maximum boom length of 2m. I really like Arne's Halibut sail. If I was to add another panel above the bottom panel, and move the clew aft 300mm I would get close to a decent sail area. Opinions?

  • 07 Apr 2021 11:27
    Reply # 10282623 on 10280669
    Anonymous wrote:

    Gary, I wouldn't bother shifting the mast 250mm if helm balance is all you are worried about - at least until you have tried it first. So many other things are at play, and anyway you can just shift your weight or adjust the centreboard a little.

    Nice little boat, exactly what I had in mind for a "junket boat" and in fact there was one for sale when I bought my Golden Bay and I would have bought it, except I wanted to see a little fleet of similar boats, and Marcus already had a Golden Bay so I followed suit. The two designs are very comparable in size and purpose. Yours will be a bit more exciting to keep upright and may be the faster - maybe!

    I too am currently making changes and adding more buoyancy, but following a different route. I am shifting the centreboard, and will put a long swivelling offset centreboard case on one side, in which the board stays inside the case at all times. The case will form the outside wall of a side buoyancy tank. There will be a matching side tank on the other side. You can see where I have sanded down to bare wood in preparation.


    I am shifting the mast a few cm from its designed position through the fore deck, just in front of that forward bulkhead. (You can't see where it was because the previous owner had a different arrangement). But I am shifting the mast for a different purpose - I want the mast on the aft side of that forward bulkhead so that I CAN offset it, and also house it in a little tabernacle with the opening facing aft. That gets everything off to one side, and will hopefully make lowering and raising the rig almost a one-handed operation which can be done while sitting down (I hope). Also, of course, to keep the centre clear for an inflatable mattress. I don't think offsetting the case or the mast will make much difference to how it sails, which, I think both boats will sail very well with a simple junk rig, and with much more ability to adjust sail area to conditions.

    PS Thanks David, for your helpful comment regarding sheeting the Halibut rig.

    I look forward to seeing the end result. We shall have to compare notes once we get sailing.
  • 06 Apr 2021 23:14
    Reply # 10280669 on 10235843

    Gary, I wouldn't bother shifting the mast 250mm if helm balance is all you are worried about - at least until you have tried it first. So many other things are at play, and anyway you can just shift your weight or adjust the centreboard a little.

    Nice little boat, exactly what I had in mind for a "junket boat" and in fact there was one for sale when I bought my Golden Bay and I might have bought it, except I wanted to see a little fleet of similar boats, and Marcus already had a Golden Bay so I followed suit. The two designs are very comparable in size and purpose. Yours will be a bit more exciting to keep upright and may be the faster - maybe!

    I too am currently making changes and adding more buoyancy, but following a different route. I am shifting the centreboard, and will put a long swivelling offset centreboard case on one side, in which the board stays inside the case at all times. The case will form the outside wall of a side buoyancy tank. There will be a matching side tank on the other side. You can see where I have sanded down to bare wood in preparation.


    I am shifting the mast a few cm from its designed position through the fore deck, just in front of that forward bulkhead. (You can't see where it was because the previous owner had a different arrangement). But I am shifting the mast for a different purpose - I want the mast on the aft side of that forward bulkhead so that I CAN offset it, and also house it in a little tabernacle with the opening facing aft. That gets everything off to one side, and will hopefully make lowering and raising the rig almost a one-handed operation which can be done while sitting down (I hope). Also, of course, to keep the centre clear for an inflatable mattress. I don't think offsetting the case or the mast will make much difference to how it sails, which, I think both boats will sail very well with a simple junk rig, and with much more ability to adjust sail area to conditions.

    PS Thanks David, for your helpful comment regarding sheeting the Halibut rig.

    Last modified: 08 Apr 2021 00:45 | Anonymous member
  • 06 Apr 2021 22:56
    Reply # 10280606 on 10279757
    Anonymous wrote:
    Anonymous wrote:

    I would like to mention a project I am working on at the moment and that is the conversion of a Bolger Cartopper to JR. 

    ...

    I am going to try the rig using the same mast position, though by my calculations the mast needs to be about 250mm further aft. However to do that I would have to offset the mast to one side of the centreboard case.

    Perhaps a mix of lower AR (longer boom/battens), larger rudder (or shape) and or banana shaped centre board? For a small craft the sail balance can also be decreased as the small sail would be more controllable. Compromises all, but with a small craft...

    Mounting the mast off centre would be a non-issue too, really. The bigger thing would be CB access, would it still be able to be raised under sail? Would battens or other rigging interfere?

    The centreboard would be fine. The rudder is already a good size, and I'm thinking a slightly larger version of Arne's Halibut sail would be ideal. 
  • 06 Apr 2021 17:56
    Reply # 10279757 on 10277367
    Anonymous wrote:

    I would like to mention a project I am working on at the moment and that is the conversion of a Bolger Cartopper to JR. 

    ...

    I am going to try the rig using the same mast position, though by my calculations the mast needs to be about 250mm further aft. However to do that I would have to offset the mast to one side of the centreboard case.

    Perhaps a mix of lower AR (longer boom/battens), larger rudder (or shape) and or banana shaped centre board? For a small craft the sail balance can also be decreased as the small sail would be more controllable. Compromises all, but with a small craft...

    Mounting the mast off centre would be a non-issue too, really. The bigger thing would be CB access, would it still be able to be raised under sail? Would battens or other rigging interfere?

  • 06 Apr 2021 05:30
    Reply # 10277367 on 10235843

    I would like to mention a project I am working on at the moment and that is the conversion of a Bolger Cartopper to JR. This boat has a Leg O Mutton rig that works quite well though a lot of care needs to be taken while gybing in any decent wind. With almost zero built in flotation this boat stayed over if capsized. To this end I have remodelled the interior and closed in fore and aft with watertight bulkheads/ storage lockers. The intended use is for riverside camping over a few days. The mast is alloy tube offcuts from Redwings battens made into two sections of a length that will store in the boat. I am going to try the rig using the same mast position, though by my calculations the mast needs to be about 250mm further aft. However to do that I would have to offset the mast to one side of the centreboard case.


    4 files
  • 31 Mar 2021 18:59
    Reply # 10257107 on 10235843

    Graeme,

    This being a new and untried idea, we have still to learn how to use it, but it does seem to have a lot of potential as an open boat's rig. My hunch is that a 2.5sqm and a 7sqm sail had better have different treatments:

    2.5sqm: no halyard, flat-cut sail that is allowed to twist, reefing upwards, one-part sheet and simple sheet span.

    7sqm: halyard, cambered panel sail, reefing downwards, three-part sheet controlling twist.

  • 31 Mar 2021 15:23
    Reply # 10256452 on 10235843
    Anonymous member (Administrator)

    Since I actually have been sailing with only three fanned panels set many times, I think the sheet setup I showed on Halibut was good, but with 7sqm, I would go for Graeme’s sheets. On Halibut I hoped to be able to stream the sail in any direction, including straight forward, so a one-part sheet would be best there.

    When I am down on three panels on my 7-panel sails, the lee topping lift will support the yard and top battens. Combined with a little camber sewn into each panel, the result was good performance to windward on both my Frøken Sørensen and my present Ingeborg. With all three panels up on the Halibut sail, there need not be any load on the topping lifts, but possibly, adjusting the running topping lifts could be used to adjust the twist and thus drive.
    The rig is still just an armchair idea, so some fiddling may be needed to get the best out of it.

    Arne


    Frøken Sørensen with 3 of 7 panels set. She tacked well with those 8.6sqm (Disp. around 800kg with me on board)


    Seconds later... The lee topping lift limits the  amount of twist. Note the leech telltale flying.

    Last modified: 31 Mar 2021 15:32 | Anonymous member (Administrator)
  • 31 Mar 2021 14:54
    Reply # 10256365 on 10235843

    Not arguing, just trying to learn: I understand that twist in a fanned sail induces camber, even for a flat sail - but what's wrong with having less twist, and getting camber from the cut of the sail?


    The reason I am pursuing this is because I am beginning to think this sail might be the way to go for the Golden Bay, but its not what you would call a stiff boat, and with that amount of sail area I think I would feel more comfortable reefing downwards, at least for the first reef. If sewing camber into the sail is the price to pay for being able to reef downwards and also do away with the boomkin, it would seem worth it, wouldn't it?


    Last modified: 31 Mar 2021 14:58 | Anonymous member
  • 31 Mar 2021 14:39
    Reply # 10256337 on 10235843

    Single span for allowing more twist. You might even think about sheeting just to the clew, and tying down the reef.

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