Conversion Westerly 22

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  • 12 Aug 2018 20:38
    Reply # 6526156 on 6285145

    We are now nearly done with the mast step and partner. Not that bad for the first time I think.

  • 23 Jul 2018 20:45
    Reply # 6394348 on 6393609
    Anonymous wrote:

     A slightly heavier mast may help to soften the motion of the boat when at anchor. If the mast is too light it leads to a much jerkier action when at anchor. 

    The downside of a heavier mast is that it is more difficult to raise it. This could be a significant factor if your boat is trailed regularly and has to be rigged and derigged on a regular basis.

    All the best with the project, David.

    Thank you David! We don't want to trailer the boat that often. So that sounds good.


    Anonymous wrote:

    Have you any idea what the existing mast and rigging weigh? Your new sail will probably be lighter than the existing mainsail and genoa and you presently have a hefty boom (and maybe some poles).

    I think you are right. Never thought about to weigh the old mast, that would eliminate the concerns probably easily :)



    Anonymous wrote:

    Weaverbird, of similar size, has a 165mm/76mm x 3mm tapered tube for a mast, and (bare) it weighs 36Kg. In comparison, I weighed the old bermudan mast, including standing and running rigging and a furling headstay, and that was about 41Kg. So yes, the 177mm tube is just a little larger and heavier than strictly necessary, but not unduly so.

    When I converted Tystie from a ketch back to a sloop, the mizzen mast, which is 177mm dia, was passed over to Rob and Maren to use in converting Blondie to junk rig. She is only 21.5ft long, and she seems to be quite happy, so I think your Westerly 22 would be, too.

    Thanks again for your answer, David. I think we will take the pole and start building the mast step and partners ...


  • 23 Jul 2018 14:48
    Reply # 6393609 on 6285145

    Weaverbird, of similar size, has a 165mm/76mm x 3mm tapered tube for a mast, and (bare) it weighs 36Kg. In comparison, I weighed the old bermudan mast, including standing and running rigging and a furling headstay, and that was about 41Kg. So yes, the 177mm tube is just a little larger and heavier than strictly necessary, but not unduly so.

    When I converted Tystie from a ketch back to a sloop, the mizzen mast, which is 177mm dia, was passed over to Rob and Maren to use in converting Blondie to junk rig. She is only 21.5ft long, and she seems to be quite happy, so I think your Westerly 22 would be, too.

  • 23 Jul 2018 08:33
    Reply # 6393129 on 6392644
    Have you any idea what the existing mast and rigging weigh? Your new sail will probably be lighter than the existing mainsail and genoa and you presently have a hefty boom (and maybe some poles).  These should cancel out the weight of yard and battens.  So I would reckon if your present mast and rigging - including bottle screws - is within 10kg of the heavier option, you'd be laughing.  Only my opinion - I'm no engineer.
  • 22 Jul 2018 23:41
    Reply # 6392778 on 6285145

    Hi Frank,

    it depends to some extent what you will be doing with the boat. A safety factor of 3 is good and recommended for boats that will be going offshore and may be subject to harder use. A safety factor of 2 is about as low as I would recommend in any circumstances. Remember that if caught in a following gust stress on the mast can significantly exceed the righting moment forces.

     A slightly heavier mast may help to soften the motion of the boat when at anchor. If the mast is too light it leads to a much jerkier action when at anchor. 

    The downside of a heavier mast is that it is more difficult to raise it. This could be a significant factor if your boat is trailed regularly and has to be rigged and derigged on a regular basis.

    All the best with the project, David.

  • 22 Jul 2018 21:02
    Reply # 6392644 on 6285145
    We have now a quote for the mast. First we were up for a 144/76 tapered 3mm aluminum flagpole but its not available from the distributor right now. So they send us a quote for a 177/76 4mm aluminum pole. The price is okay i think but its probably to hefty for our small boat. The W22 has a righting moment from maybe 700-800 kpm and the pole a breaking strength from 2530 kpm and weights about 43kg.


    Unfortunately there isn't very much data in the mast database for this specific scenario. Now it's doubtful for us to get this mast and be happy with the high safety factor or organize a thinner one with a weight under 35kg. What do you all think?

    Frank




  • 06 Jun 2018 21:45
    Reply # 6291335 on 6285145

    I think you will be OK with 130 - 150mm luff length.

    The way to increase positive stagger is to increase the batten angle relative to the horizontal. You have designed an angle of 8 degrees, which is quite low. When you build camber into a sail, there is a need to increase the batten angle, to compensate for the extra length of the diagonal due to the extra cloth. I should use an angle of at least 10, maybe 11 degrees. 

    Have you considered using Arne's transitional panel, increasing the angle of the top sheeted batten so that the top triangles get smaller? I think you would find this worthwhile. Have a look through Arne's sailplans, and compare them with what you have drawn. Their proportions have now been well proven.

    The lead should generally be around 9% of waterline length, for cambered sails, but this is a very inexact science.

  • 06 Jun 2018 20:43
    Reply # 6291024 on 6288016
    David Tyler wrote:

    Frank, the only things that I can see are that, depending on how you make the pockets, you might find that your luff length of 100mm for the top panels is too small for comfort, and it might be difficult to squeeze everything in without too much overlap. If the battens are overlong, they will clash. Also, the batten stagger on the lower panels is neutral, neither positive nor negative, which is OK, so long as you are aware of it and are sheeting a long way aft. Otherwise it looks fine.

    Thank you for you answer David! Do you think a luff length of 200mm would be enough or is this already to long? Regarding this PJR recommends for example ~130mm.

    I wasn't aware of the problem with the batten stagger, thanks for pointing that out! I hope that it will work that way. It appears to me without further research that we still might have the option to make the upper battens longer or the lower panels shorter in case it wouldn't, no?

    PJR recommends the CE for the single masted CE 6% of the WL abaft compared to BR one. Is this still the value most people calculate with or are there other experiences over the time?



  • 06 Jun 2018 09:20
    Reply # 6288016 on 6285145

    Frank, the only things that I can see are that, depending on how you make the pockets, you might find that your luff length of 100mm for the top panels is too small for comfort, and it might be difficult to squeeze everything in without too much overlap. If the battens are overlong, they will clash. Also, the batten stagger on the lower panels is neutral, neither positive nor negative, which is OK, so long as you are aware of it and are sheeting a long way aft. Otherwise it looks fine.

    Last modified: 06 Jun 2018 09:37 | Anonymous member
  • 05 Jun 2018 21:00
    Reply # 6286852 on 6285145

    Ups I just saw that you can hardly see the first one but there are 2 files, it is actually right in front of the other one.

    Frank

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