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Newbie with mast questions

  • 27 Mar 2014 00:26
    Quote
    Reply # 1525795 on 1523887
    Deleted user
    Welcome to the Association, Jerry. 

    Hope you don't mind, I added to your topic title so others will find this thread in a search for mast info. 

    Best of luck with what sounds like an interesting project and don't forget we'd all love to see pictures of your progress!

    Lesley 
    Last modified: 27 Mar 2014 00:33 | Deleted user
  • 25 Mar 2014 16:59
    Quote
    Reply # 1524544 on 1523887
    Anonymous member

    Hi,

    I am one of the few that sports a carbonfibremast. Weight wise and strengthwise it is higly recommendable, esecially in a catamaran where weigh matters. My X-99 has a rather slim foreship, and is trashed through waves when I sail in regattas. The less weigh aloft,the better.

    Regards

    Ketil
  • 25 Mar 2014 14:13
    Quote
    Reply # 1524383 on 1523887
    Anonymous member

    Thanks guys for the info.  I'll be looking through all the info on the site in the next few weeks.  The carbon mast I'm referring to is like the ones that Rob Denny (Harryproas) has developed.  I beleive he's gotten the costs down for homebuilding to about $5K a stick for the sizes we are talking about.  I have wondered about the alu utility poles myself, I'm glad to hear that they do actually work.  My wife designs large electric transmission lines for a living.  She talks to pole manufacturers all the time, I can get specs and prices from her.  I'm in love with the soft wing concept, but with all the other stuff going on in this project I think it would be better to get on the water with the simpler classic junk rig concept then do the wing if the regular sail doesn't perform to expectations.  The main thing I've learned from our crusing every year is that I really don't want to deal with flapping sails and having to get out of the cockpit when the wind and waves are up.  I'm not too old to handle it yet, but I can see in the future when it would be dangerous for me to have to do that.  I'll be starting the project in the next few years, depends on how long it takes me to finish my wife's dream bathroom project in our house.  Thanks again for the posts.

    Thanks,

    Jerry Barth
  • 25 Mar 2014 03:32
    Quote
    Reply # 1524093 on 1523887
    Anonymous member
    Jerry Barth wrote:

        My plan for the rig is a biplane junk rig using unstayed carbon masts.  From looking at other cats of about the same weight I came up with about 6-700 sq feet of total sail area.  This boat will be in the caribbean so smaller might be better because it seems to always blow about 15 knots down there anyway.  One other factor is that the longest mast I can make in my shop is about 40 feet, I might be able to splice on stubs or something to make it slightly longer.  I would like to keep it on the shorter side anyway for the fixed bridges we have in the States. 

        Some things I was wondering about since the junk rig book is about 15 years old.  What are people using for masts?   How about battens and batten material?  Does making camber (with lenses etc.) in the sails make enough difference to be worth it?

       Thanks,

       Jerry Barth

     

    Hi Jerry,
    To hoist a 350 sq ft sail, you only need about 33ft of mast above deck, so a 40ft mast should be fine.

    I think that today's number one choice for a mast is a spun-tapered alloy pole, as used for streetlighting and flagpoles. There are several links in our pages. Next choice is the hybrid mast, made from an alloy tube with a wooden topmast. That is economical, and has proved to give good service. I would only attempt a carbon mast if you have a lot of previous experience of making large carbon structures. 

    In your size of sail, an alloy tube of 1 3/4" dia x 16SWG wall in 6061T6 would be first choice for battens.

    As to camber, that's a personal choice. Some people sail in a relaxed way, and are not concerned with maximum speed to windward; they stay with a flat sail. Others are more performance orientated, and put camber in. Or you might say, as a rough guide, that the further offshore you sail the less windward performance and hence camber you need. Yes, it does make a difference, but it does take a little more time, effort and skill to make than a flat sail.
  • 24 Mar 2014 21:53
    Quote
    Reply # 1523914 on 1523887
    Anonymous member
    Hi, welcome to the JRA.  600 - 700 sq ft seems about right for your cat, especially in the West Indies.  The rig choice is also a good one and several cats have used it with considerable success.  If you can afford carbon fibre for the masts, yards and battens, that will be an excellent choice.  Aluminium is also commonly used these days and some people build hollow wooden masts (see Gary Pick's article on Birdsmouth timber spar construction in a recent JRA magazine - you can download back issues from this site.)  Many of us are also using cambered sails which give significantly improved windward performance, while others, such as the catamaran, Grand Pha, have developed a soft wingsail concept.  I like my cambered sail as it offers performance without giving up the simplicity of junk rig.  Good luck with your project.  Please feel free to ask for specific advice on this site, as members just love getting involved in interesting projects like yours.
    Last modified: 24 Mar 2014 21:54 | Anonymous member
  • 24 Mar 2014 20:52
    Quote
    Message # 1523887
    Anonymous member

    Hi,

       I just joined your association.  I read Blondie Hassler's book and found it interesting.   I have owned several trimarans and catamarans in the past.  For the last 15 years I have owned various charter monohulls in the Caribbean.  We tend to spend about 3 weeks a year cruising down there, it has been good experience for what we want in a real cruising boat.  My retirement home is in my barn, it is a 35 foot cat project that I bought about 15 years ago to fix up.  I started with a 35 foot tri they made here in Texas.  We sailed that for about 8 years or so and determined it was too small.  It was also too derelict at that point to sale to someone else.  I pulled it out of the water and brought it back to the farm.  Then an unfinished center hull of the same model came up for sale.  That one is now in my  garden.  So I have two trimaran center hulls to make a cat out of.  They are a little fat for a cat hull at 8:1 length to beam ratio, but I'm not interested in high speed and figure they'll be better for load carrying anyway.

        My plan for the rig is a biplane junk rig using unstayed carbon masts.  From looking at other cats of about the same weight I came up with about 6-700 sq feet of total sail area.  This boat will be in the caribbean so smaller might be better because it seems to always blow about 15 knots down there anyway.  One other factor is that the longest mast I can make in my shop is about 40 feet, I might be able to splice on stubs or something to make it slightly longer.  I would like to keep it on the shorter side anyway for the fixed bridges we have in the States. 

        Some things I was wondering about since the junk rig book is about 15 years old.  What are people using for masts?   How about battens and batten material?  Does making camber (with lenses etc.) in the sails make enough difference to be worth it?

       Thanks,

       Jerry Barth

     [webteam edit: topic tweaked to reflect subject]

    Last modified: 27 Mar 2014 00:22 | Deleted user
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