mast too small ?

Discussion in 'Sailboats' started by CaptainDaniel, Oct 28, 2008.

  1. CaptainDaniel
    Joined: Oct 2008
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: BC, Canada

    CaptainDaniel Junior Member

    A theoretical question. What effect would it have to have a mast that is smaller than what the boat was designed to have? Will it only reduce sailing speed or can it be even dangerous? Assuming the sails fit the mast, so the whole rig is just down-sized.
     
  2. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    I guess it depends on exacally how much smaller we are talking about. Since sails are very effective in reducing rolling moment in bad weather there is some minimum size that would be too small to provide enough to keep the boat from rolling. However this would be well below the size of functionality, say a laser mast on a 50' sailboat.

    From a practical standpoint I can't think of any reason why going to a smaller mast would present a danger, or risk the boat, but you may want to rebuild the partners to the size of the new mast diamater.

    From a performance standpoint a smaller rig will almost certainly reduce the boats performance in light air, and require a bigger breeze the really power the boat up since you are reducing sail area in porportion to the reduction in rig size. However you would likely at the same time increase the boats heavy air performance since you will be reducing the weight high up. In effect a smaller rig acts like a permanent reef, but with the added bonus or reducing weight aloft which significantly effects righting moment in a positive direction.
     
  3. CaptainDaniel
    Joined: Oct 2008
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: BC, Canada

    CaptainDaniel Junior Member

    I am not quite there yet, still need to re-build and improve a lot of other things on my boat. Eventually I will need a mast about 65 feet, but found some cheaper option of getting a shorter mast with rigging about 45-foot mast. Just a thought I had.

    Do you know of a website with graphics that shows how mast sections are joined together?
     
  4. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    Just out of curiosity, what boat is this going on, and where are you in the world?

    There are a lot of ways to repair a bent or broken mast, but they all require using a mast with the same dimensions and cross section from what I know.
     
  5. CaptainDaniel
    Joined: Oct 2008
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: BC, Canada

    CaptainDaniel Junior Member

    This might or might not go on my boat. It's a 52-foot custom built. I don't have much info, still trying to track down the boat builder. It does not have a mast at all right now. I wish I had one to just repair. No such luck though.
     
  6. diwebb
    Joined: Jun 2008
    Posts: 122
    Likes: 5, Points: 0, Legacy Rep: 65
    Location: New Zealand

    diwebb Senior Member

    Hi Captain Daniel,
    one thing to bear in mind when considering a shorter mast is that the righting moment of the boat is not reduced so the stresses on the shorter mast will be the same as on the taller one. This means that the shorter mast will still need the heavier section and rigging of the taller mast. If you are buying a second hand mast then it would probably not be sufficiently heavy (strong) to withstand the forces that may be put on it in your boat. The only way I would consider a shorter mast is if using a rig design specifically tailored to the boat and its needs.
    Its a pity you are so far away as I am thinking of rerigging my 49 foot ex racing boat and will have a Selden triple spreader mast, 65 feet long with boom, two spinnaker poles, reaching strut,jib furler, sails and all of the winches tracks etc for sale. I dont know what the shipping cost would be to Canada but with the exchange rate as it is at the moment it may be worth a look.
    If interested Email me at davidianwebb@gmail.com

    All the best with the project
     
  7. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 487, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Diwebb, hit the nail on the head. A smaller mast, will likely have a smaller section and thinner wall thickness. The net result will probably mean the rig will come down on you, in wind strengths that seemed easily save with the previous rig.
     
  8. CaptainDaniel
    Joined: Oct 2008
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: BC, Canada

    CaptainDaniel Junior Member

    diwebb suggested a junk rig. I did some reading and like that very much. Thanks for all the suggestions and advice!
     
  9. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 487, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There's reasons they call them a "junk" rig and also why they haven't caught on, in spite of the efforts of several noted designers and other promoters of the rig.
     
  10. TeddyDiver
    Joined: Dec 2007
    Posts: 2,588
    Likes: 125, Points: 73, Legacy Rep: 1650
    Location: Finland/Norway

    TeddyDiver Gollywobbler

    :confused: Not having any exp about junk rigs so who are "they" and what are the reasons?
     
  11. CaptainDaniel
    Joined: Oct 2008
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: BC, Canada

    CaptainDaniel Junior Member

  12. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 487, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Once you price up just the cordage to rig a junk, then you'll see one of the reasons that it hasn't caught on.

    Michael Kasten, Jay Benford, Phil Bolger and others have attempted to forward the rig, some with clever "modernizing" efforts, but the number of spars, number of running rigging falls, size of the masts and sailing efficiency all have conspired against the rig.

    From a poor man's view point, the rig has many benefits. If can be made reliably from scrap materials, but don't expect to keep up with the local harbor queen as you both put out to open water. There are folks who praise the rig, even writing books on the wonders of their ocean going, junk rigged dory. Just take a good look at a sail plan for a junk and see where you'll tie off all the lines, just for starters.

    [​IMG]

    This is a Kasten schooner with a junk rig. The rigging looks fairly complete. You be the string pulling judge, especially considering it's abilities with the wind on the beam or further forward. Compared to a Bermudian racer, it has less strings to cope with, but compared to an average cruiser, it's a spider web, with lots of weight and tangle potential aloft.
     
  13. TeddyDiver
    Joined: Dec 2007
    Posts: 2,588
    Likes: 125, Points: 73, Legacy Rep: 1650
    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Ok.. I was familiar with the sailplan and the "theory" allready but never sailed one:)
    So the "junk" comes from the scrap materials sometimes used.
    Nobody with a head btw his shoulders on a junk rigged boat would expect to keep up with "harbor queens" but I'd like to see also how well the "harbour queen" keeps up with a junk rigged tub after some faults in their rigs and emergency repairs after a tropical storm in southern pacific:D So horses for courses..
    "The spider web" a good description!
     
  14. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 487, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I've sailed on a few occasions with a junk rig and wasn't particularly impressed.

    Yes, the junk rig is often made from, well, junk materials. Saplings for battens, tarp material for sail panels, three strand polypropylene running rigging, but not the modern variants, just the extremely budget minded.

    Down wind they have some advantages, but up wind the windage in the rig alone keeps them at a disadvantage. This coupled with the flat panels that make up the sail (yep, no camber) all conspire against it's up hill ability. I'd hate to have to claw off a rock laden, lee shore with a junk rig.

    A modern boat of any configuration should at least fair reasonably against contemporaries in her class. This isn't to say a 40', fat bellied junk ketch should be able to keep pace with a 40' fractionally rigged Swan sloop, but it does mean it should be able to stand against a 40' Cabo Rico ketch and make a reasonable presenting of herself.

    Like I mentioned, some like Kasten have made attempts. Further refinements could include, curved, possibly pneumatic battens with cambered panels, internal halyards and other control lines, etc., but I think the rig's abilities will always be somewhat limited.
     

  15. CaptainDaniel
    Joined: Oct 2008
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: BC, Canada

    CaptainDaniel Junior Member

    The word "junk" actually comes from the Javanese word "jong" which means ship. It has absolutely nothing to do with junk as in trash. No single sailing rig is perfect for all conditions. For a low budget guy like me it is much better than a Bermuda rig or other. Junk rigs have bee around for thousands of years. No one claims to use them to race and I am not in a hurry to get anywhere. They seem like a good solution for me.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.