Aftmast rigs???

Discussion in 'Sailboats' started by jdardozzi, May 28, 2002.

  1. Kojii
    Joined: Oct 2006
    Posts: 60
    Likes: 4, Points: 8, Legacy Rep: 45
    Location: Ensenada, BCN

    Kojii All is remodelling

    our experience is just that. In 25 knots - going close hauled - we found that we could reduce sail and increase speed - to a point. Our hull would be called Ultra-narrow (9' beam on 44' WL). The foresails are indeed very efficient (lifting) and with the low CE we moved so well through the water that our problem was not getting enough sail up to make headway without getting blown down, but rather getting enough sail down to reduce drag and let the boat's aerohydrodynamics do that thing that it does.
     
  2. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    Best thing about aft-mast rig: Panoramic views

    The ideal panoramic view isn't marred by telephone poles and wires.

    I believe once more cruisers see the difference they will, like me, reconsider why they live with miles of line enclosing them in. On a small Bermuda rig I counted 23 lines coming down from the mast.

    Sitting where you see me in this photo there is just one line breaking a 180 degree view forward.

    I am encouraged by recent experiences and moving forward with some refinements.
     

    Attached Files:

  3. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    Update may 2014. Winds in the Philippines have been very difficult to work with. Most are 0-5 or 25-50. The drifter sail is performing well in light winds. I am able to get it to go to wind at roughly 55 degrees. With steady winds between 60 and 180 I have experimented adding a second smaller inner sail. Winds need to be five kn or more. Or it blankets larger drifter too much.

    This trip I moved the forward leading plates more to the front. I did this with a mid air junction point. The line is pulled to the front using a existing cleat. In the line between the mid-air and cleat I installed a spring. The spring has eliminated the stretch I was getting on my Dyneema lines. The spring was from local automotive supplier. The springs have eliminated all vibrations I was feeling in mast and pumping.

    The biggest sails I have are not going well. They need constant 8 to 25 knots. Too low too heavy to sail. Too high too big to manage. They are best in trades.
     
  4. Fanie
    Joined: Oct 2007
    Posts: 4,603
    Likes: 170, Points: 63, Legacy Rep: 2484
    Location: Colonial "Sick Africa"

    Fanie Fanie

    Hello Pbmaise,

    Your forestay is too slack, this makes a huge character change to the overall feel and working of the sail.

    Your sail foot must be kept taunt also, it is dumping down and not aft, so all it does is try to lift the boat vertical up. There is lift already due to the angle of the forestay, it is to your advantage, but you must get forward pull also.

    I added a boom that help keep the sail foot tight, what a difference ! You will be able to sail a lot more to wind too. The flatter you maintain the sail overall, the better it will perform.

    With the sail foot flat, if you look from the claw along the foot of the sail to the bow the sail must look like an arrow. You'll know when you see it.

    Sorry I want to add. I didn't see your bigger sails, but they should offer very nice performance if you just get the basics right.

    BTW, there is a huge BAT stuck to your sail in that first picture :D
     
  5. Kojii
    Joined: Oct 2006
    Posts: 60
    Likes: 4, Points: 8, Legacy Rep: 45
    Location: Ensenada, BCN

    Kojii All is remodelling

    Nice photos. I would concur with Fanie on need to flatten sail. Boom is most likely the way to do it. If you bring the sail down to the deck you can use the deck but most people like the see broad horizon. Experimentum periculosum. Thanks for keeping updates. We are currently refitting engine mounts, etc, preparing to continue down coast to California.
     
  6. brian eiland
    Joined: Jun 2002
    Posts: 4,882
    Likes: 168, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    New Lagoon 52 moves its Mast Aft

    Interesting new twist, Lagoon 52 design moves mast aft to carry larger headsails and smaller mainsail.

    http://www.sailmagazine.com/boat-reviews/lagoon-52
     
  7. brian eiland
    Joined: Jun 2002
    Posts: 4,882
    Likes: 168, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    the Virtues of Shallow Draft

    Sail mag recently posting this short story of 'shallow draft' cruising
    http://www.sailmagazine.com/cruising/sail-camping-hobie-16
     
  8. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 123, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Is it me, or is there a general trend amongst many designers moving the mast further aft? -I seem to be seeing it everywhere...

    In many designs, I'm seeing the mast being placed more amidships as opposed to the slightly forward of amidships position, facilitating a shorter boom and larger foresail triangle on a std Bermudan rig. The reasons cited in the lagoon blurb seem to make sense, what I don't understand is why it didn't evolve like this sooner?
     
  9. Yobarnacle
    Joined: Nov 2011
    Posts: 1,656
    Likes: 75, Points: 48, Legacy Rep: 851
    Location: Mexico, Florida

    Yobarnacle Senior Member

    Large foretriangles DID evolve early. Bowsprits! :D
     
  10. sharpii2
    Joined: May 2004
    Posts: 1,894
    Likes: 103, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Because of the trend towards bigger and bigger mains, brought on by the racing community.

    Some time in the '70's, IOR boats moved their masts further and further back to get a bigger and bigger jib.

    But for this to be competitive in racing, the fore stay tensions needed to be higher and higher.

    Even then, the big main sail rig could sport more sail and was therfor faster.

    Big jibs are creeping back, mainly in the cruising community, as this community and the racing community go off on separate tacks (people much rater race sports cars than dump trucks).

    Apparently, with far less than optimal fore stay tension, big jib boats go to weather fine. Maybe not as well as a good racing rig, but who cares?

    The advantages of getting rid of the long boom, having a boat that anchors better (due to the mast being behind the CLA), and having the mast closer to the cockpit, more than make up for a marginal loss of performance.

    Reliable modern roller reefing (which appears to work better for jibs than mains) could be yet another explanation.

    If I were designing a cruising boat that I wanted to be confident that I could sail in my 80's, I would design it with a mast aft rig.
     
  11. DennisRB
    Joined: Sep 2004
    Posts: 1,268
    Likes: 25, Points: 48, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    Could it be a rating rule legacy? I think a more rearward mast with a masthead/slightly fractional cutter rig would be great for cruising compared to handling a huge main, probably lighter too.
     
  12. CT 249
    Joined: Dec 2004
    Posts: 1,701
    Likes: 78, Points: 48, Legacy Rep: 467
    Location: Sydney Australia

    CT 249 Senior Member

    I have spent many years sailing unstayed cat rigs with nothing in front of me but for me, the ideal panoramic view while sailing includes the sails. Seeing their shapes easily, and the effect of the wind over them, in the same range of view as the sea and land ahead is part of the reason I love this sport.
     
  13. CT 249
    Joined: Dec 2004
    Posts: 1,701
    Likes: 78, Points: 48, Legacy Rep: 467
    Location: Sydney Australia

    CT 249 Senior Member

    Do you want to have to wind a flogging headsail in every tack when you are 80? Why not just have a rig that allows you to tack without touching a rope, like a cat rig or sloop with a self-tacking headsail?
     
  14. sharpii2
    Joined: May 2004
    Posts: 1,894
    Likes: 103, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Good point.

    First off, this flogging sail would be over the cabin, not the cockpit, were I'd usually be seated.

    Second, I'd use two jibs, each with a down haul, so I could reduce sail quickly.

    No, it wouldn't be a short tacking delight. But the boom, which is often inconvenient for reefing would be gone. The down hauls would limit the number of times I'd have to go forward.

    If I wanted an easier short tacking boat, I'd consider the 19th century version of a mast aft sailboat: a cat Schooner. It would have most of the good anchoring characteristics of the jib only boat and could have unstayed masts.
     

  15. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    Nice to see Lagoon getting more aft. Lagoon I think is looking toward some upwind capability on a vessel with a very high windage. They probably balanced this trade off

    Go full aft mast and educate customers that it is a motor yacht with a sail,

    Or, keep the boom and have some upwind capability.

    As reported before the very large foresail and heavy weight of my sail has been an issue.
    I am currently making a rotating spar. This spar will allow me to easily manage the sail.

    Initially I will only afix the spar to the mast. More like a lug sail. However, long term the idea is to stand it on its nose when down running.
     
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.