Aftmast rigs???

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

  1. sharpii2
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    sharpii2 Senior Member

    I never meant to imply she was. I only meant to point out that, though she was probably not primarily designed to sail to windward, with her low AR main, she could do so quite sufficiently.

    I actually made a spreadsheet to determine which angle to peak a gaff at, that would yield the most SA. 45 deg. indeed seems to be the answer.

    It seems that as the gaff rig made it further into the 20th century, the gaff got peaked higher and higher, probably to get a higher AR. I've seen pictures of them peaked so high I often wondered why they they didn't simply use a BR. My guess is that sail stretch was a major reason. Perhaps the high peaked gaff sail set better than a BR of the same proportions.
     
  2. brian eiland
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    brian eiland Senior Member

    Another Mast-Aft experiment vessel

    Just got back to this subject thread,...somehow I missed current notifications of new postings??

    This vessel of which you speak may be the one I have searched for for quite some time. I had a fellow send a single photo a few years ago, and then I never could find him again. I never knew where, or if, his project was going forward?? I can't even remember where I put that single photo I had?

    PLEASE have him get in touch with me. I believe I had some concerns about his rigging idea at the head of the staysail (the hounds), and maybe his use, or non-use of a aft jumper strut,....can't remember that either. (this damn age thing)


    Ah Ha, just found this photo I posted some time ago when I was going back thru this subject thread looking for something else.
    Is this the steel vessel that you speak of??
    http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-33.html#post523832
     
    Last edited: Mar 6, 2015
  3. brian eiland
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    brian eiland Senior Member

    Many 'production cruising cats' these days are variations on the popular modern-day charter cats. And many of these are under rigged on purpose for safety concerns in trade wind charter sailing.

    And many of the early 'production cruising cats' came to us from Britain where wind conditions were 'substantial', and thus they also carried under-size rigs.

    So multihulls started out with bad reputations that still persist to this day. To say that multihulls will not point up to windward became a oft-repeated report that likely is still persisting to this day. I have personally taken a Stiletto catamaran and our little Firefly trimaran and sailed TO WINDWARD of some of the best monohull racing boats on the Chesapeake Bay,...but we had to slow down and sail just a wee bit faster than them,...otherwise the apparent wind we generated forced us off the wind to a greater degree. Hell I even seen Tony Smith take one of his Gemini cats and go to windward of a lot of monohulls on the Bay.

    Yes one must weigh the windage factors of vessels when sailing to windward, but to classify all vessels with extra windage as unsuitable for windward sailing would certainly rule out many other rig types such as ketches and yawls etc,...anything with more than one mast?? ...and I certainly think there have been there share of these types of rigs utilized aboard cruising vessels. Chris White was very enthusiastic about his ketch rigged catamaran


    I have referred to my aft mast rig as a single-masted ketch,...which it is?? So I have reduced some of my windage by not having the extra rigging and the extra mast of a ketch rig. Now granted my bare-mast will experience more drag than a mast with sail attached to it. Might this extra windage be offset by the lack of extra rigging and mast?
    OR if not, I think I have a relatively cheap plan to reduce that windage of that bare mast,....

    Perhaps refer back to posting #407
     
  4. WindRaf
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    WindRaf Senior Member

  5. DennisRB
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    DennisRB Senior Member

    That's the one! Looks almost ready to sail these days. Launch day is near. I asked him a while ago to post results in this thread.
     
  6. brian eiland
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    brian eiland Senior Member

    Alright ! I had never heard from the fellow again,...only once I believe in a private email I think.

    Can you and/or he get me some more photos of the rig.

    I would really like to review them, and hopefully make some suggestions that might help avoid potential problems that could arise.....free from any fees :):cool:
     
  7. brian eiland
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    brian eiland Senior Member

    Schooner Rigged Multi

    Speaking of Cruising multi's and Cruising rigs, there are some vessels that get along just fine without being masthead sloops.

    ...case in point, a schooner rig across the Atlantic and cruising around Europe a bit,.... (just happened across this video posted over on the discussions about the recent demasting of the 55 Gunboat)

    https://www.youtube.com/watch?v=COFTwFRJlHY
     
  8. Kojii
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    Kojii All is remodelling

    Orca update FWIW Hove-to under staysail

    San Francisco Bay, January 2015. Fresh breeze. The staysail has earned my admiration. It is versatile and dependable and without drama.
    In February, same area, breeze went to 30 knots and we were heading for the marina under staysail alone. I let her fly. It goes boom vertical at times. The gust deepens the pocket. We ride the wave for a bit. The gust blows by and the boom follows it down nice and easy squeezy. Five knots with following sea and staysail doing all the work. Reminds me of Marchaj's discussion of the crabclaw. Oddly, com la grand-voile of the Marconi rig, it is our first sail up and our last down.

    On way down coast (rough ride at times), we snapped a quadrant pin while hove to in whale country. With partial steering we stopped in Brookings. There was Relentless. Art has died. The boat is owned by a Newport fisher. It is not the same boat Fred built but what the heck - it's had a lot of plastic surgery and yet same bones. It has a shallow keel and big motor, and lots of tankage and will probably cruise at 8 knots...forever. Looks like Art took another way out.
    Memento mori.
    I replaced the stainless 5/8 quadrant pin with Titanium. The S/S snapped like a candy cane. Musta hit sumpn hard.
     

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  9. markstrimaran
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    markstrimaran Senior Member

    How do you like the boom on your inner stay sail? I am sailing a 18' aft masted trimaran. Two stay sail. I have thought about a boom. It's a very custom self built trailerable.
    Always looking at like rigged boats.
     
  10. Kojii
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    Kojii All is remodelling

    it is very easy to use but there are some design issues. I am going to try and find a photo of the u-joint on the boom which allows for stand-off and twisting without jamming or bashing. They may already be on this site.
    Boom weight seems critical. Too heavy and sail won't "fly" at right gust velocity maybe, but may not be as critical on smaller boat. This is aluminum. Only aluminum spar on the boat.. I would estimate the boom at 100 lbs, on 230 sq ft of sail and about 16 ft long. Mast is carbon/kevlar.
    There is another photo - put up here years ago - of us wing and wing with boom up at 45 deg or so
    Boom is still inherantly dangerous but at least I can see it coming. Sheets run out toward gunnel so the "preventer" can always be "on".
    The other nice feature is the ability to flatten out the sail in a blow when fore reaching. Outhaul goes through block on tail of boom and forward to block inside thence back to winch at doghoue. We can hunker down on that, pull both sheets tight, and "freeze" the boom at the preferred angle, with the sail tight and as flat as we can get it. I believe you could do much the same with a wishbone boom with substantially less weight. Thanks for the post.
     
  11. markstrimaran
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    markstrimaran Senior Member

    boom

    Sailing season has not quite opened here in Iowa just yet. So my ideas are untested just yet. I did sew a batten pocket into the foot of my main stay sail. A bolt rope and aluminum boom is something too play with, this year. Last year I got it sail able in mid July and in attempting a speed record broke the welds on my mast step. I hope to resolve that issue with a better back stay. I used a front mast brace that concentrated the forces of stay tension 10 fold on the mast step.
    I see my boat at a proto type. With a small budget. Going against conventional wisdom with a aft mast. I am guessing that my fore stay tension might require a carbon fiber mast. Which cost more than my whole boat and rigging. But if I could hold the boom pivot weight with the boats deck structure it might be feasable.
    I have absolutely no previous experience sailing a conventionally rigged boat. So I have no preconceived ideas as to what will work.
    I wanted the safety of boomless. It is not an issue now, since my sails foot is high up off the deck.
     

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  12. brian eiland
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    brian eiland Senior Member

    Peter Spronk's schooner rigged cats

    Here are a number of sleek vessels designed to be sailed in the Caribbean trade winds, and almost none of them are sloops
    Peter Spronk's catamarans

    I think I may have been influenced by his thinking of keeping a 'low profile'.
     
  13. CT249
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    CT249 Senior Member

    But what is the significance of the fact that one particular designer tends to not use one particular rig for boats of one type, designed largely for one use, and generally in one place?

    Sure, if one is creating big charter cats (which I understand was Spronk's speciality) one may choose split masthead rigs. That's fine, but it doesn't detract a scintilla from the defence of the masthead sloop for other people, other boats, and other roles.

    Sure, there are popular and respected designs that are not masthead sloops; there's never been any dispute about that. In fact there are so many popular sailing craft that are not masthead sloops that they disprove any theory that people are scared of "unusual" rigs.
     
  14. brian eiland
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    brian eiland Senior Member

    I brought the subject up again as thruout this subject thread there have been many postings suggesting the much lower performance potentials of my aftmast configuration compared to the 'god-almighty' fractional sloop rig.

    It just happened that last night I ran across a number of Peter Spronk's designs on my old computer and decided to post them in a new subject thread in his honor. It made me rethink that popularity that he had with the 'schooner rigs'. And of course the popularity of the schooner rig for many years across all types of cruising boats.
     

  15. CT249
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    CT249 Senior Member

    /\

    But does the fact that Peter Spronk used other rigs (and made some stunning boats) in very large cats have any relevance at all to the question of the performance of your rig v masthead sloops in other craft?

    And sure, the schooner rig was popular for years in cruisers - but it's not as fast upwind as a sloop of comparable sail area, as demonstrated by the fact that rating rules give schooner rigs considerably lower ratings for the same sail area.

    For what it's worth, I don't personally like the masthead sloop rig, but there does seem to be a very strong tendency on BDF to denigrate sloop rigs on spurious grounds.

    BTW Spronk also used the masthead sloop rig in some boats, and while his boats look great one may wonder to what extent the design of a very large charter cat in a tropical tradewind area has to do with boats of different types for different uses.
     
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