Aftmast rigs???

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

  1. brian eiland
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    brian eiland Senior Member

    ...and then another viewpoint from that same 'main-less' subject thread...
     
  2. brian eiland
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    brian eiland Senior Member

    Sailing Challenge

    I recently caught up with an old friend who skippered Olaf Harken's unusual vessel Procyon for its first few years. I showed him a model of my 'single-masted ketch' concept, and then just the other day I sent him a copy of this 'sailing challenge' I had issued to a few naysayers in the past.



    You know I can still imagine sailing a big 65-foot catamaran with this mastaft (single-masted ketch) rig right off the mooring, and back to the mooring, without the engine, by myself, with so little effort that I might take it out having only a few spare hours to kill, or for just a carefree daysail.

    I wouldn’t have to uncover any sails, nor recover them when I returned to port. I'd likely start out with just unrolling that central 'mainstaysail' then add in more sail area as needed.

    I would be less concerned with reefing by myself if the wind were to really come up. If I were short-handed at sea, I would have many of the benefits of a ketch rig, without the necessity of slab reefing the main and mizzen sails of the traditional ketch rig. I'd be in a constant state of helm balance as I could tweak the mizzen sail for that.

    That about sums it up. I would like a 65 foot cat that I could take sailing by myself, and that might even be easier than a beach cat. Try hoisting a full batten mainsail on a 65 footer by yourself, or even a 40 footer. Most folks over 50 will have second thoughts, or will just unfurl the jib and forget about hoisting that traditional MAIN sail.

    I'm 65 (now 73), and I could sail this 65 foot cat by myself with this aft mast rig. And with the balance and low power afforded by the smaller 'mainstaysail' I could sail this vessel right off the mooring or maybe right off a side-to-dock slip.



    Here's a challenge Mr Naysayer..... Le Mans start. I'll be out sailing before you get the covers off your mainsail, and when we return for the day, I'll be at the bar sipping on a Margarita watching you put away your vessel for the day.



    Randy sent me a reply this morning...
     
  3. brian eiland
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    brian eiland Senior Member

    Ketch Rigs

    Peter Spronk was a great admirer of 'split rigs',...mostly schooner ones. But he built the largest and fastest design of the its time (1968) with a ketch rig....the 75 foot Ppalu.

    I'm going sailing on her tomorrow,...short trip from St Augustine to Daytona. Hopefully we will have some good winds for her powerful ketch rig.
     

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  4. brian eiland
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    brian eiland Senior Member

    Taming the Mainsail

    ...from another forum, discussions of furling mechanisms for mainsails (Is a furling main safe when singlehanding?)

    My solution, ....eliminate the mainsail and substitute a self tacking, roller furling/reefing staysail. Then add on a nice big headsail (genoa) for those lighter airs (also roller furling/reefing). Then add on a mizzen for balance and reaching (also roller furling)

    Sails can be be made of a lighter tougher laminate and will not be continuously creased as they stow rolled up under their own sail cover, ....sewn on (and replaceable)

    With this arrangement I could be out for a daysail before most boats get their sails hoisted and rigged. At at the end of the day I could be at the bar with a drink while they are still wrapping things up.

    Long term cruising:
    1) Most roller furling gear is pretty well sorted out now, and parts availability is not too bad. And their are hydraulic and electric options for both the furling and sheeting operations.
    2) Maybe spend a little extra on hi-tech sailcloth that will survive greater winds variations, OR just go for the econo materials that need replacement a little more often, or when subjected to extreme conditions. At any rate both options sound a bit cheaper that boom furling options.
    3) Cut down my overall mast height by 20% while still carrying the same sail area of the sloop option for the vessel.

    It wasn't a cost issue with me but rather a real questioning of effectiveness of the main-sail aerodynamically, associated with all the gear we had to invent to handle that mainsail,...in-mast furling, boom furling, bendy mast, rotating mast, boom vangs, square tops, multi-purchase mainsheets, and their quick releases, elaborate travelers, roller bearing mast cars, special full length battens, etc, etc.

    All the while realizing that the mainsail itself is a great 'provider' for a more efficient headsail. So why not substitute a roller furling staysail in its place?...so I chose to call it a 'mainstaysail'


    ...another discussion
    In-Boom Furling Experiences
    http://www.cruisersforum.com/forums/showthread.php?p=2260936#post2260936
     
  5. brian eiland
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    brian eiland Senior Member

    Cruising Catamaran in 40kts of Wind

    I saw this posting on another forum and thought I might want to reference it for future folks that might be questioning the use of a multihull craft in higher winds and sea conditions.

    In the video that is linked you might also take note of the triple reefed mainsail being utilized. I submit that the 'mainstaysail' on my aftmast rig could be performing this same task.
     

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  6. CT249
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    CT249 Senior Member

    I thought you had agreed, after reading posts from Tom and Mikka, that there was no real question about the aerodynamic effectiveness of the mainsail?

    Secondly, surely as a matter of basic logic we must compare like with like. You listed the gear a main needs, but ignored the gear a jib needs such as a pair of expensive and powerful winches, tracks and a furler.

    Much of the mainsail equipment you are referring to is used to make the mainsail even more efficient than a headsail in some situations. The vang provides superior twist control at wide sheeting angles. The boom provides superior extension and prevents excessive fullness with the sheet eased. The traveller allows superior control of twist at tighter apparent wind angles. The block and tackle on the mainsheet reduces loads compared to a one-part jibsheet, so you need a smaller winch (if any).

    You don't need any of that equipment if you are happy with a mainsail that sets as badly as a foresail tends to when running deep. If you do want a foresail that sets just as well as a mainsail in such a situation, you need a pole with topping lift and downhaul, perhaps some big-boat version of the British dinghy "dangly pole", a way of easily adjusting the transverse sheeting position, a way of easily adjusting the fore-and-aft sheeting position, etc. By the time you have added that equipment the mainsail is looking fairly cheap and easy to use by comparison.

    Yep, your rig may well make it easier to get under way. Maybe you'd have had more success in selling the concept if you concentrated on that aspect rather than making claims about its aero- and equipment-efficiency that, with respect, seem to be clutching at straws?
     
  7. Bod
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    Bod Junior Member

    i have for a while studied yachts leaving and making port to see which sails they raise or lower first. i have witnessed vast majority raise the main first and lower it last. when i occasionally see a sailor use his furling jib first to remember the boat as i know i am likely to be on the same page as them and he/she will most like be under sail much closer to port and even in the harbour.

    personally i cant stand my main sail and avoid using it. often i wont use it at all if my unfurled genoa is full and pushing my little achilles along nicely. using the jib first or alone lets me sail up rivers and around harbours with ease.

    my main sail is a pain in the arse and frankly dangerous when the conditions turn sour. leaving the cockpit in a gale heeled over is not fun. much better to stay seated and furl in the safety of the cockpit.

    a main may offer more sail efficiency no doubt. but downwind i attach a pole to the clew of my genoa giving her a nice shape. the same can be done with a furling main, and only one sheet for a furling main as its behind the shrouds.

    a little more efficiency is no trade off for comfort, safety, control and ease....
     
  8. brian eiland
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    brian eiland Senior Member

    Thanks Bod for that reinforcement.

    Perhaps its a good time to post this observation...;)
     
  9. CT249
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    CT249 Senior Member

    Well, it's all personal. Personally I find a mainsail much more controllable and easy than a headsail; you don't have to work the jibsheets each tack or gybe for a start. Nor do you have to leave the cockpit to reef if you have the reefs set up for use from the cockpit.

    The standard Achilles' rig isn't the best design to use under main alone, and of course this is very much a personal matter that is down to personal preferences. If someone loves an all-furling rig then good on them. The issue is that promotion of such rigs surely should be done on a rational basis comparing like to like.
     
  10. brian eiland
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    brian eiland Senior Member

    Double A-frame Rig

    http://www.boatdesign.net/forums/boat-design/wishbone-sailing-rig-1999-21.html#post791597

    (all 3 sails roller furl & he refers to the rig at one point as a ketch type)
     
  11. Spiv
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    Spiv Ancient Mariner

    Same here.
    I crossed the Atlantic in 17 days mainly using a Parasailor with winds >18Kn and Genoa <18kn. When it blew over 30kn, I just furled the Genoa accordingly.
    I crossed the Pacific in 19 days using the the Code 0 and the Genoa, sometimes together.

    We played card games, cooked exceptional meals, relaxed, never worried about the sails or accidental jibes.
    For me, nothing beats headsails on furlers when going downwind in the trades.

    In 5y cruising, I did use my top notch Square-Top Main, but it was on a "need to" bases and reluctantly, I'd much rather had a furling main, but that was not an option.
     
  12. brian eiland
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    brian eiland Senior Member

    "Think One"

    I don't know that I agreed with that total effectiveness of the mainsail. I still view it more like this opinion voiced by Mikko
    I did come around to his suggestions that the mast tube itself is NOT as much of a hindrance to the mainsail's aero properties as I had originally ascribed to it.

    With this 'Think One' image in mind, combined with some discussions of aerodynamic flaps, and supposed advantages of over-sheeted mainsails, I wonder if my mizzen sail on the single-masted ketch might just be made to act like an aero flap to my rig as a whole
     
  13. upchurchmr
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    upchurchmr Senior Member

    "When sailing upwind most of the surface of the jib is oriented in the direction of the motion, while most of the surface of the main is oriented perpendicular to it, the leech often even pulling back."

    This is the worst statement of "fact" I have ever seen.
    I don't know what kind of a terrible boat or sailor is being represented here, but on my old Tornado catamaran the angle of incedince of both sails is almost equal.

    Additionally, in heavy weather I easily left the jib off and sailed extremely fast and weatherly.

    I can't believe this is being quoted by anyone who sails.
     
  14. tgtony52
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    tgtony52 ...

    Current Vendée Globe yacht designs becoming more aft mast

    Current leading yacht in the 2016-7 Vendée Globe yacht race, Hugo Boss, is showing the way in competitive yacht design. The trend in the design of these IMOCA 60 boats over the last couple of decades clearly shows the mast position has moved significantly aft.
    image.jpeg image.png
     

  15. tgtony52
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    Location: Tea Gardens, Australia

    tgtony52 ...

    IMOCA yachts in Vendee Globe race

    All these yachts were launched in 2015 and are currently racing in the Vendee Globe. All have their mast aft of the middle of the boat. Proof of design is in the performance!
     

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