Aftmast rigs???

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

  1. yokebutt
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    yokebutt Boatbuilder

    Brian, while the mast-aft concept has one factor that theoretically is better than a regular bermuda rig, it still seems to me as having most other aspects working against it. Has there been any real-world testing done?

  2. brian eiland
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    brian eiland Senior Member

    Only One Factor Better?

    1) I might suggest you go back and reread posting #13 above. I think you will find I am suggesting more than 'one factor' improvement.

    2) To the 'real world testing' issue, I'll copy a letter I've taken to sending out to inquiries as a sort of 'form letter' for now:

    John J Ward wrote:

    I am John Ward and I have an interest in your mast aft system. I have read your entire web site and can not find a reference to an existing boat that I could look at. For all of the advantages of the system, I do not understand the lack of interest in building this system, unless there is a fault that has not been discussed or written about. Any information would be appreciated and the status currently of the system.

    Brian responded:
    Thanks for your patience. I have received quite a lot of interest from my website posting of this design, and even to the degree that I am experiencing some trouble keeping up with it all.

    There has not yet been a vessel built utilizing my specific mast-aft design. There have been in the past a number of experiments with various mast-aft concepts, most of which were unsuccessful due to their placing the mast at the extreme aft end of the vessel, and thus were unable to provide adequate forestay tensions for the larger headsails. I have studied a number of these attempts and collected what info I could find on them. I have chosen at this time not to publish all of this info on my website as I felt it would be a distraction to my design.

    I don't know how long you've been associated with sailing, but I would wish you to know the EXTREME difficulties of promoting new and different ideas in this very conservative market....and even more so in the very conservative USA segment. I've been associated with multihull craft for almost 30 years now, and they are just now gaining some considerable respect. Want to see some exciting innovation in sailing craft, go to France or to some lesser degree New Zealand.

    I originally put this project on total 'backburner' until several years ago when I revitalized it for my gamefishing design....boy, will it work great in this application! It will also work great in a cruising application, particularily onboard a motor/sailer. It may not work in the racing application I sight in the letter to Paul Cayard, but then these ultimate racing rigs are not what we want to emulate on a cruising boat where stability questions (particularly multihulls) and short handed crew list are important factors

    This rig possesses a number of aerodynamic advantages over those conventional rigs of today. It also possesses some disadvantages. The extra drag of a bare mast is a primary concern, but wait a minute, I don't have the extra mast & rigging required of a conventional ketch rig (mine is a single-masted ketch). The forward raked mast will experience much additional compression loading in order to maintain racing equivalent tight forestays.....but modern materials and their creative placement (mast, rigging, and bulkheads) will not present a formidable obstacle to this goal. With tight forestays and the overlapping genoa, I will put this rig design up against the best of the windward boats and give them a good run for it.

    Current status? I'm working on a client who can appreciate the potential offered by this design, and with hopefully the funds to do at least a minimal FEA (finite element) analysis prior to construction. The FEA is not a necessity to get an operational rig out there, but it sure would be nice to optimize it as much as possible at the beginning.

    Still looking for that bold, adventuresome sailor

    Regards, Brian

    P.S. There are some alternative variations of this rig concept I would like to investigate concurrently. One such variation involves the ‘bi-pod rig’ development onboard Olaf Harken’s “Procyon” project. Another considers a ‘wishbone’ arrangement onboard two custom 48 footers
  3. brian eiland
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    brian eiland Senior Member

    AftMast Tri

    This posting came up on the 'wishbone mast thread' and probably is more applicable here

    [Quote:Originally Posted by Guillermo]
    Did you know this?:
    What's your opinion?
    I've just found it.

    Yes Guillermo, this was brought to my attention a couple of years ago. Reference posting #20 & #21 of this thread: at:
  4. Guillermo
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    Guillermo Ingeniero Naval

    The guy wrecked close to Malaga:

    Nov 26, 2005
    "0800, force 3, northerly, clear, high 40s. It is cold. Drew the last €500 to pay the repair, then returned to boat, and prepared for the trip to Sotogrande and Gibraltar. Left Malaga harbor at 1100, sailing at 4 kts in force 4 wind. Pleasant day until 1500 when the wind jumped to force 7 gusting 9 by 1600. I got the sails off, and motored, first into the wind then off the wind after dark as I could not hold it into the wind. I set the sea anchor at 2200 to ride it out and was setting well, until a wave skewed the boat and one side of the bridle was cut on the bow anchor, forcing the boat to lie at a quarter to the waves. A large wave broke on the stbd breaking a hole where the patch had been made, starting the flooding of the stbd ama. About 2330 the ama was swamped and water was sloshing into the cockpit not long until the main hull swamped so I sent a Mayday while I still had battery and lights and engine. A tanker about a mile away answered. From then on for about a half hour I was able to flash the mast work lights. The wind was force 9 gusting 11 and the seas were approaching 20 feet and breaking. A breaker swamped the main hull and the engine died, the batteries shorted and the lights were gone. I showed a waterproof hand lantern as the tanker passed me the first time a 100 ft upwind at 5 kts. They made another turn to slow and came alongside downwind letting me drift down on them. I was in the water up to my chest for about an hour and a half battling the waves and flotsam in the cockpit, getting beat around a bit.
    In the process of getting from the swamped Windwalker to the tanker Aescepulis I received a line with ring buoy which I placed around my chest and the crew pulled me in the dinghy to the boarding ladder. Just as I was coming in the wave dropped the dinghy below the ladder foot and I slammed into it bruising my lower ribs and twisting my back.

    On the next wave I was cleared and the crewmen lifted me to the ladder, virtually carrying me to the ship’s deck, and to the infirmary. There I was stripped and dried, clothed in a coverall and warm socks, given a good cup of hot coffee and a couple of Snicker bars for some quick energy. As I warmed up, having been in 65° water for an hour and a half, I was examined by “Jim” and “John”, Medical Officer and the First Mat, then photographed and interviewed by John and the Captain. The Captain mentioned that I did not seem to be greatly distressed, and that apparently I had been in life threatening situations before (more than once for sure) was just damn grateful to be alive, sucking air, vertical, not badly injured and sober. I was then taken to a cabin and put to bed."

    And previously he dismasted close to Bermuda:

    May 20, 2006
    "0600, wind E - 4-6 kts, seas 3 ft, mostly clear, high 60s. Wind veered dead E right on my nose. On stbd tack heading 045° making 5 kts northing. Swell making for a rough ride. Motored for 1/2 hour getting sails set and on heading after being hove to. Big ketch on port tack crossed my bow at 0700, distant 1/2 nm. I went on a port tack, set the heading, went below to fix another cup of coffee when WHAM ------

    DISASTER - 0800 - DISMASTED - A Norseman backstay fitting failed, crystalized in the threads. 116 miles from Bermuda - vicinity of 32° 05'N, 67° 16'W - drifting and securing what I can. All wreckage, mast and sails on board and secured by noon. I still need to get antenna from end of mast so I can put out a MAYDAY.. I got the antenna and mounted it above the cabin. On the first Mayday call I got an answer from a boat just behind me over the horizon, the BABSAN from Wisconsin. They came alongside, went through a real hassle siphoning 4.5 gal of fuel for me from their tank. I calculate it will give me just almost enough if the wind will let up. The BABSAN went on ahead as they are faster. They notified Bermuda who notified the folks back home. There is another boat behind me about 5 miles, the WEED."

    He rerigged later with a conventional bermudan rig.
  5. brian eiland
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    brian eiland Senior Member


    Did you find that in his logs? I've not read them as there appears to be almost no mention of the sailing capabilities of the vessel.
  6. brian eiland
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    brian eiland Senior Member

    Inquiry with Genoa reference

    ...a recent inquiry I received making reference to the genoa sail and sail handling..

    "Are there any new developments on aft mast multihulls? I keep an eye on various internet sources and don't see much happening.

    My personal experience is that my Gemini cat is about as fast with just a big genoa alone as it is with main and jib. Maybe not as weatherly, but certainly easier to handle, it's not exactly race material anyway.

    As we look to upgrade to a bigger cat and I get older and less able your words are hard to forget.

    If there are updates on the scene I sure would be interested as we are considering having a Hughes cat custom built." Anonymous
    Last edited: Nov 10, 2006
  7. Guillermo
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    Guillermo Ingeniero Naval

    Yes, he says that somewhere, but it's difficult to find among the very long logs. The general feeling I got is that the boat as a whole was a complete disaster (And I have my doubts about the mental sanity of the man....)
  8. Richard Hillsid
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    Richard Hillsid Senior Member

    Here are 2 images of the boat 81' wl she has a keel 7'' and 2 whatsamacal them stabiliser full length.
    I just put in 22 tons of concrete and she still floats bow high at 1.2 meters stern at 1.7 meters so plenty of room for more ballast or cargo.

    Square rig sounds interesting.



    Attached Files:

  9. brian eiland
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    brian eiland Senior Member

    Mast Aft Trimaran Failure?

    As I wrote you in a private email, I also questioned the sanity of this gentleman, but that’s all another subject.

    When I was first made aware of his original website and his rig calculator, I was very surprised at the exact wording on his site that copied the wording right out of my website verbatim. Here is a gentleman who never once had contacted me about this subject he had such a great interest in, nor ask any permission of me, nor given any references on his site back to mine. I wrote him a letter about these matters, which he chose to ignore answering, and instead took down some of his web pages from his site.

    In that letter I also expressed some concerns about his interpretation of my design. I was particularly concerned about his lack of a resistance element to the forward force that will be generated by the upper aft facing jumper strut over which the masthead backstay passes. In contrast I have provided a triangulated (diamond) jumper strut arrangement to help counter this forward pressing force. I have also provided two additional backstays at this point to counter forestay loads.

    …photo of vessel under discussion:

    In other words I was concerned about his variation of my design. But since he had chose not to communicate with me about my concerns, and since he had already built it, there was not much left to do but wish him the best. Maybe his mast section would stand up to the loads, but I seriously doubted it. I was also concerned about his disproportionably long, lower mast panel.

    Another of my concerns was his use of three headsails. To my way of thinking this placed the headsails too close together to be practical. We know from past cutter arrangements that should we have the headsail and the staysail too close to one another it became difficult to maintain the trim on both such that they were always fully engaged. Plus, it became more problematic in a tacking situation. And he obviously had not sailed enough to recognize the balance that can be had with a jib-mizzen combination.

    Your reference to the rig being replaced with a conventional one was rather brief, leaving the impression that this mast aft experiment was a total failure.
    I don’t think we can assume this just yet with the VERY limited information we have. All I see so far is a failure of a piece of ordinary rigging, “a Norseman backstay fitting failed, crystallized in the threads. That could happen with any rig. Certainly it appears to be a backstay component, and if he had only a single backstay with this 3-headsail arrangement that would be a real problem. But lets not condemn the mast aft concept in general based upon this flawed design experiment.

    And finally I might even have to give some credit to this fellow. At least he went out there AND DID IT, more than can be said for many dreamers.
  10. brian eiland
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    brian eiland Senior Member

    Banque Populaire Maxi-Tri

    As reported in the new 'online' english edition of the popular French sailing magazine "Course au Large" , the new publication linked here "Ocean Racing" .

    This new edition has an announcement/article on the a new 'maxi-trimaran' to be sponsored by Banque Populaire. Interestingly there are hints of 'aftmast-ism' ;

    "The fact that we are talking about the world's largest multihull is not totally untrue, but at the same time, that does not tell us everything.... A length of forty meters is obviously impressive, but let there be no mistake; we are talking about the measurements concerning the central hull, since as you can see, the floats are around 3 meters shorter.

    The height of the mast in relation to the boat's length gives the impression of a rather cautious sail plan (although this adjective seems out of place, if we are talking about 50-knot winds!). With an eye on safety, the designer continued, we tried to achieve a relatively low center of sail force. As for the geometry, the mast is situated 2 meters behind the center of the floats, so the boat has a natural tenency to sail stern down, once again limiting her crashing into waves.

    It can be noted that the idea of pushing back the sail plan was the result of a long series of studies carried out before the construction of the 60-foot Groupama 2.

    As for her sails, the boat has at her disposal 5 different types of foresails
    (Brian's note: That one headsail is almost mast-headed, and obviously there are plans to fly two headsails at one time.)

    Here's a 3D imaging:

    Attached Files:

  11. yipster
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    yipster designer

    a racer, but what a boat :eek:
    makes me wanna check how much is won compared to say 10 or 20 years back
    "ocean racing" has some great articles, fine magazine, thanks
  12. miloman
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    miloman Junior Member

    I have a friend who built a 20 foot sharpie with a fixed fin keel which he rigged with an aft mast. According to him it was a pretty good rig, but wasn't as fast as he expected. Apparently it required a lot of attention to keep it pulling to it's best advantage. He said that it didn't seem to be noticably faster than the marconi sloop rig he has on it now. He changed the rig because It required a little less attention to sail. He said that at times the rig would pull very well and he could get burst of speed which he never gets with the sloop rig. He claims that the sloop is overall a faster rig though.

    I suspect that there were some other issues to be looked at here. I highly doubt that the forestay was tight enough for real performance. I suspect that for anything other than an all out racer this rig makes little sense. A sloop or cutter will be a little easier to handle, with less stress on the rig. The mast would have to be a pretty strong mast with a large cross section to stand up to the compression loads of a tight forstay. A bi-mast would give you the strength, but also a lot of air-resistance. Another consideration is the stress loads that your boat was designed for. This compression will tend to push dwn the middle and pull up on the bow. In a boat not designed for those kind of stresses saftey and hull-life may be compormised. I believe that a bendy-mast sloop will probably outpreform the aft mast rig all other things being equal. Up wind she'll just sail away, and with a large spinaker to set downwind, she'll out run her too.

    One other though is that the aft mast would be nice at anchor. With all that windage aft she'd just come right up into the wind. Also all the rigging weight is aft instead of on the fordeck holding the bow down.

    Phil Bolger designed a small sharpie "stailsail cat" similar to the one my friend built. He writes about her in his book Boats with an Open Mind. He has several interesting comments. Interestingly he uses a wishbone, which would be nice down-wind keeping her sail from twisting.

    I suspect that overall the rig just isn't all that practical.

    I hope this is helpful.
  13. brian eiland
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    brian eiland Senior Member

    Couple Other Experiments

    Who was that friend, and does he have some pictures to post here. I would think he might find this discussion interested and possible be interested in posting a few comments?

    You might have a look at these discussions
    Vessel Substructure to Support the Rigging Loads
    Alinghi Cat

    I will eventually post some of Boger's work in this regards after I get a little more info

    In the meantime have a look at this aftmast design:
    I'm waiting for the english translation of the article that went with this magazine photo
  14. brian eiland
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    brian eiland Senior Member

    Stylish Aft Rig Rendering

    I guess as a long time proponent of this subject of aft placed mast or mast aft, I've become somewhat of a clearing house for info related to the subject; either that info I found when I was looking around, or info from other persons that was sent to me.

    I usually try to get the person sending me the info to place a posting on this forum, but sometimes they either do not wish to do so or have some other reason. I usually ask if they mind if I post it, and I usually omit their name unless they decide to join the discussion

    Here is something I recently received that is quite 'stylish' in its rendering. And there is a website referenced:

    "For years now I have been toying with the idea of a stern mounted mast on a sailboat. I believe it is time to present my thoughts,
    for criticism, both positive and otherwise. I may learn that the theories are wrong, or that the idea is unworkable for some reason. I might receive some reinforcement for my idea as well. Either way, I am bound to learn something...and that is the benefit behind any outlay of thought."

    Attached Files:

  15. brian eiland
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    brian eiland Senior Member

    Mainsail-less (no main) Ketch

    The July issue of Cruising World had this Tayanna 55 listed in the classified section.

    It caught my eye as a prime example of something I mentioned long ago in reference to removing the conventional mainsail of a ketch and replacing it with a staysail;
    "Conventional booms excessively flatten the foot of the mainsail, and are often oversheeted, contributing significantly to the leeway forces. I once had a copy of a test on a Morgan 41' Out Island ketch , where upon removing the mainsail, the boat lost only 1/2 knot of speed, but cut its leeway in half (from 11 to 6 degrees). A staysail was then rigged between the masts in place of the mainsail, and the boat regained 1 knot of speed while retaining its decreased leeway"

    In fact I brought this subject up recently here: item #202

    Now if you could accomplish this all with one mast rather than two....;)

    Attached Files:

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