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Thread: Rotating mast .....

  1. #1
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    Default Rotating mast .....

    Hi !

    Quick question ....

    A potential multihull candidate in my list is equipped with a rotating mast...

    I've never sailed with a rotating mast so would love to read your feedback and/or feelings...

    Some positive comments I found:

    1) The leading edges of the sails are always at optimum, fair to the wind regardless of the point of sail...
    2) Sails can be raised, reefed, or stowed without changing course. This is particularly important when sailing downwind, because you do not have to turn the boat first broadside to the weather, and then into the wind in order to change sail. You hold course and just let the rig weathervane while you do what needs to be done;
    3) When sailing downwind, you can set the booms well forward of the beam with the masts pointing aft to get really great lift downwind...
    4) With the booms so far forward and set wing and wing, the boat is naturally stable and extremely resistant to broaching.
    Uncontrolled gybes almost never happen because forward-set sails cannot get caught by the lee; one sail or the other will naturally pull the boat back onto course should she ever get pushed off by gust or wave"
    But no idea on negative points, I expect more maintenance as this mast pivots... Bearings ? Grease?
    Mast stays must be super important... (no inner stays possible, etc...)
    I guess wanting to add a a screacher on a furler is looking for trouble?
    What about masthead mounted stuff ? I suppose no cabling useable as this will deteriorate quickly due to twisting? (lights, transducers etc...)

    So, major question, would you consider this on a cruising boat ?

    Thanks !
    :
    1979 Catalac 8M - 8-84 - Samimiy
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  2. #2
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    Default Re: Rotating mast .....

    Those attributes would only be for rotating, UN-stayed, masts. Rotating masts with standing rigging still require shrouds led quite far aft of the mast to support it. Letting the boom out forward as described still cannot be done. While there may be a bit more lattitude in the angle to wind for setting and dousing the sails, it is marginal.

  3. #3
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    Default Re: Rotating mast .....


    Quote
    3)
    When sailing downwind, you can set the booms well forward of the beam with the masts pointing aft to get really great lift downwind...
    4) With the booms so far forward and set wing and wing, the boat is naturally stable and extremely resistant to broaching.
    Uncontrolled gybes almost never happen because forward-set sails cannot get caught by the lee; one sail or the other will naturally pull the boat back onto course should she ever get pushed off by gust or wave"



    The above would only apply to an unstayed mast, They are a rare and expensive option. A rotating mast on a cruiser is desirable to ease the hoisting and reefing of the mainsail, this is due to the battens being at a right angle to the sliders on the mast track. Inner forestays are possible but need lowers to resist the bending force on the mast, these stays need to be arranged in the same manner as the uppers to allow rotation. Screechers are ok providing the mast is designed to accept them and will need runners. Masthead nav lights are useless but an anchor light is fine and can illuminate a wind indicator. Wiring just needs a loop at the mast base. Wind speed is fine but direction possible but complicated and expensive. (see Tacktick equipment)

    Maintenance is vital especially at the mast to stay attachment point. I have 16mm Wichard HD shackles and have replaced them twice in 10 years. There is a small increase in windward performance but full battens are best if tapered, tell your sailmaker that you have a rotating mast and if he is reluctant to modify the sail to suit look for another sailmaker.

    If you need further information look at Erik Lerouge's website and boats like Gifi. I've become a fan of rotating masts.

  4. #4
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    Default Re: Rotating mast .....

    Didier, he is right, or are you talking about a Baelstron Rig, again unstayed rotating mast as used on some of the more modern Twins designs.

    Quote Originally Posted by cchesley View Post
    Those attributes would only be for rotating, UN-stayed, masts. Rotating masts with standing rigging still require shrouds led quite far aft of the mast to support it. Letting the boom out forward as described still cannot be done. While there may be a bit more lattitude in the angle to wind for setting and dousing the sails, it is marginal.

  5. #5
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    Default Re: Rotating mast .....

    Rotating masts pose problems:

    There are a lot of forces and a lot of mass at play, so larger rotating masts require winches for positioning, and a slatting sail on an unsecured rotating mast is an invitation to chaos.

    There are systems to compensate mast rotation for mast-mounted lights and wind sensors, and possibly an electronic compensation for mast mounted radar, but these are additional, spectacular expenses.

    However

    A rotating mast does not rule out ruler furling, or spinnakers or screachers, and they do provide a much higher efficiency from the sail. They DO make it easier to lower the main without heading directly into the wind, i.e. you can continue sailing on the jib in many instances.

    So the gain is significant to a more performance oriented captain, and a PITA to a cruiser. The reason for both of them is the number of extra strings to pull!

  6. #6
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    Default Re: Rotating mast .....

    If racing, go for it!

    If cruising, KISS.

    Steve

  7. #7
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    Default Re: Rotating mast .....

    Thanks, good start !

    First thing ... the rest in the following post, long one...

    Quote Originally Posted by cchesley View Post
    Those attributes would only be for rotating, UN-stayed, masts. Rotating masts with standing rigging still require shrouds led quite far aft of the mast to support it. Letting the boom out forward as described still cannot be done. While there may be a bit more lattitude in the angle to wind for setting and dousing the sails, it is marginal.
    Quote Originally Posted by peter-lillywhite View Post
    The above would only apply to an unstayed mast, They are a rare and expensive option.
    I am talking about a stayed rotating mast, this feedback confirms my ideas on these points (3 and 4)...

    :
    1979 Catalac 8M - 8-84 - Samimiy
    http://facebook.com/groups/catalac/

  8. #8
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    Default Re: Rotating mast .....

    Long post now with lots of quotes... Sorry but trying to summarise...
    here's a pic of the mast base :

    Quote Originally Posted by peter-lillywhite View Post
    A rotating mast on a cruiser is desirable to ease the hoisting and reefing of the mainsail, this is due to the battens being at a right angle to the sliders on the mast track.
    Quote Originally Posted by Sandy Daugherty View Post
    They DO make it easier to lower the main without heading directly into the wind, i.e. you can continue sailing on the jib in many instances.
    So a definite advantage is the fact that reefing is easier (and we all hope we never need to pray for a quick and easy first or additional reef).
    Also having the possibility to hoist at (m)any point of sail is a plus...

    Quote Originally Posted by peter-lillywhite View Post
    Maintenance is vital especially at the mast to stay attachment point. I have 16mm Wichard HD shackles and have replaced them twice in 10 years.
    Thanks Peter !
    Yes, I do think too that the mast needs more attention in the maintenance schedule, stays and stay attachments as you mention, but what about the mast fixing? I suppose it is on some kind of bearings ? I guess this might require special attention ?
    How about the stay tension ? Anything particular in that area ?

    Quote Originally Posted by Sandy Daugherty View Post
    There are systems to compensate mast rotation for mast-mounted lights and wind sensors, and possibly an electronic compensation for mast mounted radar, but these are additional, spectacular expenses.
    Quote Originally Posted by peter-lillywhite View Post
    Masthead nav lights are useless but an anchor light is fine and can illuminate a wind indicator. Wiring just needs a loop at the mast base. Wind speed is fine but direction possible but complicated and expensive. (see Tacktick equipment)
    As I thought, you're probably limited to just an anchor light and maybe wind speed... No deck light or other fancy stuff...
    Peter, do you have wind direction ? If so, is it set-up on a separate pole on the Azuli ? (nice boat by the way !)

    Quote Originally Posted by steve sharp View Post
    If racing, go for it!
    If cruising, KISS.
    Quote Originally Posted by Sandy Daugherty View Post
    So the gain is significant to a more performance oriented captain, and a PITA to a cruiser. The reason for both of them is the number of extra strings to pull!
    Sandy, I am not sure what extra strings need to be pulled, as you know, I'm only looking at smaller boats (the one I'm looking at is a 30ft cat) so no immense masts and sails...

    Steve, I agree, and my intent is cruising, not racing, but can't a well maintained rotating mast be a KISS solution ?

    But for now with regards to cruising, 1 pro (Peter), and 1 contra (Steve)... Sandy, do I count you in the pro or contra side ? I guess contra (as you mention the PITA word )
    I should have made a poll

    Thanks so far !
    :
    1979 Catalac 8M - 8-84 - Samimiy
    http://facebook.com/groups/catalac/

  9. #9
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    Default Re: Rotating mast .....

    djeeke,

    I'm just away on an ISAF Survival course, when I get back, Tuesday and Wednesday I'll try to answer your questions and enclose pics of how we are rigged on our a Azuli.

    Peter.

  10. #10
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    Default Re: Rotating mast .....

    Quote Originally Posted by peter-lillywhite View Post
    djeeke,

    I'm just away on an ISAF Survival course, when I get back, Tuesday and Wednesday I'll try to answer your questions and enclose pics of how we are rigged on our a Azuli.

    Peter.
    I hope you'll survive then !!!

    Thanks a lot !

    :
    1979 Catalac 8M - 8-84 - Samimiy
    http://facebook.com/groups/catalac/

  11. #11
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    Default Re: Rotating mast .....

    Quote Originally Posted by peter-lillywhite View Post
    djeeke,

    I'm just away on an ISAF Survival course, when I get back, Tuesday and Wednesday I'll try to answer your questions and enclose pics of how we are rigged on our a Azuli.

    Peter.

    Our mast is a 15m aluminium section (Sparcraft F590C) supported by 3 10mm stays via. Wichard HD shackles linked onto a 18mm bail. The mast foot has a vertical hole through it that engages with a vertical pin attached to the mast foot, a plastic donut acts as a bearing between these componants. The stays are moderately tight (not as tight as with a fixed mast) but when powered up the lee stay is slack and can flop about up to about 250mm, we have shockcords to absorb this movement (slacksuckers). Going to windward our forestay sags to leeward, not a problem if the jib has been cut to accept it.

    Wind direction and speed (the important part) is read at the mast head, you soon get used to reading the direction from the mast centreline rather than the boats, in fact beating I find it more useful to position the arrow on the mast than the boat. A previous owner fitted twin transducers on booms mounted on the sterns but it must have been a hastle switching them on every tack or gybe.

    Halyards remain at the mast and hoisting and reefing is done here, this reduces friction and the number of control lines across the deck. I usually tighten the reef pennant using the windward genoa winch, its more powerful and its easier to watch what is happening from here. With wide sidedecks and a beam of 6.5m its easy. We also have inboard jackstays making movement around the deck safe.

    The only additional line is the spanner locking line, 2:1 continous 8mm rope controlled by a couple of Spinlock jambers. The loads on this line can be high with full rig but we have always managed, sometimes even using the movement over waves. Some Azuli's were fitted with a winch to trim the spanner.

    I've made repeated attempts to attach some photos to make my description clearer, however the technique has defeated me! If anybody can point me to a solution I would be delighted, I can upload the images but always seem to lose the text in the process.

    Peter

  12. #12
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    Default Re: Rotating mast .....

    Count me sitting on the fence, directing traffic. By "extra strings to pull" I'm referring to exactly that. Compare a charter cat to a racing machine; the main on a charter boat has a main sheet, halyard and out haul for controls. As the performance requirements increase, you add luff tension, vang, cunningham, and spend a lot of time tweaking the batten tension. Then there's back stay tension for mast bend, and running back stays. More strings to pull, and some of them require their own winches, hydraulics, kickers, etc. If the mast rotates, winches may be required to control it, meaning a dedicated crew member just for that purpose in a tacking duel. But wait! that's not cruising! No extra crew, no tacking duels! No extra winches (they each represent a couple months in the cruising kitty.)

    I doubt a rotating mast contributes a 10% increase in the power of the main, and it compromises the power of a genny cut for roller furling. Come to think of it, a racer would not have a genoa on a roller furler!

    My position is this: a rotating mast is for a boat with a very strong slant toward the performance end of the spectrum, and that is why they are found on so few catamarans. They are an enormous expense for damn little gain, they are a continuing expense after the initial investment, and they add to the confusion and mayhem in a crisis. To much for a single person to deal with on a cold, wet night watch.

  13. #13
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    Default Re: Rotating mast .....

    OK Sandy, I'll run with it.

    Quote Originally Posted by Sandy Daugherty View Post

    Compare a charter cat to a racing machine; the main on a charter boat has a main sheet, halyard and out haul for controls.

    A rotating rig would add one control line to that.



    As the performance requirements increase, you add luff tension, vang, cunningham, and spend a lot of time tweaking the batten tension. Then there's back stay tension for mast bend, and running back stays. More strings to pull, and some of them require their own winches, hydraulics, kickers, etc.

    Sounds to me like the old one tonners I used to crew on in the 80's with a crew of 8 or 10 that needed to feel wanted. Even the keen racers around here tend to sail simple multis with few strings as any more than 3 or 4 crew means too much weight.


    If the mast rotates, winches may be required to control it, meaning a dedicated crew member just for that purpose in a tacking duel.

    Don't do tacking duels, if racing too slow, if cruising find another destination, I do however single hand the boat helped by a Autohelm 4000 tiller pilot


    But wait! that's not cruising! No extra crew, no tacking duels! No extra winches (they each represent a couple months in the cruising kitty.)

    We haven't found the need for a winch, but I could buy a Lewmar 16 for around 200


    I doubt a rotating mast contributes a 10% increase in the power of the main, and it compromises the power of a genny cut for roller furling.

    I would be suprised if we get half of that advantage, and on our mast the diamonds compromise the genny trim, either pointing high with a draggy mast or ease the jib and sail low and fast with rotation, the VMG seems to be the same.



    Come to think of it, a racer would not have a genoa on a roller furler!

    We have won a number of offshore races with a roller jib, our usual changeable conditions can soon tire a shorthanded crew. Trying to remove a 130% jib on a 40' cat in 20 knots true wind offshore can result in damaged sails and crew. Its a pity the poorly written Multihull ISAF Special Regs don't recognise roller reefing as it makes it very difficult for the cat owner to enjoy the occasional race legally. What the hell we all ignore the rule as it would be illegal under them to race a multi at all!

    My position is this: a rotating mast is for a boat with a very strong slant toward the performance end of the spectrum, and that is why they are found on so few catamarans. They are an enormous expense for damn little gain, they are a continuing expense after the initial investment, and they add to the confusion and mayhem in a crisis. To much for a single person to deal with on a cold, wet night watch.
    I agree with most of that, not sure about the expense issue however. If I were sailing permantly and using my boat as my home I would own a different boat. As I cruise around N Europe with just my wife out of winter time often for a few weeks at a time and I enjoy steering with a tiller extension and competing a couple of local races each year, a charter type cat wouldn't satisfy me. The ability to pull a reef in downwind makes life easier and safer and tips the balance for me.

    Horses for courses as we say in these parts.

    Cheers

    Peter.

  14. #14
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    Default Re: Rotating mast .....

    As a 'lurker' who has been following this with a great deal of interest, thank-you all for so much well written, well expressed, considered information.

    Thank-you.

    Mike
    Nothing works on an old boat, except the skipper.

  15. #15
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    Default Re: Rotating mast .....

    I forgot to mention that, four cats ago, I had a Stiletto 30. Rotating mast, boomless main, Screacher on a traveller from bow to bow, tiller extension, and a 2-stroke outboard smack dab in the middle. I loved pulling strings, convincing myself I was doing so for scientific, aerodynamic, and superior seamanship reasons. It was a blast! When overpowered in a gust it would lift a hull, and devoid of the extra drag it would accelerate from "oh, my, god" to "ho, ho, holy shi, shi, shihosephat!" in rapid order. I once flew a hull from abeam National Airport (in D.C.) to just past the Wilson Bridge on the Potomac River, at nearly 20 knots. Calm water, steady wind out of the West at 20 mph.

    I'm older if not wiser now. I no longer think that sleeping in a hot, mildewed coffin is all that great, and after about three days without a shower I start to dislike my own smell. Ah, well. Still I miss it.

  16. #16

    Default Re: Rotating mast .....

    Quote Originally Posted by peter-lillywhite View Post
    [B]
    The above would only apply to an unstayed mast, They are a rare and expensive option.

    Rare? Perhaps, but definitely not expensive.
    The unstayed mast on http://www.youtube.com/watch?v=8chR6DAFjGA is on a 15m harryproa with the same righting moment and rig size as a Schionning Wilderness 12m cat. When built, it cost the same as a locally supplied alloy mast with stainless rigging.

    The unstayed mast does not require chainplates, seagull striker, forebeam or all the beefing up these require. It does need some local beefing up at the deck and heel bearings but this is miniscule compared to the beam under the mast of a stayed rig.

    The unstayed mast has a virtually unlimited lifespan. Stainless rigging requires replacement every 5-10 years (depending who you talk to).

    The stayed rig will need regular checking to ensure nothing has come loose, and unstepping each year to check for corrosion and wear. The unstayed rig does not, as there is nothing to wear, break or corrode.

    Stayed masts wear out sails by rubbing them against the shrouds. They are also harder to raise, reef and lower as the mast cannot be pointed into the wind on all points of sail. This is also a safety issue when ruuning square in a building breeze, retrieving man overboard and shortening sail.

    regards,

    rob

  17. #17

    Default Re: Rotating mast .....

    I have never sailed on a boat with a rotating mast and this was my concern using my wind indicator and speed instruments. If I understand this correctly the old standard wind indicator is really hindered by the rotation of the mast. The indicator is providing the apparent wind in relation to the position of the mast. I would have to believe the electronic wind/ speed indicator would provide reliability? If I had and electronic wind instrument package I would believe a notebook would be a worthy tool to determine optimal speed and angle and making note of all conditions. I do understand that the wind/ speed indicator is only one tool there is all the other variables such as sail trim, conditions, course and so forth that are just as valuable. I am more racer now than cruiser, somewhere I got bit by racing around buoys and regattas so the speed factor is important to me. Any thoughts?

    Thanks

  18. #18
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    Default Re: Rotating mast .....

    I have puzzled as to how it can work as well.

    Assuming this is a specialist instrument designed for rotating masts, is there no information from the supplier of the instrument. They must have to answer this regularly.

    Mike
    Nothing works on an old boat, except the skipper.

  19. #19
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    Default Re: Rotating mast .....

    As far as I'm aware four instrument manufacturers allow for mast rotation to enable access to TWD/TWS. They are B and G, Nexus, NKE and Tacktick, all are too expensive for my taste but I guess that all depends on how badly you need the info! I'm about to fit Tacktick kit but it wont include a mast rotation sensor, I can't imagine knowing TWD/TWS would change my race results or make my cruising more enjoyable.

    Cheers

    Peter.

  20. #20
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    Default Re: Rotating mast .....

    I think each of the systems Peter mentioned use mast rotation sensors, adapt rudder angle sensors, or have a separate heading sensor on the mast. This was recently discussed at panbo.com, one of my favorite forums, but I was gently chastized for proposing a purely mechanical solution, keeping the mast head sensor platform correctly oriented by making it align with the forestay while the mast rotates underneath it. I haven't seen this idea implemented anywhere, so I've applied for a patent.

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