Replace Traveller and Track With What?

Discussion in 'Sailboats' started by MMNet SEA, Jul 2, 2007.

  1. MMNet SEA
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    MMNet SEA Junior Member

    Issue :- Have 35 yr old Dutch Built Steel Ketch - good cruising yacht in excellent nick!

    length 12.5 meter = 41'

    breath 3.63 meters = 12'
    mast height 13 meters = 42' 3" above deck

    depth 2.1 meters = 7'

    Height of boom off cockpit floor = 6' 2"

    Distance from main mast to point of attachment of mainsheet
    = 12' 6"


    However

    Centre Cockpit 6' x 6' bisected by a track and traveller at 2' off the cockpit floor, which is the only pain in the groin on this yacht. We are in the midst of a 10 year maintenance refurb and mods here and there.

    Cannot move the 6ft track and traveller to another position out of the way.

    Question :- If the track and traveller are removed from the cockpit - what arrangements of blocks and pulleys could replace them . A schematic would help.
     
  2. Steve B
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    Steve B Junior Member

    Are we to assume the track and traveller are for the lower mainsheet block?
    Regards
    Steve
     
  3. alan white
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    alan white Senior Member

    The workable solution is to place the traveller across the companionway up high enough to not obstruct entry, requiring an analysis of relocation of boom attachment (involving stress to boom) and change of purchase (to maintain same ease of sheeting).
    This involves a pair of stanchions at aft corners of the cabin house. If steel, this is very simple, involving pipe or similar on which to mount the track.
    Alternatives depend upon boom length, and if the track is already crossing the cockpit, you probably have a big jib/small main in the seventies fashion, so the boom doesn't extend to the rear of the cockpit, meaning that location for attachment would not be feasable.
    I had a similar situation with a small cruiser several years ago. I had a bridgedeck (step-over into cabin) and I re-mounted the traveller there. my boom was very short, so this worked fine.
    Twin sheets will also work, with dead ends terminating at the sides of the cockpit and leading to boom, then the mast, and then back to the cockpit across the cabin top. More complicated, but real nice once underway for any period of time because the slack sheet isn't in the way (it will lay on the cockpit sole though, but can also be detached on the windwaed side and stowed on the leeward side) and the live sheet is on the leeward side, leaving the cockpit completely free of obstructions.


    alan
     
  4. PAR
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    PAR Yacht Designer/Builder

    You can use a single sheet with deck mounted blocks, well outboard and aft of your cockpit. Most of these decisions would be made easier if a photo was posted so we could see what you have to work with, instead of guessing.
     
  5. MMNet SEA
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    MMNet SEA Junior Member

    To Steve B, your assumption correct.
    --------------------------------------------
    To Alan, Thanks for your ideas - they initiated a train of thought (in Savannahkhet on the Mae Khong River , Laos - S.E. Asia , 4th July) leading to
    one linear solution :-

    Because, the existing track bisects the cockpit just forward of the binacle, its height ensures that it is an obstacle and an obstruction. It prevents easy safe access to the wheel and aft cabin from the saloon companionway.

    The initial solution would be to build a combination gallows/track - however
    it would not allow sufficient space between the traveler and the boom.

    One idea was to lower the track to the cockpit floor, however this results in the narrowing of the angle of sheeting . And when running downwind the mainsheet would foul the cockpit seat combings.

    Returning to one linear solution - have a look at the attached sketch put together a couple of days ago - also a lousy photo of the cockpit (will get a better one when back on the boat)
     

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  6. alan white
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    alan white Senior Member

    Several issues:

    One, I think the boom structure will twist the boom at the gooseneck when both sheets are attached and one is eased before the other.

    Two, you would like a gallows to double as your sheet attachment point, and that is a very good system if at all feasable.

    Let's say you can build a gallows at the boom-end. You would like a traveller on the gallows, which makes sense. However, a vang will do what the traveller will do, which is to apply down-pressure to the boom in any position to flatten the sail. So for a moment, consider the gallows without a traveller.
    Let's say the gallows is aft of the boom slightly, and the blocks, when passing are not vertically oriented but diagonally, or closer to horizontally oriented (when close-hauled) relative to the boom-end.
    I will assume a four part, which ought to be adaquate for a location at the boom's end. From the gallows, port side, the sheet dead-ends. Then up to double block (not fiddle) on boom, down to single at gallows center, up to same double block, and down to single block on starboard side of gallows, and lastly, down that pole to cam cleat.
    Now, the gallows won't support the boom if the boom isn't over it, but then, the boom can't hit the gallows either if topping lift or halyaerd is ket go incautiously. So another part, attached by pivots halfway up on the forward face of the gallows (and shaped to nest in the gallow's silhouette) is swung forward to an angle that IS under the boom (much like a dodger frame in operation). It could be stainless pipe, with a padded canvas covering to protect the boom's underside and provide some friction.
    The gallows can do all those things gallows are handy for--- hand-hold, antenna, lighting, tent, etc., in addition to supporting the boom.

    I could draw this if you'd like. I can see what you mean about the cockpit being a stumbly area.

    A.
     
  7. Aramas
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    Aramas Grumpy Old Man

    Yeah, that sketch is a bad idea.

    If the mainsheet attachment can be moved along the boom to above the companionway, you could have either a double sheet atached at both aft corners of the deckhouse, or effectively move the traveller to the front of the cockpit - in which case it would make getting in and out of the cabin a pain.

    The current arrangement is the way it is because it's the simplest solution. If there was a better way with no drawbacks it would probably be that way already.
     
  8. alan white
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    alan white Senior Member

    It's not so bad up on the bridge deck. If you have a single anchoring point rather than a traveller (like I said, a vang will do), then it is always to one side or the other. This does put the release right where you can get at it from below in certain circumstances of wanting to ease in a squall at night, etc. Not having a bar completely across is a big plus. I had this arrangement once, and it was handy and I never noticed it in the way. If you don't step ON to the bridge deck, but over it, just relocate the traveller. Remember to maintain your purchase--- might have to add a part, since your boom attachment is more forward.
     
  9. MMNet SEA
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    MMNet SEA Junior Member

    In the first post identified the boat as a Ketch, the Mizzen mast is 4" away from the aft end of the boom, This mast sits on the aft cockpit combing. Cannot add a gallows ( this was the initial modification considered)

    Alan, I take your point:- "I think the boom structure will twist the boom at the gooseneck when both sheets are attached and one is eased before the other."
    Earlier your "Twin sheets will also work, with dead ends terminating at the sides of the cockpit and leading to boom, then the mast, and then back to the cockpit across the cabin top. More complicated, but real nice once underway for any period of time because the slack sheet isn't in the way (it will lay on the cockpit sole though, but can also be detached on the windwaed side and stowed on the leeward side) and the live sheet is on the leeward side, leaving the cockpit completely free of obstructions."
    How did you cope with twist in the twin sheet system ?
    Another question (maybe unrelated ) When running on a reach the boom naturally assumes twist ?
    A sketch would certainly help if you have time.
    Thanks again
     
  10. MMNet SEA
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    MMNet SEA Junior Member

    Aramas,

    Thanks for your input ,

    Why do you believe the sketch is a bad idea ?

    Would you accept that if one never moved from the current design, boat development would not advance ? The changes in keel design really illustrate
    that innovation is the key to improving performance. I remember when furling headsail systems were first introduced. Whatever, I agree that the KISS principle is still the first port of call. However, I am intent in getting rid of the existing track and need some help in finding an alternative.
     
  11. Aramas
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    Aramas Grumpy Old Man

    As a machine for destroying goosenecks it would work pretty well :)

    The setup in the sketch puts loads on the boom that rigs were never intended to take. The leverage of the extensions would apply huge, erratic twisting forces to the boom and hence to its relatively small attachment point on the mast. Imo it would fail quite quickly, particularly if it's aluminium, which would work harden and fracture while you watched.

    Still, when the boom falls off (as it will) you might be able to use what's left to dig postholes :p
     
  12. alan white
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    alan white Senior Member

    I'll do a sketch later. I'm on the fly right now. The twin sheets would attach to the boom in the same way a twin sheet system works on a jib boom. The sheets can detach (unclip), however, one or the other, so the slack one is no longer crossing the cockpit sole. Both sides attach directly to the same bail on the boom.
    I missed your saying it was a ketch. Is the mizzen so close to the boom end that a gallows as described couldn't attach directly to the mizzen mast?

    Alan
     
  13. MMNet SEA
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    MMNet SEA Junior Member

    Hello Alan,

    Following your good advice, had another look at possible options once the offending track is removed. Definately no place for a gallows - the Mizzen mast is too close and above the cockpit presents other problems (attached a pix of the base of the mast on the edge of the aft of the cockpit combing)

    Your

    "Twin sheets will also work, with dead ends terminating at the sides of the cockpit and leading to boom, then the mast, and then back to the cockpit across the cabin top. More complicated, but real nice once underway for any period of time because the slack sheet isn't in the way (it will lay on the cockpit sole though, but can also be detached on the windwaed side and stowed on the leeward side) and the live sheet is on the leeward side, leaving the cockpit completely free of obstructions."

    appears to have the components that would fit - and with those in mind, I sketched a couple of twin mainsheet systems that would work within the confines and parameters of the cockpit and the aft cabin. Do either of these come close to what you were describing?

    NB :- The existing track only provides 20" movement either side of centre at 2' 0" off the floor. While the twin sheet options give 42" either side of centre at 5' 0" of the floor - which means that the sheets no longer would foul the
    edge of the cockpit combing when on a broad reach.
     

    Attached Files:

    Last edited: Jul 9, 2007
  14. alan white
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    alan white Senior Member

    The double mainsheets, but with cam releases on the bottom instead of the top, and a means (snap shackle) to disengage and stow either, would be what I was decsribing. Can't have the releases at the boom end, they will be pretty hard to ease going from reach to run if they're several feet out over the water.
    The alternate would be they dead-end (with snap shackle) at the bottom, and lead forward to the boom and back across cabin top to cam cleat on the aft end of the companionway bulkhead.
    Twin sheets will make short-tacking more work unless you are satisfied using just one of the sheets for both short tacks.
    The other drawing is workable, the single split sheet. It will be more in the way, always having a part crossing diagonally in your way. That type is used a lot with end-of-boom applications, especially when the end of the boom is well aft of the cockpit.
    But really, the simplest would be a four or five part single sheet terminating waist-high on the forward face of the mizzen mast. You might reinforce that point by having an inverted U-shaped pipe stanchion attached to both sole and mast, but wouldn't that be a reasonable place to put it?
     

  15. MMNet SEA
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    MMNet SEA Junior Member

    Alan , thanks - much appreciated !

    Mia culpa !! I screwed up in sketching the double mainsheet drawing by having the bottom blocks as standups attached ! When I intended to have each tackle terminate with a snap shackle - I will probable add a couple more pad eyes, to allow a little extra flexability. Here is the modified sketch :-
    (The cam releases at the bottom on snaps)

    Richard
     

    Attached Files:

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