Increasing jib/forestay height

Discussion in 'Sailboats' started by neris, Oct 22, 2012.

  1. neris
    Joined: Oct 2012
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    neris Junior Member

    Im buying a quater tonner in the next few weeks to race under IRC. The boat currently has an overlapping headsail and runners. Under IRC overlap is penalised. Rather then loosing the sail area I was thinking of changing the rig to a rig with a higher forestay and creating a taller jib with out the over lap but the same sail area and swept back spreaders. Could anyone forsee any issues that may arise in relation to this idea?
     
  2. Perm. Stress
    Joined: Jan 2008
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    Location: Lithuania

    Perm. Stress Junior Member

    It will involve serious re-engineering of the mast, with new position of cap shrouds, and consequent rearrangement of all the other transversal rigging, at very least.
    If spreader sweep will need to be increased, new chainplates with supporting structure will be necessary.
    Is the penalty for overlap and runners so prohibitive, as to go for such lengths to eliminate them?
     
  3. gggGuest
    Joined: Feb 2005
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    gggGuest ...

    You'll probably get a much more useful answer on somewhere like SA than here. Better yet talk to the folks who are reviving 1/4 Ton racing .
     
  4. CT 249
    Joined: Dec 2004
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    CT 249 Senior Member

    I've done it and agree with the advice to go to SA.

    I modified my ancient, small and scruffy half ton cruiser/racer in the same way. The job was easier since the boat had originally had swept spreaders on the gunwale in the original '68 configuration (why a short masthead rig had swept spreaders is a mystery). Years later I modified it to a fractional rig with double in-line spreaders mounted to inboard chainplates, runners etc. When I went short overlap last season, I just returned to the old chainplates.

    The biggest problem going to the short overlap/swept spreader setup has been the fact that it causes me to rave about how great it is, every time I go sailing. The improvement in ease and joy of sailing is enormous. Mind you, that is sailings in a reasonably breezy location and often in a very narrow waterway where short tacking is required, and the unusual design of my boat made the old 150% overlap #1s unusually hard to tack.

    One point is that if you lift the forestay without changing anything else, you may run short of stability in a breeze (IMHO). I kept my forestay at the same height because I chucked out the old diesel around the same time and the switch to an outboard seems to have reduced drag enough to compensate for the reduced genoa area in light winds.

    Acceleration is wanting under the smaller headsail, although more than compensated for by the ease and speed of tacking. The biggest surprise has been the improvement in upwind speed and height in a breeze, because we now carry the #1 (a flat cut second hand #3 from a Mumm 30 style boat) right up the range by barber-hauling outboard aggressively, resulting in a flat sail with a very clean, open slot.

    Jamie McWilliam from Hong Kong has written a good piece on re-doing a QT into a short overlap rig, using an Etchells rig IIRC. Google his name and "Sai Kung Belle" for details.

    I moved the chainplates in my 2100kg boat when I installed the in-line spreaders and found it no big issue, but she is a tough old girl. IMHO just accepting lower rig tensions reduces loads dramatically and the Etchells/J/24 section is showing little if any sign of strain compared to what it formerly received. Many of the small ODs (Tasars, Flying 15s) purposely race with low rig tensions in high winds, so IMHO the need for tight forestays and accompanying high loads can easily be overstated, although we're just club racing. I do have concerns about the loads being transferred to the mast around the spreader root as there seems to be deflection there.

    We have only done a few twilights and some cruising, but overall the boat has been enormously improved.
     
  5. Paul B

    Paul B Previous Member

    What you are describing is similar to the route most QTs have taken for IRC racing.

    It depends on what boat with what rig you are buying.

    If the rig is already marginal or is very bendy ("Farr-Type" taper) you will have to get a new rig.

    It will probably not be possible for you to get back all the sail area by simply raising the hounds. You would probably need a bigger main as well, so a new rig.

    I don't think you will get a good answer on any message board. Best you contact a local designer who has experience with the IRC rule. Maybe Mills? He would be able to help you maximize the benefit while minimzing the rating.
     

  6. Ja guar
    Joined: Jan 2013
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    Location: English Bay

    Ja guar Junior Member

    There is a local sistership to mine that had the forestay raised some 5-6 feet. Not as simple as it sounds, but from the looks of it, this is what was done:

    1. Jib and spin raised to within 1-2 feet of masthead on original mast.
    2. Spreaders in same position, but increased in length by about 1.5 feet
    3. Shroud tangs moved up to hounds rather than spreaders moved up
    4. Chainplates moved outboard about 1 foot and moved to second bulkhead about 18" aft of main bulkhead. These changes increased sweep and athwartship position of spreader tips.
    5. Running backs ditched (no longer required since they were only there for forestay tension) since the boat is now effectively masthead.
    6. Adjustable forestay with tackle system to control forestay tension on the fly (rather than runners)
    7. Went with a lapping jib rather than genoa
    8. Put on a large roach main
    9. May have gone to slightly larger diameter shrouds.

    Not done for IRC since we don't have that around here. I think it was mainly to get rid of runners and run a more efficient headsail, plus oversized kites.

    Anyways, here are some photos:
     

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