Shroud control: Mast Heeling Line setup, tension, and rake

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This page looks at setting up the mast (shroud tension and rake, further below)  and shroud control through the mast heeling line.

  Catapult's unique shroud control (to assist rigging and allow capsize recovery) uses a 6 X 1 tackle at the bottom of each shroud (pictured below) with a single line for both, running across the boat. To heel the mast, one tackle is slackened while the other is pulled in.

 Most boats are set up with the line running across the boat a little aft of the dagger-boards. 


  Most of us have experienced this you are doing well on the first beat and you have the inside slot with the windward mark coming up fast its great isnt it! You put in a neat tack and bu**er your foot fouls the heel line & the rig uncleats!! Its so frustrating all that hard work on the beat gone to waste!

 Many have gone for another solution reverse the heel line to run forward and position the cleats just aft of the forward cross beam. Job done perfect solution you might think
(and see photo further below.)

  However Jon Montgomery never supported this arrangement - his objection was that the line was now out of reach if you are in the water aft of the shrouds, as you likely to be after capsize. In the end Topper kept to JMs original design and to help Jon added fair leads inboard (see below)  to minimise accidents.

catamaran rigging

 This worked well for me if the shrouds were kept fairly tight but we all know that a lot more power can be generated if the shrouds are slack.

 With the slack rig set up, I struggled to keep the heel line cleated in the heat of a race. So last winter I gave the heel system some more thought and came up with a new arrangement pictured below.

As can be seen with my arrangement the heel line now crosses the deck forward of the dagger boards and so is much less prone to accidental tripping.

 Also the heeling system can worked from a position aft of the shrouds and if on capsize you find yourself forward of the shrouds then my arrangement is also convenient to use.


Its nice to think that JM might just have approved of my new heel line arrangement.

Here is a list of the items needed:
   12metres mast heel line
   2 x HA 182 fairleads & screws
   2 x HA 2020 20mm blocks or similar
   2 small D shackles
   2 small carbine hooks.
Note the forward facing barrel cleats and blocks are not essential

   John Peperell

(Right: The close-up shows the heel line fair-leads (the two little "drums" top left) inboard of the cam cleat, giving protection from tripping the cleat.)

  Left, and top photo: TENSIONING THE SHROUDS

  Both these boats bring the "tail" of the heel line out from the blocks to a clam cleat (John on both sides, see top photo,  and Alastair on starboard only, shown.)

This makes it simple to finally tension the shrouds after setting the mast up with loose shrouds.

  The picture left also shows Alastair's use of the solution which John describes in the article above, with the heel line led forward rather than back from the blocks, running across the boat a little aft of the forward cross-beam.

(See more on this at Repositioning the mast heel line )


       SHROUD TENSION: a debate

   Everyone agrees that it is essential that the rig is not set up so tight that mast rotation is restricted, as an un-rotated mast drastically cuts power and speed until it is noticed and pushed around. This also needs a smooth mast ball, well-lubricated.

   Beyond this, some are confident that the boat goes best with the shrouds a little slack (about 6 inches easy movement sideways at shoulder height) while others argue that only ensuring the mast rotation is the key.


  The photo right gives an idea of the 6 degrees of rake most use, as the designer recommended.

    Alastair comments "I tried varying the rake, by adding a 3cm shackle to the forestay in strong winds (to add rake to reduce bow nose-diving) and taking a shackle out in light airs (to bring the mast upright.)

This is easy with the
shroud adjustment shown above, and I marked the three settings with an indelible pen. Having done all this, I found I couldn't detect a
real difference in speed in the light winds. (It risks premature stalling also)

  In heavy winds, there is so much going on that seeing a difference may be lost, and the advantage of less pressure on the bows may be offset by less responsive tacking. So at the moment I have given this up"

 Others may have other ideas on adjusting mast rake, but sticking to the 6 degrees above seems best.

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