Flying Fifteen – Adjustable Mainsheet….

This belongs in the series of articles about NZ 3166, a radical bit of thinking….

NZL-3166: Adjustable Mainsheet system

  • On NZL-3166 we run a 8mm 1:1 mainsheet that splits into two 4mm Spectra (core) lines that exit out of two Harken Carbon blocks at the booms end. They then attach at the gunwhale.
  • This system utilizes a powerful kicker and a strong boom to maintain leech tension on the mainsail. The mainsheet, in everything but light conditions, is essentially the traveler.
  • While this self-centering system is used on a few Flying Fifteens and maximizes the leverage on the boom laterally (and minimizes mainsheet tension), it does lack self-centering in very light (sub 3knots) conditions were you require the boom on the centre line and no kicker and very low mainsheet tension.
  • Thus, if you look at the photo, I have attached the green rope to the white spectra mainsheet, this runs around a very small block, through the deck, under the floor, and exits forward by the chain plates (where the helmsman sits in light conditions). Under the deck it converts to 2:1 and when pulled brings the boom onto or above the centerline.
  • This is the port side and is duplicated on the starboard side.

NZL-3166: Mainsheet system

  • This shot shows the split spectra mainsheet running through the Harken Blocks at the booms outer end. The alloy mounting bracket allow the blocks to run freely from side to side and clear the boom (no chafe).
  • The red line is the outhaul.
  • All ropes on our boat are either spectra, vectran or Dynax and spliced. This allows minimal creep or stretch in the entire rig thus every kg of wind pressure put on the sails is directly transferred to boat speed and not rig movement.
  • Rig tension and sail shape are also maintained with minimal creep and stretch in your rigging.

(Thanks to Graham Brown)

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