Submitted on October 6, 2003 by Bob Jennette

Question: I plan to have a Schaefer furling boom installed on my 40 ft, (Ocean Cruising) sloop. Since the boat was designed having intrinsic weather helm with the board up, I have had good luck with a conventional mainsail, cut fairly flat, having inverse roach and having no battens. Is this the type of sail to be built for the furling boom or does the easy cockpit (powered winch) reefing allow a more standard sail?

I also have a removable inner forestay. Its only purpose is to deploy heavy weather sails, thus the stay is almost always stowed out of the way, near the mast. Is it ok to replace this wire stay with a very low stretch braid (polyester/spectra), say 10mm? Should the new jib hanks be super large because of the higher friction of the braid?

Signed: man and wife over sixty years old.

Answer: Dear Bob, the Schaefer boom will accept a full batten mainsail with moderate roach. The system has a plastic luff foil that uses the bolt rope groove to handle the tension loads and a channel aft of the luff rope groove that captures the batten end caps to handle batten compression loads. The sails are a little flatter than a conventional full batten sail which makes them roll up better. A flat, open leeched full batten mainsail will not add significantly to the weather helm that you experience. Weather helm is caused by both the center of the area of the sails in plain view, and the amount of curve, or return to windward in the sails. A new sail built for the Schaefer boom will have less return in the leech than your current battenless sail. That should offset the difference in the center of the area.

You can replace the wire inner forestay with a plastic coated aramid stay, or with a spectra braid rope. The aramid stay is similar to what race boats use for running backstays and fixed backstays. It is lightweight, low stretch and rugged but also expensive. A spectra braid rope will have more stretch than the aramid stay and significantly more than your wire stay. However, if you have a turnbuckle or adjustable lashing, you can reduce the sag to an acceptable amount. Your choice of material should be restricted to Spectra or Dyneema. Spectra/Dyneema is much stiffer than polyester with about the same UV degradation properties. Choose a 12 plait braid without a cover. The cover material does not add to the stiffness of the rope, and it does add to the cost. If you go with a core only construction like Sampson Ropes Amsteel Blue line, you get much greater stiffness and durability for a given diameter. You can use regular bronze or steel hanks for the purpose you describe.

Regards,
Dan Neri

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