[MHml] Main Halyard

[Creighton Smith]

I absolutely agree that knots reduce the strength, particularly of high tech 
line, by half or more but in my work as a rigger I came upon a great number 
of instances of chafe and wear in the halyard's last foot or two.  This was 
caused by the line's constantly working several inches through the masthead 
sheave in response to load variations transmitted by the sail in response to 
breeze, pitching, and other normal sailing transients.
In a normal multi of around 12m loa with halyards led to the cockpit we are 
working with a halyard length of nearly 40 meters.  Even with a line which 
stretches only 0.4% @ 20% of load, this is a stretch of over a meter. 
Coupled with the stretch of the sail's luff the result is a surprisingly 
active 300cm or so constantly running back and forth through the sheave. 
(stretch is elastic)
This is why I don't like splices at the head as the thick section of the 
splice tail runs constantly through the sheave, which is usually sized for 
the halyard.
When wear is detected a knot can be cut out and the worn section discarded. 
Splices are functionally impossible on used line.  We cruiser-racers deal 
with this set of conditions by oversizing the halyards, in which case the 
strength reduction of the knot is a non-event.  I use 12mm covered vectran 
which is seriously over strong.
Yes it's heavy, yes it's expensive, but it lasts a long time and it solves 
nearly all the problems.
Kudos to Ross!  The remote masthead jammer neatly addresses all the problems 
I've discussed and is a great candidate for a spliced halyard, provided the 
masthead sheave is large enough and the jammer is positioned to jam the 
line, not the splice tail.  The stretch/creep on half a meter of line is 
negligible.
Creighton