Yeah, this tidbit is common knowlegde (at least should be in F16 circles) ever since 2004. Ronston (plastic) blocks should not be used in the spi halyard systems. Several of us have had this experience. In my opinion the simple steel Harken small blocks are best in this use.

Mainsheet ? Simple (small) shackle on the bottom and a 8 mm or thicker S-hook on top. Quick release possible (even quicker then with a shoft shackle) and heavily tested over 5 years now. Never failed on me.

Wouter

Wouter