I read the black arts on rigging;
"The next issue is to get the mast centered in the boat (side to side). I add a spare sail slide in the mast track (put it on before you feed the slides for your main so it sits above the other slides), then I use the main halyard to hoist the slide, with a tape measure attached, up to the top of the mast."
What "slide" is the author referring to in this text?
Hunter van Leeuwen
1984 C&C 27 MKV 006
Whites Lake, NS