I had APS Ltd 's rigging shop make up my mainsheet...it is Maffoli Swiftcord 5/16 (or metric equiv.) where I hold it. This line is very easy on the hands and provides a great grip (soft, fuzzy, not hard). Tapers to a 3/16 (3mm) spectra (dyneema) tail that runs through most of the blocks when fully sheeted on hard. I have 9:1 on 57mm quad blocks (upper) plus a lower triple with two 40mm blocks hanging off the cleat support arms.



The line flys with this taper.

Here's another extreme example:




But, I've now got a cool 9:1 internal (boom) cascade to swap in the next time I head out for a sail. It's similar to this one:



I also had APS make up a forked tail of more 5mm spectra section on my traveller line. The fork is used to tie off to the beam after the traveller car. There are two small ring fittings either side of centerline which is where the tails are tied. This setup gives a very good centering effect on the traveller when pulled in.

You can measure out what & where the splicining/tapers need to go and APS will do the rest for a reasonable fee. It is fussy to get the whipping/tranistions done right so they hold up well...esp. for the mainsheet.