The old sheet is stiff and sometimes pops out of the V cleat after the winch. What type of rope is recommended, there are various types but I am a not clear on them. Do I have to get the same size ?
A good quality double braid is fine. Unless you are grand prix racing, and they might use spectra or something similar.
With regard to size, it is not so much about strength, but more about what is comfortable in your hands, therefore 10mm is usual. It is also what size cleats and jammers you have, if you go smaller, you may have to change them.
Easier to stick to the same size.
I bought a whole roll a couple of years ago, cheaper, but only problem most of my lines are all becoming the same colour! ( pull on the blue one, no not that blue one, the other blue one!)
I use 14 mm double braid on two speed self tailers. Usually 4 turns on the winch with 14 mm will give the required grip. Good to hand hold. Any smaller would not have enough surface area for the winch. Does not matter what size yacht.
Early this year replaced my jib sheets. 12mm Donaghys Yachtmaster XS. Australian made, excellent quality.
Got 50m for $110 from ropegalore.com.au
Don't buy the cheap imported stuff on ebay.
General rule for length is 1.5 x boat length.
Diameter would be dictated by what suits the v cleat. The winches would be suitable for anything 8-14mm.
Select to expand quotekeensailor said..
The old sheet is stiff and sometimes pops out of the V cleat after the winch.
If being stiff is the only problem and they are otherwise in good condition, put them in the washing machine and wash them using Nappi San.
Hmmm... I just found this jimmygreen.com/content/56-running-rigging-liros-recommended-line-diameters
Select to expand quotecisco said..keensailor said..
The old sheet is stiff and sometimes pops out of the V cleat after the winch.
If being stiff is the only problem and they are otherwise in good condition, put them in the washing machine and wash them using Nappi San.
and add some fabric softener, makes them smell nice too!
I just replaced mine on my ns 27. I replaced the 12mm for 10. Best thing I've done. I found the 12mm was right on the limit with the cars and turning blocks, always got jammed and tangled during tacks, especially in light breeze. With the 10 I found it easier to tack and cleat off as well. I use to clean my sheets on the careel with wool wash. I like the smell. 
... Wife wasn't happy when I threw them in the machine on gentle. Bundled up of course.
Select to expand quotemjames said..
I just replaced mine on my ns 27. I replaced the 12mm for 10. Best thing I've done. I found the 12mm was right on the limit with the cars and turning blocks, always got jammed and tangled during tacks, especially in light breeze. With the 10 I found it easier to tack and cleat off as well. I use to clean my sheets on the careel with wool wash. I like the smell. ... Wife wasn't happy when I threw them in the machine on gentle. Bundled up of course.
I have the same boat and have the same issue with the sheet jamming during tack!
I will go with the 10mm then, i'm sure the winches will still be happy
I just got an email from ropegalore.com.au
33% off everything and another 5% off using code 123ropeforme
and free shipping
30m of Donaghys 10mm Double Braid =$69 (I think another 5% off this)
Not a bad price!
