A company called C & C Plastics and Toolmakeing in Sydney Australia has used 50% Carbon fibre filled Nylon 6 for a floating winch handle for yachts.
Theu normaly use GF nylon 6 and for the higher stressed models, they use long glass fibre, but for some specials for use in serious races like Admirals Cup, America's Cup and Sydney to Hobart etc, they do some in carbon for extra stiffness.
They have much experience with design and weld line position.
They use type 6 as it is easier to mould, and at 50% fibre, flex mod is virtually identical to 6.6. That is at room temperature. At elevated temperatures, 6.6 will still have an advantage.
e-mail me at patprimmer@optusnet.com.au if you want more info, as I do not like to be to commercial in this forum, but this time, I only know one moulder with the experience. Regards
pat