Thank you very much for the reply.
FYI, here is the hobie kit
https://westcoastsailing.net/hobie-kaya ... kit-ai-ti/I understand this about Spectra and Dyneema
The easy answer is they're pretty much the same. Spectra is a brand name fiber made by Honeywell. Dyneema is produced by DSM. They are chemically the same material: Ultra-High Molecular Weight Polyethylene.
The rudder downhaul line has to fit inside the white tube and I believe that is the constraint on the diameter. I measured the inside diameter of the tube (these are the tubes inside the rear of the hull) and it is 3.8 mm
I am probably going to just purchase the line itself as the kit comes with a lot of stuff I just dont need.
Here is 3 mm Dyneema with a strength of 2300 - 2500 pounds ($.60 a foot).
https://westcoastsailing.net/3mm-samson ... eema-line/Here is 2.7 mm Dyneema with a strength of 1400 to 1600 pounds ($.38 per foot)
https://westcoastsailing.net/2-7mm-sams ... eema-line/Im just going to order 25 foot of each type and use the largest one that runs smoothly in the Hobie White tube.