The size of the eye depends on how you attach your sling to the porty. If you're like Carl and use a shackle/biner to attach it then your eye can be pretty small. However if you're girth hitching the porty directly to the sling I'd say you'll probably want at least an 8 inch eye.
As far as length, it depends on what size trees you have around. If you want to be safe make it longer than you think you'll need.
wondering what the rule of thumb is to work out the length for the short section of fid and long section of fid for making marks 2 and 3 for double braid.
this is right isnt it for the first mark on the rope its 24 rope diameters, since i dont have fids i use fire wid and splice wand but am unsure about the 2nd mark on the core whether i do it 8 diameters? what does 1 1/2 tail lengths mean on the bt directions?? ive got 5/8 inch line im trying to splice.