When it comes to running rigging on our boats, often times the specified diameter of the line is not so much due to the needed strength, but due to the "feel", in other words..... on a boat where you may often be adjusting the line (thinking mostly of Jib sheets or Main sheets) we often go up a size to have a line that is easier to comfortably grip in the hand. I could probably almost get by with 3/16" line for the mainsheet on my DS II (strength-wise) but use 3/8" to allow a more comfortable grip.
One caution, don't use a line size bigger than the capacity of the sheaves.
BTW: I haven't retyped the specs for all the listed boats, but have retyped the 25 for my Manual. as always..."your mileage may vary"
O’DAY 25
Running Rigging Specs.
All Lengths and specifications are approximate and are subject to change without notice
Main Halyard (rope) 5/16” x 59’ (K/CB)
5/16” x 64’ (Keel)
Jib Halyard (rope) 5/16” x 60’4” (K/CB)
5/16” x 63’4” (Keel)
Mainsheet 3/8” x 40’
Jib Sheet 3/8” x 48’ (24’ x 2)
Mainsail Outhaul ¼” x 9’
Boom Downhaul ¼” x 4’
Topping Lift (rope) ¼” x 31’ (K/CB)
¼” x 33’ (Keel)
Centerboard Pendant (need to find this)
Rigging specs for optional sails
Spinnaker Halyard 5/16” x 67’ (K/CB)
5/16” x 71’ (Keel)
Spinnaker Pole Lift 5/16” x 43’ (K/CB)
5/16” x 45’ (Keel)
Spinnaker Pole Downhaul 5/16” 30’ (K/CB)
5.16’ x 31’ (Keel)
Spinnaker Sheets 5/16” x 48’ (2)
Genoa Sheets 3/8” x 60’ (30’ x 2)
All running rigging is typically double-braid Dacron (Polyester) rope
Standing Rigging Specs.
Headstay 5/32” x 30’10” (K/CB)
5/32” x 32’10” (Keel)
Upper Shroud 5/32” x 28’9” (K/CB)
5/32” x 30’ 9” (Keel)
Lower Shroud 5/32” x 25’8 ½” (K/CB)
5/32” x 16’8” (Keel)
Backstay 5/32” x 32’8 ¼” (K/CB)
5/32” x 34’8” (Keel)
All Standing rigging is SS 1x19 type wire and lengths are with turnbuckle (where applicable) closed, from eye to eye (most riggers measure with turnbuckles half-closed, so be sure to note this and/or bring old rigging to rigger to measure for replacement)