DN NA Class

Guests & Members Post & Read => Building, Maintaining and Repairing => Topic started by: wnethercote on December 22, 2022, 10:11:41 AM

Title: Bob Gray's Runner Plank Proposal
Post by: wnethercote on December 22, 2022, 10:11:41 AM

My own proposals for specification updates have avoided substantive change in favour of clarification of what is allowed now, but there are areas where substantive change could be beneficial.  Bob has proposed one of them.

I am one of those lightweights that Bob describes.  I used to weight 170, like 'normal' guys, but my post heart attack weight floats around 140 to 145 lbs.  Building an 80 lb/in runner plank is a challenge, absent balsa cores and composite sheathing.  A straight wood plank is both cheaper and more predictable for a home builder.  Using the Goodwin plank design spreadsheet suggests that a 1 inch plank can easily meet the stiffness (softness) needs of lighter sailors.  The current minimum plank thikness requires shaping of planks to reduce stiffness for lightweights like me and such shaping often leads to planks that twist under load and don't maintain alignment.

I am all for Bob's proposal!  It is a definite help to the home builder.

Warren Nethercote
KC 3786