Rule Interpretation 17-03 BACKSTAY ADJUSTERS

RI 17-03

Q1: The factory-original backstay adjuster is a single-acting unit made by Sailtec. What other backstay adjusters are allowed?

A1: Brands of integral hydraulic backstay adjusters that have double-acting handles have previously been dis-allowed due to a perceived advantage of the double-acting handle. However, that decision was made when there were multiple brands of single-acting backstay adjusters available. Presently, Sailtec is the only brand of single-acting integral hydraulic backstay adjuster that is available. There are double-acting units available from Harken and Selden.

Due to dissatisfaction with the reliability of the Sailtec units among many owners, to allow parts procurement options, and after consultation with J-Boats, the Technical Committee has reversed its previous position. Any brand of integral hydraulic backstay adjuster is allowed, whether single-acting or double-acting, and with or without a pressure gauge. J-Boats recommends that the backstay adjuster pressure relief valve be set such that the maximum tension allowed is 3000 lbs to prevent overbending the mast. Note this is a tension rather than pressure value. Depending on the piston surface area, the hydraulic pressure that corresponds to 3000 lbs tension may be higher or lower than 3000 psi. It may be necessary to alter the length of the backstay rod rigging to accommodate different brands of backstay adjuster and care should be taken to prevent too much slack in the backstay when sailing downwind.