One of the Wharram design philosophies is technical simplicity and ease of repair. Some designs use a Poynesian-style rope lashing to hold the hulls to the beams and the rudders to the boat. Piggy has used steel brackets for both but we decided to replace the corroding pintles and gudgeons with rope lashing.
The first step was removing the old rudders. The rudders were dried out, strengthened with more fibreglass, and lashed with a technical rope: low-stretch and low-creep dyneema with a breaking strength of 5100 lb. Each rudder was lashed in 4 places with 10 turns each – this could withstand 50-100 tons before coming close to breaking the rope. Not bad for a 1/4″ line meant for halyards! In an extreme situation I would assume the fibreglass/plywood will tear out before the rope fails.
The beauty of the figure-8 lashing is in the rolling mechanism. The rudder and mating piece of the hull are circular and roll across the rope with no rubbing or pinching of the rope. One downside could be increased drag in the larger gap between the hull and rudder, but on the other hand, removing the metal hardware creates a smoother profile overall.
Removing the gudgeons and pintles also leaves us without any substantial metal below the waterline. One less corrosion problem to worry about!