Design
The turboed Gunboat 66 Phaedo revelling in her new and not so subtle blood-orange paint scheme. The RORC Caribbean 600 was used as the course model for the latest upgrades to this fast all-carbon – but still very comfortable – world ‘cruising’ cat, which included a modest reduction in all-up weight but an 18% increase in sail area plus new and more aggressive appendages
Orange crushed
Design engineer Dave McCollough was tasked with pulling together an aggressive range of performance upgrades to the already turboed Gunboat 66 Phaedo…
On 15 July 2013 the Gunboat 66 Phaedo hit her new 24-hour record of 427 miles in the Transpac Race. Hours later she lost her rig. Debris was cleared and the boat secured before a long motor back to New- port Beach in California. Before stepping ashore the comeback was already being plotted… Owner Lloyd Thornburg was leading the charge with varying options and ideas. I was privileged to be part of that crew and six days later I left the boat with a notebook full of ideas.
In an attempt to organise the improve- ment possibilities available to Lloyd, we created a grid of option packages similar to what you encounter when purchasing a new car. The low, medium and high pack- ages were codenamed Boom, Sonic Boom and Super Sonic Boom. Careful research was conducted to support each decision, and gradually it became clear that Phaedo was to receive the Super Sonic Boom
options package. This included but was not limited to a new mast, longeron, forward crossbeam, full set of sails, daggerboards, rudders, rudder bearings, cabinhouse windows, exterior paint, interior paint and deck hardware. The new rig was quickly determined to be our longest lead-time item and became our initial focus. Lloyd flew off to visit several spar manufacturers. In the mean- time, I began to draw sailplans, determined to restore helm balance to the boat. Over the years Phaedo had grown some nasty lee helm characteristics. She was difficult to keep in a groove upwind, and easy to stall downwind, losing apparent wind speed. About this time I was also participating in sea trials in Maine on Phaedo’s Gunboat 66 sistership Slim. She had just received new longer daggerboards. The helm balance on Slim was, frankly, the best I had felt on a Gunboat and provided wonderful valida- tion of the preceding numerical analysis. By now Lloyd had completed his recon- naissance mission and Southern Spars were selected as the manufacturer of the new mast, boom, longeron and forward crossbeam. Paired with this decision, Burns Fallow from the North Sails New Zealand loft was selected as Phaedo’s new sail designer with support from Mark Sadler of North Sails Palma.
Rig height was increased 9% while maximum upwind sail area was increased
by 18%. Focus was given to maintaining a reasonable vertical centre of effort while still boosting the available area for optimal light-air performance. As the sailplan and initial appendages were developed the decision was made to optimise for the RORC Caribbean 600 race. This is Phaedo’s home racetrack and an adven- ture that she has already enjoyed twice. A custom mast section was optimised using CFD analysis and issued to Southern Spars who built a new female mould specifically for Phaedo. Engineering advances in the TPT Gold laminate and EC6 rigging allowed Southern to remove further weight from the mast (around 27kg) within the confines of the aero - dynamic section. The result is a spar that is taller, lighter, yet some 140mm lower in vertical centre of gravity, and more aero- dynamically efficient than the original rig. We spent some time looking at the option of a rotating rig, but in the end stayed with the fixed rig. There are those who believe a rotating rig is always the right answer on large performance cruising catamarans, but the facts are not that black and white. For example, the Gunboat 66 is an extended Gunboat 62 that was drawn in 2002. By 2014 standards Phaedo’s hulls have ample rocker and very round sections. This combination does not offer the longi- tudinal stability of modern hull forms. The result is that Phaedo pitches somewhat in a
SEAHORSE 45
ALL IMAGES RICHARD LANGDON
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