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This post analyzes a transatlantic delivery on a Gunboat 68, focusing on the techniques and technologies that enable high average speeds in light conditions. It covers the relationship between speed and comfort, advanced sail aerodynamics, and practical rules for optimizing mast rotation.
Author: Shayne
What defines a true performance cruiser? It’s not just top speed in a blow, but the ability to maintain high averages in challenging conditions. On a recent delivery of a Gunboat 68 from the Americas to Europe, we faced light winds—never exceeding 11 knots—yet consistently logged 180 to 210-mile days.
The secret isn’t a single piece of magic equipment, but the synergistic effect of a well-designed platform, expertly trimmed.
The Comfort-Speed Paradox: Why Going Fast is Smoother
A common misconception is that sailing fast is inherently uncomfortable. In reality, in light airs, the opposite is true. By sailing at or near wind speed, we dramatically reduce the apparent wind, which in turn flattens the sea state.
“As soon as we hit double-digit boat speeds in 10 knots of breeze, the motion becomes incredibly easy,” Shayne explains from the cockpit. “The boat isn’t pounding or heeling; it’s gliding. This transforms what could be a slow, rolling passage into a fast, comfortable delivery.”
Sail Trim Deep Dive: The J-Zero Aerofoil
The key to our light-air performance was the J-Zero (also known as a Screecher). This large, fractional headsail is a light-air powerhouse, but its effectiveness hinges on perfect shape.
Reading the Sail’s Aero Profile:
The boat was equipped with Doyle’s Structured Luff sail, which uses built-in technology to support the luff and minimize forestay sag. This provided a rare opportunity to see a near-perfect aerofoil shape in action.
“Look at the telltale stripes on the sail,” Shayne points out. “You can see the classic airplane wing shape: a curved, powered-up section forward that creates lift, which then flattens out toward the leech to efficiently exhaust the air. When we talk about a sail being ‘full’ or ‘flat,’ this is the shape we’re chasing.”
Sail shape on the J0 is indicated with blue lines. Shayne uses sail design software to analyse sail shape and forestay sag.
This Doyle sail has glow in the dark stripes at these points to allow the crew to trim the sail correctly at night.
Mast Rotation: The One Simple Rule
A rotating mast is a powerful tool, but it’s often overcomplicated. The guiding principle is straightforward.
The Rule of Thumb: Rotate the mast so its centerline is pointing directly into the apparent wind. On this passage, with an apparent wind angle of 34 degrees, the ideal mast rotation was 30-34 degrees.
“A common mistake is over-rotation,” notes Shayne. “Pushing the mast past this neutral point doesn’t generate more power. Instead, it creates a large separation bubble on the windward side, increasing drag without benefit. The fastest trim is almost always with the mast neutral and facing the wind.”
Mast Section Tolerance: Gunboat vs. Paikea
The Gunboat’s rig is designed for powerful, reliable cruising. Its mast section is substantially more rounded than the fine-tuned, elliptical section we have on Paikea.
“For a performance cruiser, the Gunboat’s section is the perfect shape as it is quite tolerant,” Shayne explains. “Paikea’s rig, on the other hand, is a much finer section inherited from an America’s Cup campaign. It is incredibly efficient but demands vigilance with rotation trim. The difference highlights how design priorities—bulletproof cruising versus top-end racing—dictate the systems we use.”
Inside an Atlantic Crossing: The Gunboat Series
This is the first in our Gunboat Atlantic Ocean crossing series, offering an insider’s view of what a professional delivery is like on one of the world’s premier performance cruisers. Shayne documents the passage of a Gunboat 68 from Antigua in the Caribbean to Toulon in France.
While this video focuses on excelling in very light conditions, the crossing presented a real mixed bag of weather, and the Gunboat handled itself superbly throughout. It’s a masterclass in how a well-designed vessel and expert crew can maintain high performance and comfort across varying ocean conditions.
Transatlantic on a Gunboat Part 2
Shayne,
Really enjoyed the video and the sail and mast trimming tips. In fact we always enjoy all your videos. I have a somewhat unrelated question. I am wondering if you know the blue color on this Gunboat 68. We are looking for a blue for our new cat and this would be great.
Cheers,
Joe
Hi Joe! thanks for the great feedback. Awesome to hear you are enjoying the videos and that you get some real value out of our content. I think the paint was a custom job but next time I see the guys I’ll see if I can get the colour code for you.