As far as seaworthiness goes, Gemini’s construction is all about strength. Really, she is overbuilt, to give confidence when dealing with rough weather. The structural, oak ribs are set just 6 inches apart, and every second rib is double-thickness timber. As I’ve already mentioned, the canoe stern also gives a very strong structure.
She has twin forestays, so if one breaks, the other is backup. And the narrow hull and heavy lead keel mean she is exceptionally resistant to capsizing, and if it should ever happen, she would flip back up within seconds. Many modern boats, with their broad hulls and ballast keels of just a few hundred kilograms, are remarkably stable when upside down.
Most of Gemini is actually under the water. That 5 ½ tonne keel pulls her down. It means that down below, there is plenty of headroom – more than 6 feet. Nevertheless, she doesn’t have much freeboard – the expanse of hull above the water. This is a good thing. Freeboard acts like a sail, except you have no control over it. The wind force against the side of the boat can be a significant factor, pushing the boat down to leeward when you really want to stay up to windward. Compare that with modern boats. Their light weight and flat bottom means that in order to provide a comfortable amount of headroom inside, they have to build hulls with lots of freeboard. The combination of large freeboard and light weight makes for a boat that falls down to leeward rather easily.
Read on to find out how the design brief was fulfilled: