Mr. Smith's Amazing Boats

As you may know, the Vesta Sailrocket is based, in part, upon some of the ideas of Bernard Smith, who wrote "The 40 knot Sailboat" back when that was quite fast for a sailboat. For those interested in unusual small sailboat design ideas, Smith's configuration, with canted sail, the force line of which passes through the center of lateral resistance, is fun to play with.

About 20 years ago, I built such a boat (a proa) from a pirogue I had sitting around. (Most pirogues are symmetrical fore and aft.) I made a small skinny outrigger hull (8' long, maybe 150 lb. buoyancy) and two ogival section rudder/daggerboards. The small hull was mounted at the end of an 8' 2x4, the other end of which spanned the pirogue gunnels. The mast (from a windsurfer) was stepped on this 2x4, and angled over the pirogue. The sail was an isosceles triangle, and tacked to the end of the outrigger in such a way that the tack would become the clew after shunting (the proa equivalent of a tack).

This whole thing took not much longer to build than it does to describe it. So there was a huge payback on construction time because the boat was a hoot to sail. In gusts, the boat would just accelerate, without even a hint of heeling. Shunting is easy... reminiscent of a failed tack with a beach cat with no jib.

I mention this to encourage anyone prone to experimenting to try one of these out -- you can make a pretty fast, fun little boat easily and quickly. The basic configuration can yield world record speeds, so there is some room for experimentation.

I'll elaborate on a couple details in one or two more posts.

 

The rudder/daggerboards:

These were relatively sharp entry (and exit) ogival sections. They were mounted near opposite ends of the pirogue. I made a linkage (which I might be able to find) that could adjust both boards to about equal angles to windward (say 4 degrees). This would cancel leeway entirely, without requiring the whole boat to be aimed slightly to windward (which is the standard sailboat condition, meaning that a standard sailboat is actually always crabbing.) This adjustment was done with a small knob turning a threaded rod. After shunting, the knob would be turned to reverse the board angle, again aiming the boards to windward.

The tiller would steer both boards in an arc. So to steer to port, the front edge of the forward board aimed to port, and the front edge of the aft board aimed to starboard. There was no tiller feel, because the boards were pivoted about their vertical centers... but there was no need for weather helm or lee helm.

Why bother with the threaded adjuster? I was thinking that I might build a fast, very slender hull (after trying out the general layout with the pirogue). No hull benefits from being dragged slightly sideways through the water, but this is especially true for a slender hull, because for equal displacement it has more lateral plane.

 

The sail:
This was cut hollow on luff and leach, to keep it relatively flat, and had wire in both, I think. I used harken ratchet blocks at the tack and clew, providing two part purchase, and the benefit of the ratchet. In the shunt, the previous clew was pulled down tight to become the tack and cam cleated.

 

That's it. Go build one!

 

I am unfamiliar with Bernard Smith, but I am interested in his ideas. Thanks for the post.

I have been thinking about a modified crabclaw design that is more like a hang glider type sail mounted on the top of a mast. One wingtip or other could be brought down as a tack or let out to tilt for more righting lift and as a way of reefing. It could be worked in a very traditional fore and aft fashion or something like a parasail.

 

I bought The 40 Knot Sailboat book many years ago, probably in the late 50s. I still have the book as one of my old treasures. Smith was onto something but he did not manage to pursue the concept to a functional end. As I recall, he once sailed a model of his design in the Reflection Pool in DC.

 

I sailed an RC model of my first wing-powered boat in a pool too. I set up fans at the local Holiday Inn pool, which they let me use for free.