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American Outrigger (RoyB)
Describing an article by Jim Luton in 'WaterTribe'.
Jim Luton sails canoes from the Sebago Canoe Club, Brooklyn, N.Y., especially on the waters in and around the marshes and islands of Jamaica Bay and "just romping around in the consistent 15 to 18 knot summer sea breeze". (Consistent, summer, breeze - this sounds idyllic!) On occasion however, he has been scared, returning downwind in waves. So he set about designing a "stable platform... kept simple... increasing speed, safety and range, yet retaining all of the desirable characteristics of the canoe".
He decided on a single outrigger (single float) for reasons of economy, weight, ease of docking and speed (provided he could keep the float unweighted on either tack). A disadvantage, however, could be a shift of helm balance from one tack to the other, "due to different hydrodynamic forces acting on an alternately loaded and unloaded float, and there would surely be a different 'feel' on either tack, the one with a buoyant force (submerged float) providing righting moment, and the other with ballast (the combined weight of float plus crew out on the hiking seat)". A hiking seat, by the way, is an extra seat projecting slightly beyond the gunwale to counterbalance the heeling moment on the sail when required.
Based on calculations and intuition, Luton "came up with a beam from outside of main hull to outside of float of around 8' 6". The aka length was 9' 3" and extended about a foot outboard of the canoe on the side opposite the float, to carry an 'offside' hiking seat. I kept the float hull to just under 12' long and 10.5" wide amidships, with a submerged displacement of around 240lbs." He constructed the float hull of 3mm, tortured ply, stitched and glued together, and the akas as hollow box beams.
The rig for this new craft is an unstayed, sleeve luff main of 70 sq. ft. with a simple two piece aluminium tube mast, similar to a Laser's. Rather than a "fussy, bolt-on arrangement for the akas" Luton followed James Wharram's tried and tested - and "simpler" - lashing system. He notes: "I think that for a pure 'racer' a totally rigid structure would be best, but for the outrigger I was much more concerned with simplicity and speed of set-up, rather than with absolute performance". So how does the outrigger perform? I think it worth quoting Jim Luton at length:
"Better than I ever expected. The float dampens its motion so there is no quickness or tender feeling, and no tendency to 'death-roll' off the wind. It is interesting to watch a 5 Meter regatta in gusty conditions. You can see the puffs move through the fleet as each boat in turn gets slapped rail down, then comes back up as the sailor hikes out. The outrigger stands up to the gust, and instead of heeling, accelerates immediately. This is particularly exciting on a reach in a breeze. The bow comes up, you shift your weight aft, and she takes off on a plane. Tacking the boat is a bit different than what I was used to with the monohull. She's a bit slower to come through the wind, and can't be rolled onto her bilge. Also, she needs forward speed to come about, and should be sailed around. I had suspected that there would be a 'balance' issue with the asymmetrical design. When the float is to leeward, the centre of resistance moves outboard and aft, creating a little lee helm. My solution was to set the leeboard further forward to correct the helm when the float was downwind, and to pivot the board aft when on the other tack.
I had assumed (incorrectly) that the outrigger would be fastest with the float upwind like a Pacific proa. In fact, the opposite was true. The canoe hull is really quite wide for a multihull, with a lot of wetted surface. When the float is downwind, it absorbs more of the rig load, unweighting the canoe hull. Since the float is much finer and more easily driven, the boat is faster. The offside hiking seat is then used to control the force placed on the float.
This design is moderate in many respects and the boat is not over-canvassed. The limiting factor here is the canoe's low freeboard. For this reason, it will sail best in protected waters, and is truly at home on lakes, bays, or tidal estuaries. Performance is much like a well-sailed dinghy. I would encourage anyone with a desire to build a small sailboat to consider the outrigger".
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