I don't want to hijack this great thread but there was a bit of interest on this wingsail Contour 50 so I dug a little deeper and found this email
that a friend sent me some time ago. He's a retired Boeing aeronautical engineer
and worked on the Oracle's wingsail. He calls this boat a Condor 50, but it looks like he's talking about the same vessel:
" there's the Harborwing X2 prototype: https://www.flickr.com/photos/basili...7628104639679/
. Mark Ott has also worked with Morelli & Melvin on the conceptual design of a cruising wingsail powered catamaran
: Harbor Wing Technologies - Autonomous Unmanned Surface Vessel - Commercial Applications
I had a chance to visit with Mark Ott onboard the Harborwing X2 when it was in San Diego
, tied up to the Scripps Flip. It is a modified Condor 50 trimaran
, and it's capable of operating offshore
. At the time, Mark was looking to do some voyages to show the offshore
capability, and was trying to find the funding
to continue the boat's development. There was a lot of the interior
taken up by the mounting structure of the cantilevered wing, but that's to be expected with a prototype. I think a purpose-designed boat wouldn't sacrifice as much to the rig. But it is really important that the wing have very good bearings and a support structure that won't bind up when it flexes or be subject to fatigue failure.
Both boats use an aerodynamically controlled wingsail. Jenkins' tail is an innovative application of an aircraft configuration in which boom-mounted tails extend the span of the wing for reduced drag. (Unfortunately, I can't find the reference just now). The twin tails of the Harborwing configuration avoid the problem with "hunting" at low angles of attack, when the wake of the wing can affect the ability of the tail to precisely control the wing near zero lift
, as when the wing is feathered when moored. Harborwing's X1 prototype, a modified cruising cat, discovered that even though a wing can be feathered to produce zero net lift
when moored, wind
shear could still generate a dangerous heeling moment. That was the genesis of their split wing approach, in which the upper and lower halves can move independently to control heeling moment as well as lift.
My experience with an aerodynamically controlled landyacht rig showed the rig was quite good a gust load alleviation and was better than my manual wing-trimming skills when sailing in light, shifty winds.
I think there's a lot of potential for aerodynamically controlled wing rigs on cruising boats. The really big question is how well they work under extreme conditions. In principal, a wing can be feathered to produce less drag than bare poles. But whether or not the wing will respond quickly enough in gusty conditions, or be affected by motion in a heavy seaway, will determine if wingsails are safe for use offshore."