Mike,

I just want to make 100% sure that I understand. If I go with a round mast, I can fix the boom to the mast, and just have one thing that rotates, right? I want to make sure I am clear on that. The wingmast requires the boom to rotate independently of the mast (basically +/- 20 degrees or so)?

I don't want to give the impression that I have been focusing on the cost "lately". That is, has been, and always will be, my first priority. Unless I just want to dream about a boat forever, it better end up pretty cheap!

I know you have mentioned that soft wing mast on a number of occasions, but it still just looks too complicated; too many moving parts. I don't see it being particularly cheap, if you count your time. That is pretty much how I am counting costs; assuming that I will contract out the construction. Otherwise, it is too easy to just say that labor doesn't count. I would much rather pay more for materials, to save labor time, whether I am building it myself or not.

The schooner is my preferred rig, I think. It seems like it provides a bit of a backup for the steering, which is still a concern of mine with the harryproas. It also makes it easier to keep the mast height to 40' for container shipping and maybe trailering. My problem is that it seems like the masts cost a significant fraction of the price of the boat, and having 2 smaller ones is considerably more expensive than 1 larger one.

My interest in wingmasts is more that I thought it might be less labor intensive than a round mast, even if it does use more materials. I am not primarily concerned with a performance boost, because I have ongoing worries about the behavior of wingmasts at anchor in a storm. I am just trying to keep focused on cheap, fast and comforatable.. I want all three!!

- Gardner

On Sat, May 21, 2011 at 9:44 PM, Mike Crawford <mcrawf@nuomo.com> wrote:

 

Gardner,

  The two would definitely need to be independent; otherwise, instead of a graceful foil generating lift and directing airflow onto the said, the mast would just be a big slab out there creating turbulence.

  However, as with standard rotating masts, you can find a relatively happy medium that will work for many wind angles.  With a noticeable part of the wing aft of the center of rotation, and with the sail itself pulling on the wing's trailing edge, the mast will automatically want to rotate into a reasonable angle. 

  If you limit the rotation with a rotation limiter, you'll be set for just about everything except a tight beat and a run.   And even in those cases, you'll still probably be more efficient than a standard D-section aluminum stayed mast.  If your rotation limiter were adjustable, you'd have even more chances for optimization.  I pretty much leave mine set on tight-medium and adjust it only if I refuse to let someone else out-tack me downwind.

  Of course, if you did want to race, and eek out every possible eighth-knot from the boat, you'd need a set of blocks to fine-tune the mast angle relative to the boom on all points.  But that's a lot of work.

  However, now you need to strong sets of bearings: one for the mast to rotate freely from the boat, one for the vang-less boom to rotate freely from the mast.  That's more complexity, more expense.

---

  If you're serious about keeping expenses down, another option is the swing-wing soft wing sail described by Kim and Rudolph.  One mast, no boom, no rotating bearings anywhere, no sail track.  I know you're plans haven't revolved around this rig, but I thought I'd mention it again since you've been focused on cost lately.  Unless you're going with a schooner rig (where I'm not sure the swing wing would work), it would be hard to beat in terms of price.

        - Mike

 
 
Gardner Pomper wrote:

 

I am under the impression that with a wingmast, you need to rotate the
boom independently of the mast, so that the wing is at a steeper angle
to the wind than the sail. Am I correct in this?

If so, that seems like you could no longer have the boom fixed to the
mast and use the mainsheet to adjust the angle of attack. Wouldn't you
need extra lines to trim the wing seperately from the sail, especially
in light air? If so, that seems like a major disadvantage for a
cruising boat.

Thanks for any help clearing up my confusion.

- Gardner