Head boards for head sails

That's OK, they must have some way to crank it up tight.

 

This whole thing sounds suspiciously as if our friend, Doug, is suggesting that he is the only guy out there in sail world who has seen the obvious application of a square head jib for boats. All the world's most talented sailmakers/designers; the same guys who derive tenths of a knot of boat speed with any performance edge they can possibly toss at a sail package for a racing boat... not one of them has ever thought to apply the square topped jib as the knife in the heart to the opponent sailmakers.

Good grief, Doug. That's pretty bold stuff. How in the world have the crafty folks at North, or any of a dozen other large lofts managed to keep themselves from signing you up as head sail guru for worldwide production?

When you say, "it shows promise"... what promise, exactly, does it show... and most importantly, WHY? What is the technical explanation for the so-called promise? Why does the promise exceed the added complexity of utilization? Why does the promise propose to deliver more to the performance of a boat than existing and highly refined systems?

Want to make your case? Then do it with some quantifiable substance in the form of data that compares the suggested type against a well-known system. Right now, there is none of the stuff that would drive a form switch and you look to be pretty much the only "visionary".

Can you produce the comparative data which would tell the story?

 

Think of the rig as one complete foil, it's how sailmakers have been doing it for at least 20 years or more.
There is no advantage to a square head headsail, the whole rig is one foil, the slot is critical to keeping flow attached. A big, square head just lowers the slotted area unless you use massively complex solutions like the floating crane pictured earlier.
You don't gain any total area, no advantage to the headsail leech twisting off, and it will probably make controlling the slot more difficult.

Regards, Andrew.

 

Perhaps that is why it seems like a black art

Over what? The only useful function for the pin end of a pin head is to support the part of the sail that actually does something, and that is the part that has a chord long enough to change the wind direction in a somewhat controlled way. OK, its lack of function also means a lack of tip vortex.

 

Why not just forget the jib and go with a high aspect square top una rig with a flying code 0 on a bow sprit for off the wind . Seems simpler to me . I am not suggesting I now any thing about it but from what I have read it is my understanding that a lower aspect rig with a slot works better off the wind and that a single high aspect sail works better upwind . Do I have it wrong?

 

Wing Tip Rig(tm)

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Timothy, I think a properly implemented square top Main+ square top Jib has a lot of potential especially in light of the success of the USA 2 element rig that Tom Speer describes as follows: "It may look different, but it really is a sloop rig".... (a sloop rig with a square top jib!dl)
The one I sailed had no serious issues with perfect control of the jib and complete adjustability. An interesting feature is that because the jib gaff is attached to the rig at about 30% of the upper chord aft of the luff the whole rig has a slight amount of twist-like "washout" in a wing. Both sails can be adjusted to twist off in gusts as well-giving much greater control over sail/rig shape. Different versions of this rig have featured an upper outhaul, buoyancy pod/ endplate dating back in my experiments to 1972 in models and 1975 in full size boats.
http://www.boatdesign.net/forums/multihulls/why-so-stable-31516.html post 7

Pix: my new boat(proto model), old boat(same rig) and USA-
click on image and then on new image:

 

Deleting the jib would be simpler just like a Hobie 14 but the H14 Turbos would leave them for dead. Eventually they would all end up in their natural state, pole down
Upwind, close hauled is what matters, any old sheet will go downwind.

 

Why is it that wing sails close the slot upwind and are faster upwind without a jib ? Or is this not true.

 

Possibly because the wing was designed to be more efficient that way. I don't have a wing.

 

Sorry. I was not trying to suggest that this would be an appropriate solution for your boat . I was just speculating that a single square top main of the same area and aspect as a main and square top jib might be more efficient.

 

One downside of combining the 2 sails into one with the same AR is that the CE is higher so you have to reef sooner.

Marchaj (ST&P p155-163) seems to think that having clean air on the lee side of the main is beneficial. With a single skin mainsail it is difficult to do both this and get adequate drive from the windward side, maybe a rotating teardrop mast section is better in this regard. An overlapping jib and appropriate slot allows both sides of the mainsail to work with minimised turbulence.
No idea what happens in the non overlapping case which is what we were discussing.

 

If you're talking about a square top main + square top jib its important to realize the both square tops have automatic gust resonse which actually lowers the CE in gusts. Also a squaretop compared to a "pin-head" sail with the same area AND boom length starts out with a lower CE....
Further, it is possible to design a "peaked up" square top with an adjustable upper outhaul. The square top jib "gaff" facillitates an adjustable upper outhaul.