Friendly discussion of NZ AC boat and possible practical application the Moths (ya right)
George Bailey Writes: Walt, If the NZ AC boat can sport an appendage that extends the hull but is not counted as hull, can we do this too? - George
Bill Schill Writes: George, I don't remember the class rules allowing "appendages" of any description. Bill Schill, Jr.
Walt Collins Writes: George, In a word......NO. - Walt
George Bailey Writes: Walt, now, wouldn't it be great if the AC had an equally assertive and reasonable jury to deal with such issues?
Well, a rudder is one, and that is why team NZ is pulling this stunt, as if what it has added is not a part of the hull . . . as if it were analogous to a rudder . . . - George
George Albaugh Writes: Aw, come on, George, cut 'em some slack. Team NZL is just trying to push the rules a little. I mean it's not like they have a hump in their foredeck ;-) GPA
Joe Bousquet Writes: Would CMBA sanction a "centerboard" near the stern and a forward rudder? If so, how would the "no concavity greater than an inch aft of the centerboard" rule be applied????
George Bailey Writes: Joe, what you suggest seems legal to me given our current rules. Warren tried a forward rudder in the 50's and found it difficult to use since the boat pivoted around the stern not the center, which was hard to adjust to, among other things. This made mark roundings "interesting."
George A., My "lump" did not allow something that could not otherwise be accomplished by raising the entire foredeck as other moths already did. Of course, as team NZ pointed out, everyone else can add an appendage (if they do it soon enough? I lost track of the date by which they can no longer change their hulls). That everyone else can add an appendage makes a difference, I guess. Though by that reasoning everyone else in our class could add a hiking board if one person did.
Team NZ says "We have made sure the Hula does not touch the hull at any time."
I am courious about how the "hula" is attached. Has anyone read how?
I guess they do not count the bits that attach the hula to the hull as parts of the hula. Interesting distinction. - George
Walt Collins Writes: True, but we had the good sense to identify the allowed appendages as cosisting of one centerboard or daggerboard and one rudder.
Is a centerboard, not in the center, a centerboard. I tend to think...NOT.
The loophole is that a dagger board can be used. An aft daggerboard and forward rudder would mean no centerboard, so I guess there would be a problem identifying the allowabe area for concave. As a point of interest, a forward rudder would make a moth extremely unstable at planning speeds unless it was sized so small as to be inneffective at normal rates of motion. this could be overcome by installing a fly-by-wire computer similar to F-16's which would sense the unstable motions and countersteer to damp them out. I guess this would then have to be named a sail-by-wire computer. - Walt
Jamey Rabbit Writes:So now that we have a moth with the "daggerboard" in the stern, and a rudder in the front (rather than going with the CNC steering I'd suggest a balanced rudder) with as much hollow as you can put in it, who's to say that you can't clip on your kiwi clip on to the daggerboard? There's no rule against transverse foils so there's no reason you can't make your secondary hull skin part of the fixed appendage or daggerboard. - Jamey
Walt Collins Writes: Sorry, but I do not see, and never have, any authorization for any "foils" other than rudder, centerboard or dagger board. There is no such thing as a rigidly mounted dagger board. Vertical movement is contained in the definition. Even having a horizontal section change as part of a daggerboard is questionable, if the daggerboard cannot be removed by raising through its housing, as opposed to being removed from below. Centerboards must be capable of being housed completely within their mounting housings, so if you add a horizontal portion to one you must make provisions to house it in the well. I guess you will need an articulated cover for the effected portion of the well. By the way, I, your measurer, define hull as being that part of the boat which supports it while sailing. So any foil which provides support is part of the hull and will have to meet the concavity rule, and could not logically, therefore, be wider than 1.41 inches on each side. Draw one out and you'll see what I mean. From a practical standpoint, what the kiwi's are up to is to artificially influence the displacement characteristics aft so that effective displacement is different from measured displacement. Since we don't measure displacement in the first place, just make the "hula" shape part of your stern shape or forget it! - Walt
Joe Bousquet Writes:I would think "centerboard" means "on the centerline" as opposed to leeboards which are definiately not on the centerline. How would a measurer decide how far forward or aft a centerboard could be placed and still qualify as a centerboard? A related question: is a fixed keel a "centerboard"? Most sailing dictionaries would say no.
George Bailey Writes:I am confused. From Blackheart (and other sources) one reads things like:
"The new "hulas" on both boats are sleek second skins almost, designed to fool the water into thinking the boat is longer."
Whereas on Scuttlebutt we have:
"Oliver says the idea of the hull appendage which "makes the boat seem longer to the water" came when trying to figure out a way to create a lower transom. " . . . With an appendage, you can integrate the shape you want and lower the transom." . . . The hula, rigid and strong and made from a structural component Team New Zealand has worked on, is shaped as part of the hull. It only touches the hull where it is allowed to - within a 500mm strip down the centreline. - TNZ website, full story: http://xtramsn.co.nz/teamnewzealand/0,,7136-2060241,00.html"
After seeing the photos, I have no idea why this addition which is under the boat not at the end makes the boat seem longer.
Can anyone explain this? - George
Walt Collins Writes:Wouldn't that be a centerlineboard? A fixed keel is not a centerboard, but a centerboard, or even a dagger board is sometimes fitted within a fixed keel. The key is the "fitted within" part as far a distinguishing between keels and boards. Also, don't forget bilge boards on scows. Are the twin boards on some cats centerboards? They are on the centerline of each pontoon, but noton the centerline of the overall boat.
Remember the "bustle" on HERITAGE. Lots of theories came out about why it did or did not work. Only after the trials did most agree that it did not. A "longer" displacement hull is faster because a longer wave length wave system travels faster in water. The halo is intended to change the water flow to match the pattern a longer hull would make. Since the modified wave pattern travels faster, the hull can too. Remember that these hulls have extensive overhangs aft. If the halo delays formation of the stern portion of the wave system, the wave system is stretched out. Here's the tricky part. It requires energy to modify the water flow to delay the wave formation. If the energy required is more than the energy required to push an unmodified hull to the additional speed, the halo will not increase speed attained, since the total energy the sails can transfer into the hull is not a function of hull shape, but of sail shape and size.
Scott Sandell Writes:Sports Fans!
All this discussion about appendages (something perhaps better kept to oneself anyway) is academic. Even if Walt issued an open invitation to protrude at will, would anyone build anything that did???? With all due respect, I doubt it, but I would encourage you all to exercise these fantasies in the Modern wing of the class, where, as our official measurer says, "anything goes, baby".
Cheers,
Scott Sandell
Walt Collins Writes: Well said, Scott! You can really tell when the cabin fever sets in. Its time for us to all go down to St Pete and get the some sailing in. This fantasy stuff doesn't do it for me! - Walt