This might be a good time to jump in with
some clarification points about US rigs and sails..... If you read all the articles on the
505 NA web site, you have probably come across ukex.htm (if you
have not, you may wish to read the description of the various rigs
in that - it is from an excellent handbook put out by the UK 505 Class). That
description refers to American 505 rigs as "straight" rigs to contrast them to
the semi-straight and bendy rigs used elsewhere.
In point of fact there have been TWO -
maybe three - American rigs. By some European standards they may all be straight, but one
was rather straighter than the others!
US East Coast Rig
In the late '70s a lot of development work
was done on 505s in the USA. A lot of things were happening.... the one-off boat that
Larry Tuttle and Ethan Bixby won the North American Championship in, the twelve
Parker-hulled Lindsays, the Hamlins, the Lindsay-hulled Lindsays, carbon fiber masts, etc.
A lot of mast and sail development was going on at roughly the same time.
A Proctor D-based rig that used high rig
tension in heavy air, had higher (than was normal at the time) spreader brackets, and was
relatively straight was developed. I only started in 505s in '77, and was not aware of all
this till later. I'm not even sure of all the people who were involved, but I think of the
resulting rig and sails as having been developed - at least in part - by Ethan Bixby and
Larry Tuttle.. I expect with people like Steve Taylor, Mark Lindsay and a bunch of top
sailors all working hard on their 505 programs, there were a lot of people who had input.
In any case, in my opinion, the current US East Coast rig with North sails is a direct
descendent (and not very different) from those rigs. I think the measurement from deck
band to spreader bracket has been 124" since 1979 or earlier, spreader length about
17" and shrouds (at spreader) about 4"-5.5" behind the back of the mast
.... shroud height has moved up and down slightly, but has continued to be above the
forestay, and somewhere not too far away from the spinnaker halyard height. We also rake a
little more in big breeze, but other than that.....
The sails for this rig have evolved over
time, but are still - in my opinion - part of the same "family". I think the
last really major change in the mainsail (Ethan, please correct me if I'm wrong) was for
the 1981 worlds, when it became fuller up high. There have been lots of refinements since
then, but I'm not aware of any "start from scratch, with a clean piece of paper"
designs in that time.
I suspect you could lay out a 1976 Van
Zandt main, a 1982 Hood, a 1986 Johnson and a current (actually up to late 1996)
North (Ethan worked at all four lofts) and you would see the similarity (though the Van
Zandt would be flatter up top). I know I have sailed with the same numbers and adjustments
with the Hood, Johnson and North mains... I would expect that the jibs are not that
different as well, though there have been some interesting sidesteps with radial cut jibs,
and full entry wave jibs along the way. The spinnakers have changed considerably (though I
have a North watermelon that gives me a feeling of deja vu [grin]).
Ed. Since this article was written,
Ethan Bixby at North Sails Gulf Coast has developed a new main design from a clean sheet
of paper. The "D81" mainsail referred to above was finally replaced with a new
design in 1997, the "D97". Further development, design variations and testing
are going on in early spring of 1998, in preparation for the 1998 World Championship. So
far the new North mainsails look a little different from the D81 or D97 mains, but
continue to be setup with the same rig numbers.
Here is the
current
North Sails (Ethan Bixby) Tuning Sheet, and just for fun, here is
a late '70s North tuning sheet
Here is the
North rig in medium air. Not a great photograph - sorry - but note the mast bend on
Macy Nelson's (blue hull, center of image) rig. Macy is most probably still at 25' 8"
rake (standard), as it is not blowing hard enough to depower. He does have some bend
though, and most probably a fair bit of vang.
Here is the
North rig in heavy air.. Seems like a fair bit of bend (and rake) for a so-called
straight rig! This is in 18-22 knots. The mast is raked close to maximum - probably about
25' 2" or so - and there is quite a bit of bend. The ram is at about the lowest
setting for this rig. It would be pulled down at first as the mast was raked, and then
left as the mast was raked more and more for more wind.
Further information on how to use the US
East Coast (North) rig is available in the Tuning are of the
web site.
The Steve
Benjamin Straight Rig
OK, now for the "REALLY STRAIGHT
RIG"... Steve Benjamin got into the 505 class (Oh, about 1978), and eventually
starting developing a rig based on the Proctor epsilon mast. This may have been what he
was familiar with from 470s. This rig had the shrouds attached to the mast at the same
height as the forestay (no induced fore and aft bend), and rather high trapeze wires to
support the mast tip (with tweakers to effectively lower the trapeze attachment point when
he wanted more tip bend). Benji also attached his shrouds to cars on tracks bolted to the
rail, so he could move the shroud attachment fore and aft; I believe this was similar to
changing spreader angles. The mainsail had rather less luff curve than the North, and the
mast was kept very straight. As Tom Kivney pointed out, this rig required two mainsails, a
flat top for heavy air (and maybe very light) and a full top for power-up conditions.
Deciding which main to use (predicting the weather) is a major pain in my opinion.
Benjamin
had considerable success with this rig (winning the '80, but not '81 worlds with it).
Others used it (e.g. Macy Nelson, Mark Wheeler), with some success, but it fell into
disfavor, as it seemed to be too critical, and the rig did not have the "gust
response" that the Proctor D-based North American rigs had. One by one, everyone with
an epsilon in the North American fleet has switched back to the D. The sails that went
with this rig were from either Ullman or Sobstad (depending on who Benj was working with).
I sailed boats with this rig a few times and had no clue how to make it go. Seeing
Robinson/Masterman with a very straight mast in the windy race at Hayling Island (and then
noticing the high trapeze wires and trapeze wire twings as Benjamin had) make me wonder if
the current Robinson/M2/Sobstad 505 rig is similar to the Benjamin/epsilon rig. Check out
a partial Steve Benjamin tuning sheet for the epsilon mast.
As a matter of interest, in a recent e-mail
to me about a Hyde Sails announcement that they were going to develop a Superspar M2 based
straight rig, Steve Benjamin told me, "Great narration by Hyde but it was a D in the
505 not an Epsilon which is too stiff sideways."
I distinctly remember that Steve used an
epsilon, not a D, but it was over 15 years ago, so who knows...[grin]. I think some people
were also experimenting with a D+, a D with a thicker sidewall to get a D that was a
little more like an epsilon and also with a squash tip epsilon, that seemed to be
an attempt to make an epsilon more like a D.
US West Coast
OK, now to the US West Coast Rig with
Danger sails. With Howard Hamlin going to most World Championships, there have been lots
of ideas and influences on the West Coast rig. The masts have same spreader bracket height
as the East Coast, but angle the spreaders aft more, for more fore and aft bend. A number
of different sail cuts have been used, with Number One, and Pattison sails popular some
time ago. Most now use Ullman/Danger sails. I believe these are probably closest to the UK
P&B sails in design, but I am not familiar with either Ullman/Danger of P&B, so
cannot be sure.
Apparently the Ullman/Danger tuning sheet
calls for more rig tension as the breeze comes up (as the North tuning sheet), but I
believe Howard and Mike Martin do not use much rig tension in breeze; perhaps they are no
longer following the tuning sheet.
The Norths and the Ullman/Dangers are not
that different, the major difference being the greater luff curve on the Ullman/Dangers
than on the Norths. You would expect this, as 505s using Ullman/Danger set up their
spreaders to get more fore-and-aft bend. Both rigs attempt to keep the mast fairly
straight sideways until overpowered.
Conclusion
In conclusion..... There are two varients
of the Proctor D rig in use in the USA. The East Coast is straighter than the West Coast.
The no-longer-used Benjmain/epsilon rig was rather straighter than either of these rigs.
When UK sailors talk about the "American straight rig", I'm not sure which of
these three rigs they are referring too; they look quite different to me!
Some Uninformed Thoughts From Ali
While the above is what I have heard and
believe to be true... the next section is my own thoughts, so take them with a grain of
salt...
I do not think lots of fore and aft bend
versus little fore and aft bend in and of itself results in different mainsail shapes, as
long as you have an appropriate luff curve on the mainsail to match the mast bend. The
differences could be:
-
jib luff sag - the straighter mast should
be able to carry more forestay tension for less sag. Or you would use mainsheet tension to
keep the jib luff straight (tightening the vang does nothing for forestay sag)
-
sideways bend - if you run with low
tensions in breeze, and the windward shroud is tight whereas the leeward is slack, one
spreader pushes the mast sideways more than the other, so spreader lengths become more
critical than if both shrouds were tight, and overall the mast should go to leeward,
creating some sideways bend, which will alter the fullness of the main.
-
additional bend during puff - This may
require a little calculation, but a close to straight (in column) mast may bend a smaller
additional amount in a puff than an already bent (out of column and therefore softer) mast
would in the same puff. This would be affected by spreader settings, and rig tension. A
bent mast with lots of rig tension should be softer than a straighter mast with lots of
rig tension.
A Final Suggestion
Don't worry about it too much. Any of these
rigs can go fast, and the quickest way to go faster is to go sailing, not to worry about
which rig and which sails to use....[grin].... see you on the water!
Ali Meller
