There has been some discussion on the 505 e-mail list recently about "Euro" rigs. Some North American 505 sailors tend to think that all the UK and European sailors are using similar rigs (there are actually several distinct rig styles common in Europe). In a similar manner, a frequently expressed UK or European view is that all North American 505s are using a rig the Europeans describe as straight. In fact, there are two or three distinct rigs that have been used in North America over the past 20 years.
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!
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.
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.
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.
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: