Seeking some IOR history

Hi, Everybody.

I'm curious about when the wider stern IOR boats with larger mainsails than jibs started coming on the scene.

Was that caused by a change in the IOR rules?

I imagine the wider stern boats would be much faster off the wind, but not necessarily faster up wind. Am I right?

 

Robert Perry discussed the IOR in an article in the March/April 2012 issue of Good Old Boat magazine. He mentions that fraction rigs with smaller fore-triangles and larger mainsails becoame dominant for "late IOR-era boats", but doesn't provide a data. Also no mention of being caused by rule change.

 

I wouldn't consider Perry to be a Go-To guy for explaining the IOR rule.

The wide-stern, fractional boats came about at the same time the masthead pintails boats did. Peterson and Holland did their first boats (masthead pintails) in 1973. Farr did wider stern and fractional rig the same year.

The lightweight, wide stern fractionals were better in the breeze and the masthead pintails were generally better in light air and lump. That was the trade off (weight for sail area).

Some early lightweights also seemed to lack the keel area needed to hold their line upwind. That was probably more due to the keel design than the entire light/wide/fractional design.

The rule always favored the fractional rig. The problem was the sail materials were not good enough in the early years, especially in bigger boats. As the materials and cuts improved the logical move was toward fractional rigs. So after about 1983 all serious IOR boats were fractional rigs.

By 1975 Farr won the QT cup with the wide stern, fractional 727. The same year Peterson won the HT, 3/4 Ton, One Ton, and Two Ton cups with masthead pintails.

In 1977 Holland won the QT cup with a fractional pintail, Farr won the HT, 3/4 T, and OT regattas with fractional, wide stern designs. After this virtually all level rating cups were won by fractional rigs, even in light air venues. The two tonners and larger continued to be dominated by masthead rigs for a few more years.

Most of the major sailing venues in the Northern Hemisphere are light. Most of the major venues in the Southern Hemisphere are breezy. So each type tended to mature in the area where they fit.

The rulemakers also tended to lean toward the type that fit their venue better. Since most of the rulemakers lived in the Northern Hemisphere they tended to look hard for ways to close any loopholes the wide-sterned boats were taking advantage of.

By the early 80s the boats all started to get closer to a compromise. Pintail sterns had started to get wider by 1976 and wide stern designs were narrowed. Sail materials had improved enough to allow fractional rigs to become more prominent in larger sizes, even up to the Maxi class.

 

"I imagine the wider stern boats would be much faster off the wind, but not necessarily faster up wind. Am I right?"

Depends on how much wind we're talking about. Downwind in the light was actually the wide-stern fractionals' worst point of sail for years, because the wide stern increased their wetted surface area and their spinnakers were smaller.

This lead to the spectacle of boats like the extremely heavy and successful modified "Finnestere" type Sunstone (4 time British offshore yacht of the year in the '80s and '90s(?)) actually performing very well downwind in light winds, compared to the competition of light fractional 1/2s and 3/4s.

Another classic case could be when Farr's first one tonner was beaten in a breezy dead downwind Hobart by the Peterson one tonner Pied Piper. The Farr had been all over the Peterson (the world champ boat, sailed by the America's Cup winner) in the earlier races, but on the square run she didn't have enough power.

Of course, given more breeze the lightweights would start to fire up, especially on the reaches and runs.

This is the Australian situation; our conditions tend to be different and so do our boats, but as Paul notes the same factors applied there.

As technology (especially rigging and sails) and technique improved, the fractionals improved as he said. I think the last competitive mastheaders were the Frers and R/P 50s and maxis (Sovereign etc) of the 1988 era.

 

I read that article. That's what got my interest up.

 

Thanks Paul and Ct.

I thought the wide sterns and 3/4 rigs were an evolutionary step.

Now it appears they existed side by side with the narrow stern masthead boats, but were chosen due to the wind conditions of the region they were sailed in.

The Bob Perry article I read, didn't give that impression at all.

The impression I get now, is that the wide sterns are faster in strong winds and the 'pintails' are faster in light winds. And the fractional rig needed to improve it's mainsail shape control (fuller in light air, flatter in strong winds) in order to compete effectively with the masthead boats, which could just hank on a jib that best suited the conditions they were sailing in.

Am I getting it?

 

Although 45 South was Farr’s first serious attempt at an IOR design he still adhered to his earlier approach. The boat was designed entirely for speed with little bending or distortion of hull shape to make IOR rating gains – blatant distortion would slow the boat and was unacceptable. Compared to Titus Canby, 727 had more beam, sail area, a dinghy-like ¾ rig on a Baverstock mast with fixed, swept spreaders. The low boom for the large, low aspect ratio main appeared unusual to international crews and upon arrival in France the yellow Farr was considered so weirdly different it was considered a no threat. The English skipper of Minestrone watching the two Farr’s 45 South and Genie being rigged commented, “There are two boats we won’t have to worry about.”
Titus Canby’s keel allowed it to sit on the bottom for grid work but 45 South’s was deeper, narrower with a purist hydrodynamic tip that had no considerations for working practicalities, just performance. To get the minimum CGF (Centre of Gravity Factor) under IOR, keel weight on 45 South, unlike Titus Canby, was carried closer to the hull. Farr said for Sea Spray, “Light displacement relies largely on hull form for stability rather than ballast. But if the keel is too small, the boat will be blown sideways and if it is too big, the boat trips over itself and goes sideways anyway. My keel is quite large by displacement standards with a tapering profile from keel top. Being of high aspect ratio, it lifts the keel centre of effort under the boat and decreases heeling moment. And having weight up under the hull gives a better Centre of Gravity Factor; this produces a better sea boat because keel weight is concentrated closer to the boat’s centre of pitch.”
For speed the waterline was long, entry fine, run aft flat carried to a wide stern. Compared to the fleet at Deauville 45 South was not very wide which allowed it to handle sloppy sea and flukey wind conditions well; an area where light displacement boats usually perform poorly. A crack Auckland crew of Dickson, Woodroffe, Martin and Crockett aboard 45 South was able to extract speed in both light and breezy conditions – but other crews had reservations about the constant rig tweaking required for boat performance

 

Thanks, Gary.

I liked the bit about the deeper keel making the boat more tender (due to the IOR rules.)

Now for another question. And I need the answer for a scene I have written for a screen play.

What is the fastest speed a half ton IOR boat has been known to sail at?

 

You seem to be reading things that are not there.

A deeper keel does not make a boat more tender.

The IOR rule did not cause any such thing. The rule did require designers to aim for a minimum CGF, so the distribution of the ballast in the keel did make the boats more tender.

 

I read that interview years ago and Farr wasn't saying that keels were too deep, he said that if they were "TOO BIG, the boat trips over itself and goes sideways anyway". This of course is very much what happens in a dinghy when you have too much board down in strong winds, which Farr would have known from his dinghy experience.

If righting moment was not restricted then a deeper keel could create more RM and therefore compensate for the extra heeling moment, but when the RM is restricted that doesn't occur, so this was perhaps an effect largely restricted to IOR boats.

 

The topic of deep keels allowing a boat to trip on itself in heavy wave action has come up in other threads lately and is a factor I was not previously aware of...It seems that deep fin or even "full-er" deep keels do have this one major drawback,i.e., they become a liability due to this "tripping" effect in heavier seas wave action despite the fact that they allow a boat good upwind capability, increased canvas and lighter weight....these traits seem to be canceled out at a certain beaufort number or sea-state. By heavy wave action I mean driving sheeting whitecap conditions....when the boat's forward motion or upwind ability is overcome by the sidesweeping forces of the upper say 5-10 feet of surface water basically acting as a conveyor belt taking the boat to lee...whereas a shoal draft boat keel is not as subject to the conveyor effect because it has less lateral area exposed to this "slipstream"? I am not as erudite on these matters as most of you on this thread and I realize there are many other factors but is this the crux of the issue?

 

A quote from the Jim Young book:
"Checkmate was a design independent and a little earlier than the first Farr One Tonner, Prospect of Ponsonby, [a larger extrapolation of his outstanding 727] which belonged to Noel Angus in Tauranga; Prospect was sent to Auckland and I was amazed to see it was very much the same type of boat as my own, even though I’d designed Checkmate completely without knowledge of Farr’s design. So when I first saw this Farr boat come out I thought, now that’s just what I’ve been doing but his looks a little better than mine in some ways. Prospect of Ponsonby was such a spectacular success that the future IOR boats completely changed.
During the 1976 One Ton Cup trials, most racing was held in very boisterous weather. It was remarkable how the new, lighter boats fared so much better than the heavy Doug Peterson US designs [with their large area keels]. It blew hard for most of the 150 mile race and all the heavier boats retired with broken gear and other problems. [But being beaten by the light displacement designs did not bring forth any admiration from the heavy brigade, quite the contrary]. It really marked the end of the deep forefoot bow and mutilated stern designs that had developed under the Rule; though the fashion did last for some years."

 

I think Jim sees things as he likes, not as they were.

In fact a heavy boat with narrow stern and deep forefoot won that year. Second place was taken by the winner from 1975, a Peterson design.

 

We're talking about NZ trials, Paul, not the OTC; it was blowing to 60 knots during the 150 mile race and ALL the heavy boats failed while the light boats cleaned up. We were in Port Fitzroy on Great Barrier on Vim during the blow and very glad we were in there; even so, at anchor, we dragged about the harbour because the savage williwaws coming down were even higher than outside.

 

The fastest I've logged was in the 1986 HTC in Helsinki: 17,8 kn, with over 17 kn for at least 2 minutes. Our average speed on a 18,5 miles run that day was 14,5 kn... big swell with a south easterly gale on the relatively sheltered Gulf of Finland. This was on a calibrated log with a 40 sec damping - damping makes a big difference. I'm sure you would easily get over 20 kn with a 10 or 20 sec damping on the log - GPS did not exist at the time.

I should know.. I raced all the half ton cups between 1980 and 1991.