performance racing

I am investigating whether the design issues involved in performance racing dinghies, reflect those involved in modern day racing yachts. And also am interested in the type of people who sail both racing dinghies and yachts and whether they find one more appealing and why? if anyone can suggest areas of research or discussion which may be useful, i would be most grateful.

 

I'm not a designer, but I've been interviewing many of the top dinghy designers.

The typical performance dinghy (if there is such an animal) seems to be quite a different beast to the modern racing yacht. The dinghies must perform through a huge range of speed, from fast planing speed when control is of the essence because the hull can sometimes be entirely out of the water, to moderate planing speeds, hull speed and low speeds.

In contrast, very few (if any) yachts plane fast for a significant proportion of the time; an Open 60 planing speed is much slower than a skiff planing speed if one looks at speed/length ratios AFAIK. The Open 60 is probably (almost certainly) slower in absolute terms in top speed, faster at the bottom speed.

Other factors include the fact that some dinghies must be designed to be sailed at heel (like a 12' skiff which has a huge rig) while others (16' skiff) have different SA/RM ratios or other factors and can therefore be designed to sail upright.

Dinghies and skiffs are also hard to design because it is difficult to scale up or down a successful shape. DLRs change radically in dinghies, even in performance dinghies. Look at International Canoes against 12' skiffs. They are roughly similar in pace, but the Canoe is 17' long, has 107ft2 of sail, and has a crew as light as 70kg or less. The 12' skiff has about 700ft2 of sail downwind and can have a crew of 160kg or more. The DLRs are totally off each end of the scale. Performance yachts are much more similar to each other AFAIK.

There also seems to be a problem in that, at the size we're talking about in dinghies, the size of waves has a much greater effect on something like a 12'er than a 16 or 18'er. And finally, some "performance" boats don't normally plane fast upwind (12' skiffs, 16' skiffs, National 12s, Moths) while others do (18' skiffs, 49ers) so once again, they have do be designed to operate at different S/L regimes.

The result is that yachts tend to be easier to scale up or down, applying the lessons from one size to another. Something like a 30'er (IMS, IOR, IRC, OD, whatever) can scale fairly closely to a 40'er or longer boat.

Look at a Farr 31 IMS v a Mumm 36, Farr "High 5" 40, and early IMS 50 like Full Cry - they are very similar boats. Look at an old Ron Holland Eygthene 24, Shamrock 30, Nicholson 33, one tonner, and two tonner; it's the same shape sized up and down. The same applies to IRC boats, and ODs; look at a Mumm 30, a Platu/Beneteau 25, Farr 40, IC 45, and Farr 52 OD. The family similarity os obvious.

However, you just can't do that in a dinghy, it seems. A proven champion shape in 18' skiffs doesn't work in 12' skiffs, or 14s. A winning National 12 shape is a dog in Merlin Rocket 14s.

This effect is also worsened by the fact that dinghy designs are normally developed under class rules (Int 14, Merlin Rocket, NS14, Moth etc) which have a major influence on the shape. I suppose the same applies in yachts (Mini Transat 6.5) but not as often; IRC and other rules allow yacht designers more freedom.

So dinghy designs tend to be a bit more idiosyncratic. There's no one "fast" general shape. There's no skiff equivalent to (say) the modern IRC/OD shape you see in a Kerr 31, Farr 40, TP 52 etc. There's not the same resemblance you see in cruiser/racers like Beneteau 40.7s and 31.7s and IMX 45s. Instead, 12' skiffs are radically different from 14s, 16s are totally different again, and 18s are something else still. Moths, Cherubs, 49ers, H Jolle, Merlins are radically different from each other. And dinghy designers (with one exception AFAIK) tend to stick to just one type of boat; it's not like the way Farr designs a 25 and a 90 and an Open 60.

One very good source mentioned to me the other day that not even DLR reveals shows any relationship between the shapes you find at the front of different classes.

One thing which I never realised is that while we tend to think of dinghies and skiffs as being light, dinghies are in fact normally fairly heavy in DLR terms and skiffs are often even heavier (because they carry big crews). The dinghies and skiffs are therefore heavy and powerful, while I think most of us think of them as being light and tippy - I know I did. That has a radical effect on the lessons you can take to and from yachts AFAIK.

I sail racing dinghies (Laser, Radial, International Canoe, Tasar at the moment, some Moths, skiffs etc in the past, and performance cats and sailboards of various types) and yachts (old IOR boats, J/24s, IMS racers, occasional maxi/fast 40/sportsboats etc). Today, I'm finding the yachts much less appealing. The small cruiser/racer or offshore racing yachts are fading away, and if all I'm going to be doing is day racing I'd much rather do it in the big fleets you find in dinghies. Sportsboats don't appeal to me because they are just an expensive and slow version of a dinghy, with smaller fleets.

Sailing big yachts is a bore; one just does one job and spends most of the time sitting around, so I sail a 60+'er about once a year just to remind myself how boring I find it.

I dream of a class of fairly cheap lightweight (maybe 1400kg) 28' cruiser/racer capable of offshore racing. The boats do exist, but the yachting scene is all caught up on big boats and sportsboats. That's a major problem for the future of sailing.

 

Performance Dinghies

One of the most profound things to happen in the history of monohull dinghy design has occurrred only in the last few years:the successfull(race winning) application of hydrofoils. Hydrofoils have allowed the 11' Moth class monohull to be one of the fastest dinghies around regardless of the number of hulls or length. The configuration is important in that the fastest of these(so far) boats are sailed on just two hydrofoils as compared to the three or more that were "required" until Ian Ward sailed the first successfull bi-foil monofoiler around October 1999. These bi-foiler boats are in their infancy yet have already proved faster than an A class catamaran downwind with speed upwind approaching parity as well. The A Class cat is 18'LOA. What is trully remarkable is that after all the development of sailing hydrofoils that the bi-foiler concept did not emerge until just five years ago-a trully historic first! These boats use an altitude control system first pioneered by Philip Hansford on the Mayfly in the 70's and refined on multihull foilers by Dr. Sam Bradfield on the Rave. They use a "wand" dragging in the water to sense altitude and I believe the first succesfull application of the wand technology to a bi-foiler was by John Ilett in Perth Australia-one of the great pioneers of race winning monofoilers.
Until late 2003 it was questionable whether or not a foiler could win in competition in the Moth Class around a "normal" race course. The foiler Moth has not only won just about every regatta it has entered it has done so in light medium and heavy air.
So I don't think any analysis of the current dinghy (monohull) scene is complete without the recognition of what these boats have done and what their potential is in the future. Individual and group efforts to convert I14's and even a 49'er(or two) are underway now.Steve Clark of C-class and Vanguard fame is developing a foiler based on an A-class main hull but using surface piercing foils. Several other individuals and companies are developing foilers for the "mass market" (whatever that is these days).
But there is more to this still developing phenomenon: I suspect that within just a few years canting keel equipped yachts will also sport foils in the bi-foiler tradition using some of the same basic systems pioneered in the Moth class with improvements like fully retracting main foils and flaps on the canting keel strut to allow more righting moment to be developed when the boat is flying.
Foils will play an ever increasing roll in the development of high performance dinghies as well as yachts as time moves on...