1.26: Laser lines -the shape that launched 200,000 ships

Kirby’s design portfolio was still slim on the day he doodled the Laser whilst chatting on the phone to Ian Bruce. “Up until then I had designed only four International 14s, and my Mark V 14 was done either just before or just after the Laser. So I was a long way from being an experienced designer and there was a lot of blind intuition lurking around the drawing board” he says.  The vital matters like lateral resistance, helm position and buoyancy were all born from “hunches” and sailing experience, instead of calculations.

Some have claimed that the Laser’s hull is little more than a Contender copy, but Kirby confirms there was no connection. “One of the things that gives me the greatest satisfaction with the Laser is that it really wasn’t related to anything that had gone before” recalls Kirby.  He had sailed the original prototype for the Contender one blustery day in Sydney years before, but at that stage Lexcen’s design was still a hard-chine flat bottomed sharpie type, very different to the Laser or to the Contender as we know it.

Kirby had actually designed a boat for Paul Elvstrom to sail in the final ISAF trials that chose the Contender, but the project fell through. “Later, Bob Miller stayed overnight at our house, and I showed him the lines of the boat I had drawn. He thought that my boat would have been faster in light air and the Contender in heavy air.”

Although all of the minds behind the Laser were Finn sailors, Sarby’s design had no influence on Kirby’s hull shape. “I liked the Finn a lot. But it was a big guy’s boat, much too heavy to be a “cartopper”, too expensive to build for the market we wanted.  At that time it wasn’t even self-bailing. The Laser had to be a simple, easy to build, tidy little package.  I was more surprised than anyone when the Laser turned out to be faster than the Finn most of the time.”

Kirby identified a waterline of 3.8m (12 ft6in) as the shortest length that would provide the required performance. To ensure that it was light and easy enough for women and children to sail and easy to handle on the beach or the cartop, he kept the beam down to a slim 1.37m (4ft6in) and the freeboard at the bow down to 305mm (1ft) “to keep the weight down and to make it look swift”.

The Laser’s ability to perform with a small rig, which may be one of the secrets of its popularity, may come from the way that it generates considerable planing lift from a slender hull. Kirby’s earlier writings and older boats give an interesting angle on the Laser’s shape. He had realised years before that “boats do not plane on their afterbodies as I had read….the real lift – the shape that makes a boat good or bad on a planing leg – is to be found in the forward half. What is important is the …flatness of the floor forward.”

Kirby had long been working towards achieving a higher prismatic by spreading displacement into the ends, creating bows with a U shape that was shallower but had more underwater volume than the typical Vee shape of the era.  These bows, wrote Kirby years before he created the Laser, were not as easy to get “into the groove” as the deep Vee bow (something many Laser sailors would confirm), but they allowed the boat to plane and surf earlier. A “steep V forward” he noted “lacked the lift to make the boat climb on top of her bow wave.”

 

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For its day, the Laser had very flat sections along the keel line, especially in the bow. The dynamic planing lift that the flat bow sections create may be one of the reasons that the Laser is faster than similar boats with bigger rigs.

The Laser takes the theme of flat underwater bow sections even further; since the amount of planing lift increases with speed, an intrinsically slower boat like a hiking singlehander must have a shape that develops more lift if it is to plane well. The keel area is extremely flat in section, all the way to the stem, by the standards of a boat designed in the late ‘60s. Outside of the keel flat, the shape developed very soft bilges. “With the 14s I had gradually worked away from the deep, sharp Vee of my Mark I, to more U-shaped sections” remarks Kirby although rather surprisingly he feels that “there might have been a bit of subconscious transfer from 14 to Laser, but I doubt it.”

So under water, the Laser may follow the themes of Kirby’s world champion Int 14s. But above the water, the Laser takes the opposite tack. In the 14s, Kirby had been developing bows that were very fine above the waterline, to allow them to slice through chop. In contrast, the Laser bow flares out widely in the topsides. “The Laser is flat forward with a lot of flare to give the bow sufficient reserve buoyancy” explains Kirby. “The boat had to be light (it was to be a cartopper), so I had to keep skin area down. This meant low freeboard, which meant in turn that there was not much boat between the waterline and the gunwale. So what was there had to be given flare, to keep the boat from submarining in hard reaching and running. It worked pretty well. When you jam the bow, you sometimes survive!”

The flare in the Laser bow does make it hard work upwind in a chop, when it bounces rather than slices, but Kirby says that it’s an inevitable trade-off for the boat’s other qualities. “The best upwind bow – fine above the waterline – would be a disaster on a small, low-freeboard boat like the Laser when you round the corner and head downwind in heavy air. If you cut the Finn’s freeboard down to Laser level forward and kept the section the same as it is now, she would have difficulty with the bow jamming in fast offwind sailing.”

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Kirby says that the Laser has a very flat bow wave downwind; a sign that the flat and flared sections are developing enough lift to stop the low-freeboard bow                      nosediving. Although it comes with a penalty upwind, when the flat and flared shape tends to bounce over waves rather than slice through them, the Laser’s bow shape may be one of the secrets that allows it to sail faster than boats with much bigger rigs. Incidentally the first time I saw the sailor in this photo, I had to choose whether to cover the guy who had been 4th in the Open worlds and the three-time world Masters champ, or to cover this unknown little red-haired kid called Tom, who was so young his boat was called Nappy Rash. Young Tom (seen a few years later in the pic above) picked the right side, and it almost cost me the only Laser championship I won in my short ‘career’ in the class. Now that he’s won world titles, an Olympic gold medal and the America’s Cup I don’t feel too bad about getting outsmarted by someone who was so young he still had nappy rash.

“You will notice that the off-wind bow wave of the Laser is very flat – the water is thrown off to the side, but in the Finn the wave rises more steeply, and frequently the Finn’s freeboard saves the day.  Perhaps a good expression is that the Laser has a “softer” bow” notes Kirby.  “One of the early Laser rip-offs had serious problems with nose-diving and gybe broaches, and never prospered.  And one of the recent attempts at a mini Laser also stubs its toe very easily because it is too fine above the waterline. It’s surprising the number of designers who have missed many of the features of the Laser that have made it work.”

One designer who moved to a finer bow in a similar boat is, ironically, Ian Bruce. When he designed the Byte as a sort of “baby Laser”, he made it finer along and above the waterlines at the bow. The finer shape works well upwind, when the Byte seems to slice through chop more effectively than a Laser. But Ian feels that the Byte does tend to nosedive more than a Laser downwind. “If I did the boat again, I’d fill it out here (indicating the Byte’s waterline) between three and six feet aft of the bow.”

The flattish U-shape sections continue all the way through the Laser hull. The stern is narrow at the waterline, keeping the prismatic coefficient to a fairly low figure of around .57. Downwind, the Laser planes with a flat fore and aft trim, unlike many contemporary boats that plane with their bows high in the air. “I think the boat planes easily and flat just because it is light and does not have much fore and aft rocker” says Kirby. “And turning that around – it does not need much rocker because it is light. The flat angle is not a feature that crossed my mind during the design process.”

Many club-level Laser sailors stay too far back in the boat downwind, as if they are subconsciously trying to get the Laser’s snout into the sky as they have done in other boats. In fact, the Laser sails so well bow-down that the class had to introduce a rule saying that the skipper must stay behind the mast. Sailors were finding it faster to sit on the foredeck on light square runs, lifting the stern out of the water to reduce wetted surface and steering by body weight alone.

The centerboard was designed with a 12:1 thickness ratio and the case was shaped to fit, so that foils could not be filled or sanded into an “optimized” shape without jamming or becoming loose in the case. The rudder is small, and raked in the traditional fashion of ’50s and ’60s dinghies. To some of us who are used to more balanced rudders, the weight on the Laser’s rudder is its worst feature. Kirby has gone on record that a new rudder would be the only change he would make to the Laser; it should, he says, be four inches deeper, elliptical and of 10% more area. Ian Bruce recalls that Kirby’s plans showed a rudder with even more rake. Ian changed the pivot point to bring the foil more upright, but over 200,000 Lasers later, you can still see the trace of Kirby’s intended rake – the tip of the rudder is angled down to fit the designed rake, rather than horizontal.

Despite the small rudder, the Laser is an extremely manoeuverable boat; one of its joys is the way you can flick it through tacks and gybes with roll alone. What’s the secret?  “I think any little boat that doesn’t have a deep sharp bow will turn easily” muses Bruce Kirby. “But the Laser is on the narrow side, which helps keep the balance (helm) from getting out of whack when she is heeled. Perhaps the most obvious answer though, is that the boat is small and light enough to be really man-handled. The crew weight makes a huge difference; it’s a bit like being firmly in charge of a pair of skis – you can make a Laser go where you want it to go with your own body movements. And like a skier, you can also go ass over teakettle if you get it wrong.”

 

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Author: cthom249

A former sailing journalist and magazine editor, I was lucky enough to grow up in Sydney, one of the world's sailing hotspots and to win national and state championships in classes like J/24s, Windsurfer One Designs, offshore racers, Laser Radial open, Windsurfer OD Masters, Raceboard Masters and Laser Radial Masters, to get into the placings in a few other classes, and do a few Sydney to Hobarts.

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