Above: the Park Avenue boom on Enterprise meant the sail foot was cut flatter with shape induced by allowing it to slide to leeward. Stops on the tracks locked into place the desired foot camber and depth. The interior on Enterprise (centre) looking aft with the nav station in the background; the handle at the right drives the topsail winch on deck. Runner winches were also below deck. And looking forward (right), also from amidships, note the smaller boom downhaul wheel attached to the duralumin mast, the half-cockpit and the big centreboard winch in the foreground. Top of frame is the mainsheet brake with the mainsheet take-up reel furthest right
developments over the years, the new boom was built in secret at Herreshoff Manufacturing Co in a shop closed off to visitors and only introduced late in the campaign. It was installed on 10 August. When it appeared it was a surprise to competitors left with little time to react. The Enterprise team had always wanted
to test how effective the slider system was. They got their opportunity in an impromptu tuning trial against fellow defence candidate Yankee, setting one side to the optimum curve and the other fixed at centreline. The test was successful: Enter- prise proved faster with the foot curved using the cross track system. This was an ‘advance’ over the deep
depth ‘plank on edge’ booms that bent sideways to achieve the same foot curve, with struts and stays controlling deflec- tions. In both cases the booms were built in wood using aircraft methods of the time. The Park Avenue had the advantage of
more endplate effect but was heavier; the early deep-depth booms were lighter but were less durable and broke from time to time. Ironically in 1934, while the Ameri- cans were impressed with Shamrock’s 1930 deep-depth boom and copied it, the Brits copied Enterprise’s Park Avenue boom. Vanderbilt claimed he could not see a performance difference between the two but simply ‘preferred the former’. In 1937 both Ranger and Endeavour II had devel- opments of the lighter stayed booms, with Duralumin now replacing wood. Burgess also sold Vanderbilt on fitting a
smaller rudder to Enterprise that month. Apparently, though possibly faster, it took much more steering input and Vanderbilt never really got used to it, remarking in his book that in the future he’d strongly advise against major changes late in a campaign – something repeatedly borne out in Amer- ica’s Cup history. *Loose-footed mainsails, today so preva- lent, were deemed impractical at the time due to the inferior strength and resistance to stretch of cotton sails.
Tacking luff mast (not used) One idea that was seriously considered complete with a full detailed design and working model was a mast system like the
32 SEAHORSE
boom’s enabling the mainsail also to ‘tack’, allowing the sail to get closer to the leeward side of the mast, eliminating much of the turbulence of the mast on the low pressure or lifting side of the sail that drives every sailboat. It required two tracks and heavier athwartships sliders, significantly adding to weight aloft. Also, Vanderbilt and Burgess worried it might be deemed illegal in a protest. For both reasons, it was never tried.
1934 In 1934 rules were changed introducing a minimum mast weight of 5,500lb, on average 500lb heavier than wooden masts to date. Not only was this a response to Enterprise’s overwhelming rig weight advantage but also to account for the evolution from triple-head rigs to double- head rigs that induced higher shroud loads. Double-head rigs prompted three develop- ments: l Quadrilateral jibs l Three-spreader rigs l Bar rigging The significant sail development of 1934
was the quadrilateral jib. Vanderbilt noted that Francis Herreshoff had suggested a quadrilateral jib to him years earlier, sketching it on an M boat sailplan. Typical of what we all do sometimes, Vanderbilt failed to see the advantage and never ordered one. Then in 1934 TOM Sopwith, Endeav-
our’s owner, never having seen or heard of Herreshoff’s idea, thought of exactly the same thing, believed in it and developed it. It wasn’t long before word got back to the US and copies appeared on the American Js. Had Sopwith kept it quieter a bit longer he may well have won in 1934, instead of losing a very close match. (Personally, I think it a shame that such
sails are outlawed on the current Js. What fun it would be to see and sail with quads on today’s vastly better-equipped boats.) The three-spreader rig with its narrowed
staying base substantially increased shroud loads. Further adding to mast compression loads were now much larger hounds- mounted runners. The higher minimum spar weight was
welcome. But cable shroud sizes required for the three-spreader rigs exceeded the
capability of manufacturers, so single-piece shrouds could not be made. Burgess sug- gested having two or three parallel cables serving as side shrouds. As previously men- tioned, Vanderbilt obsessed about windage. When the three-shroud solution was sug- gested, he balked at the extra drag.* Starling Burgess responded by develop-
ing ‘bar rigging’ or what we now call rod rigging. But there was a catch: although sizes could now easily be reached, no bar longer than 17ft could be heat treated in the vertical ovens of the day. The solution: connect the bars in the middle with a threaded turnbuckle-like connector with lock nuts at each end to be tightened to prevent rotation once the rig was tuned. Worried about fatigue cracking in the
highly heat-treated bars, steel experts for- bade drilling holes in the rod ends for cotter pins – later we’ll look at how 24-year-old Rod Stephens learned perhaps the hardest lesson of his career with such fittings as rig boss on Ranger. US boats Rainbow and Weetamoe, and ultimately Endeavour, were all fitted with such shrouds in 1934. Starling Burgess-designed pear-shaped
aluminium masts were made for both Rainbowand Weetamoe. Interestingly, in 1936 Vanderbilt for-
sook his aluminium mast for a Frank C Paine-designed ‘round and slender’ steel mast that he judged had less windage than the aluminium one which set up ‘too many eddies on the lee side of the mainsail’. * Ironically, for its 2003-generation IACC yachts Luna Rossa determined that two smaller shrouds placed unconnected one behind the other had lower windage than a single larger stay and would therefore be faster. The ghost of Vanderbilt may well have remarked to himself, ‘Hmmm’.
1937 When the NYYC received a challenge in the summer of 1936 most agreed that, after 1934’s hair’s breath defence, sticking with the existing US fleet was too risky and a new yacht was commissioned, but not with- out serious funding problems. Other than Vanderbilt, no one at the New York YC offered to contribute. Vanderbilt seemed ready to go it alone when Starling Burgess talked the owner of builder Bath Iron
MORRIS ROSENFELD
EDWIN LEVICK
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