This page contains a Flash digital edition of a book.
Opposite: Harken Air pedestal on Provezza. The package (left) created for Alinghi’s winning AC32 campaign in 2007 was the first pedestal-driven drop system, with a moving feed (on the yellow track) which ensures the line is wound flat on the drum. Harken’s 1:1 Y-Box bevel gearbox (above) fits directly onto the hub of the carbon ratchet line drum below deck (left, Provezza)


the sewer person disengages the hub to bring the kite back forward toward the forehatch for rehoisting. The retracting line stays either wound around the now free-spinning drum or slightly in tension between the drum and the centre of the kite now forward. The red bevel gearbox with its 1:1 drive ratio was specially designed for this application. This gearbox is unique in having two disconnects that are linked to one control. Thus it operates as a ‘Y-Box’, where the crew is either grinding the winch or the drop wheel system – but never the two at the same time. The TP teams are in different places in terms of the hardware they use at the hatch opening. These solutions remain unique to every boat and every project manager. The general trend has been to install a roller, often a Harken carbon drive shaft re-engineered to span the hatch or suspended from the underside of the deck just aft of the opening.


AC Class that preceded them, TP52s have stanchions and lifelines with a nasty appetite for sails.


In the beginning the teams developed their own drop systems independently, with varying degrees of success. Most of the boats started the process using the existing cockpit utility winch or an on-deck halyard winch.


The challenge with this winch solution was 1) you had miles of 6mm cordage in the cockpit after dropping the kite; and 2) the pit person had to be very fast in the pit to hoist the jib, unload the winch and then get it reloaded and ready for the drop. The tactical prospect of being able to keep the kite up and drawing, sometimes to within a single boat length of the mark, was so enticing that development was bound to continue.


Progress to date


Soon a few TP52 teams, where sailors coming out of the AC had seen the benefits of the below-deck systems and how well they kept the take-up line tangle-free and out of the fray, approached Harken. They worked with us to develop a new below-deck take- up system. The heart of the resulting solution is now a mechanical ratcheting hub that mounts directly to a gearbox and a large but lightweight carbon drum.


When engaged, the ratcheting hub prevents the drop line from unwinding, preventing sections of kite that have already been brought below deck from being swept back out of the hatch by breeze or water. Following the drop, in the process of tidying up,


Most recently several boats have instead opted to incorporate larger radius hatch openings. This is simpler on the water and potentially just as effective. It just takes more time to create the tooling to form the amazingly fair hatch perimeter that is required. These systems all integrate well with our various winch packages. Today Harken supplies winches to 100 per cent of the TP52 fleet, plus hydraulic systems driven by Harken MX Wing and Air pedestals were selected by eight boats; these pedestals offer the ability to accelerate output speed by a factor of almost three. This in turn rotates the carbon wheel very fast indeed, taking up the drop line and pulling the spinnaker through the hatch and down below within three to five seconds.


The future


For what other types of boats would equipment like this be appropriate? In fact, we’re already seeing racing monohulls of a wide range of sizes being designed and launched with these systems incorporated.


They are already well-developed in the Maxi 72 Class and are increasingly popular onboard custom and semi-production race boats between 40 and 50ft. Each design requires different sizing and system design, but all seek to apply the same general solution and are doing so with very positive results.


At Harken we stand ready to collaborate on new projects in this important, ever-evolving technology. We’re not standing still. Recently we’ve also begun to deploy hydraulic and electric winch powered string drop systems for much larger maxi-sized cruiser racers. Progress never stop.


Mark Wiss, director of new business development The Provezza crew discuss the development of their customised TP52 string drop system at www.bit.ly/Provezza-Harken


q


To be involved in the Technical Brief advertorial column please contact – graeme@seahorse.co.uk SEAHORSE 29


Technical Brief


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85