A Bow for a Bow: The Interview, Part II
A Bow for a Bow: The Interview, Part II
The Prada design and construction teams were busier than any of their contemporaries during the Louis Vuitton Cup. After a discouraging 4-4 record in Round Robin 1, they did the first of two major facelifts to ITA-74, the second coming after the quarterfinal loss to Alinghi. In addition they also did some major reconfiguring to the bow and stern of ITA-80, their second boat, which never sailed in the competition. The changes did help significantly, Prada went 7-1 in the second round robin and was able to survive until the semifinals, but they were unable to completely make up for their slow start, losing to OneWorld in the semifinals. To get a better idea of how a team goes about modifying or flat-out replacing a major chuck of an Americas Cup boat we interviewed four key people from Pradas shore crew. The story appeared in the February issue of Sailing World. The second half of the interview is below.
For the first part of the interview, click here
During this interview, conducted on Dec. 13, 2002, youll hear from the following four members of Prada:
Aeronautical Engineer Andrea Avaldi (Italy)
Composite Engineer Will Brooks (UK)
Naval Architect Claudio Maletto (Italy)
Lead Boat Builder Sean Regan (New Zealand)
For their complete biographies, and the complete Prada design team, please scroll to the bottom of the story
SW: When youre rejoining these structures, how do insure that strength and integrity are not compromised? Common sense says a broken and re-bonded joint isnt as strong as the original, and you dont have a large safety margin in these boats.
Will: It is a compromise. When you rejoin something and youre doing something in a hurry, you will allow for a little extra safety margin. Which carries a slight weight penalty. But the actual area that that youre joining, the actually joint itself, is quite small so the weight penalties you pay are small. Then what you do is keep a thorough check of the joining process, you analyze it as it goes along and then at the end you will structurally test the boat to make sure everythings sound before they go sailing.
Andrea: Since the beginning of this campaign, we started using ultrasound inspection technology, which gives us the ability to inspect composites [electronically].
SW: Sean, carpenters always say, "measure twice, cut one," whats the rule of thumb for these projects?
Sean: Its purely the setting up. You measure twice. You always doubt yourself even though youve marked it, because unfortunately by that stage youre quite tired, its usually the middle of the night when youre doing the cut. But theres nothing nicer that lifting the new piece up—everybodys standing around watching at this point—and putting the new piece in. When the new piece goes clunk, thats three-quarters of the project done. The bow is really as simple as that. Cut the old one out, put the new one on and taper up those basically. The biggest part in the bow is actually the painting and fairing side, getting the lines right. And especially with Prada, the colors have to look right too when she goes out of the shed.
SW: Whats the curing time for these projects. How long do you need before you feel comfortable that everything is solid and ready to be stressed?
Sean: The epoxies have come a long way now and we can pick and choose really. Usually youd be trying for the superior products, but usually the superior products involve post-curing. Weve got to cut corners, were always trying to use a system with enough time to get the laminate on, but minimum post-curing time. The boats do have to be post cured before they go back out, but the critical thing is making sure the steps all take place, one after another. Making sure that one steps cured, where you can take the bag off, do another stage, re-bag it, and post-cure it. Its a time thing, you cant put a million people on the job to make it go quicker.
SW: Once all the modifications are made, the boat must be re-measured. How does that get arranged?
Claudio: In general when we start this kind of modification we are planning carefully each step of the process and also we have a very accurate calculation of volume and weight. We were launching the boat only a few minutes before starting the official measurements, so we had to know that everything checked out before. Everything went well because the boat was properly modified and all the calculations made in advance were very accurate. We had discrepancies of around 1 mm in checking the free board and the weight on the scale of the official measurer was exactly as expected. This the final result of a very accurate process and good planning of the modifications.
SW: So thats the last step, doing the measurement before you splash the boat and take it sailing?
Claudio: Yes. We launch the boat and after a few minutes we have the official measurement, after we went sailing to check the boat both from structural point of view and later on, on the performance side against the other boat. Everything was done at the last minute so the planning was very important.
Andrea: Theres another measurement stage that we had to go through—this involving more Will and myself—and that is the checking of the minimum hull thickness and the weight of the panel of the new pieces added. This process normally can happen a couple of days before the official measurement of the hull lines.
|©Courtesy Team Prada/Carlo Borlenghi|
|Team Prada, two-boat testing with ITA-80 in the foreground and ITA-74 to windward.
SW: So this is something that you do before the official measurement, measuring the hull thickness and getting a guess on the weight?
Andrea: You take samples, like barrels, and then the measurer comes and they measure thickness and the weight.
Will: This is really critical part as far as the engineers go, because theres such a large weight up in the new piece of bow you have to keep it down to the rule minimum otherwise you will pay a big weight penalty. So its for us to design the resin content, the laminates, so that were right on the rule minimum without going below it. Its quite a knack because the resin contents change and you have to keep a constant monitoring of the build process.
SW: Whats the minimum time you need to build a new bow, to get that piece ready before the boat comes out of the water?
Sean: About three times longer than it takes us. Theres never enough hours. The initial bow work we did on ITA-74 was a bit of a combination. We made a new piece and we did some re-fairing on the boat because we didnt have enough time to actually build a new mold. The typical process is the construction of a male mold and laying up over that as you would in building a boat. Where it would usually take three or four days to build a mold—the mold itself before you even lay up—were trying to do that in a day and an overnight. Its that short. Were cutting the time down immensely. The laminate layup is a procedure where you have an inner skin, a core, and then an outer skin which all have be done in separate stages. Its around the clock basically. Each of the projects weve done, I dont think we couldve maximized the time any better. We have a time table which we set, myself and the engineers and Claudio, weve all got to combine together so we have a time table that sets it up so the whole process comes together at the last minute. The boat is going up on its keel and going out the door as the painters are painting and the rigs going in. Its just like a production line going into the water.
Andrea Avaldi (Italy) - Aeronautical engineer. Andrea was born in Milan, Italy, in 1964. This is his second Americas Cup experience; both have been with the Prada team. He, along with Will Brooks, is responsible for the structural design of the yachts. In 1991 Andrea graduated from the Polytechnic in Milan with a degree in aeronautical engineering—specializing in structures. He then moved to Turin, where he worked at the Fiat Research Center, specializing in structural analysis by finite element methods. In 1994 he returned to Milan and worked for various aeronautical firms. In 1995 he began consulting in computation and structural design for F1 teams, including Ferrari. He is married to Maria and has two children, Pietro and Paolo.
Will Brooks (UK) - Composite Engineer. Will is in his second Americas Cup with the Prada team. He was born in 1967 in Plymouth, England. After earning a degree in mechanical engineering at the Heriot Watt University in Scotland, he earned a masters degree in naval design from the University of Southampton in England. He has several years of experience as a consultant in the maritime industry. For four years he worked for SP Technologies in England, where he was in charge of the structural design of several cruising and racing yachts, including the avant-garde Tiketitan and a new Wally 105-foot yacht with canting keel. He is married to Amanda and has a daughter, Rose.
Claudio Maletto (Italy) - Naval Architect. Born in 1948 in Varese, Italy, Claudio is also in his second tour of duty with the Prada team. However, this is his third Americas Cup, having worked from 1989 to 1992 with the design team for the Il Moro di Venezia challenge. After earning his degree in architecture in 1972 at the Polytechnic of Milan, he began designing racing hulls with Flaviano Navone at the offices of Franco Fontana in Como. FMN earned its first important international result in 1978 when one of its designs won the world Mini Tonner championship. This was followed by many national and international titles in the five IOR Level Classes. After the 1992 Americas Cup, Claudio focused primarily on IMS racing boats. His designs recorded victories in the 1995 and 1996 national championships and in the Commodores Cup and Sardinia Cup of 1998. A passionate sailor, he has been active in international racing in the 470 and Laser as well as the IOR and IMS classes.
Sean Regan (New Zealand) - Head Boat Builder. Born in Christchurch, New Zealand, in 1967, Sean is in his fourth Americas Cup. In addition to Prada, he has worked, as a boat builder, for New Zealand in 1992, Chris Dicksons Tag Heuer challenge in 1995, and John Kolius Abracadabra effort in 2000. He was also involved the construction of Steve Fossetts PlayStation.
The rest of the Prada design team includes: Alessandro Benigni, Sail Design and Development; Steve Calder, Sail Design and Development; Mattia Carpini, Design and Drafting; Guido Cavalazzi, Sail Design and Development; Miguel Costa, Deck and Systems Design and Development; Michele DellAcqua, Mast Design and General Construction Design; Luca Donna, Structural Design; David Egan, Technology Director; Scott Ferguson, Mast Design; Jan Howlett, R&D and Design; Michel Kermarec, VPP Development Coordination; Juan Kouyoumdjian, Naval Architecture; Jed Lowry, CFD Development; Juan Meseguer Torregrosa, Sail Design and Development; Paolo Periotto, Deck and Construction Design; Giorgio Provinciali, VPP Development; Bruce Sutphen, Measurement Instruments Development.
For more on Prada, click here.