Monday, August 24, 2009

Analysis of the new TP52 rule

In July 2009, the TP52 Class Administration issued a press release titled "Lifting The Lid Of the Box..." which educates the sailing public about the direction the class design rule will be taking. There are still some details left out of this press release, but we spoke with Rob Weiland to get more information. At the TP52 event in Cagliari, Italy, these changes met with approval of the class association.

Valencia Sailing asked Schickler Tagliapietra to look at the changes in the rules and provide a graphic presentation of the boats.

Without a doubt, the boats build from 2010 onward will look more like current IRC types, many of which are converted TP52 sporting more bulb mass and bowsprits. By 2011, the intention is to phase in all of the rule changes and blur completely the division between these types.

It is clear with the claim that the yachts will be built for 5-10% less than today, with the very strict limit on number of sails, and with the reduction on crew weight, that these are changes in tune with the current economic times. Build cost varies with displacement, as a rule, but secondarily with righting moment. So, with a 2.5% change in overall displacement it is not unreasonable to expect a less expensive boat. Righting moment, on the other hand will climb, with a 27% heavier bulb and a 5% deeper fin (and thankfully the end of the VCG requirements of 2009 and earlier). Less crew means less crew RM addition, of course. Rules for steel fin weight are not immediately clear, but must be expected.

Structural scantling rules will change to the ISO 12215 as opposed to the now outdated ABS 1994 Guide. The ISO standards will be authorized by Germanischer Lloyd, a company with whom ST has a long relationship. Structurally the boats have been quite refined already, but this will be more important than ever, to achieve maximum stiffness, bulb mass and minimum displacement. One would expect such refinement to cost in terms of engineering and building technique. In the end, if there is any reduced cost of the yachts, it is as likely to come from lower labor costs, as from the class rule changes. Cost of campaigns should see a significant drop, due to sail and crew limits.

2009 TP52 sailplan (left) compared to 2011 TP52 (right). Copyright 2009, Schickler Tagliapietra

The sailplan of the TP52 will come in line with current trends. Main heads will become fatter, jib overlap is still limited as before, and the downwind sails come off the pole onto a bow sprit. The maximum area of each of these sails changes only moderately, except for the gennekers. The fat head main will require the now-legal split backstay, but this will be to the top of the mast and not a set of runners. As the mainsail area if moved into a higher aspect ratio shape, the boom length will logically be reduced. The larger genneker on the bowsprit is the most obvious change of all. While upwind SAD ratios will increase by about 3% from 2009, downwind SAD will increase by almost 6%. The downhill sleighrides may not be at deep angles, but they will be quicker than ever. The guide for the sailplan changes are the IRC optimized TP52, such as Ran, Cristabella, Synergy (2007), Artemis (2008) and others (the certs have more mainsail area and much more displacement).

2011 TP52 overlay on 2009. Copyright 2009, Schickler Tagliapietra

The flush deck designs of 2009 will be even more advantageous with expected changes to the interior standing headroom area. However, the winches which have migrated to the main companionway hatch will almost certainly be back on deck based on regulation. The two "versions" of the TP52 rule have been rendered to draw attention to the changes described and expected. Initial indications are that the use of furling downwind headsails, a big part of crew reductions in the VOR, don't meet the needs of the TP52. They remain primarily W-L course and not trans-ocean racers.

2009 TP52 overview (left) compared to 2011 TP52 (right). Copyright 2009, Schickler Tagliapietra

There are some subtle changes to be expected, such as tweaks of mast position, keel position, size of the rudder. Many of these hinge on the crew weight changes, interior headroom and mainsail area rules. As always there will be the need to perfect balance. Apart from showing the box rule dimensional changes, the above images reflect such modifications as well.

2009 TP52 cockpit layout (left) compared to 2011 TP52 (right). Copyright 2009, Schickler Tagliapietra

In summary, the TP52 is telegraphing major changes to suit the mood of the marketplace. It should work, with more teams prepared to enter a class that can cross-over to local regattas more easily. The success of these changes will hinge on how it is phased in, and the willingness of IRC owners to adopt one season earlier than the "real" TP's. The existing fleet should be easy to convert unless, for example, masts are right near the compression limit dictated by the old VCG rules. It is doubtful that many of these converted yachts will be competitive in 12-18 months, however.

ST applauds the bold steps that the class is taking. There will be a shuffling of the deck with regard to design optimization, and we look forward to the re-moding of existing boats, and to purpose built 2011 TP52's.

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