1
6 2
Figures 1-4 are all based upon measured vs predicted performance for a 2015 TP52. Figure 1 (upwind) and 2 (downwind) show the variances between VPP and the actual measured data along with net differences expressed as a percentage. Figure 3 shows the same variances but now expressed in sec/mile. Figure 4 similarly displays measured variances, in this case for the rudder and heel angles of a TP52 sailing upwind. Figure 5 pitches a TP52 vs a Maxi72: upwind (red) shows the Maxi72 ahead above 8.5kt TWS but ahead overall (blue) only from 9-14kt TWS (downwind in green). Figure 6 shows the different wind shear in stable (left) and unstable breeze
Maxi72 comes in at 51.68kg/m2 .
The advantage of the Maxi72 in upwind sailing (where length is generally still king) is a direct reflection of the advantage enjoyed by the TP52 downwind where its weight/sail-area ratio of 19kg/m2
also 3
becomes significantly more favourable against the 24.59kg/m2
of the Maxi72. 4
In reality the downwind TP52 ratio is around 23% better so it’s reasonable to expect promising performances despite the shorter hull length. Considering the full crew loaded boat weight, the TP52 weight/sail-area ratio is still ahead by 19%. In terms of outright boat speed, obviously the Maxi72 is faster offwind but the difference is very often surprisingly small and in some cases it’s less than 0.5kt with a maximum gap of around 1.2kt. TWA is also biased to a ‘speed mode’ for the Maxi72 and is always on the narrower side; for example, in very light wind the bigger boat struggles to accelerate and needs a ‘hot’ 133° TWA against 139° for the TP52.
Considering the overall picture over the complete windward-leeward race, the Maxi72 has good potential in the TWS range between 9 and 14kt, seeing its maxi- mum advantage of 190 seconds on corrected time at 11kt. However, in lighter winds below 9kt TWS, the TP52 defeats the bigger boat by several minutes; and then as the breeze climbs above 14kt, the ‘faster’ offwind pace of the TP brings it back into the lead with a maximum gain of 109 seconds at 20kt TWS.
5
Upwind the Maxi72 is strong and wins on corrected time from 9kt TWS upwards. Obviously the long hull and high stability make the Maxi72 almost unbeatable as soon as the breeze has any weight to it.
42 SEAHORSE
However, in the lighter ranges it suffers because of the larger weight/sail-area ratio. In a direct comparison of the two boats’ main parameters, the weight/sail-area ratio of the TP52 upwind is 42.68kg/m2
while the In practice the TP52 has a wider TWS
range of winning opportunities but the Maxi72 has the advantage in the 9-14kt range. And, statistically speaking, that is the most commonly encountered wind range in normal meteorological conditions. After plotting the corrected time data (Figure 5), it is interesting to move on to
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