Opposite: the first Trentadue 32 out of the factory on its way to winning IRC Class A at the 2016 Circuito Atlántico Sur Rolex Cup in January – just three weeks after going afloat. As well as a very detailed approach to the design optimisation of his most important commission to date, Sebastian Carlini has taken a welcome refreshing approach to creating a contemporary yet functional interior
including the winners of every major race and regatta in the USA, Europe, Asia and South America. During this exercise our key – but still preliminary – parameters were moved around to locate Trentadue in the most desirable area within the IRC design space, using more than 30 compar- ative graphics generated from our own in-house spreadsheets.
These graphics, a few of which are shown overleaf, not only directly compare numbers to numbers, but also different coefficients and rates of change outputted from specific equations analysing hydro- statics, performance and stability values. Then we moved on to the CFD stage of the process, where a suite of now more detailed potential hulls and appendages were studied with the main goal of reduc- ing drag across the speed range we had defined as being the most relevant. We also compared other major factors including heel, plus rudder and leeway angles taken from our VPP. So an interactive process was now being conducted between CFD and VPP analysis, which in turn generated an extensive matrix of data values for all of the different hulls being studied. Meanwhile, more than 30 sailing load- cases were being performed using the WinDesign Wolfson VPP, trading off dif- ferent sail and rigging arrangements, keel types, hull overhangs, performance and
hydrostatics coefficients, and so on. When all of the various matrix results were finally pulled together our ‘best five boats’ could now be identified.
As soon as our study had reached this point IRC trial certificates were required to close the design-performance circle, allowing us to evaluate predicted boat speeds in our chosen range of conditions alongside the IRC ratings of our top five. That precious information was finally processed using another, more complex, in-house spreadsheet that we had specially developed for the Rolex Cup champion - ship, which emulates all of the historic championship races and various weather conditions in a single computational tool. In hindsight this next-step design and per- formance resource proved essential to win- ning the championship at our first attempt. Using the software, the best five boats previously chosen competed ‘virtually’ on all of the various courses used in this championship, applying the expected wind speeds and directions for each race, boat speeds for the specific conditions, the points weighting of each race and of course the fleet’s IRC ratings.
The spreadsheet travels through four different steps in processing all of the data:
Step 1: boatspeed and rating The outputs from the VPP for each of the
five boats are incorporated in this first step. The speed values used for calcula- tions are upwind and downwind VMGs, with two extra cases used for the study of the regatta’s offshore races (for 70º and 135º TWA). Then the IRC rating of each boat is also entered to finalise the main data input.
Step 2: race data and time estimation
Each race of the championship is studied separately in a different page of the spread- sheet. To start, the average Wind Direction percentages during the race under study are defined and entered.
For this particular study this information
was taken from the historical wind statistics applicable in the area during the same calendar period. Account was also taken of the time of day that each race would take part; as at most sailing venues, the wind in Punta del Este demonstrates different char- acteristics and velocities at different times of the day due to variations in the sea and land temperatures (among the numerous other weather influences).
Then, combining the wind direction percentages above with the VPP data input from the first page, a set of calculations is performed automatically to create a table and graphic representing ‘real-time com- parison per mile raced’ for all five boats.
SEAHORSE 35
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