Zoals in het topic over Lelystad Regatta al aan de orde was zijn de Downwind Angles op de meetbrieven in 2016 nogal veranderd.
Was het eerst een geleidelijk verlopende lijn (steeds minder afkruisen met toenemende wind), nu is het een 'knik' bij ca 13 kts. Minder wind is ca 150 TWA DA, meer wind is 170 a 180 TWA.
Big Time had er ook al vragen bij of dit nu een verbetering was.
Ik heb de vraag gesteld aan ORC.ORG, en keurig antwoord gekregen.
Mijn vraag:
Subject: Downwind Angle in 2016
Message: Dear Sir, Madam, many sailors noticed a change in the range of Downwind Angles this year. In the past the DA gradually increased with the wind increasing from 6 to 20 kts. This year, there seems to be a sudden increase in DA around 12 to 14 kts. It is our experience (with sym spi) that the old DA's were faster except at very light wind (6 kts). Also several genaker-sailors (J109) are of this opinion. We are curious to hear why the VPP was changed this way, and we would also like to hear your views on this 'improvement'. Kind regards, Thomas ten Kortenaar NED 6890 Capolavoro
Het antwoord:
dear Thomas,
the aerodynamic model, and in particular the aerodynamic coefficients of the spinnakers, have been adjusted in order to give more reliable results in terms of best VMG angles.
Specifically, the downwind best VMG angles were believed to be too large for asymmetric spinnaker on bowsprit.
What you are writing partially confirms that the change went into the 'correct' direction. What I do not understand from your message if you think that now the predictions are closer to the reality or not, could you explain and comment more in detail your experience in comparing the predictions 2016 with those of 2015 ? It's always helpful for us to have some feedback.
thank you, best regards
Davide Battistin
ORC VPP programmer
Hoe verder: graag onderbouwde meningen over deze wijziging, dan kan ik dat bundelen en doorgeven aan ORC.
