Polar Diagram Sportina 680

Hey everyone, I recently found back an old hard-copy of a polar diagram of the Clever 23 ‘Hertog Jan’ given that was in the papers given to me by @tonmitz. As it also included a table with all the data points I fed it into ChatGPT to see if it could recreate the diagram in a fresh digital format.

Well, working my way through some funky python code I was able to arrive at the graph below.

The dots mark the boat speed one should be able to achieve given the true wind speed and the wind angle. Apparent wind angles depicted on the right, true wind angles on the left. The outer values on top and bottom of the lines should indicate optimal pointing and downwind angles which vary according to the available wind. With more wind you should be able to get under the 45 degrees when pointing. Going downwind, with more wind you should steer closer to the 180 degrees.

Please note / disclaimer: This just a reference and probably the best we will ever have. The quality of the data, method of measuring, boat setup and trimming used are all unknown.

In the pdf below I have included a table depicting the source data used. I guess with the right equipment and software and A LOT of time and effort you could create an updated personal version. If so please do share :grinning:

Polar Diagram Sportina 680 (Clever 23) - version august 2023.pdf (656,5 KB)
Print double sided to use as a reference card

At once my home build Log (I’ll make a post on it) gets even more interesting to log those diagrams.
I’ll have only to add a wind meter to the setup and make (and store) continously polardiagrams.

I’ll see what it does, planning to sail my boat back tomorrow and the coming days…
Thu Oudega-Stavoren (marina on the Ijsselmeer)
Fri Stavoren- Roggebot
Sat Roggebot- Biddinghuizen

Hi, an interesting diagram!

Especially so because we (Arend en Carla) are the present owners of the Hertog Jan, now named “Swalker” (Friesian for “zwerver”) and based in Terherne, Friesland.

@tonmitz, is there other worthwile info on the Hertog Jan? The diagram is likely from the first owner who sailed the Hertog Jan in contests. We bought the Swalker from the second ownner who used the boat for family sailing only.

Arend and Carla

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Het diagram komt van de ORC database.
Er is nog een tabel bij: Verdere info over de Hertog jan zat er niet bij.

Op de listo hebben we deze gebruikt bij de 24-uurs. De tabel lijkt gemaakt zonder halfwinder of spi; we moesten de downwind waarden nogal wat ophogen.
Dat bijstellen is niet zo moeilijk; zet het diagram in excel en pas het aan. Rak24 leest het in in gebruikt het om de optimale 24 uurs te varen.

Gr Rob

Ah kijk dat is weer mooie info Rob.

Link naar de Google Drive met rak24u software en ook de pooldiagrammen: rak24u

Zijn er nog die meedoen deze editie? Ben zelf even uitgezeild. Twee weken in Friesland en daarna het wad op geweest. Prachtige avonturen. Zal nog wel een aparte post maken daarvan.