The lake is lac Monteynard, close to the town of Grenoble in France.
It's a great spot for windsurfing. Usually, thermal winds are very light in the morning (1-3 Bft) but starts to pick up at noon up to 4-5-6 Bft until dusk, and this cycle repeats itself every days in the summer.
No, I don't use a 60 cm fin. I did try once a 54 cm race fin with an 8.2 m2 sail in ± 10 knots wind. Pointing upwind is less efficient as expected but speed improves a bit. I also tried a 80 cm fin; pointing was a bit better but speed was dramatically reduced, so I keep using the stock 70 cm fin which is a good compromise between best upwind angle and good speed downwind. I also tried the stock Drake shallow 40 cm plastic fin when I was overpowered with the 11 m2, but I'm not using it anymore because I prefer to swap board and fly at higher speed on the large slalom rocket.
As for kiters, they are a no show unless it's blowing a steady 7 knots wind on my home lake. I've seen once a kitesurfer planing in 5 knots wind but he was using a race kiteboard with 4 big fins and a very large 22 m2 sail. As soon as he was hitting a lull, he was sinking full stop while I was still gliding full speed on the Serenity.
You need a minimum of 2-3 knots of wind to move the Serenity forward with a sail. You can even ride her in no wind by pumping the sail with ample and slow motion.
Yes, I also tried paddling the Serenity in no wind, either with a small 32 cm fin, a 40, a 54 or the stock 70 cm fin. No matter which fin is screwed into her tuttle finbox, the Serenity is quite tippy because of her rounded hull bottom. By comparison, the K15 SUP (± same dimension and outline as that of the Serenity) has a flat hull bottom and is less tippier than the Serenity. I also tried a SUPer 12'6" and this is way more stable and less tippy than paddling the Serenity. So to me, the Serenity is clearly a no-compromise high-performance windsurfing board with limited SUP potential whereas the K15 is a high-performance flat water SUP board with limited windsurfing abilities (only small sail, no railing up with feets pushing over the edge of the windward rail because of the deep monoconcave deck form shape).
As for scratches, I do pay extra attention because it very easy to remove a small chip of gelcoat paint on the hull when hitting the dock, a rock, a pole, a chair or table while lugging her around. It's sheer lenght of 455 cm must not make you to worry, but always keep an eye on her bow and stern. I do keep my woody baby in a dedicated boardbag when not sailing. Dings on the wood deck are immediately sealed with a dab of superglue (Elmer's Products Aron Alpha® 221F
Cyanoacrylate Adhesive (Industrial Krazy Glue
™) marketed in the US or 3M's Products Cyanolit® Plastic 221-F marketed in Europe).
Cheers and enjoy your serene ride in Boston !