Aha! I get it! So we can't escape splashing around in a bathtub or a water tank after all.

I think we could use a vessel similar to the one you showed in the photo, with one difference: the fans (the "wind wall") would be outside the tank and could be positioned at various angles to the sail. The sail itself would be inside, on a floating platform connected to the scales via "mythical" springs (strain gauges?). Much like how Marchaj did it.

The hardware part is a bit of a mystery to me, but it doesn't seem impossible. Maybe we can find someone who knows how to figure out those specifics. Additionally, we would need to measure the wind force and a few angles. These days, probably primary school kids play around with this kind of stuff; someone's son or grandson could likely design such a setup in a few minutes and hook it up to an Arduino. As for the Arduino—I've used one for measurements before, but a friend put the electronics together for me. The data-logger software shouldn't be an issue.

Let's put that aside for now. However, I am wondering whether testing a single panel would be enough, or if we need the whole sail. What do you think? We know that a single panel behaves differently than a full sail. We would likely need to measure both. As for the SJR sail, we know we'd use a typical set, similar to the "Amiina." But what would an unsplit junk sail look like? Is that known?

Also, what scale should the models be? Would the mast really need to be at least 2 meters high, as Marchaj recommends?

Those are all my doubts for now. Best regards, Jan

I would suggest using "attach file" (at the bottom of the edit window) instead, because in my opinion, copy-pasting causes the image to disappear after a while. However, those added via "attach file" stay put. While I was digging through the forum this winter looking for materials on SJR — (smile) — I noticed that many photos uploaded via copy-paste had vanished from the forum.
By the way, was the hoverboard idea really implemented?

Regards- Jan

Hi Slieve !

Thank you for the reply. I don't think anyone wants you to run tests.

Keep writing your memoirs, because they will definitely be interesting. We are all waiting! (I won't say for how long).

However, it seems to me that it would be interesting if we all conducted a thought experiment titled: "What is the simplest way to compare two sails without making major mistakes?"

Especially since, as I understand, you occasionally take part in model testing? The idea with the air cushion sounds intriguing. I must admit, this is the first time I've heard of such a thing. Could you send a link? I also don't think a heel angle study is necessary. As I've just checked, Marchaj seems to have intentionally limited the heel in his research.

Sorry, but I still can't imagine how that pond stand was set up. I'm asking because I'm curious if Karl's idea and a few others could be used to create a simple sail test stand. It would be enough for the conditions at such a stand to be repeatable; it doesn't have to be a wind tunnel, after all, and even if it were – it's a simplified version – I'd call it a "wind generator." For example, a few computer fans creating a "wind wall."

As is known, Marchaj used a platform submerged in water for his tunnel tests. Unfortunately, it's impossible to ask him about the details and reasons for this solution, but it seems to me that he wanted to limit heel if he used a platform. In Karl's test, heel is considered an unfavorable phenomenon, but Marchaj measured that the heeling force vector (Fp) in upwind sailing is several times greater than the thrust force (Fc) and increases with camber, so I understand that it could also indirectly indicate thrust.
Therefore, it would be better to measure thrust, not heel, especially since the heel of the sail changes its operating conditions.

However, I think Karl is heading in the right direction, and if we work together to develop a simple measurement setup, perhaps our plan will finally succeed?

However, there are a few other topics to discuss before anyone starts taking measurements, so that we can be sure we know what we're measuring and how we're measuring it.

Best regards, Jan.