Doug Halsey

Also not a video, but some fun reporting of a dismasting in 1964.

Because they win too much when they try other classes.

Do you have a specific link for that? I haven't had any luck googling "The Very First SailBoat Built of Fiberglass" I'm gathering material about the Trailer Class (which the original Snipes were part of) and I think this distinction for the Snipe would be relevant.

Are you saying that the marks couldn't maintain their position because of the kelp, or that they created an obstacle to the boats near the marks?

I'm not really a hoarder (well maybe about some things). But I happened to find these in the 1981 Nicro Fico catalog

It helps to think of the drag curves as representing perfectly balanced conditions, but with either stable or unstable equilibrium. When the curves have positive slope, a slight imbalance in thrust and drag results in an acceleration or deceleration that tends to reduce the imbalance. When the curves have negative slope, the imbalance gets larger until different regions of the curves are reached.

Your description is exactly what happens to foiling Moths.

I don't think that's correct. Drag curves of planing hulls (or foilers) can have regions of negative slope, like the case below (from Hoerner's Fliuid Dynamic Drag) and those boats manage to decelerate just fine anyway.

I was referring to the last paragraph in the post I quoted "Planning occurs when hydrodynamic lift results in a reduction of drag, and allows the boat to accelerate well beyond hull speed with no increase in the thrust the engine (sails) is/are providing"

It looks "plany" to me too. My intention was to counter Crash's implication that planing necessarily causes a reduction in drag as the speed increases. Yes, the chart was taken from Marchaj's Sailing Theory and Practice, but I couldn't tell from the text where the data originated.

I guess you wouldn't consider the Inland Lake Scows to be planing boats then.

He was an engineer at NACA and later one of the top honchos at NASA. Robert R. Gilruth | NASA

That's also the definition of "pinching." Every boat can do that.

Without the wands, or an expert crewmember actively controlling the foils, how will you keep the boat from crashing? The foils you've sketched won't be self-correcting, and "deployable & retractable" isn't enough.

One of the components of a daggerboard's drag is induced drag, which increases in proportion to the lift squared. Sharing that lift with the rudder will reduce the total induced drag of the two foils (for the same reason that (2 * 0.5^2) < 1).