Have these two been discussed together here

Starboard Phantom Batwing:

http://www.star-board.com/2012/products/boards/index.php?id=phantom

Layden Paradox:

http://www.freewebs.com/paradoxbuild/

Have some things in common on cursory inspection I'd like to think....

 

One sinks, the other floats.

What do they have in common?

 

What to call it- a shelf projecting out from the hull....

Which one sank?

 

The batwing's trick is that when going slow, part of it sinks below surface .... when fast, it planes ....

I still do not get how they are similar. One is a micro-cruiser, what is the other, 'a surfboard?'

 

A windsurfer-

It seems to me that at slow speeds, both work as anti leeway devices, but at speed...

Oh screw it. Life's too short.

 

Does the windsurf board have "chine runners"?

 

Yes Paul at first glance they do seem to have a little in common, but they work in different planes. The raceboards use the appendages as horizontal lifting strakes and eventually (my assumption) is they transition into the plane patch, at least at high speeds, as not much else will be "engaged" except the foils.

Chine runners on the other hand though also horizontally arranged work more like a STOL fence on an aircraft's wings or as an end plate does on a rudder. It delays separation and pressure bleed off. If used by themselves in a sailboat, they aren't that effective, except on certain hull shapes. If used in concert with other appendages (fixed or other wise) they can improve efficiency considerably (much like the STOL fences I mentioned). Runners also can control flow characteristics a bit, smoothing out eddy making, tip votices and flow streams. In terms of Matt's efforts in these appendages, he has to compromise underwater shapes to taker advantage of the runners abilities, most notably in rocker and under water volume distribution.

Do you have specific questions about these two hydrodynamic approaches and don't be scared by the voices behind the curtain, he doesn't like himself, let alone anyone else.

 

What is this?. Does this answer any questions of Paul Scott?. Let's be correct, gentelmen.

 

The "voices behind the curtain" comment is a reference to the movie "Wizard of OZ", which seemed appropriate for this reply to a query he couldn't answer.

 

I beg your pardon, PAR, I have not been able to relate your comment to the movie. I thought you meant someone in particular, without mentioning his name. Sorry again.

 

I did mean someone specific and I'm pretty sure he knows who he is.

 

I see the 'bat wings' as a feature that helps lower the planing speed of a hull. I don't see any good coming from them at lower thrust so I have been thinking of being able to deploy or retract them on a double end hull. Is this reasonable and accurate?

The chine runner and Matt L's appendage designs are a little less obvious. Is a "Chine Runner" something that has been used elsewhere and characterized? If so how are they sized? I am not sure what to think but my gut tells me that a simple lee board swapped from side to side would improve upwind performance 5 degrees or more. I am very impressed by the travels of these ML designs, but I suspect they are more about waiting for right weather and the ability to survive than what other boats this size would consider sailing ability. The heavy displacement in such a small hull is off my map of experience. In the back of my mind I suspect that the real brilliance of the whole design is the low CE sail rig with continuously variable area -adjustable from inside no less.

Now with the above in mind, what I want is a human and wind powered cruiser for one (100-200lb) with plenty of supplies (~300). I like ML's designs but I think I would be more capable in a longer narrower canoe with a similar adjustable rig. As an added benefit, when the canoe was not loaded down with supplies it could be an entertaining performer with 'bat wings' added.

 

External chine logs have been used by Bolger among others but that was more for simplicity of construction. Chine runners aren't going to match the performance of a lee board or daggerboard, but they will work in a heavy dew.

The microcruisers shown in the link don't seem to be moving very fast considering the heeling angle - and I don't suppose anyone would expect them to.

I don't see what a pedestrian sailboat and a windsurfer board have in common.

 

Idle speculation was this:

Boats go fast and slow, so at some point the function of the plates sticking out from the hulls overlap whether windsurfer or otherwise, since at least both operate at heel at lower speeds.

Whether the cruiser would plane with enough power? Probably. Rocker not to out of the ballpark for that.

The main difference I see is the placement of the plates.

Both experience leeway.

How big a difference be that?

 

These are difficult questions to answer, mostly because they're too wide in scope. Chine runners only work on certain hull shapes, which typically are deeply emerged. On a long, lean sharpie hull they'd be nearly useless. On the Bolger box boats, who's chines at often quite wet, they do work to a degree.

The hydrofoil blades on the board boat, work in a different fashion. To some degree they'll help with leeward skid, but not much, because they're in turbulent, detached water. When speeds increase enough and you can keep the board upright, they will have a dynamic relationship with the flow, to offer additional "bearing area" so the board can plane off sooner and more efficiently.