The classic Charles Dickens foil board quiver. Interesting in the very different approaches.



source: www.facebook.com/groups/271504922974281/permalink/2325559150902171/

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Paducah said..
The classic Charles Dickens foil board quiver. Interesting in the very different approaches.



source: www.facebook.com/groups/271504922974281/permalink/2325559150902171/

The fmx and the patrik are quite similar, the FF kept the formula / slalom style cutouts. The FMX and Patrik both have deep, big stepped cutouts, with the patrik being a little more extreme. The center tail section however is almost the same.

Logical the tails come from the same design ideas if you consider Alex Cousin rides patrik and Thomas Goyard the FMX, they train a lot together and both work on development.

I guess I'm wondering as I hack away at old boards and rebuild the tails, for example:
if the V shaped cut outs of the Patrik are less efficient than the squared off FMX in getting off the water
if the much greater area of the FF makes it plane quicker, slower and whether it makes it too bouncy or draggy?
do the deck shapes at the tail, matter much? The Patrik and FF both extend further back and are more square - is there a risk of dragging a corner if you touch down in a jibe?

I realize a bit of the design is artistic license but if one is starting from scratch, what characteristics each of those tends to promote.

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Paducah said..
I guess I'm wondering as I hack away at old boards and rebuild the tails, for example:
if the V shaped cut outs of the Patrik are less efficient than the squared off FMX in getting off the water
if the much greater area of the FF makes it plane quicker, slower and whether it makes it too bouncy or draggy?
do the deck shapes at the tail, matter much? The Patrik and FF both extend further back and are more square - is there a risk of dragging a corner if you touch down in a jibe?

I realize a bit of the design is artistic license but if one is starting from scratch, what characteristics each of those tends to promote.

Well, what I see when looking at the photo is that the cutouts on the FMX and PD are similar in terms of removed wetted surface area, but the PD's cutouts remove a little more volume. This might not mean so much since the PD also has a fatter tail.

Not quite sure whether straight or v shaped cutouts would be best, but rounding the very end of the tail section behind the fin box makes the board considerably looser (again something the FMX and the PD share).

I also think taking the botomshape into account is important. For example (I dont know if this is true), if the PD has a double concave in the tail section and the FMX has v, the straight or v cut of the cutout results in practically the same wetted surface / performance.

Another interesting difference, which definately has impact on performance is that the step starts half way through the finbox for the PD (where they start for regular slalomboards aswell), whereas the step starts behin the finbox for the FMX.

Saying that, I have also talked to shapers who feel cutouts all do the same thing, independent of shape.

Edit: Funny how just by looking at a picture one can do new realizations. I designed a racing board in Fusion360 once for fun, but I think after this discussion I'd do some things differently. I'd go less deep on the cutouts and cut away a little behind the finbox to make the board more free. I did however then also think about the V vs flat and opted for more v shaped since the board has a double concave running to about halfway between the finbox and the front of the cutout.

Thanks much for your detailed thoughts - very helpful in thinking about what factors matter. This is what I've been working on and I have another donor board to work on after this. It'll probably sail like crap but it's been super fun and learned a lot along the way.

I'm just asking, I know NOTHING about building a board.

A. Cutouts shaping. How about adding another layer at the bottom that contains the cutout? Wouldn't that be easier than shaping from a single core.
If the cutout is 1.5 cm deep; get a foam sheet that's 1.5cm think; cut out to the shape you want an than glue it to the main body.
Cutout depth in this case would be limited to what is available commercially.
You would also have to form the bottom shape on the thinner sheet.

B. It seems that there are two distinct levels to the cutout on the boards. For each board there are two 90 degree bends. Why not have a slope and get rid of the 90 degree ledges. Let's assume there's a 1cm and 2cm level. Why not go for the starting point a 0cm and slope down to 2cm? Glassing would be a lot easier!

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CYVRWoody said..
I'm just asking, I know NOTHING about building a board.

A. Cutouts shaping. How about adding another layer at the bottom that contains the cutout? Wouldn't that be easier than shaping from a single core.
If the cutout is 1.5 cm deep; get a foam sheet that's 1.5cm think; cut out to the shape you want an than glue it to the main body.
Cutout depth in this case would be limited to what is available commercially.
You would also have to form the bottom shape on the thinner sheet.

B. It seems that there are two distinct levels to the cutout on the boards. For each board there are two 90 degree bends. Why not have a slope and get rid of the 90 degree ledges. Let's assume there's a 1cm and 2cm level. Why not go for the starting point a 0cm and slope down to 2cm? Glassing would be a lot easier!

As for A, wouldnt know.

B, cutouts have to have as sharp possible corners to release the water properly, any part of the board which is gonna touch the water when getting on the plane should be flat, or nonexistent. Surface area which isnt flat (in the direct direction of waterflow) either creates drag (pushing water), or "vacum" (pulling water). Neither is really wanted. Boards make use of slanted surfaces in the cutouts, but really only for parts which will not really ever touch the water, for example to make sure the corners on that PD (and pasucah's board) won't catch during the jibe they could've tucked them up ;). (At the expense of volume in the very end of the tail, which might also be a noticable downside)

@paducah, looks awesome! I think it will work just fine.

There are what.... 14 production companies?
Within each there are different cutouts.
There are easily 20 more main custom board builders.
Each with a different cutout shape.

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CYVRWoody said..
I'm just asking, I know NOTHING about building a board.

A. Cutouts shaping. How about adding another layer at the bottom that contains the cutout? Wouldn't that be easier than shaping from a single core.
If the cutout is 1.5 cm deep; get a foam sheet that's 1.5cm think; cut out to the shape you want an than glue it to the main body.
Cutout depth in this case would be limited to what is available commercially.
You would also have to form the bottom shape on the thinner sheet.

B. It seems that there are two distinct levels to the cutout on the boards. For each board there are two 90 degree bends. Why not have a slope and get rid of the 90 degree ledges. Let's assume there's a 1cm and 2cm level. Why not go for the starting point a 0cm and slope down to 2cm? Glassing would be a lot easier!

I know nothing about building boards either. Well, I know enough to have a ton of respect for those that do. The more I do this, the more I understand board prices.

A - It was easier (but helluva messy) in this case to route out the existing bottom. Gluing on to existing foam, getting a good bond, getting it even, etc introduce whole levels of complexity. That's what I faced with the side extensions (to square the rail) and especially the deck extensions. However, see my note to LeeD below.
B - WoH nailed it. You want square edges for the best release. If you want to read more about it, look up Kamm tails (Kammbacks) for one thing. That's why you are starting to see square rear quarter panels on cars/trucks instead of the rounded fenders in years past. The only slope I've seen is on the back edge of the Tabou deck, probably so it stays clear of the water.

WoH, thank you very much. I appreciate it. Just wanted you to know that there was a practical reason for my asking so many questions and why your thoughts are meaningful.

LeeD, true about the different cutouts. But some seem to have faded. My next project is redoing an old Exocet with the super deep "Turbo" cutouts in which case I'm going to be adding material. I'll probably do more what CYVRWoody is talking about - an additive process. I can imagine why they did it at the time - deep around the fin box for total release but material on the rail for jibes - but I think there are better shapes for a foil board.

For CYVRWoody source: motochassis.com/Articles/Aerodynamics/AERO.htm

Thanks for the explanation and diagram that's extremely helpful.

He's got different cutouts designs depending on the size of the board. The Flying Camel series all have flat stern.

ff-boards.com/

Have fun learning..