Nice one, thanks RDM & Bill.
Don't let the bastards grind you down.
Monk - here you go
"We ain't on our way to Wembley,we ain't gonna win the league. No matter how much they let us down - Westham's still our team"...
Nice. Love the sidecuts. Somewhere floating around here there is a twingle set up with the tail dug out, almost like a giant concave. I want to say Huck shaped/posted it. He posted a shot of a guy riding it too. I wish I could find it now. Huck?
Send me your dinged, damaged, and yellowed.
...doesn't ring a bell. There have been several posted over the years, and I've built a couple, but nothing that matches your description comes to mind.
"Everybody is ignorant only on different subjects." - Will Rogers
After I posted that I thought, "maybe it was LeeV". I don't know. I'll look for it. It was a beautiful board whoever made it.
Is the first time I write in this forum, the first thing I want to thank the thousands of messages so instructibos that you have written. Thanks to this, nowadays I can do my own surfboards, My english is terrible, I beg your pardon
I've been looking for a table feel I've never gotten, with single, twin, 3 or 4, I want a good parec grip for my boards around 6.0 to 8, but they have a very crazy tail, easy to cross, Similar to a skate tech slide
To see this configuration I have lit the sky, I can put 2 parallel keels, something ahead to get this grip but I will stay very crazy tail ul
I'm not an engineer, but I've been investigating on the subject, especially the separation of the keels, I think you put them together, then found the surfboards of Neal Purchase Jr. (NPJ) duo. That seemed more logical, but with my concern, I decided to design and analyze fluids
I have been studying the separation of the wings in the biplane planes, this is minimum the width of the wing.
Translated to surf, if we have a keel of 120mm of base (4.72"), the parallel would have to be at 120mm separated as a minimum, so that the turbulences do not collide, otherwise we can have an opposite effect to the desired one, something like ejector venturi
I attach a photo of the analysis I have done. A keel of 123mm (4.84") of base separated to 75mm (2.95") of the other, you can see how it ajecta the turbulence against each other
he estado mirando tambien tablas de windsurf, usan muy a menudo esta configuracion, con la suerte que he encontrado estas quillas http://www.k4fins.com/product-category/fins/
I think the http://www.k4fins.com/product-category/fins/ can be very valid and economic, what do you think? What size do i have to put to a short table type the hipto crypto hayden shape in 6.2? Separation between keels 150mm (5.9"). But how much of the tail to loose? I will put lanes us box of 10 inches
Thanks a lot for everything
I have taken this very interesting page for the singlefin assembly and multisistem, could you do something similar to calculate the position of the duo?
I'm sure I don't have an answer for you, but happy to keep the conversation going in the hopes of further insights showing up.
Fin placement interests me, but I'm not too savvy on the subject.
For a Thrailkill type twin-gle setup (placed 2" apart center to center) I believe placement is the same as it would be for a standard single.
For a Neil Purchase Jr. type twin, I dont know, but my gut feeling is that he is placing them a little further forward.
If you use single fin boxes you can allow yourself some adjustment room.
Since you're going in a little different direction, with your own research, the thing to do is probably start a new thread with an explanatory title. It would be nice to include some pictures of the twin fin boards you have, and are working on. Just a suggestion.
I placed my twingle boxes a little farther up the board than normal with the idea that the fins would still be able to hold. And I was right. No measurements now but I'm guessing 6" from the tail?
With the tables of http://www.mckeesurf.com/?page_id=267 and the area and weight of the keels, I have drawn the center of gravity for both trifin and cuard.
Careful, not the momentum center of forces on the yaw axis. I am not an engineer and this is costing me, but I have started working with the free program xflr5, which is to make airplane models. I hope that in a few days I can give some more information
But doing it by intuition I think that for a 6.3 we can put the fins to 8 or 9 inches from the tail. These are of a shape centered just between the 4 fins of a cuad. As the mckee table marks a separation between fins of 6 1/2. For a tail of 15 inches wide
what do you think? crazy?