So I kow there are a few threads on here covering tail design, but they mostly boil down to the general “wider vs thinner” and talk about angles as biting points. What I would like to do, both for myself and others thinking about trying a new tail shape, is compile info about all the different tail shapes we can think of, and their intended effect. We can keep it general, but not too general. What I’m looking for is something like the following:
“Diamond tail: intended to blah blah blah”
As I’m sure you can see I don’t have a lot of info to stoke the fire, because all I have is knowledge about what I’ve experienced and that may not necessarily be correct as I’m still a new shaper. But I’d like to talk about all the major tail shapes, such as swallow tail, winged, bat-tail, pintail, rounded pintail, rounded tail, squash tail, square tail, winged rounded pin, and anything else I’m forgetting.
I know it’s going to be a general thread, but I just wanted to have a resource out there with some basic explanations of the intentions of tail shapes, without getting too crazy into the technical details (keep it laymen)
Scroll down towards the bottom, Rusty has a pretty detailed explaination of tail shapes with some interesting history. I tried to find the video version that he did that was a bit more condensed but couldn’t find it.
I’d say its all pretty much spot on. He’s been gracious enough to share some of his knowledge. If you can find the video it has some priceless info the effects of wings on outline and function of what a wing does. Also if you watch the video closely there are tricks/techniques that were “Ahaa” moments for me.
After you read the portion on tail shapes go back to the top and read it all. Its all inter-related.
What is the point of diamond tails, and what defines a “properly done” diamond?
My thought was just to bring the end of the rail line closer to your foot, as opposed to having it end at the rear of a board like a chopped square tail would. And I guess you get that point at then end too, although I’m not sure what that would do. Pivot point? My first board I ever bought had one, and I’m looking to add one to my next shape.
it also provides a nice clean exit for the water behind the fis - loved that link there was a lot of great info at the bottom breaking down each tail and its purpose
Make one and ride it, draw your own conclusions. Not sure about “proper”. Maybe “enough of” as in an actual diamond tip instead of a little bump on a squash.
They do shorten the rail line. Makes the board feel like it’s shorter than it is when turning. The point of the diamond provides a center point feel for wider tails. Wide squash and swallows have a vague inbetween feeling when transitioning from rail to rail. A diamond gives more feedback as to the location of the tails center line. So quicker more precise turns, less slide.
Look up Lost “Rocket” and Roberts “White Diamond”. Lots of refinement on the design between those two. Lots of copies by many many shapers.
It’s not just the outline of the tail, but how it’s integrated with the bottom contours, and to a centain extent the fin set up and tail rocker. A properly executed tail design is one that allows the bottom contour to smoothly flow out from. Vee is to allow a flat planing surface when the tail is leaning on one side during turns. As the Vee bottom runs out the tail, the points of a diamond or swallow outline are a natural termination. If it’s deeply Vee’d, then a swallow is best since in turns the board would almost be standing on the rail, and water flowing up the deck at the tail end will just go over one pin of the swallow and release. With fairly flat Vee, the rail is lower to the water in turns and a diamond would work better than a swallow since there isn’t as much water flowing up the deck. The diamond also has more area than a swallow which gives the tail more flotation. On a double-concave bottom, a bat or modified diamond is a good match. As the concaves get deeper (more like channels), they start impacting the fin set up not just in placement but also in fin height. On a single concave, the two points of a square tail matching the edges of the concave blend well.
For me, tail design is based on what kind of bottom was selected and the flow along the outline (rail shape). Bottom contour and rail shape are functions of the conditions the board will be used in and the tail design follows those. So, to say how each tail outline works is dependent on 75% of the rest of the board design and where it will be used.
I think diamonds… and other, similar rail-shortening tail shapes, transition rail to rail easier, too. So not only do you get that tighter turning radius (at the expense of drive) but you get a faster, easier transition back to the other rail. The feeling is closer to me to a round tail than a square or squash tail, except a round tail is a smoother “rolling” type feel, where as a diamond has a sort of “tippy” feel… quicker, and more sudden/sensitive, and less smooth, I guess.
As far as matching up tail outlines with bottom contours, I go either flat or slightly veed behind the trailing fin. Occasionally, I’ll do double barrels straight out the back. But I base tail shapes primarily on rail rocker, centerline rocker, and tail kick. Never really put the shape of bottom contours ahead of the trailing fin into consideration. Something to think about.