I have browsed the forum for info on this and found some good info. However, i still have some questions regarding some of the echnical aspects of shaping in a double concave to vee. I am shaping something roughly similar to a Rusty Happy Shovel, 6’6"x3"x23" with a 5-fin setup and rounded diamond tail. That board is flat entry to shallow double concave (only about 1/8" deep concaves with stringer maybe 1/16" deep) to shallow vee out the tail. After researches the benefits of each bottom shape, this actually sounds like a good setup for the use: high volume small wave board. If anyone wants to steer me away from that, go ahead. Here are my questions, hopefully in enough detail:
Starting from the nose:
going to start the double concave about 12" from the nose. Considering I will be going to a vee at the tail, do I cut in the double all the way to the tail exit, and THEN shape in the vee? Or do I transition from the double to the vee somewhere near the front fins. The biggest issue here is the stringer height in relation to rails. If I take the double all the way through the tail, my stringer will be just a bit higher than my rails. This would cause my tail rails to have to go even higher with the vee to take them above the stringer. If i stop the double concave before the fins and let the stinger drop back down to pre-contour height, then my tail rails dont need to come up as much to create the vee.
on the double concave, how wide should i take it rail to rail? blend it all the way to the rail? Or leave and inch or two of flat at the rail?
on the vee out the tail, I’ve read that flat after the tail fin provides a little more stability and lift. Should i take the vee all the way from the front fins and out the tail, or flatten it just after the trailing fin?
I shape rocker first, then vee then concaves. With this method if your copying a rocker from another board you have to compensate for any concaves on the stringer, as if the board had a flat bottom. As far as the design of the bottom just copy the board you’ve taken a fancy to.
Thanks for the input. I have the rocker where I want it now. So shape in the Vee, which I’m only going about an eighth of an inch up on the rails to get my V. I am planning to keep my stringer where it is currently. Then shape in my double concave and blend into the vee that I just shaped? As I do that, the stringer through the double concave will go a little higher then it is through the Vee. Does that sound right?
If you shape a double concave from a flat by just taking out foam each side of the stringer you end up with the stringer at the same height as the rails as it was when the bottom was flat. As the double moves into the vee the rail line falls away from the stringer line,(this was set when the vee was cut). Put another way double concaves don’t have to affect the relationship between the rail line and the stringer line. BUT often the double concave leads from a single concave so the stringer line will rise from where it would be if it were a continous single concave. Sometimes a double concaves stringer line will not rise as high as the rail line. If a double concaves stringer line rises higher than the rail line then thats a concave vee in my book and if i was shaping that the vee would already have been cut before the concave was put in . Others here may have a different take on shaping these details and may give you input - if your lucky.
A subtle inset double through the length can ride really well when there is a slight ruffle to clean waves, like what you get when there is a strong offshore. It seems to me that it cuts, funnels and shoots the ruffle and feels awesome. At the risk of sounding like sticking to mainstream norms, the single to double seems more user friendly in a variety of conditions. You can do as you say, shape in the ve at the tail and blend in the doubles. Just be mindful of any altering to the rocker in the tail rail area. My advise, for its limited worth, would be to keep it all subtle as it sounds you are, can’t go wrong. I tend to usually like my inset double starting just ahead of the fin cluster. You can see how it marries into it. Bare in mind this comes from the feelings of a surf craft rider and very inexperienced shaper. A lot of people love the speed and hold through turns a single concave can deliver, but I reckon subtle double to vee would be on the money for the dimensions you have shared. If your after something to deal with the chop and slop in small junky waves then a displacement hull as you describe could be ok but not sure how to approach this when you have already shaped your rocker, not knowing if you have your thickness and profile shaped in yet. Someone more experienced maybe able to help you out a bit more there.
Can you give me any benefits of single all the way thru and deepest at the front fins? I am assuming you are saying no vee, just single. Where do you recommended starting and ending it.
Thanks for the input guys. I was considering single to double to vee and went to look at a Lost board that I know has that setup. It wasn’t at the store anymore, but I did look again at the board I am more or less copying. I was able to get a better look (standing in the middle of the shop with a straight edge on the board!) and it actually goes from double to vee a little forward of the center of the board. It really only carries the double for about 24" then goes to shallow vee thru the tail. This may be a good option as the board is a grovler and I am widening it because I’m a big guy. Added vee may help turning edge to edge. Anyway, thanks for the input. We’ll see what I finally decide to do once I start sanding…
Rusty & Lost (MatB) are two different animals. Without giving too much away (and don’t ask how I know), you will find that the stringer and rail curve are identical in the Rusty double. I think it is important to know why you are doing the bottom adjustments that you are considering (aside from rocker curves). If you are a surfer that continually transitions from rail to rail, a double concave has certain benefits. Most guys surf a board flat (watch a lot of youtube vids) for a large proportion of the time, and this type of bottom may not be be the best for those guys/girls. Different models are designed to appeal to different types of surfers searching for the “magic” board. If you are just shaping for yourself, try all different combos until you find what works best for you. As far as the shaping goes, the double concave is to exit water thru the fins when the board is on rail. Cut the board (rails & stringer) flat first then dish in the concave. Do a mild concave the first time you do this. If you like the way it surfs, you can go deeper on the next one. Start around the front foot area so you don’t shape in anything that will bog the board down. Vee in this case is a little bit overboard, as if you carry the concave thru the fin area you are almost duplicating the effect of vee. (just my 2 c…) If you want to try vee, start with a flat bottom (which is the exact curve of the rail) then add vee in front of the the side fins out thru the tail. Spiral vee adds concave thru the panels of the vee/fins. Surf it and see what you like. If you have shaped flat bottomed boards of similar dims, then single concaves, then doubles, and then added vee to all of these bottoms, you will find what best works for you and what you like, and maybe, what’s best for the guys who might buy a board or 2! Just my 2 c…
So how do you know… Just kidding! I see what you are saying about the vee. But I guess one question would be why does Rusty throw a double and vee on this small wave board unless it’s a good contour for the use? (Maybe the answer is just personal preference and a specific board for a specific type of rider, ie rail to rail). I am on board with going subtle on my first go around and would be willing to nix the double to long vee if I still end up with a rideable board. Ideally I’m looking for something that will be a good small wave utility board for here in San diego. Would you agree with starting off with a shallow vee from tail to front fins, then add in a single concave (1/4-3/8" deep) to about the front foot, then flat to nose? Or am I being too stubborn on wanting to use vee in the tail? Also, I’ve seen it both ways, but is your preference shape the single then the vee, or vee then then single?
You’ve done the rocker first, which is appropriate. I put the doubles in first, and then the vee. I put the deepest part of the concaves between the side bites (I mostly shape thrusters) and where my back foot sets. Then I shape my vee, and I put the deepest part of the vee at the side bites and feather it forward and back. I usually flatten out my vee at the tail, as opposed to running it off the end. Many shapers have their own ideas, but mine works for me. The doubles make my boards squirt forward when I pump it, and the vee makes the rail to rail transition much quicker and more fluid. This image should help you conceptualize (for you-the tail part). I alternate between flat to double and single to double (as shown in the picture) depending on board type. In my experience, you’ve got to blend the contours well and do it in graduations (not extremes).
hey Matty thought u might show off those double barrel longboards and talk a little story about them too in this thread haha! I think if a design element or blend of elements works, it should be filed according to what it does, not tied to a time period, future, past, whatever. I’m more interested in how it affects the ride. Myself, just a backyarder learning as go, prefer a flat through the middle, regardless of what the nose is doing, to a subtle double channel v in back, usually flattening back out as it exits. I’m not a rail to rail type surfer, a lot of my wave time is just trimming, with a few turns thrown in for mild entertainment, lol.
I’m not looking to revolutionize the surfing industry with new and innovative bottom contours on my first surfboard shaped in my living room. I think I’m looking more for tried and true.
Don, I like to get the rocker perfect with a flat bottom and then cut the single in. Doing like you suggest and starting at the front foot and cutting toward the tail should produce what you are looking for. I always cut in the vee last. I do like vee in thrusters for most riders. If you are a blow-tail guy, you might be able to tell the diff from a flat tail. Make all your cuts shallow for the first time and blend in the concave from the stringer out to the bottom rail band. Any dips or humps that you might have won’t hurt the performance that way. I don’t do my vee past the front of the front fins. Set your fins at 7 degrees cant if you go with the vee to keep your variables down. Rusty shapes bottoms in his models to give customers variety. Studying his boards is not a bad way to go, trust me! Anyway, the first pic is of a band to band concave and the second is of tail vee in a quad fish. Hope they help. Just my 2c…
Ha ha thanks Huck. Yup, married with a baby on the way. Need to get this thing done before the baby shows up. It’s tough living in a condo with no garage or outdoor space. Gotta make due. She has been ok so far. I’m doing a lot of vacuuming… She only gets tired of the sanding sound, and me not paying attention to her :)
