Before this post, I have spent the better part of the past hour searching threads, but I can’t find an explanation to why boards chatter. Particularly, I shaped my 3rd board, a 5’9" McKee based quad, 20" x 2.5" and kept the volume out most of the way to a down rail with fairly hard bottom (fred tooled the bottom rail, about 3/8" up to the apex). Flat bottom, slight vee w/ double concave starting in front of fins. Paddles great, makes every wave I go for. However, it chatters like crazy. Almost feels like it’s about to become a skipping rock. I can take off as late as I like and make the drop no sweat, but if the waves are overhead as they’ve been lately, once I hit the bottom turn I’m lucky if I make it, and if I do, I usually start chattering and almost bouncing back from rail to rail trying to recover. What gives? This has never happened to me before. The rails are pretty beefy, and I’m wondering maybe they are too bouyant for me to hold the rail engaged, and thus they skip in and out causing the chatter? Are my fins to small? Can I compensate for the beef in the rails with a stiffer or bigger fin? There is a heck of a lot I don’t fully understand about surfboards after surfing boards that were shaped for me for the past 20 years and my building them is an attempt to learn, but the mechanics of the thing aren’t always obvious.
Chattering is not a common term used to describe surfboard behavior, so I am trying to understand what you are describing. Are you refering to a vibration or hum in the board? Are you refering to a sliding motion the board makes during the bottom turn? Are you feeling a sliding motion when coming out of the bottom turn? You said the board is “bouncing back from rail to rail”. Any of these general types of surfboard behavior has a somewhat specific origin in board/fin design. I am curious why you are making a 5’9" with mckee ratios as this is not common for quads in this short of a length. Also, you didn’t mention where you are at and what type of waves you are riding, a very important point for designing a good board that works the best in your waves. In general terms and based on what you are saying, & without pictures of the board, I would gently surmize that your problem may be fin oriented. If you have a reasonable outline, reasonable thickness foil, reasonable rail profile, the way new board creators go wrong in is fin selection/placement. I have also retrofitted boards from the Big 3 where the fins were off in location, canted wrong, toed wrong, etc… from side to side or from front to back, you name it, I’ve seen it. All of these conditions create a board that does not perform as is expected. I’m sure that a lot of Sways guys would like to help, please post pics if you can & be a bit more specific in what the board is doing as you surf it. Just my 2c & trying to help…
I’m guessing that by “chatter” you mean your rail won’t stay engaged or buried when you lean into a turn?
While others are on the right track regarding the actual rail volume and profile, I would suggest you move your front foot a bit forward and put more weight on it.
EPS is more notorious for feeling the effects of chop or surface texture as you’re plowing over it. One of PU’s redeeming features is its vibration damping.
The few non PU boards I’ve tried were Surftech longboards that belong to friends. Two that I recall were a Takayama and a Velzy design. Both felt odd. Springy, bouncy, too much flex. I’ll stick with PU/PE, thanks.
@ chrisp: Yeah, I’m pretty much a full epoxy convert at this point, and figure cork has to improve this issue big time.
The OP still hasn’t told us what kind of blank it is, but I just know I’ve felt this myself (on a surftech that I otherwise loved) and heard others comment on it as well.
Thank you so much for offering to help. I’ll upload a pic I have on my phone for outline, but I’ve left town for a couple days and won’t be able to take any rail pics. As for chatter, I mean when I bottom turn, the board feels like a rock skipping across a lake. I can’t keep the rail engaged after making it to the bottom. It paddles extremely well, takes off as late or early as I want, but the faster I go, the more I skip. As if there is a lot of wind chop on the surface even though the waves were glassy. Sometimes I can recover, but as I mentioned this can result in me bouncing from rail to rail, as the second the board is flat to the face between rails it really starts to lift off. Bottom turns tend to spin out from the back slamming me face first into the wave.
I would like to believe the outline is reasonable, though I designed it myself with a nod to a 5’10" I love for larger, hollower days. The rail is as best I could copy off another board I like for the average smaller surf I get in New York (3-4’ at 8-10 seconds). I wanted an everyday board with a smaller looser tail than the wider quads I generally surf. The McKee setup was an attempt to force myself out of the box I tend to surf in (generally long drawn out turns on singlefins or when I want a little more speed with the same flow, rail finned quads. I generally don’t enjoy thrusters.)
And a note about my experience on the board: while I did intend it for shorter period average surf, the first chance I’ve had to surf it is while visiting back home in San Diego this past week at a couple reefs which were decidedly not 3’-4’, nor 8-10 seconds, but a whole lot of fun none the less. However, I’ve definitely pushed other boards I’ve had in larger than designed for conditions and not had this chattering issue, so I figure I’ve made a poorly designed board and I really appreciate any insight people with more understanding may be able to offer.
I’ll have to wait to get you rail pics as I’m out of town, but yes, generally tucked rounded edge. Top rail profile lets say about 45 degrees. Copied from another small wave board I have, fairly close. But I’ve had that board in head high waves and not had this problem. However, never had it in a period over 12sec, if that matters, and I believe the last swell I surfed the new board was closer to 18 sec, which is a big difference. Is that it? The board was overpowered?
Just looking at your pics, that looks like a lot of fin for that size board. Your NY waves should be similar to back home in SD, so I would advise you to post up what your fins are & the layout you used. In a functional quad, too much fin can translate into a feedback of every little bump in the wave and more of a tail drag and no drive. I normally use a standard quad set with a rail set instead of mckee if the board is under 5’10. Your board doesn’t look out of proportion. I am concerned with the toe-in on the back fins. It should be around 2" off the nose and it looks like you have quite a bit more. Without exact numbers, it’s kinda hard to know what you have. I would suggest if you have a set of small double foiled fins, you put those in the back and see what you have. The fronts should be a normal 4.5" base single foil fin in this config. Just my 2c…, you really need to play with the fins to see what you have a be very exact on your fin layout. I’m going to be posting a couple of pics on the asym thread, so you might want to look at those layouts even though they are on fins style boards. Ain’t this fun? LOL
Wow ok, thanks. I was thinking maybe the fins were too small and thats why I couldn’t grab. As for exact placement, I did the best I could at my current skill level to follow the specs on the McKee chart. The camera is at a bit of an angle to the board because I was having reflection issues in the gloss, so maybe the antle is distorting the appearance of toe in. I’ve attatched a pic of the fins I used, maybe when I get back to SD later this week I’ll hunt around for a smaller set of rears, it looks like the swell in the coming days will be significantly smaller, but if I line up a new fin set and manage to find some decent conditions I’ll report back. In the mean time, here is a pic of the fins I used (mine are futures) single foil front, double rear. Specs as previoiusly indicated.
For what its worth, I have had a similar problem with a board I have.
It is a 6’2" shortboard with thrusters with a really flat bottom, alot of foam, and thickish rails with hard tuck, as chrisp mentioned. It is pu/pe also, and has a lightish glass job.
The board is really good in small waves. I had taken it out in some overhead+, and I had the same problems as you mentioned.
I could get in real early, on some waves but when I picked up speed it chattered so much it actually hurt my ankles. It kinda felt like running a boat with a flat bottom in the open ocean. I don’t surf perfect conditions, and normally surf waves with a bit of texture.
Other waves where the drop was a bit, I would consistently miss about 3 waves a session, where I couldn’t set a rail right if I took too steep of a drop, and the board would just kinda wobble under my feet. I am not a great surfer, but it is a spot I surf a fair amount, and I normally would say it was me not the board, but it this time it was definitely the board.
Without more pictures, I would say as above, it is a combination of ,
alot of foam, flat rocker, hard tuck, and probably a little wide.
I am definitely curious if you can get it to work better with some bigger fins. I just wrote my board off as a small wave board.
This is all of interest to me - I have and ride several boards with a lot of volume, wide with fat down rails with a tuck. (all of them polyurethane foam, ‘tho) Not exactly flat bottoms, but all my bottom shapes are pretty subtle, so not all that far from flat either. My boards are much bigger than those described. So far I haven’t had any issues in up to 6’ surf, but I’m gonna try and pay special attention to see if I can notice anything like this going on. Sounds like it might be an issue just in larger waves than I generally surf. When I used to surf more in overhead waves, I can recall getting bounced off my board on the way down the face. IMO in bigger surf surface irregularities on the wave face are really magnified in their affect on the surfboard. I’m guessing this is one of the advantages of the single concave in bigger waves.
All things being equal, it looks like you have a ton of outline curve in that board, and so when you are on rail, you are on very little rail due to the curve. Compound this with a more bouyant rail and you have even less rail engaged in the water. The widepoint is also really far forward, and with such a curvy rail behind it, it looks like it would be really hard, if not impossible to engage enough rail to get that board to work. Your front foot is probably behind the wide point, which is probably compounding the problem (as Sammy mentioned). You could put your weight and front foot further forward and it might improve things a bit but in general it looks like a wonky shape (no offense, I know you are early in the shaping game). Make another…
Based on your description of the board; Your problem is the the bottom shape/foil. Playing with the fins as mentioned may improve the ride. You will be toying with fins to compensate for a mis-shaped bottom.
