bogging rails in turns, what causes it, how to prevent it?

had a couple of surfs on a new board i made, and although it goes well for the most part, I found myself bogging on my heal side rail when doing cutties this arvo. now the surf was pretty gutless, and the shoulders fat, so this would have factored into the problem, as it wasn't as bad when i rode it in slightly bigger waves. a little bit about the board. it's a 5'7 x 20 x 2 5/8 diamond tail, wide point forward, pretty thick foil with a fair bit of volume carried all the way to the tail and also the nose. Also has a pretty flat rocker.

So afterwards I was thinking what design issues specifically would cause a rail to bog in turns like this? what are some ways to avoid it?

During the late 70’s, early eighties in Florida, Kurt Wilson was my main rider/designer, he went on the east coast pro tour with Rabbit, Mark Warren, Dane Kealoha, Critter Byrne, Buzzy Kerbox.

Up to then, wide spots were ahead of center, but when he got back at the end of summer, he had me pull back the WP to center.

Mark Warren was riding McCoy shaped boards, with full boxy rails and more rocker, these were working well in the small contest venue waves.  Clark had a 7’0" McCoy blank out at the time, so I immediately ordered 40 of them, Dick Morales questioned whether I really was going to use them or have them clog up the warehouse in Florida.

They boards worked very well in cleaner waves with a wall, but in contests, you get what you see, the increased rocker was NOT letting Kurt get through dead spots, where the competitors could glide through the flats.

Kurt drew up a new rocker, flattening the tail dramatically, the board bit donkey sack so much, as soon as you were to get on your feet and applied any rail to the wave, it was like something grabbed you and wouldn’t let go, the result was usually a face plant.

I had built polypro plugs for my own removable fin system and kept routing in new boxes and test riding over and over, it became what could be deemed ridable only when the fin angles became very cross eyed, intersecting far behind the tip of the nose, but the board rode flat and not on the rail at all, after that it was back to full bore rockers again and the problem went away. Rockerless tail = straight lines and rail digs

both of the above posters are far more knowledgeable than i but, i had this problem with one of my first boards and, adding a sharp tucked edge nose to tail pretty much fixed it…

Could be any one of a number of things… or any combination…

My initial thoughts are trying to do too tight a turn on a too small/weak a wave on a board with not enough rocker. Flatter boards tend to push water if you just lay into the turn too hard with not enough speed… trying to bury the rail on a flat board at slow speed is difficult to maintain speed through the turn… unless you’re riding on one big fat keel on a fish or something… A little more curve in the entry, or a little bit thinner foil (to get some flex going), or even a touch of vee in the nose can help. Also consider how your weight is distributed through the turn. Too much weight forward?

Other stuff like outline, fin setup, rail foil… play a significant role too.

Hi Jim,  Not hijacking just paying respect.  Have'nt heard Dick Morales' name in a long time.  He was a fine person and always willing to go the extra mile at Clark.  R.I.P. Dick.  Thankyou.

thanks for the input guys. I suspect that the problerm with this particular board is that the rails blend from hard to round too quickly, and are too rounded from the mid point forward, along with a relatively flat rockered tail. will keep it in mind for the next build.

When Sean Mattison was at Surf Ride, he had gotten an M10 demo board, the tail rails to the front of the side fins were square and very vertical, but coming to an abrupt rounding within 6 ", it had the same type of problems in turning, did nothing, then went spastic.

I had my first EPS performance longboard, longbox + FCS, put a set of Rusty G5’s for side fins, it did the same kind of crap, gouged, gagged, in to the bottom, then went into a kick out, there was no transition between the 2 actions, I could push it tail slide style through a cut back.

I had used one of Danny Dolphins pre-molded blanks and took all the thickness off the bottom, it is like the Marco blanks, with a nearly finished rail.

The blanks was super thick, so when I took an inch out of the bottom, it put me very high in to the rail crown and the blanks are close to finish width, the result was a wafer thin rail.

I thought the too thin rail was my problem, Greg Loehr came by to see me and I told and showed him the board, he took one look and said he thought the side fins were too big. I made a set of micro’s that would fit in one FCS plug, magic board instantly. 

Just made the mistake of trying to sneak behind Val’s reef on an upcoming swell on it, 2 piece board

you don’t have to wait 'til your next board Pirate, you can add an edge on the current one… just sand, tape a dam, add some resin, then sand / shape your edge… worked for me

If you check out the recent topic on McCoy design videos on his website , it will give you some food for thought....

There was a post a few years ago where guys discussed using wax and other malleable materials to re-shape rails on finished boards to check out theories prior to hacking and reglassing.

Taylor-O used some epoxy putty to do just that

first thing i might try some smaller fins, currently running 7 size sides with a smaller trailer. might throw on some 5 s as a thruster. if it's still boggy, then will try the rail mod and see how it goes.



In "Official Speed Test" thread Bill Barnfield has the following to say. Some of which may add to the discussion here in this thread.

"It might be more accurate to say that really good surfers are constantly moving in and out of the primary power pocket where the most amount of energy can be gained.  As they absorb more power they use it to move out onto areas of the wave where there is less available power but much more space to do entertaining things.  As their absorbed power begins to run out, they must move back into the primary power pocket to compile more energy again.  They don't necessarily have to slow down to get back there.

Sometimes a wave will present a power pocket that is out in front of the surfer (sections and bowls) and he can move forward to access it instead of returning back to the power pocket behind him.  

Many people think that things like cutbacks are a speed reducing maneuver and surely they can be if utilized incorrectly. Inexperienced surfers slow down to do maneuvers because they need collect their wits to feel in control before doing them.  This is one of the two primary reasons why inexperienced surfers catch their outside rail, when doing top turns.  They simply run out of speed and energy in the middle of the turn because they don't begin the turn early enough.  They tend to wait too long after the bottom turn when they slow down a bit to therefore feel more in control and comfortable doing the top turn.  Which in the end fails them.  Many blame this on rail shape or hard edges, but that is rarely the problem.  But it is near impossible to convince people otherwise.  Just ask Griffin, he knows.  Hard edges are a hard sell almost 100% due to this misconception.

On the other hand...... Experienced surfers stack maneuvers gaining speed or compiling energy with each maneuver.  They move to each new maneuver at the absolute peak of energy and speed generated from the previous maneuver.  The don't wait for the pause like inexperienced surfers do.  That pause is their enemy, not their friend.

Truly there are ways to slow down when surfing and times when it is effective.  I hope you don't think I am saying that surfers never slow down from time to time.  As surely they do.  But how this feels and looks may sometimes not tell the true story of what it happening based on a speedometer or GPS reading.

A cut back should be a way to gain more speed and power.  Not lose it.  If it is executed at the top of the wave and usually it is, then the greater height should allow huge acceleration on the descent.  And even though one seems to be heading the opposite direction from going down the line, this seemingly "backwards motion" doesn't mean it is or has to be done more slowly.  

Even a stall accelerates one's rise up the face of the wave.  It might seem slower or like one is slowing down on the horizontal plane but it is an acceleration on the vertical plane.  It is a big mistake to always think of speed as only being valid when going forward down the length of the wave. "- Bill Barnfield