Round rails in the rear third?

How would making the rails rounded (reducing release) in the rear third of a board make it handle?

My assumptions:

- Plenty of hold

- Limited speed

- Slower turning


I’m designing a board with BoardCAD that has a wide nose and tail, and a narrower mid section for very parallel rails. I’d like to have a board that can line up in the power section of the wave and glide (preferably after a bottom turn) without speeding away too quickly. I like single fins, but since the tail is wide, to reduce slip I want to add two little stubby sidebite fins (this way, I could pivot the board for a little extra speed to make a section).

What do you think? Any advice?

I have a simm that only has a hard edge a couple inches in front of the keels and if your foot is not right over the fins/hard edge, it spins out very easily.


Closer to a longboard with 50/50 rails.

Line up the power section, and glide, without speeding away too quickly? 

Learn to stall.  Weight the inside back rail, and drag your hand in the face.


I like doing this, but I feel I need to be more towards the tail of the board. I love to ride up near the front third (feels like a freight train).

Generally speaking , you do need releasing edges through or behind the fin or fins , to allow some speed…

In my humble opinion, you are heading down the wrong path.  You are trying to slow down, and speed up from the same spot on the board (front third).  It just doesn’t work like that.  Weight in one orientation to slow down.  Weight differently to speed up.

Round rails in back will drag water, and the tail will get pulled up the face on a steeper wave.  You will be giving up rider control, and instead will end up with a board that is unresponsive, and goes where the water drags it.

Great for a stable noserider that stays where you put it.  But give up on high performance.

Or worse… you could try up rails on the tail. I love mine on the 10’

Horses for courses eh toaster…I love me soft-tail Pig !

Plenty of hold:  No, much less control unless you’ve got some kind of fin setup to compensate.   Limited speed:  Yes, if it’s a LB, you’ll be moving to the nose more.  Slower turns:  Yes, more drawn out.

All of this is effected by other factors.  You need to look at the total package when examining design.  Weighting the factors: (1) Rocker/bottom contour, (2) Fins, (3) Rails, (4) Outline.

If you've tried the 'spoon in faucet' trick you'd probably agree with Skip "Round bottoms suck - literally" Frye.

That said, there are plenty of round bottom, soft rail, kick tail, wide point aft 'Pig' aficionandos who today think Velzy was on to something.  Many pig style boards have big D/skeg type fins to counteract all the curvature in those tails and they work.  They fit the pocket well and allow sharp turns but do suffer from terminal velocity in certain situations.  I'm amazed to this day at the surfing that was being done during the filming of "The Endless Summer" by Mike Hynson and Robert August on pig style boards.

Like PeteC says, "You need to look at the total package when examining design."