Hey I was riding my new shortboard this week and it's a little undersized for me I'm 6'3 145lb and my board is 6'3" x 18 1/2 x 2 1/2 but every time I seem to grab a nice wave I can immediately turn and ride closer to the top of the wave or I can go down the wave and go for a bottom turn causing my rail to dig in and I lose speed and bail. How do I fix that?
For a frontside wave, if you are catching your inside or toeside rail, transfer more weight to your back foot. This can be done be simply pointing your lead arm up to the spot on the lip you would like to hit. By raising your lead arm you will naturally transfer weight to your back foot and pull the nose/rail out of the water. Good Luck.
It's not necessarily the width at the wide point, but how far it carries that width towards the nose, tail, where the mid-point is, etc.
6'3" @ 145? Hello growth spurt!
Man, I think you're just trying to ride a HPSB in waves you should be riding something with more width and volume. It sounds like you're not getting enough planing speed to carry your momentum through the turn--it's more like you are bogging the rails instead of catching a rail.
For instance: I'm 6'3" @ 170.
My semi-gun is a 6'6" x 18.25 x 2.25 and has less volume than any of my other short boards. I can't ride the thing in anything less than head high and forget it if it's mushburgers no matter how big it is. The board is magic in the right waves, though.
My step-up is 6'3" x 19 x 2.33 but I can ride it in waist-high surf if I have to (which I have been forced to do the past week because I cracked the rail on my Coil daily driver), it can just be frustrating because the rails are so foiled and will give that sticky/boggy feeling. There isn't much room for error in smaller waves because of this, so I guess it's good practice.
My Daily Driver is a Coil Wider Widerboard: 5'10" x 19.75 x 2.37 (or something like that) and has the most volume. It carries the volume throughout the board and has softer rails than my other HPSB's, so it's way more forgiving--especially in the gutless stuff we get a majority of the year. This board maxes out when the waves get overhead unless it's glassy and throaty.
Moral to the story: The board you have is probably not good for you as a daily driver. Maybe try out some different fin combinations that might give you some more lift or size down to loosen it up. I think ultimately you need to be looking for something with more groveler characteristics.