My latest board is working awesome for me, but i never stop thinking of things that might make it better. It is made from 1/2" marine ply, no rocker and has square rails ( yeah you can tell how much time I put into this ). I have checked out Xylem Surfboards and their boards are made out of paulownia wood, using rolled bottoms. The rails are 3/8" inch thick with the center of the board being between 3/4" and 1 1/2" thick.
Using the same outline as my current board, what differences could I expect from the difference in wood as well as the rolled bottom instead of a flat bottom?
flat is the fasted you are going to get. the type of wood does not matter so much some wood floats better then other but I have made them out of oak to balsa some times the heavy one have more momentem when they get going in other words they sh*t and get, but you don't want to get konked by it.
Paulownia will float a little higher and be lighter then most ply.
As Mike said, flat is fast; rolled bottoms will be slower but more manueverable.
I have two boards made with Paulownia, both less then 3/4" but they are long/thin alaia type sticks.
I looked at the xylem boards and they appear to be more bodyboard styled. (no flex)
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?
I asked Josh Klein from Xylem and this was his response:
Hey, good to hear from you. I find the rolled bottom helps to hold the board in steeper waves.
The water flowing under the board causes a slight suction which happens to pull the board into
the wave just enough to keep the rail biting the face or under the surface. So the bottom roll helps to
keep the rail buried so the rail can do it's job. The roll also allows more volume, which means more
boyancy. The ancient Hawaiians put roll in their boards too and they had hundreds of years to perfect it.
You should put a about 3/8" roll in a board and expiriment with it. I've expirimented a ton with concave, flat
boards and super rolled boards and the rolled is by far the best riding and it lets me keep a fine rail
no matter how thick the board needs to be. Hope This helps answer your question!
-Josh
work better too.
Volunteering at the SHF I've seen MANY original old Hawaiian boards from small paipo to monster olo's .
FWIW, All the boards I've seen with rolled bottoms have been in the ±100lb category.
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?
I too agree, or at least believe, that flat is the fastest when compared to rolled or concave bottoms. I can see where the rolled bottoms would help the board to turn easier. If the ancient boards were around the 100 lb category, then any and all help to turn those boards would be necessary.
I am not a fan of flex in a board, but I do love the shock absorption of wood. The type of wood being used for the board, I too do not see a difference other than strength and weight.
Josh mentions about a slight suction on a boards rolled bottom. What are the pros & cons of this?
There is an interesting little trick that illustrates how different shapes react with water.
Turn on the faucet so that the water is flowing evenly. Then hold a spoon loosely between two fingers so that the outward curved (convex) side is in the stream of water. Instead of being pushed away, the spoon will be drawn into the rushing water. Suction.
Turn the spoon the other way and notice how the water is pushed away and shoots out of the concave side.
Bernoulli!
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?
I use a nominal amount of rocker in my boards -- not much because the forward part of the board is also a planning surface. Rail shape is also important in the nose so that the nose automatically wants to slice out for an easier recovery when some pearling occurs.
rodNDtube "Prone to ride"
I love my papa li`ili`i
"The sea doth wash away all human ills."
-- Euripides.
Does rail come into play very much when we are talking a 1/2" thick board? I just square them off mostly because I have no woodworking tools nor do I know how to use them. Also square rails are fast to make!
I don't know why this board keeps splintering, but it is the closest thing to my ultimate board yet. A day does not go by where at least one person comments about how fast it goes or just what is it and it looks like I am having a blast.
I noticed in the OP you said it was marine ply.
Most of the readily available marine ply is domestic or Canadian stuff made with Douglas Fir which is highly prone to splintering (and checking on the faces).
It's often glassed in final use.
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?
Interesting! The Home Depot stuff was furniture grade birch. It is too flexy for my likes. This stuff is much more stiff, but still absorbs the bump. If memory serves me right, it is Douglas Fir. Is that a bad wood choice for a paipo?
Lots of the old plank boards were a combination of Redwood and Doug Fir and/or White Pine.
The Doug Fir was almost always used as stringers so there was no worries about splinters on the rails.
It's often used in boat building due to it's good strength to weight ratio and it's fairly high rot resistance.
The main problem with Doug Fir is the fact it can be difficult to sand and it's tendency to split and splinter.
So as far as building paipo with Doug Fir lumber or plywood, It's better then some but not as good as many.
). I have checked out Xylem Surfboards and their boards are made out of paulownia wood, using rolled bottoms. The rails are 3/8" inch thick with the center of the board being between 3/4" and 1 1/2" thick.
!