Everything you need to know...

MrSteve

Nep status
Oct 1, 2015
573
61
28
NJ
Came across this. Nothing ground breaking, but thought it was interesting, for various reasons: https://www.surfertoday.com/surfing/everything-you-need-to-know-about-surfboard-design-and-performance

The Forces
1. More buoyancy means easier paddling above water;
2. The more area of the surfboard is in contact with the water, the more friction drag will exist and, the slower the surfboard will be;
3. The greater the rocker, the greater the drag force;
4. The greater the velocity or speed, the greater the lift;
5. Bottom shapes with concaves and channels produce an upward force or lift;
6. Wave faces flow and move in orbital fashion and create lift;
The Variables of Surfboard Shaping
1. More surfboard area means more planing potential, less sinking and bogging;
2. The elements of a template are total and half length, nose shape and width, outline curve, location of the wide point relative to the center, width, tail shape and width;
3. More curve in the outline means easier turning;
4. Longer boards provide faster paddling, greater risk of nose diving and more effort required in turning;
5. Wider surfboards plane better in dead or slow wave spots;
6. Wider boards turn easier at slow speeds but have poorer rail-to-rail transitions;
7. Wider templates have poor hold in the wave face at high speeds on rail;
8. Wider surfboards are stiffer;
9. Rounder noses provide more lift and buoyancy, but create form drag;
10. Pointed noses suffer less "baseball bat effect" and are easier to hold in rail turns;
11. Pin tail surfboards have extremely low surface area and high holding power;
12. Square tail surfboards have high planing area and looseness;
13. Thicker boards have greater buoyancy and have easier paddling;
14. More thickness in the middle of the board means difficulty to lean on rail;
15. Thicker tails are looser at slow speeds;
16. More rocker means easier turning, harder paddling, and slow speeds in a straight line;
17. More rocker means less nose diving;
18. Vee bottoms create less lift and are slower than flat bottoms in neutral position;
19. Vee bottoms allow for easier rail-to-rail transitions;
20. Single concaves create more lift and speed and are harder to turn;
21. Double concaves keep the rails free and are looser and faster;
22. Harder rails plane very well but have a stiff, less smooth response to turning;
23. Soft rails are slower but provide better hold in subtle turns;
24. Tucked under edge rails balance the characteristics of hard rails and soft rails;
25. Greater fin area means better holding power;
26. Streamlined fin foils have higher holding power;
27. Asymmetrical side fin foils provide better directional holding power;
28. Greater fin base length/rake resists lateral turning;
29. Greater fin height creates greater resistance to rail-to-rail turning;
30. Further forward fin placement will loosen up the board;
31. Further back fin placement will create more holding power and drive;
32. More space between the front and rear fins means more torque required for weaving;
33. Toed-in fins create more drag and are easier to turn;
34. Bigger fin cant/camber means looser turns;
The Construction Types and Techniques
1. Traditional construction includes solid timber and hollow wood. They are strong, but they are heavy;
2. Sandwich construction puts strength only where it is needed, and offers high strength relative to weight;
3. Conventional manufacturing is all about moulding a foam blank from polyurethane beads, hand shaping the pre-moulded foam blank, and applying fiberglass and resin by squeegee;
4. Shaping machines cut foam to a predetermined shape designed in a computer software;
The Core Materials
1. More weight means more force needed to accelerate and turn;
2. Greater density cores add more strength but are less flexible;
3. Foam core is roughly half the weight of a surfboard;
4. Balsa is five times heavier than foam;
5. Doubling core stiffness is doubling the strength, but the flex remains the same;
6. Increasing foam core density means increasing strength and weight;
7. Carbon fiber is two times stiffer, two times stronger, and only 1.1 heavier than glass;
8. S-glass and E-glass are three times more flexible than carbon fiber;
9. Extra layers of glass can triple the load capacity of a board;
10. Choosing epoxy over polyester resin has negligible impact on strength, stiffness, weight, but epoxy is more impact resistant;
 
Last edited:

Driftcoast

Michael Peterson status
Aug 5, 2002
2,558
58
48
Maybe there are only three tail designs: round, square, and fish.

All else is variations or combinations?

Then there is the rider.
 

everysurfer

Miki Dora status
Sep 9, 2013
4,890
674
113
Santa Barbara County
Came across this. Nothing ground breaking, but thought it was interesting, for various reasons: https://www.surfertoday.com/surfing/everything-you-need-to-know-about-surfboard-design-and-performance

The Forces
1. More buoyancy means easier paddling above water;
2. The more area of the surfboard is in contact with the water, the more friction drag will exist and, the slower the surfboard will be;
3. The greater the rocker, the greater the drag force;
4. The greater the velocity or speed, the greater the lift;
5. Bottom shapes with concaves and channels produce an upward force or lift;
6. Wave faces flow and move in orbital fashion and create lift;
The Variables of Surfboard Shaping
1. More surfboard area means more planing potential, less sinking and bogging;
2. The elements of a template are total and half length, nose shape and width, outline curve, location of the wide point relative to the center, width, tail shape and width;
3. More curve in the outline means easier turning;
4. Longer boards provide faster paddling, greater risk of nose diving and more effort required in turning;
5. Wider surfboards plane better in dead or slow wave spots;
6. Wider boards turn easier at slow speeds but have poorer rail-to-rail transitions;
7. Wider templates have poor hold in the wave face at high speeds on rail;
8. Wider surfboards are stiffer;
9. Rounder noses provide more lift and buoyancy, but create form drag;
10. Pointed noses suffer less "baseball bat effect" and are easier to hold in rail turns;
11. Pin tail surfboards have extremely low surface area and high holding power;
12. Square tail surfboards have high planing area and looseness;
13. Thicker boards have greater buoyancy and have easier paddling;
14. More thickness in the middle of the board means difficulty to lean on rail;
15. Thicker tails are looser at slow speeds;
16. More rocker means easier turning, harder paddling, and slow speeds in a straight line;
17. More rocker means less nose diving;
18. Vee bottoms create less lift and are slower than flat bottoms in neutral position;
19. Vee bottoms allow for easier rail-to-rail transitions;
20. Single concaves create more lift and speed and are harder to turn;
21. Double concaves keep the rails free and are looser and faster;
22. Harder rails plane very well but have a stiff, less smooth response to turning;
23. Soft rails are slower but provide better hold in subtle turns;
24. Tucked under edge rails balance the characteristics of hard rails and soft rails;
25. Greater fin area means better holding power;
26. Streamlined fin foils have higher holding power;
27. Asymmetrical side fin foils provide better directional holding power;
28. Greater fin base length/rake resists lateral turning;
29. Greater fin height creates greater resistance to rail-to-rail turning;
30. Further forward fin placement will loosen up the board;
31. Further back fin placement will create more holding power and drive;
32. More space between the front and rear fins means more torque required for weaving;
33. Toed-in fins create more drag and are easier to turn;
34. Bigger fin cant/camber means looser turns;
The Construction Types and Techniques
1. Traditional construction includes solid timber and hollow wood. They are strong, but they are heavy;
2. Sandwich construction puts strength only where it is needed, and offers high strength relative to weight;
3. Conventional manufacturing is all about moulding a foam blank from polyurethane beads, hand shaping the pre-moulded foam blank, and applying fiberglass and resin by squeegee;
4. Shaping machines cut foam to a predetermined shape designed in a computer software;
The Core Materials
1. More weight means more force needed to accelerate and turn;
2. Greater density cores add more strength but are less flexible;
3. Foam core is roughly half the weight of a surfboard;
4. Balsa is five times heavier than foam;
5. Doubling core stiffness is doubling the strength, but the flex remains the same;
6. Increasing foam core density means increasing strength and weight;
7. Carbon fiber is two times stiffer, two times stronger, and only 1.1 heavier than glass;
8. S-glass and E-glass are three times more flexible than carbon fiber;
9. Extra layers of glass can triple the load capacity of a board;
10. Choosing epoxy over polyester resin has negligible impact on strength, stiffness, weight, but epoxy is more impact resistant;
That looks like it was written by Swaylocks Stoneburner
 
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VonMeister

Tom Curren status
Apr 26, 2013
11,640
656
113
THE TERRORIST OF TERRAMAR
When I think of lift I think of the board riding higher in the water....and a single concave would provide the opposite of that. Catching water rising up the wave face makes sense short of, but hard rails would do that also and that lift would only be working when you were parallel with the wave at a sharp enough angle to create that condition.

I always thought single concave was for control.

I would say a flat bottom would provide the most hull lift, increasing with speed, where a single concave would flatten the center rocker, which would make passing over water more efficient, resulting in increased speed, except now you have the lower rails.

What's more efficient, more or less surface area in contact with the water?
 

Duffy LaCoronilla

Tom Curren status
Apr 27, 2016
12,778
1,631
113
Your mom�s house
When I think of lift I think of the board riding higher in the water....and a single concave would provide the opposite of that. Catching water rising up the wave face makes sense short of, but hard rails would do that also and that lift would only be working when you were parallel with the wave at a sharp enough angle to create that condition.

I always thought single concave was for control.

I would say a flat bottom would provide the most hull lift, increasing with speed, where a single concave would flatten the center rocker, which would make passing over water more efficient, resulting in increased speed, except now you have the lower rails.

What's more efficient, more or less surface area in contact with the water?
People seem to forget that boards aren’t ridden flat on water going straight. The direction of water flow under the board primarily on the back half of one side, diagonally from rail to center. That flow is also at an angle from the ocean surface you are riding on, like cutting a thin slice of cheese. The cut piece angles away from the cheese block as you slide the knife through.
 

everysurfer

Miki Dora status
Sep 9, 2013
4,890
674
113
Santa Barbara County
When I think of lift I think of the board riding higher in the water....and a single concave would provide the opposite of that. Catching water rising up the wave face makes sense short of, but hard rails would do that also and that lift would only be working when you were parallel with the wave at a sharp enough angle to create that condition.

I always thought single concave was for control.

I would say a flat bottom would provide the most hull lift, increasing with speed, where a single concave would flatten the center rocker, which would make passing over water more efficient, resulting in increased speed, except now you have the lower rails.

What's more efficient, more or less surface area in contact with the water?
Most stable, doesnt want to turn, but wont buck you off in chop is a panel vee or hull bottom. Curved stringer rocker, with straighter rail rocker.

Fastest top speed, steady acceleration, is flat bottom. Rail rocker matches stringer rocker.

Quickest acceleration is concave if you pump it. But it won't match the top speed of a flat bottom.

Easiest turning on a rail is concave. Straighter stringer rocker, with curved rail rocker.

Easiest to turn, but most unstable is a single concave All the way through.

My preferred blend is single concave to spiral vee( similar to single to double, but the spiral veeconcave reaches the tail railswhere a single to double keeps the tail double concave more within the rails.
 
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VonMeister

Tom Curren status
Apr 26, 2013
11,640
656
113
THE TERRORIST OF TERRAMAR
Disagree. A full V-bottom is the correct answer to both of these. They aren't speed demons though.
Depends on the rail line and what part of it is engaged. Equal V bottom from nose to tail would not turn appreciably better than any other bottom. Most V's on surfboards is a lifting of the nose or tail rail rocker from centerline, allowing the rider to access more of the rocker at the part of the board.

When I think of center single concave I feel to offset it you need additional rail rocker. For instance, it seems to me if you had two identical rocker boards, one flat, one single concave nose to tail, you would need to add even more rail rocker to get the single concave board to turn equally to the flat bottom
 
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GromsDad

Duke status
Jan 21, 2014
24,255
770
113
West of the Atlantic. East of the ICW.
A V-bottom shortboard turns in the pocket and goes vertical out of a bottom turn better than anything I've been on. Its a design rarely seen these days. The only stock board I am aware of using it is the Curren version of the CI Black Beauty.
 

GromsDad

Duke status
Jan 21, 2014
24,255
770
113
West of the Atlantic. East of the ICW.
Depends on the rail line and what part of it is engaged. Equal V bottom from nose to tail would not turn appreciably better than any other bottom. Most V's on surfboards is a lifting of the nose or tail rail rocker from centerline, allowing the rider to access more of the rocker at the part of the board.

When I think of center single concave I feel to offset it you need additional rail rocker. For instance, it seems to me if you had two identical rocker boards, one flat, one single concave nose to tail, you would need to add even more rail rocker to get the single concave board to turn equally to the flat bottom
As an experiment about 10 years ago I made myself two identical boards. Both were modern copies of my all time favorite board from the early 90s. One with a full V bottom and one with concave. Under my feet I preferred the V-bottom.
 

manbearpig

Duke status
May 11, 2009
16,657
532
113
in the bathroom
I’ve found deep singles to be best for turning. Just as Maurice cole describes and demonstrates it, when on an angle it creates an uninterrupted flat bottom for water to move across. Whereas going straight it gives the feeling of lift.
 
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