El Paipo Knee Machine 54
Find the complete article here from my paipo.
Thanks to Dr, Robert for this GREAT PIECE.
This is just a taste.
Newport Paipo Concave Vector
11. You've written that there are two definite things about a paipo: "edge control is a major thing in successful paipo and they work best on hollow, fast waves." What design features enhance speed in a paipo? How can you maximise speed when surfing a paipo?
Okay, a little side trip into physics plus a hiccup or two of Naval Architecture/Marine Engineering; A paipo is a relatively small planing surface. But it's loaded relatively heavily. By way of planing hull design, the more power you put to a planing hull (weights remaining constant ) the more lift you get per unit area.
Now, taking that along, the paipo (and its cousin the kneeboard) have a theoreticly higher top speed (I'll oversimplify with 'lower surface area = less friction = higher top speed'), but also a higher stall speed, that is the speed at which the small planing area fails to generate enough lift for the thing to plane at all.
So, what I said was that hollow, fast waves are pretty much a necessity for paipos (and kneeboards) and that you need good edge control. Going back to the power required to push the paipo at a plane: what you have is pretty much MG * sinW, where MG is the mass of the board-rider unit multiplied by gravity and that in turn multiplied by the sine of the angle the board-rider unit are headed down: the wave face, which I have called W. The component of power produced by the motion of the wave itself is pretty much something that can be ignored.
Vertical wave face? Sin W goes to 1, maximum power and thus maximum speed. Bare roller-type swells, sin W is pretty low, no power available and the paipo won't go.
Okay, but... you can't just be going straight down the wave. Instead, you're at an angle along the wave face. The steeper the better, for maximum power available and thus maximum speed..... and maximum fun. But, to hold that edge skittering along a near-vertical wave face, you gotta have an edge that will hold. The thick round-railed Dextras, Hansens and their ilk wouldn't do it, but plywood will, or a thin down-railed edge on a well made foam paipo (or kneeboard) like the Newport Paipos. And, as I recall, the El Paipos were not nearly as sophisticated that way as the Newports, at least not early on. Romo would know better than me.
12. What are your thoughts about flex in paipo, kneeboards and mats?
I think it's a very good idea and where the bodyboard people lost sight of what made the original Morey Boogies such successful surfcraft.
Rocker, on a non-flexing board, is always a compromise. The bottom doesn't conform to the water surface of the wave when planing, at least not entirely, so drag goes up. Kind of like how the Space Shuttle or other lifting-body aircraft come in at low speed, the angle of attack is kinda high, trading off drag for increased lift.
On the other hand, a flexible bottom kneeboard...or paipo, or mat, it conforms to the curved water surface of the wave face, lowering drag considerably. In a hard turn, you're not dragging a stick through the water for all intents and purposes, you're using something that flexes into the turn, conforming to the waterflow much better and losing less energy in that turn. 'Cos in a turn on a surfcraft, you are trading off momentum and speed as you turn, until you pick up a new line down the wave and start accelerating again.
Now, I should also say that this and the 'edge control and wave power' things that preceded it are massive oversimplifications. They'll do as short explanations, but the reality of it is much more complex.
13. You've said fins cause drag what design features might compensate for this in a bellyboard/paipo?
Well, minimize the fins, anyhow. Terry Hendricks has said (and I agree) that fins are not especially necessary in a paipo, it can all be done with the rails. There have been a whole lot of very successful paipos that were no more than pieces of finless plywood, held on down the line by the edges.
14. What are your thoughts about buoyancy and paipo performance?
Uhmmm - to paraphrase the Borg, 'Buoyancy is Futile.' The idea of the paipo is, really, to be a better planing area than bodysurfing. But with the same intimacy and more speed, controllability and to allow more of the wave to be used than you could with just the rather oddly shaped human body as a planing surface. At least that's my take on the essence of using a paipo.
But, if you're working that tight to the steepest part of a wave, buoyancy can be a hindrance. You need to go deep fast and easy. Catching waves very steep/very late, well, buoyancy doesn't help.
15. Hulls, mini-Simmons and paipo? Any comments?
Uhmmmm - bear in mind that I am a half-assed, incompletely trained Naval Architect/Marine Engineer, so I have Opinions......
Hulls...ain't any more or less hulls than board with flat bottoms or concave bottoms. What they are is convex planing surfaces, like the 'skimming dish' sailboats of times past. Can they be used profitably as paipos? Sure, though as the angle of bottom to edge changes you have less edge holding ability and this in turn detracts from the function of the thing.
Mini-Simmons - I'll confess that I don't know much about these beyond thinking that Simmons himself might have disowned them. Simmons was an interesting cat, Caltech -trained, he was the kind of guy who studied and Did the Math. Unlike Greenough, but very much like that other Caltech-trained innovator, Terry Hendricks. An iconoclast, if he'd been around twenty years later it might have been him and not Greenough who was the kneeboard ideal. I am pretty certain that Simmons wouldn't be going backwards, he'd be tank testing things with damned clever gear.
Paipos... should have as little to do as possible with mainstream surfboard design theory. First off, most of mainstream surf theory is akin to astrology in its relationship to real science and engineering. Next, paipos ain't the same thing as a surfboard. They plane differently, weight loading and accelerations are different, turning/controlling 'em is different. Paipos cannot and should not follow surfboards, it should be the other way around.
16. By weight loading - do you mean the weight distribution of the surfer? Can you to elaborate on your comment regarding the difference between paipo and surfboard design?
Let's see- yes, that plus how weight transfer is used for turning and what have you. Consider a surfboard with the sort of usable flex that you'd get on a flex paipo or kneeboard. First time somebody stood on it, it'd turn into a banana or more like a "U". Surfboards have effectively single point loads.
The center of mass of a surfboard-surfer unit is up pretty high, so that the inertia and momentum are centered higher too. Might be able to put more force into a turn... if someone had amazing traction and very strong ankles.... but there's drawbacks. The pivoting forces that a stand-up can use are not present in paipos at all and to a much lesser degree in kneeboards.
17. Also, is there anything more that you want to say about paipo design theory, especially in relation to the factors you mention in the above quote?
If you go with a paipo that's a scaled down surfboard, well, it's essentially like the old Dextra paipos, a horribly inefficient way of prone riding. On the other hand, take my old steed, the Concave Vector - note the rails, note how the planing surface does no more and no less than give optimal planing.
Whole article here........
His website.....
El Paipo Knee Machine 54
Find the complete article here from my paipo.
Thanks to Dr, Robert for this GREAT PIECE.
This is just a taste.
Newport Paipo Concave Vector
11. You've written that there are two definite things about a paipo: "edge control is a major thing in successful paipo and they work best on hollow, fast waves." What design features enhance speed in a paipo? How can you maximise speed when surfing a paipo?
Okay, a little side trip into physics plus a hiccup or two of Naval Architecture/Marine Engineering; A paipo is a relatively small planing surface. But it's loaded relatively heavily. By way of planing hull design, the more power you put to a planing hull (weights remaining constant ) the more lift you get per unit area.
Now, taking that along, the paipo (and its cousin the kneeboard) have a theoreticly higher top speed (I'll oversimplify with 'lower surface area = less friction = higher top speed'), but also a higher stall speed, that is the speed at which the small planing area fails to generate enough lift for the thing to plane at all.
So, what I said was that hollow, fast waves are pretty much a necessity for paipos (and kneeboards) and that you need good edge control. Going back to the power required to push the paipo at a plane: what you have is pretty much MG * sinW, where MG is the mass of the board-rider unit multiplied by gravity and that in turn multiplied by the sine of the angle the board-rider unit are headed down: the wave face, which I have called W. The component of power produced by the motion of the wave itself is pretty much something that can be ignored.
Vertical wave face? Sin W goes to 1, maximum power and thus maximum speed. Bare roller-type swells, sin W is pretty low, no power available and the paipo won't go.
Okay, but... you can't just be going straight down the wave. Instead, you're at an angle along the wave face. The steeper the better, for maximum power available and thus maximum speed..... and maximum fun. But, to hold that edge skittering along a near-vertical wave face, you gotta have an edge that will hold. The thick round-railed Dextras, Hansens and their ilk wouldn't do it, but plywood will, or a thin down-railed edge on a well made foam paipo (or kneeboard) like the Newport Paipos. And, as I recall, the El Paipos were not nearly as sophisticated that way as the Newports, at least not early on. Romo would know better than me.
12. What are your thoughts about flex in paipo, kneeboards and mats?
I think it's a very good idea and where the bodyboard people lost sight of what made the original Morey Boogies such successful surfcraft.
Rocker, on a non-flexing board, is always a compromise. The bottom doesn't conform to the water surface of the wave when planing, at least not entirely, so drag goes up. Kind of like how the Space Shuttle or other lifting-body aircraft come in at low speed, the angle of attack is kinda high, trading off drag for increased lift.
On the other hand, a flexible bottom kneeboard...or paipo, or mat, it conforms to the curved water surface of the wave face, lowering drag considerably. In a hard turn, you're not dragging a stick through the water for all intents and purposes, you're using something that flexes into the turn, conforming to the waterflow much better and losing less energy in that turn. 'Cos in a turn on a surfcraft, you are trading off momentum and speed as you turn, until you pick up a new line down the wave and start accelerating again.
Now, I should also say that this and the 'edge control and wave power' things that preceded it are massive oversimplifications. They'll do as short explanations, but the reality of it is much more complex.
13. You've said fins cause drag what design features might compensate for this in a bellyboard/paipo?
Well, minimize the fins, anyhow. Terry Hendricks has said (and I agree) that fins are not especially necessary in a paipo, it can all be done with the rails. There have been a whole lot of very successful paipos that were no more than pieces of finless plywood, held on down the line by the edges.
14. What are your thoughts about buoyancy and paipo performance?
Uhmmm - to paraphrase the Borg, 'Buoyancy is Futile.' The idea of the paipo is, really, to be a better planing area than bodysurfing. But with the same intimacy and more speed, controllability and to allow more of the wave to be used than you could with just the rather oddly shaped human body as a planing surface. At least that's my take on the essence of using a paipo.
But, if you're working that tight to the steepest part of a wave, buoyancy can be a hindrance. You need to go deep fast and easy. Catching waves very steep/very late, well, buoyancy doesn't help.
15. Hulls, mini-Simmons and paipo? Any comments?
Uhmmmm - bear in mind that I am a half-assed, incompletely trained Naval Architect/Marine Engineer, so I have Opinions......
Hulls...ain't any more or less hulls than board with flat bottoms or concave bottoms. What they are is convex planing surfaces, like the 'skimming dish' sailboats of times past. Can they be used profitably as paipos? Sure, though as the angle of bottom to edge changes you have less edge holding ability and this in turn detracts from the function of the thing.
Mini-Simmons - I'll confess that I don't know much about these beyond thinking that Simmons himself might have disowned them. Simmons was an interesting cat, Caltech -trained, he was the kind of guy who studied and Did the Math. Unlike Greenough, but very much like that other Caltech-trained innovator, Terry Hendricks. An iconoclast, if he'd been around twenty years later it might have been him and not Greenough who was the kneeboard ideal. I am pretty certain that Simmons wouldn't be going backwards, he'd be tank testing things with damned clever gear.
Paipos... should have as little to do as possible with mainstream surfboard design theory. First off, most of mainstream surf theory is akin to astrology in its relationship to real science and engineering. Next, paipos ain't the same thing as a surfboard. They plane differently, weight loading and accelerations are different, turning/controlling 'em is different. Paipos cannot and should not follow surfboards, it should be the other way around.
16. By weight loading - do you mean the weight distribution of the surfer? Can you to elaborate on your comment regarding the difference between paipo and surfboard design?
Let's see- yes, that plus how weight transfer is used for turning and what have you. Consider a surfboard with the sort of usable flex that you'd get on a flex paipo or kneeboard. First time somebody stood on it, it'd turn into a banana or more like a "U". Surfboards have effectively single point loads.
The center of mass of a surfboard-surfer unit is up pretty high, so that the inertia and momentum are centered higher too. Might be able to put more force into a turn... if someone had amazing traction and very strong ankles.... but there's drawbacks. The pivoting forces that a stand-up can use are not present in paipos at all and to a much lesser degree in kneeboards.
17. Also, is there anything more that you want to say about paipo design theory, especially in relation to the factors you mention in the above quote?
If you go with a paipo that's a scaled down surfboard, well, it's essentially like the old Dextra paipos, a horribly inefficient way of prone riding. On the other hand, take my old steed, the Concave Vector - note the rails, note how the planing surface does no more and no less than give optimal planing.
Whole article here........
His website.....
