thruster

thrusters make the bboard faster because they help hold line better, right? why else? thanks.

thrusters make the bboard faster because they help hold line better, > right? why else? thanks. Nope. Think about how thrusters are mounted, toed in toward the nose, and canted (cambered) out away from the stringer. Toe-in and camber are about 5 degrees on each fin, but mentally take toe-in and camber angles to 45 degrees. Such a board would pull lots of deep water from under the board and throw it upward and outward. In reaction the board would suck into the water and stop. Surfing in a striaght line, normal 5 degree thruster toe-in and camber add stability. But the thrusters also work against each other to add drag. Larger thrusters with more toe-in and more camber add more drag. When you lean on a rail you force that rail’s thruster deep. You pop the other thruster (mostly) out of the water. The inboard thruster turns vertical, and its toe-in skates the board’s tail toward the outside of the turn. The thrusters stop working against each other and the drag goes away. If you want speed out of thrusters, you have to turn. If you want to pull into a tube you must stall. Thrusters stall automatically. All the board builder hype about thrusters making a board go faster is crap. Faster isn’t always better. But the majority of board buyers want to ride whatever Slater’s riding this year. How is a boardbuilder supposed to sell boards by saying they “really stall well”? So you read things like “generates great down-the-line speed”. Don’t complain. You bought it. You’re welcome.

Thanks, that and having to ride a thruster from the tail on your back foot is exactly why thrusters bored me and I don’t own one. I enjoyed riding twinnies in the 80’s because even though they were skatey, with the proper fin, wing, swallow tail you could surf them from your front foot. If you have a moment could you apply your knowledge and explain the speed vrs. drag theory for twinnies and the single fin! Iv’e been trying to explain this to some of my tri fin clone buddies and even my kids. They all look at me as if I’m speaking jibberish.

Thanks, that and having to ride a thruster from the tail on your back foot > is exactly why thrusters bored me and I don’t own one. I enjoyed riding > twinnies in the 80’s because even though they were skatey, with the proper > fin, wing, swallow tail you could surf them from your front foot. If you > have a moment could you apply your knowledge and explain the speed vrs. > drag theory for twinnies and the single fin! Iv’e been trying to explain > this to some of my tri fin clone buddies and even my kids. They all look > at me as if I’m speaking jibberish. Sorry, I’m not as far into twin theory. I would think twinnies would be a little less skatey than tri’s, but with the turn arc moved forward toward your front foot. Twins are toed in and cambered too. They don’t sit as close to the rail as thrusters, so you wouldn’t pop the outboard fin nearly as far up when you turn. Single fin boards rely on rocker to turn. When you lean on a rail a single fin board creates a roll axis from the entry rail to the center of fin drag. The lower that drag center is on your fin, the more your body weight will torque the board, and the quicker it will roll. Turning V also allows greater ease of rolling onto a rail. From there, the rolled board’s rail will carve out a turn arc. Think of the rear rocker/bottom of the board as being part of the surface of a cone with its point deep in the water. Your turn follows the inside of this cone. You need enough rail surface to form this cone, so get a board with a nice even curve in the rear rail outline. Single fin boards use rocker and rail curve, rather than thruster drag, to stay in the pit. When you’re tight in the pit the rocker fits the wave’s curve and the board can rip. When the board rips out of the pit onto flat water, the tail rocker creates drag. As the board tries to curve water upward the board goes downward, and you stall. If you want a board that coasts well, reduce the tail rocker. However, this board won’t turn well. For good single fin turns, get a board with about 3% tail rocker. To measure rocker, mark a board’s midpoint with a pencil. Extend the mark to a rail where you can see it. Lay the board on a flat surface and support it so that it rests on your center mark. Measure up from the flat surface to nose and stern tips. Water flowing across under the curved rail causes lift (upward drag) when you are in the pit, drawing you higher into the lip. When you trim shoreward out of the pit water stops flowing across the rail and flows along the rail, eliminating the rail drag. You shoot forward.

hey noodle, ease up dude. first, i was just curious. second, i dont give a %^$& what slater is riding. i am a longboarder. ain’t complaining, actually, im praising. i think i disagree to some extent. seems to me that thruster helps hold line in a turn, less slide, which is faster. but what do i know. i dont give a rats @#$ about speed. but, thanks for the input. hope you dont drink too much caffeine…>>> Nope.>>> Think about how thrusters are mounted, toed in toward the nose, and canted > (cambered) out away from the stringer. Toe-in and camber are about 5 > degrees on each fin, but mentally take toe-in and camber angles to 45 > degrees. Such a board would pull lots of deep water from under the board > and throw it upward and outward. In reaction the board would suck into the > water and stop.>>> Surfing in a striaght line, normal 5 degree thruster toe-in and camber add > stability. But the thrusters also work against each other to add drag. > Larger thrusters with more toe-in and more camber add more drag.>>> When you lean on a rail you force that rail’s thruster deep. You pop the > other thruster (mostly) out of the water. The inboard thruster turns > vertical, and its toe-in skates the board’s tail toward the outside of the > turn. The thrusters stop working against each other and the drag goes > away.>>> If you want speed out of thrusters, you have to turn. If you want to pull > into a tube you must stall. Thrusters stall automatically. All the board > builder hype about thrusters making a board go faster is crap.>>> Faster isn’t always better. But the majority of board buyers want to ride > whatever Slater’s riding this year. How is a boardbuilder supposed to sell > boards by saying they “really stall well”? So you read things > like “generates great down-the-line speed”. Don’t complain. You > bought it.>>> You’re welcome.

Sorry, I’m not as far into twin theory. I would think twinnies would be a > little less skatey than tri’s, but with the turn arc moved forward toward > your front foot. Twins are toed in and cambered too. They don’t sit as > close to the rail as thrusters, so you wouldn’t pop the outboard fin > nearly as far up when you turn.>>> Single fin boards rely on rocker to turn. When you lean on a rail a single > fin board creates a roll axis from the entry rail to the center of fin > drag. The lower that drag center is on your fin, the more your body weight > will torque the board, and the quicker it will roll. Turning V also allows > greater ease of rolling onto a rail.>>> From there, the rolled board’s rail will carve out a turn arc. Think of > the rear rocker/bottom of the board as being part of the surface of a cone > with its point deep in the water. Your turn follows the inside of this > cone. You need enough rail surface to form this cone, so get a board with > a nice even curve in the rear rail outline.>>> Single fin boards use rocker and rail curve, rather than thruster drag, to > stay in the pit. When you’re tight in the pit the rocker fits the wave’s > curve and the board can rip. When the board rips out of the pit onto flat > water, the tail rocker creates drag. As the board tries to curve water > upward the board goes downward, and you stall.>>> If you want a board that coasts well, reduce the tail rocker. However, > this board won’t turn well. For good single fin turns, get a board with > about 3% tail rocker. To measure rocker, mark a board’s midpoint with a > pencil. Extend the mark to a rail where you can see it. Lay the board on a > flat surface and support it so that it rests on your center mark. Measure > up from the flat surface to nose and stern tips.>>> Water flowing across under the curved rail causes lift (upward drag) when > you are in the pit, drawing you higher into the lip. When you trim > shoreward out of the pit water stops flowing across the rail and flows > along the rail, eliminating the rail drag. You shoot forward. Thanks Noodle great info. Keep surfin’ JW