I am asking this again as I got no responses last time. i am sure someone out there can clearify this. Thanks. I am just seeking some others imput on the theory of concaves their placement and functionality.(as applied to shortboards) Vs. the use of convex or displacement hulls like Vee. This is my understanding of it. please contribute to or affrim and info. here To achieve a looser board (side to side) - the single concave carries further towards fins before double concave develops in order to increase the amount of board that is lifted as to provide a more “skatier” looseness (side to side). But you lose some of the rail ro rail action because of the increased lift due to the concave correct? As well as sacrificing some of the projection or drive out of bottom turns due to the smaller double concave section which when properly instituted acts as a compression area to force out the water that is in that area at the time of making the turn. Less area equals less water in the area which equals less compression or force to assit in creating drive or projection out of the turn. Right? Driver boards - single concave transitions into double concave closer to the wide point. In this case you lose some of the “skatier” looseness (side to side) because the lack of single concave but increase the amount of drive or projection out of your turns because of the incrreased double concave area which equals more compression providing more projection out of the turns. Right? When using a convex bottom like slight roll in he mid section to vee in the tail. You lose that “skatier” side to side feel but increase your rail to rail actions because your bottom now has some what of a pivot point. Right? But in the case of drive out of your turns there is no increase projection because the water has a clear exit line an is not being trapped due to the vee. Because of the constant exit flow it would seem as if no project is lost either. Correct? So what ever bottom contour one incorporateds into the board something is always sacraficed. Please, I would really like to know if what I have stated above in the various combination is correct info. If there is anything wrong or lacking from this info. please state it so that we all here at swaylocks can have a better understanding of the different bottom configurations and the functions. Sorry to lengthy Thanks
Andy, You seem to have a good feel for the dynamics of water over those three surface or bottom configurations (or the dynamics of the surfaces over water.) Concaves certainly require a lot of attention to detail and can produce a variety of results. All other variables held constant, the position and depth of the concaves defines the area of a shortboard that will have the most lift. The length of double concave will determine greater or less projection. Tranfer from rail to rail can be dialed with the side to side configuration of the deck. A more crowned deck tips or goes rail to rail with greater ease than a flatter deck. Consider the deck line will effect rail volume. Convex bottoms also a variety of results, but are more forgiving in design and use. The length and depth of vee in the back half of the board determines the radius and projection of turns. Rather than considering the " sacrifices" of each design, you may want to make the assumption that each design is a “plus” or is specifically functional for surfer and conditions. The dominant single concave at it’s best in small waves where the type of turns it generates are most relevant / the more dominant double concave in small and medium waves where greater projection is an issue / and the convex bottom in significant conditions where control is a dominant design consideration over generating speed and power. Additionally, some surfers simply prefer the “feel” of one boards’s bottom configuration over the other and who’s to argue with that ? When the bottom contours become problematic for any shortboard, but you want to continue to incorporate them into your boards because of the positive contribution they have, “fine tune” the concaves or vee and “dial in” the other variables - rocker / foil / rails / templates. Recognize how these affect the board and build on that base of experience and knowledge. All three bottom designs perform well in a variety of conditions. Although I trust variations of multiple concaves to contibute the most to maximum performance in riding a shortboard convex bottoms remain very functional as well.>>> I am asking this again as I got no responses last time. i am sure someone > out there can clearify this. Thanks.>>> I am just seeking some others imput on the theory of concaves their > placement and functionality.(as applied to shortboards) Vs. the use of > convex or displacement hulls like Vee.>>> This is my understanding of it. please contribute to or affrim and info. > here>>> To achieve a looser board (side to side) - the single concave carries > further towards fins before double concave develops in order to increase > the amount of board that is lifted as to provide a more > “skatier” looseness (side to side). But you lose some of the > rail ro rail action because of the increased lift due to the concave > correct? As well as sacrificing some of the projection or drive out of > bottom turns due to the smaller double concave section which when properly > instituted acts as a compression area to force out the water that is in > that area at the time of making the turn. Less area equals less water in > the area which equals less compression or force to assit in creating drive > or projection out of the turn. Right?>>> Driver boards - single concave transitions into double concave closer to > the wide point. In this case you lose some of the “skatier” > looseness (side to side) because the lack of single concave but increase > the amount of drive or projection out of your turns because of the > incrreased double concave area which equals more compression providing > more projection out of the turns. Right?>>> When using a convex bottom like slight roll in he mid section to vee in > the tail. You lose that “skatier” side to side feel but increase > your rail to rail actions because your bottom now has some what of a pivot > point. Right? But in the case of drive out of your turns there is no > increase projection because the water has a clear exit line an is not > being trapped due to the vee. Because of the constant exit flow it would > seem as if no project is lost either. Correct?>>> So what ever bottom contour one incorporateds into the board something is > always sacraficed.>>> Please, I would really like to know if what I have stated above in the > various combination is correct info. If there is anything wrong or lacking > from this info. please state it so that we all here at swaylocks can have > a better understanding of the different bottom configurations and the > functions.>>> Sorry to lengthy Thanks