Numéro : 2147 - Year : 1991
Parametric studies in the improvement of the resistance of SWATH
O. LEFORT, BASSIN D'ESSAIS DES CARENES DE PARIS
P. HERNANDEZ, BASSIN D'ESSAIS DES CARENES DE PARIS
P. STIEVENARD, BASSIN D'ESSAIS DES CARENES DE PARIS
E. SURGET, BASSIN D'ESSAIS DES CARENES DE PARIS
Prospective studies about a SWATH with a deplacement between 2000 and 4000 tons are carried out at the Bassin d'Essais des Carènes de Paris. Resistance tests in witch length, beam, draught and trim vary, are presented. It is pointed out that, in order to reduce residuary resistance and pitching moment, the torpedo shaped underwater hulls should have a sharpness L/D>12, relative beam B/D>4 and draught limited to H/D=1,3. By using the computer program CHERIE, and taking account of spray drag we obtain a good agreement between theoretical and experimental estimates, up to Fr=0,45. Rules of procedure witch include programs CHERIE and SOIF have been defined and used as an example on a SWATH with a displacement of 3800 tons. We obtain a profit of about 20 % on the total resistance, between 20 and 30 knots. Expectations of reachable speeds in terms of power and displacement are also included
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