Sec. X1.2 



SYMBOLS AND THEIR TITLES 



901 



^0 — ^Area, disc, of a screw propeller 



Ap — Area, projected blade, of a screw pro- 

 peller, outside the boss or hub 



Ap , Au — Propeller coefficients of D. W. Taylor, 

 dimensional in character. When T is in lb, Q is in 

 Ib-ft, n is revolutions per sec, Va is in ft per sec, 

 and P and D are in ft, Ap = (P/D) (55.0330,,)/ 

 (1 - s^y and Aa = (P/D)(8.7587Cr)/(l - s„)' 

 [Taylor, D. W., S and P, 1943, p. 101; PNA, 

 1939, Vol. II, p. 141]. 



Ar — Area, projected, of a rudder or other 

 vertical movable control surface, lying generally 

 parallel to the ship centerplane 



As — Area, projected, of stern diving planes of 

 a submarine 



Au — Area, immersed transom, projected on a 

 transverse plane; this does not necessarily cor- 

 respond to that embodied in the after perpendicular 

 area ratio fn of D. W. Taylor 



A tr — Area, waterplane, of a ship floating on 

 the surface; not to be confused with A, 



Ax — Area, maximum transverse section, of the 

 underwater body of a ship floating on the surface; 

 for a submerged body or ship such as a submarine, 

 the maximum area as projected on the transverse 

 y-z plane, preferably indicated in the latter case 

 as A^ , using a lower-case subscript 



A WA — Area, waterplane, of afterbody 



Awe — Area, waterplane, of entrance 



A WF — Area, waterplane, of forebody 



A WR — Area, waterplane, of run 



A I Ax — Section-area ratio, referred to the 

 section of maximum area 



Ad/A^ — Developed-area ratio of a screw pro- 

 peller 



As/Aa — Expanded-area ratio of a screw pro- 

 peller 



Al/{LHm) — Lateral-area ratio of a surface ship 



Ap/Ao — Projected-area ratio of a screw propel- 

 ler 



A u/Ax — Immersed-transom-area ratio, referred 

 to the section of maximum area Ax ■ If the tran- 

 som is at the AP, this is the value of / at the AP. 



dA/dL — Rate of change of section area with 

 length along the ship 



dA/dx — Rate of change of section area with 

 distance along the x-axis of a ship, when referred 

 to cartesian coordinates 



h — Breadth or width in general 

 h — Span of a hydrofoil, tip to tip, or support to 

 tip when cantilevered 



h — Vortex spacing, longitudinal, in a vortex 

 street or trail 



B — Beam at the designed waterline, at any 

 designated station 



B — Buoyancy force on a body or ship, whether 

 the body is in equilibrium with the gravity force 

 or not 



5„ — Bouss inesq number, expressed as U/ \^gRn 



Be — Beam at the chine, at any designated 

 station, for a V-bottom planing craft 



jBc(Mnx) — Beam at the chine, maximum, wher- 

 ever occurring on a planing craft 



Be — Beam, extreme, wherever it occurs on the 

 main hull, above or below the designed waterline 



Bm — Beam, designed waterline, at midlength 

 between perpendiculars 



Bp , Bu — Basic propeller design variables of D. 

 W. Taylor, dimensional in character. When T 

 is in lb, Q is in Ib-ft, n is in revolutions per sec, 

 Va is in ft per sec, and P and D are in ft. 



Bp = {D/P){23.772VCo)/{l - s^Y' 



and 



Bu = (I>/P)(9.4835VCr)/(l - s^y 



Bu — Beam, designed waterhne, of the immersed 

 transom 



Bx — Beam, designed waterline, at the section 

 of maximum area 



Brx — Beam, maximum, of the immersed or 

 underwater body, wherever it occurs 



Bwx — Beam, maximima, at designed waterline, 

 wherever it occurs along the length 



b^'/Aproi — Aspect ratio of a hydrofoil of any 

 kind; also b^/An 



B/Bx — Ratio of the designed waterline beam 

 at any section to the designed waterline beam 

 at the section of maximum area 



Bx/Hm — Ratio, beam-draft, based on the 

 mean draft H^f ; Bx/d is the alternative form 



Bx/Hx — Ratio, beam-draft, at the section of 

 maximum area; Bx/dx is the alternative form 



c — Celerity or velocity of a wave with respect 

 to the undis turbed hquid in which it occurs, = 

 VgLw/{2T) 



c — Chord length of an airfoil or hydrofoil, such 

 as an expanded propeller-blade section, a rudder 

 blade, a fin, or other device; alternative symbol I 



Ch — Shallow-water wave speed, in depth h 



Cc — Critical wave speed or velocity in shallow 

 water of depth h, = wgh 



