Section 1 Plans and particulars

1.1.1 A plan, in triplicate, of the propeller is to be submitted for approval, together with the following particulars using the symbols shown:

1. Maximum blade thickness of the expanded cylindrical section considered, T, in mm.

2. Maximum shaft power, see Pt 5, Ch 1, 3.3 Power ratings, P, in kW (H, in shp).

3. Estimated ship speed at design loaded draught in the free running condition at maximum shaft power and corresponding revolutions per minute, see Pt 5, Ch 7, 1.1 Details to be submitted 1.1.1.(b) and Pt 5, Ch 7, 1.1 Details to be submitted 1.1.1.(d).

4. Revolutions per minute of the propeller at maximum power, R.

5. Propeller diameter, D, in metres.

6. Pitch at 25 per cent radius (for solid propellers only), P _0,25, in metres.

7. Pitch at 35 per cent radius (for controllable pitch propellers only), P _0,35, in metres.

8. Pitch at 60 per cent radius P _0,6, in metres.

9. Pitch at 70 per cent radius P _0,7, in metres.

10. Length of blade section of the expanded cylindrical section at 25 per cent radius (for solid propellers only), L _0,25, in mm.

11. Length of blade section of the expanded cylindrical section at 35 per cent radius (for controllable pitch propellers only) L _0,35, in mm.

12. Length of blade section of the expanded cylindrical section at 60 per cent radius, L _0,6, in mm.

13. Rake at blade tip measured at shaft axis (backward rake positive, forward rake negative), A, in mm.

14. Number of blades, N.

15. Developed area ratio, B.

16. Material: type and specified minimum tensile strength.

17. θ_s, skew angle, in degrees, see Figure 7.1.1 Definition of skew angle.

18. Connection of propeller to shaft — details of fit, push-up, securing, etc.

1.1.2 For propellers having a skew angle equal to or greater than 50°, in addition to the particulars detailed in Pt 5, Ch 7, 1.1 Details to be submitted 1.1.1, details are to be submitted of:

1. Full blade section details at each radial station defined for manufacture.

2. A detailed blade stress computation supported by the following hydrodynamic data for the ahead mean wake condition and when absorbing full power:

   1. Radial distribution of lift and drag coefficients, section inflow velocities and hydrodynamic pitch angles.

   2. Section pressure distributions calculated by either an advised inviscid or viscous procedure.

Figure 7.1.1 Definition of skew angle

1.1.3 For blades of fixed pitch propellers with skew angle of or greater, the stresses in the propeller blade during astern operation are not to exceed 80 per cent of the propeller blade material proof stress. Consideration is to be given to failure conditions and a factor of safety of 1,5 is to be attained using an acceptable fatigue failure criteria. Documentary evidence confirming that these criteria are satisfied is to be submitted.

1.1.4 The maximum skew angle of a propeller blade is defined as the angle, in projected view of the blade, between a line drawn through the blade tip and the shaft centreline and a second line through the shaft centreline which acts as a tangent to the locus of the mid-points of the helical blade sections, see Figure 7.1.1 Definition of skew angle.

1.1.5 Where propellers and similar devices of unusual design are intended for more than one operating regime, such as towing or trawling, then a detailed blade stress calculation for each operating condition, indicating the rotational and ship speed, is to be submitted for consideration.

1.1.6 Where it is proposed to fit the propeller to the screwshaft without the use of a key, plans of the boss, tapered end of screwshaft, propeller nut and, where applicable, the sleeve, are to be submitted.

1.1.7 Where a sleeve is fitted, details of the proposed type of material and mechanical properties are also to be submitted.

1.1.8 In cases where the ship has been the subject of model wake field tests, a copy of the results is to be submitted.