Calculation of the Minimum Diameter of the Propeller Shaft
Calculation of
the Minimum Diameter
of the Propeller Shaft
This tool allows you to calculate the minimum diameter of the propeller shaft based on the transmitted power, rotational speed, shaft type (solid or hollow), and the mechanical properties of the material used.
The calculation (RINA Rules for Pleasure Yachts, 2019) takes into account the main parameters of strength and structural safety to ensure the shaft’s reliability under continuous operating conditions.
Calculation of Minimum Shaft Diameter
Result:
The result returns the minimum shaft diameter (d) in millimeters, which is necessary to ensure adequate mechanical strength and long-term durability.
Warning
The data and calculation tools presented in this section are provided by ENAVE for informational purposes only. ENAVE does not guarantee the formal or substantive accuracy, nor the up-to-date nature of the data, reference standards, calculations, or results contained herein. All content must be considered indicative and non-binding and cannot in any way replace a design calculation performed by a qualified professional. The use of these tools for purposes other than informational ones is the sole responsibility of the user.
k
Coefficient:
- 82 for non-toothed intermediate shafts equipped with full-flange couplings or keyless clamping couplings;
- 90 for keyed intermediate shafts (e.g., with a keyway for non-full-flange couplings);
- 104 for propeller shafts made of corrosion-resistant steel or for propeller shafts equipped with a continuous bronze lining or an effective oil lubrication system;
- 109 for propeller shafts equipped with a continuous bronze lining in contact with seawater.
P
maximum continuous power in kW
n
rotational speed of the propeller shaft, in revolutions per minute, corresponding to power P
Q
Coefficient equal to:
0, in the case of solid shafts;
it is the ratio of the bore diameter to the outer diameter of the shaft at the relevant cross-section; in the case of a hollow shaft where Q ≤ 0.3, Q must be considered equal to 0
Rm
Minimum tensile strength of the shaft material, in N/mm²
*Rm coefficient values
| Material | Material code | RM (N/mm²) |
|---|---|---|
| Carbon steel | Fe 37/360 | 360 |
| Carbon steel | Fe 43 | 430 |
| Carbon steel | Fe 510 | 510 |
| Stainless Steel | AISI 304 | 500/700 |
| Stainless Steel | AISI 316 | 500/700 |
| Stainless Steel | AISI 410 | 730 |
| Stainless Steel | AISI 420 | 800 |
| Stainless Steel | AISI 430 | 400/600 |
| Stainless Steel | AISI 630 | 1270 |
| Stainless Steel | Aquamet 17 | 931 |
| Stainless Steel | Aquamet 22 | 1000 |
Note
For calculation purposes, the maximum usable value of Rm is 930 N/mm²
Please note
The data and calculation tools presented in this section are provided by ENAVE for informational purposes only. ENAVE does not guarantee the formal or substantive accuracy, nor theup-to-date nature of the data, reference standards, calculations, or results contained herein.
All content should be considered indicative and non-binding and cannot in any way replace a design calculation performed by a qualified professional.
The use of these tools for purposes other than informational ones is the sole responsibility of the user.