Appendages Dialog - Resistance Factors Tab
- Last UpdatedAug 15, 2023
- 2 minute read
If appendages are to be included within the Powering calculations, then the total wetted surface area and average resistance factor (1+k2) of all appendages is required, since these contribute to the overall resistance of the vessel. The data is entered on this tab sheet using the grid control.
All appendages should be included here (up to a maximum of eleven).
The following is a brief description of each column in the grid control:
|
Use |
As mentioned above, all appendages should be defined here, but they can be included or excluded from the powering calculations by checking/unchecking the "Use" check box. |
|
Description |
A textual description is included in the output, so may be included here. |
|
Wetted Surface Area |
The total wetted surface area of the appendage. If, for example, two rudders are defined together under a single grid row, then the total of both rudders should be entered. |
|
1+ k2 |
The resistance factor of the appendage (example values are given by default or can be found from the Holtrop & Mennen, References 1 and 2). |
The following table, taken from Holtrop & Mennen References 1, gives examples of 1+k2 values for various appendage types:
|
Appendage |
1+k2 |
|---|---|
|
Rudder behind skeg |
1.5 - 2.0 |
|
Rudder behind stern |
1.3 - 1.5 |
|
Twin-screw balance rudders |
2.8 |
|
Shaft brackets |
3.0 |
|
Skeg |
1.5 - 2.0 |
|
Strut bossings |
3.0 |
|
Hull bossings |
2.0 |
|
Shafts |
2.0 - 4.0 |
|
Stabilizer fins |
2.8 |
|
Dome |
2.7 |
|
Bilge Keels |
1.4 |
For each appendage "used", the wetted area is summed to give a total at the bottom of the page.
For each appendage "used", the wetted area and "1+k2" value are used to give an average resistance factor.