There is an impact of 3 main forces on the yacht.
1.) Wind force
2.) Kinetic energy (caused by movement of the yacht)
3.) Energy caused by current & waves
Energy caused by current and waves results in a major force impact on cleats and ropes.
Wind, current and waves often come from different directions.
Therefore the yacht jerks between the ropes.
The thereby created forces can be very strong.
These forces can be calculated with the following mathematical formula.
It is the same formula used to calculate wind pressure.
The water density, however, is 1.000 times higher.
Consequently, the forces created by current and waves are immense.
F = 0,5 * p * Cw * A * V²
F … flow force [ kg ]
p … water density [ kg/m³ ]
(e.g.: p = 999,84 Kg/m³ at 0°C / p = 995,64 kg/m³ at 30 °C)
Cw … resistance
(e.g.: round plate = 1,11 / square plate = 1,50 / convex bowl = 0,34 )
A … exposed area [ m² ]
V … current [ m/s ]
Example 40 yacht
Area exposed to water: 8 m²
Weight: 10 tons
Water density p: 998,0 kg/m³
Resitance Cw: 0,20
Current | Flow force | | |
[Km/h] | [m/s] | kg/m² | kg | | |
1 | 0,3 | 0,8 | 6,3 | | |
3 | 0,8 | 7,1 | 56,5 | | |
5 | 1,4 | 19,6 | 157,0 | | |
7 | 1,9 | 38,5 | 307,7 | | |
10 | 2,8 | 78,5 | 628,0 | | |
15 | 4,2 | 176,6 | 1.413,0 | | |
20 | 5,6 | 314,0 | 2.511,9 | | |
30 | 8,3 | 706,5 | 5.651,8 | | |
Force on 1m² 
|  Force on 40' yacht |
Curent and waves can have a hight impact on the yacht.
Therefore high safetly measures need to be taken when securing the yacht.
To ensure the highest level of safety when using the DualDocker the following safety instructions apply:
1.) The DualDocker can only be used in Marinas with adequate breakwater
2.) Maximum allowed wave hight: 0,5 m
3.) With a wave height of 0,3 m or more, spring lines and diagonal lines have to be attached
4.) Maximum allowed rapid current (speed): 3,6 m/s (~ 10 Km/h).
5.) With a rapid current of 1 m/s or more, diagonal lines and spring lines have to be attached.
