What does this Excel App do?
This Excel app helps the user calculate the complete wind load for a vessel with cargo/topsides
Windload is given by:
FW = K * ρair*VR^2*(AL sin^2θ + AT cos^2θ)/cos(α – θ)**
ρair = Density of Air, VR = Wind Speed relative to vessel , AT = Cargo + Hull Transverse area exposed to head wind (and factored for Height and Shape)
AL = Cargo + Hull Transverse area exposed to beam wind (and factored for Height and Shape), α = true wind angle, θ = relative wind angle
The windage areas are factored for the shape and height coefficients derived from ABS MODU Rules (see reference)
Upto 15 Cargo/Topside/Superstructure items can be added
The height coefficients for different zones are automatically calculated by the app
The windage area of the hull is calculated considering it as a rectangular box
How to use this App
The user has to provide all the inputs highlighted in blue.
The user is asked for some dimensions, draft and shape coefficient of the Vessel, along with wind direction and speed
For Cargo/Topside/Superstructure, the dimensions and shape coefficients are to be provided
For shape coefficients, Table as per ABS MODU Rules has been provided
Shielding effects have been neglected
Hull and cargo/superstructures are considered as box structures for windage area calculation.
1. ABS Rules for Building and Classing Mobile Offshore Drilling Units, 2019, C 3-1-2/1.3.2
2. Principles of Naval Architecture (PNA), Vol 2, Sec 5.2