A Practical Approach to Ship Slamming in Waves

Bow flare slamming can cause very large impulse loadings to a ship’s structure that can result in local damage or severe whipping responses that may adversely affect the ship’s ultimate strength and fatigue life in a seaway. The current work is intended to develop a fast and accurate method capable of long term simulations of ship in a seaway from which statistical properties of impact loads can be derived. This procedure includes an approximation method based on Momentum Theory enhanced with pile-up effects due to the immersing bow and the draft dependent static bow wave. It is shown that the latter effects are crucial for a good prediction of the impact force. The method is tuneable to specific ship characteristics, but it captures the effect of different wave conditions and different headings well. The tuning can be done using a dedicated set of experiments, either in the towing tank or by CFD. The CFD option is illustrated with a calculation in head seas showing a very good agreement of the force on the bow and of local pressures to experiments.