Wet-deck slamming loads and pressures acting on wave piercing catamarans

Background:

The wet-deck height and centre bow configuration in wave piercing catamarans are critical design factors which influence slamming occurrence and severity.

Objective:

In this paper, the wet-deck slamming loads and pressures acting on a 112 m catamaran with a centre bow were investigated in regular waves in two wave heights.

Methods:

A 2.5 m hydroelastic model with three alternate configurations of wet-deck vertical clearance was tested at a speed of 2.89 m/s (38 knots full-scale equivalent).

Results:

The results showed that at the instant of slamming the centre bow immersion depth relative to the undisturbed incident wave elevation was less than two thirds of the maximum immersion depth during the wet-deck slam event. The location of maximum slamming pressure was found to be in the range between 77% and 80% of the overall length from the transom. The relationship between the relative velocity at impact and slamming force indicated that slamming loads in the order of the vessel weight can occur for the parent design when the relative velocity at slam is about a quarter of the forward speed.

Conclusions:

Overall, increasing the wet-deck height was more beneficial for reduction of slamming loads and pressures in smaller waves than in large waves.