EXPERIMENTAL EVALUATION OF THE EFFECT OF INTERCEPTOR AND SIDE KEELS ON THE LONGITUDINAL STABILITY OF A STEPPED HULL

摘要

This paper concerns the experimental work that Azimut|Benetti Group is doing on the evaluation of performance of high speed boats. When increasing the speed and reducing the displacement of the boat, attention must be paid to have the correct trim angle of the boat at the different speed condition, and in particular to avoid porpoising effect. There are a number of possible systems to control the trim angle and this paper shows some of the analysis that Azimut|Benetti group is carrying on in such an important issue, at the moment for high speed boats, but, in the meanwhile, undertaking feasibility studies for medium speed ones (through numerical and experimental analysis). Experimental results have been conducted in particular on the application of interceptor and side keels to control the trim angle during the towing tank of a stepped hull. In fact the difference between towing and thrust direction, the absence of vertical components of propellers action, and the scale effect on the trim angle can influence the trim angle of the model, reducing the speed of inception of porpoising, preventing the completion of tests and influencing the evaluation of results. The application of this work on the trim control system is increasing the quality of medium speed boat at the moment in production and is an interesting way to better study some possible application for high speed small boat.