A Novel Technique for Reducing Transom Stern Hull Resistance

Research Project, 2017 – 2018

For boats and ships running at speeds in the semiplaning and planing speed ranges transom sterns are the only viable option. Cruiser type sterns cannot be used since the hull lines would then be strongly curved on the aft body, creating a large suction force increasing both resistance and trim by the stern. At low speeds a transom stern hull drags the water along with the hull in a massively separated zone behind the transom. This is not efficient, evidently. Through this project, we want to reduce the loss in the separated flow behind the hull which consequently results in reduction of the hull resistance and required sailing power. To this end, we have proposed a modification to the hull transom by mounting an extra device behind the transom to absorb the energy of the forward moving water in the recirculating flow region. In our initial studies, we have shown that the power consumption can be reduced up to 9% through such an enhancement. The first objective of this project is to better understand the physics of the resistance reduction with our proposed technique and then use this knowledge to improve the performance the technique. The current investigation will be carried out through a series of computational simulations of a transom stern hull flow along with our proposed device. Eventually, a set of towing tank measurements will be performed to confirm the findings from our computations.