Fishing Craft Technology

Unit 5 - Marine Engine and propulsion system

5.6.Stern tube arrangement
Stern tube is a pipe which extends from the stern post of the hull below the transom of the vessel. The position of the stern tube in vessel is given as below. The purpose of the stern tube is to support the shaft with the help of stern tube bearings and to make a water tight joint on the hull where the shaft enters the hull. It also keeps the propeller shaft on the centre line of the vessel.

The stern tube is made up of steel in modern vessels. Brass or steel bushes are fitted on the forward and aft ends of the tube. These bushes are called stern tube bushes. The bushes are locked to the stern tube. The bushes are lined inside with soft material like lignum vitae, cutlass rubber and white metal. This complete part is called stern tube bearing. The propeller shaft or the tail end shaft rotates inside the stern tube or these stern tube bearings.