TWIN RUDDERS AT SEA

Evening Post, Volume CXX, Issue 132, 30 November 1935, Page 31

TWIN RUDDERS AT SEA

The use of twin rudders by seagoing vessels was referred to in a recent number of "The Syren and Shipping Illustrated" in connection with the mysterious disappearance of the big all-welded lake ship Josepii Medill on her maiden voyage across to Canada. As far as ocean-going craft are concerned, the twin rudder, in mercantile practice, is virtually unknown except on a group of four ships with special hull form recently completed for the United Netherlands Steamship Company and on the passenger liner Colombia, of the" Royal Netherlands Steamship Company, engaged in trade to the Caribbean Sea. All these ships have many original points of design and the particular hull form which they have makes it very convenient to adopt the twin-rudder method of steering. If, as is the case with these vessels, the ship rises sharply aft, it does mean that certain complications may be introduced in construction. In particular on the Colombia herself,"a very special'casting had to be made to take the rudderhead. On the later ships which were built in the same shipyard, experience showed that this casting could be considerably .modified and that a built-up structure could in part take its place. Even so it cannot. be pretended that the twin-rudder arrangement on oceangoing ships is one to be welcomed. Particularly does this criticism appear to hold in cases where a special hull form is adopted. On the other' hand, it may be argued from the naval architectural as opposed to the constructional point oi view that with special hull forms if maximum advantage is to be taken, then a rudder should operate behind, each screw, not so much from the point of view* of better steering qualities as. from the idea- of reduced hull resistance. The Joseph

Medill's twin rudders were intended to facilitate manoeuvring in the somewhat difficult waterways £nd canals connecting the St. Lawrence River with the Great Lakes. Whilst not the first Lake ship to .be so fitted, she is among relatively few, because most Lake ships are single-screw vessels.