The Drydock - Episode 171

Contra-rotating propellers have been successfully used on aircraft and torpedoes for many years. Have contra-rotating propellers been used on any Naval vessels? Cost aside, are the technical obstacles regarding having a shaft within a hollowed shaft and the complexity of getting and maintaining the inner shaft bearings to play nice, not overcome able? What additional technical issues might their be? I get rotational speed is limited by cavitation concerns, but with a contra rotating propeller aren’t you just (essentially) doubling the surface area of your propeller blades without increasing diameter or rotational speed? Would it have been theoretically possible to engineer such a system for a fast destroyer, cruiser or even battleship? Would such an arrangement on a ship with four shafts (8, actually) hideously complicate optimization of efficiency for all shafts? Hypothetically extrapolating, if you could have achieved this on a fast battleship, say the HMS Vanguard or one of the Iowa class battleships, how might this theoretically improve their speed and/or operation? Or not…

Capitano Lorenzo

Morning Drachman!!!

Capitano Lorenzo

Drac if you get the Lithuanian MREs that are available the include what is basically hard tack. I got a couple for camping last summer and while all the rest was delicious you could have knocked tent pegs in with the biscuits

Hi Drach love your work. I’ve been so impressed at the vast difference in ability of admirals directing the tactics and course of a battle. They have to make immensely important decisions which (as you said in the Battle of Jutland) which can even change the course of a war. Did any navies put effort into training admirals or testing their decision making skills before putting them in charge of a fleet? Or were they generally relied on to use whatever skills they had when they were promoted?