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[Neil.G]

Age is creeping, memory is challenging!! Building a Rotterdam, need some advice.
Both motor run the same rotation, do I need a left and right screw? Or do the motors run one left and one right. About to buy some brass ones, so any advice I appreciated. Probably logic, but at 84, that’s a challenge. Thanks

[captain_reg]

For twin screws, I have always had the motors turn in opposite directions with one left and one right screw. You then have the choice of if they turn in towards each other at the top or the bottom, one way is supposedly better than the other but I can't remember which.
I have mine like this https://www.sbmar.com/articles/typical-twin-engine-prop-rotation/

[Ralph]

As the captain says, contrarotating is best. If both screws turn the same way they will keep trying to push your model round in a circle.


Ralph

[Neil.G]

Thanks for the info. Have a good day👍

[meechingman]

What kind of model?


For a tug, I'd go outwards turning, partly because that's what my Dad's 1:1 tug 'Meeching' had. All three of my model twin screw tugs are like that. Very manoeuverable. 


But I can remember seeing some of our car ferries with controllable pitch props splashing away as they neared the berth, and they were inwards turning.


Plenty of threads on here, no doubt but the bottom line is that they must be contra-rotating.