Home |
Search |
Today's Posts |
#13
|
|||
|
|||
Propeller rotation - important? - Yes, it is.
Thanks for all your replies.
I've cleared things up this much: The transmission is designed to run equally fine in both directions. Ratios are almost similar. The transmission has two "modes" - A and B. A is the "normal" mode where the propeller-shaft runs in opposite direction of the engine. B is normally reverse - the propeller-shaft runs same way as the engine. Here's the funny thing: From the factory, the boat is delivered with a LH propeller - which means that the transmission has to run in the "B"-position to have the boat move forward - i.e. reverse of "normal"! I called the Norwegian factory to ask why. They replied that "the boat liked the LH propeller the most"! (Don't know what that means.) So it all narrows down to this: Assuming that transmission is not an issue - are there any "hull-issues" that should imply that a given hull simply "runs better" with a LH instead of a RH - or vice versa? Anders Denmark "JAXAshby" skrev i en meddelelse ... fair winds, guy. As you point out, if the tranny is designed to take a prop going either direction things are fine. ah, you just might wish to remember that the prop MUST push against the prop shaft which pushes against the thrust bearing to push the boat forward. Got to. In other words, the thrust bearing takes 100% of the horsepower developed by the engine. That is a lot. In forward. There is also a thrust bearing needed for going in reverse as well. However, as the horsepower used in reverse is much less and the time it is used is hugely less the reverse thrust bearing need not be anywhere near as big. Now, change the prop so the former reverse thrust bearing becomes the new forward thrust bearing and operates at 100% power over extended time the potential to trash that bearing becomes very real. Most people forget that the prop has to push against something to push the boat forward. That something is the thrust bearing. Yes, all these things are right ones. Question is: How has been designed (engineered) the Thrust Bearings Box ? (sorry I don't know its English code-name) Our ones are designed and manufactured with a couple of Heavy-Duty Taper Rolling Bearings, # 322xx, a couple of Rubber Seals for Lube and Water Cooling devices. Used in Clam Dredgers working in Reverse... they are tailored to be operating in both directions. Heavy-Duty Bearings in Forward and Light-Dutry ones in Reverse were used times when Bearings were very expensive... but actually it is a "poor" spare, requiring different machining on both sides, double the Stocks of spares on shelves and aboard. But they could be till existing... Glad to have meet someone involved in Technical matter. I'm a newcomer in this NG but I will visit it at least once a week. I hope to have some interesting questions to put to NG attention. Thank you for your time, WinXP. |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
How much does chain stretch and is it important? | General | |||
YSx8 propeller size | General | |||
propeller engineering question | General | |||
stuck propeller | General | |||
Counter rotation vs normal rotation | General |