Props backwards on a twin screw?

[pipes]

So my uncle has a 30 foot weekender, last season he hit something softly! He had the props removed by his mechanic, and he said the engines are backwards.? Is this possibile? I have been boating for some time, but not too familiar with twin screw. I guess by what the mechanic said is that the props were working against each other. He said the engines were backwards? The engines were put in about 3 yrs ago, and as far as we know, the boat was geat in the water. It didn't seem weird coming into port, never thought anything was off, or weird. I thought engines only spin in one direction. Wouldn't it be the trannsmission thats backwards?

Any help? Thanks

 

[azhunter]

Re: Props backwards on a twin screw?

Most twin engine boats use one standard and one counter prop. I would suggest your uncle find a new mechanic!!

From the iboats home page, select the "boat propellers" link. In the "Search Boat Propellers" section you will see an information icon by the "prop rotation" drop down menu. Move your mouse over the "i" icon and read the print. It will clearly tell you that the twin engines typically use a prop of each direction. Hope this helps. Good luck!

 

[reelfishin]

Re: Props backwards on a twin screw?

Do you mean that the motors are swapped? In other words the left motor is where the right motor should be?
The port or left motor is normally the reverse turning motor or prop. This is done to make the boat more stable. I've seen a few go fast boats done in reverse to supposedly gain some top end.

 

[Bondo]

Re: Props backwards on a twin screw?

Ayuh,...

There's been the same debate ever since there's been Twin Screws....

It really doesn't matter whether the screws turn Inward, or Outward....

Tell your Uncle to find a Different Mechanic....

 

[Silvertip]

Re: Props backwards on a twin screw?

Counter rotation means one engine runs normally and the other runs the other direction, hence the need for a counter rotation prop. I won't get into why as there is ample reading available on counter rotation systems.

 

[Tim Frank]

Re: Props backwards on a twin screw?

Not sure if this constitutes "hijacking" since I think it is a Q that relates to this thread.....
Have no idea about twin screw setups, but reading this i am not sure if it is saying that the engines actually run in opposite rotation or whether the required change in rotation is accomplished from the engine output to the prop to get the prop shafts turning in opposite directions.
Or is it just a reverse pitch prop put on the shaft?

 

[Dhadley]

Re: Props backwards on a twin screw?

The crankshaft rotation can be reversed in either the motor itself or in a transmission.