Propeller direction on D3-160 twins

[Portoroz]

Hi everybody,

I just bought Campion Allante 925 with two Volvo penta D3-160. As the boat is out of the sea for the winter, I am spending time examinating the boat. So I have some questions:
The boat is 2006 and both engines were replaced under warranty in the year 2008. I did not know the reason, beacuse I bought the boat from the bank. The fact is that old engines were D3-130. I was advised by the producer to change the propellers with higher pitch as the boat was reaching highest RPM very easy...I just bought two different pairs of propellers and hardly wait to test them. When ordering the props I expected that I had LH and RH propellers, but my boat had originally two RH propellers. The producer says there is no need to have two opposite rotating propellers and they explained, that they do this only on high power petrol engines. The thruth is that I had no problems operating the boat so far... I am only interested, if any of you have experience with that.
Another question is, that by replacing the zinc anodes I noticed on my SX drives a hole at the end of the drive and it looked in documentation like a place for an other anode or trimming fin. I checked with Volvo-Penta manuals and both was possible a plug or to mount the fin. I do not know does trimming fin has an affect on manouvering the boat?

Thank you for your answers and regards from Europe Slovenia

Tomaz

 

[Don S]

Re: Propeller direction on D3-160 twins

If it had 2 RH propellers before, you need to replace with RH props. You can't just change the prop, you would also have to change direction of drive rotation to use a LH prop.

 

[Portoroz]

Re: Propeller direction on D3-160 twins

If it had 2 RH propellers before, you need to replace with RH props. You can't just change the prop, you would also have to change direction of drive rotation to use a LH prop.

I know I bought 2xRH four blade 18p and 2xRH 19p three blade - I would like to know if there is any need to change the direction of props anyway - I have not expected twin engine boat with 2xRH rotation? On SX drive you can have both rotation.

What about the trimming fin on the SX drive unit - do I need them or not? As I said I had no probs with manouvering - just I
felt there is not enough speed or plane - RPMS raised to 3.600 and then to 4.100 and speed the same...
Thanks,

Tomaz

 

[Don S]

Re: Propeller direction on D3-160 twins

Those engines have a max wide open throttle rpm of 4000 rpm. Over propped will cause lower speed, as well as under propped.

That trim tab is usually not needed on boats with power steering.

 

[Portoroz]

Re: Propeller direction on D3-160 twins

Those engines have a max wide open throttle rpm of 4000 rpm. Over propped will cause lower speed, as well as under propped.

That trim tab is usually not needed on boats with power steering.

Thank you! So this is normal, that on the boat like this, propellers rotate same direction?

Tomaz

 

[steelespike]

Re: Propeller direction on D3-160 twins

Speaking very generically It would seem that with twin screws turning the same rotation there might be more resitance in the steering in one direction.Power steering would probably negate that.Also on plane hard turns response may be different port and starboard.
Turning sharper one way than the other.
Also there may be prop steer in reverse though not so much with an I/O.
If outdrives are left straight in reverse prop torque may pull the stern to port if rh rotation.
Again with an I/O steering counter acts the prop torque.
With both the same rotation its certainly easier to select and afford testing props.