Bukh Gearbox Ratio

[stevd]

Hello,

Would anyone know off hand what the likely gearbox ratio would be on my Bukh DV20 in my Moody 33. I am looking at sizing up a new propeller but I need the likely ratio. I am away from the boat so any suggestions.....thanks

 

[Champagne Murphy]

Is it a ZF?
Fastest answer is to call Bukh UK, 01202 2668840

 

[vyv_cox]

The ZF BW-6 can have ratios of 2 or 2.5:1. I believe that this box was superseded by the BW-7 quite a few years ago, with a ratio of 2.5: 1 for the DV10 and DV20, but 3:1 for the DV36.

 

[Mistroma]

Assuming you don't have saildrive (unlikely on Moody 33), the technical manual says:

ZF BW7 on DV20 reduction FORWARD 2.5:1 REVERSE 2.77:1
ZF BW6 also listed ratios of FORWARD 2.5:1 REVERSE 2.77:1.
However, BW6 also listed FORWARD 2:1 REVERSE 1.76:1


I'm pretty certain that my old DV20 on Southerly 95 (1980) had ZF BW6 with FORWARD 2.5:1 REVERSE 2.77:1

Worth keeping these figures in mind when speaking to Bukh UK, it might prompt comments about different gearboxes.

 

[Tranona]

Expect it is a 2:1 reduction. The Moody 33 is very restricted in the diameter of the prop. Think the maximum is 13".

 

[LittleSister]

I think you'll find it's stamped on the Identification Plate on the gearbox itself (assuming it's a ZF), below the serial number, etc. - marked M. ADELANTE (ahead) and ATRAS (reverse).

(If hard to access to view the Plate, take a photo of it.)