Correct propeller for Bavaria 30 CR

[Robbo]

My Bavaria 30 Cruiser seems to struggle a little under motor. I have a Volvo Penta MD2020 motor and it only does about 4.5 knots under power at 3200 rpm. I have a four blade folding prop on the Volvo Penta sea leg. Wondering if anybody has the details of their propeller on the same configuration that provides a better performance?

[Matay]

I hope this helps

[sunshine]

I still have the factory 2 blade on by C30 and she'll do 6kts at 3000 revs, even with a bit of growth on the bottom. Volvo D1-20 19hp but much the same as 2020.
Is your prop definitely opening up fully? To only get 4.5kts at max revs means its either been mis-specced or isn't unfolding fully.

[Symphony]

The list posted above shows the correct propeller is a 15*11 2 blade fixed. This works very well and you should get around 6.5 knots at 3500 rpm and cruise at 5.5 knots at 2500 rpm. There really is no need for a 4 bladed propeller but without knowing the design it is impossible to say what size it should be. Find out who made the propeller and ask them for their recommendation for size.

You boat was made at the time when engines were changing from the MD 20X0 design to the DI series and the saldrive from 120 type to 130, and some were made with the older engine mated to the newer saildrive. There is conflicting information as to what gearbox ratio was fitted in this situation as the 120 drive was normally 2.47 and the 130 is 2.19. This reflects the fact that the new engine revs to 3200 rather than 3600 rpm. The effect is that the shaft speed stays the same. However if a 2020 is mated with a 2.19 the shaft speed rises meaning you need a different size propeller.

So it is worth checking exactly which reduction ratio you have.