Have I got a problem ?

[billmacfarlane]

Thanks

Thanks for all your replies guys. I've had a word with both the agents who sold me the boat and the Kiwi prop people. I simply asked SD Marine, the boat agents, what speed I should do at 2500 rpm and quick as a flash he said 5.3 knots. The Kiwi prop is about 05. knots slower than the standard 3 bladed Volvo folding prop. Vectra Marine, the Kiwi prop people, had my prop set up on their records and suggested tweaking the pitch by 1 degree which should give the prop a bit more bite. I'm out on Friday and I'll do the prop then. We'll see what happens after that.

 

[lucresai]

have i got a problem

Your problem is the KIWI prop.they advertise this as acceptable.However we had similar problems and difficulties going up river and going down river the current was stronger as we could make in reverse to stop.
with lots of manouvring we also broke our demper plate after 6 months resulting in gearbox removal to exces. I wonder wich insurance company will at the end accept a prop wich can not produce simmilar to fixed props or better.

 

[michael_w]

I think you've got a prop problem. My old Contessa 33, 4.5 tons and 18hp would cruise at 6kts at 2200 RPM. The prop was a Gori 2 bladed folder. Flat out she'd nudge 7.2 Kts. Sweet Rob Humpheys design helped!

Current boat 37ft, short overhangs, 7 tons and 31 ponies on tap cruises at 6.3 at 2100 RPM and max 7.4, through a 3 bladed Maxprop.