radice folding prop vibration

[jason -and the arguenauts]

This is a duplicate post but I didnt get more than one answer when I attached it to someone else's thread (sorry!) so I'm asking again:

can I ask the owners of Radice folders about vibration

I have a problem that if the boat is going forward at (say) 2knots and the engine is put into reverse, there is a lot of vibration (as if someone was using a percussion hammer on the hull) until I really rev the engine and get the prop fully open. Then its smooth.

Silette reckon that what's happening is that the prop is flapping ie opening to varying degrees as the wash from the boat going forward tries to close the prop and the engine revs try to open it - bit like a performing seal clapping its flippers together. Sounds feasible since the prop is well balanced and vibe free at other times. But it does worry me as Bowman used a grp stern tuibe when they built the boat so I'm nervous about damage.

Anyway, does your Radice do that? And do you have a P bracket or a shaft log?

 

[jason -and the arguenauts]

woops, sorry. put it down to senility. I had forgotten that I posted this question a week ago.

mind you if anyone has any further comments they'd be appreciated.

 

[cowpat]

Folding Radice

I have read all the replys to your last weeks post.Yes it is v anoying to have poor rerformance when you have bought an expensive prop.I have a Radice type and bought it about 3 years before I finished building the boat. when launched the boat was hopelessly underproped and the manufacturers would not take it back even though they agreed that they had made an error in their original sizeing to suit boat. I then increased the diameter of it by adding 2"to the diameter. It did then give good performance (astern acceptable) At my request,they then sent me at reduced price a 3 blade of correct size and wow how the boat performed then.I say all this because any advice would be to change to a 3 blade.However your boat is of lighter displacement than ours and a 3 blade would cause proportionatly more drag as a result. Our boat 17 tons disp.with original folding 22x15,increased to 24x15. Subsiquent three blade 22x14.Kept the folding as a spare and used the 3 blade(25Years)Hope this helps.chris

 

[JAYEL]

Hi Jason, I have a Radice folder on my 28ft Trapper300, which I fitted because of precisely the same problem that I had when the boat was fitted with free moving blades[ not linked by gears]. Perhaps your boat has broken a tooth off the gear so one blade fully extends while the other blade only deploys halfway, thus causing the terrible vibration almost like someone hammering on the rear hull. I grease my folder liberally before lift in and when it is scrubbed off. Had no problem at all with my Radice. The previous vibration with the original folder caused the P bracket to come loose John.