Quieting Boats down

[oldlugs]

....Duane, Those couplings are for use with a solid 1/4 shaft supported in bearings. You can't use them with a flexi shaft because the unsupported part of the coupling will immediately run out of true and destroy the shaft system and the probably the boat hull too. Dave

Thanks Dave. Is there any reason that a flex cable can't be supported in bearings close to the engine, allowing one of thise rubber couplers to be used...? I'm thinking for .21 size boats, not those with big, high torque engines. It's not that hard to solder bearings into the end of a brass tube, and I think up to about an inch or so of unsupported flex cable between the bearing and engine coupler shouldn't hurt anything...(?) Just trying to think of a few ways to help make 'em quieter... That's what this thread is supposed to discuss; right...?

Duane

 

[Joe_Knesek]

Duane I think the noise comes from the tube resting on the hull which causes the hull to resonate. I don't think the Lord mount would hold up even on a 21. You may look at some of the 3 lug couplers that use a spider bushing.

I'll post a few shots of the mount I made for my 40 mono which keeps the tube off the bottom of the hull. It's all made of graphite and it allows the tube to float if the shaft has any runout.

 

[DaveMarles]

Joe, Duane,

Those couplings do not break. I have used a 25mm diameter one on my 7 hp Zenoah for 2 years. Its old technology over here.

For a flexishaft maybe its better to fix the front part of the tube into the boat with silicone RTV.

Dave