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I repeat quadruple redundancy, taper plus 2 nuts plus cotter pin. IMO does not really make any difference, But I would go with big nut, little nut as jam and cotter pin and would forget it. If one is really worried use two big nuts the second one castellated and cotter pin.
after that weld it on!
Larry Eddington
1984 F-36 Tri Cabin "The Phoenix II"
1978 F-28 "The Phoenix"
Fish Master 2350 Bay Boat
9.5' Dink
I agree with Commissionpoint on this one. I didn't go to Clarkson, but the University of Massachusetts teaches the same thing. The large nut keeps the propeller on the shaft, the small nut keeps the large nut from loosening. Keeping the propeller on the shaft requires more strength than keeping a nut from loosening, so the large nut is used first.
1993 Sea Ray 200 Overnighter OB with 1993 Mercury 150 hp Outboard
1979 Starcraft 14' Rowboat with 2011 Mercury 9.9 hp Outboard
Former boat: 1971 Trojan F26
You are the Prop and you are on a shaft. We are turning you in a direction that you have to fight against to make my 17000 lb boat go forward. You being the prop will naturally want to climb up my shaft to avoid work. To keep you from avoiding work I will put a big nut on my shaft so you cant climb my shaft. And just to make sure I will put a smaller nut on my shaft to help the big nut keep you from climbing my shaft.
There you have it folks...
Big nut closest to the prop narrower nut helping the thick nut stay in place.
Barry
I love my boat! It takes all of my money and doesn't bitch.
prowlersfish wrote:....After lapping in the prop , I install the prop using the big nut and tighten . I then remove it install the small nut retighten and install the large nut .
++1
Wow, somebody that does it right!
Small is left on first and large last. Tightening the large nut on the jam nut slightly distorts it jamming the threads. Having said that, walk through any marina and 90% of these are reversed in practice. I'm okay with that because I like getting paid to correct the results.
She was a 1969 36 ft wooden beauty with big blue 440s that we'll miss forever.
And thanks to the gang, 2012 Trojan Boater Of The Year
prowlersfish wrote:....After lapping in the prop , I install the prop using the big nut and tighten . I then remove it install the small nut retighten and install the large nut .
++1
Wow, somebody that does it right!
Small is left on first and large last. Tightening the large nut on the jam nut slightly distorts it jamming the threads. Having said that, walk through any marina and 90% of these are reversed in practice. I'm okay with that because I like getting paid to correct the results.
In the case of a propeller, small nut first. Tightening the back nut last will remove some of the applied retaining force from the threads of the front nut. That being said, the rear nut will be carrying the bulk of the load which is why it makes sense to have the larger nut at the back.
The idea of using the large nut to seat the taper and then switch it out is a good one.
Paul
"Cruise Control" 1978 F-26HT
"No Control" 2012 9' Grand RIB