While working feveriously to get the boat winterized for the 1st time (and contorting a body (getting behind engines) that hasn't had this kind of bending in... well.... it's been a while... ). I just happened to look at the starboard tranny/shaft coupling and saw in horror that 1 of the 4 bolts holding the 2 together had FALLEN OUT. Checking further found 2 of the other 3 loose enough to require a couple of turns to tighten to make contact with the coupler. 4th bolt was able to be finger loosened but was still snug against coupling surface. Don't know if this is something that should be regularly checked or the result of poor maintenance by PO's maintenance guy(s).

Ok, disaster averted. But the fact remained that this had occured. And the question is how to keep it from happening again.

--> Has anyone ever considered/used "castle nuts" as a means of ensuring a high vibration connection from separating? They were/are used in the airline industry and in the military extensively (such as on helos). I figured that using these with a cotter pin through a hole drilled in the bolt would ensure no loosening / backout of the bolt.

Thoughts?

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As an aside, the bolts remaining in the coupler have no plastic sleeves which would mean that there's (electical) continuity between the engine and the shaft/props via the bolt heads/washers. That's something to be addressed as well?

... looks like winter's gonna be spent with the boat. Thank heavens for torpedo heaters (boat's parked on the hard at the marina).

Bill

Bill,

BTW Those S.S. 316 nylon-insert hex locknuts can be found @ McMaster -Carr on pg.3182

Norm,

Big s Live on

You can get shoulder bolts - they have a smooth shaft with a smaller thread on the end. The advantage is that you can sleeve them with an insulator like delrin tubing or some such. This takes a shoulder bolt, flatwasher under the head, plastic washer, plastic tubing to fit shoulder, another plastic washer, a flatwasher to fit threads, and an aircraft nut. McMaster.com has all this stuff.

Give me a call, My coupling is disconnected now, and I have the parts.

This thread's taken a turn for the verse, er, ... you know

Disclaimer: The term " ... you know " is a borrowed term and is used only with the acknowledgement to its "coiner" <coinee>, FastJeff.