42 searay broken shaft

Lapping is the only way to ensure that the contact between the hub and shaft tapers is reaching the maximum level to 100%.

If your yard is not doing or offering this, they are cutting corners and taking the easy way out..............

Not to mention it's really easy to do. Just put the prop on with valve grinding compound without the keyway on the shaft, put the nut on most of the way by hand and spin the prop around about 30 revolutions. Remove, clean, install keyway, prop, nuts, cotter pin and you're on your way. The big props are a pain to do because of the sheer weight of them.

Hi,

Here is a good set of pics of how to do this properly and to check what you've done.

Lap Fitting A Propeller To A Shaft Photo Gallery by Compass Marine at pbase.com

Hi,

As the failure seems to have been right at the end of the keyway this location might have been a good contributing factor if the keyway was not well finished in the first place.

Has your friend owned and operated the vessel for all 18 yrs and never had any incident with hitting something or grounding?

Hi,

This might explain why the nut was not entirely super tight.

Ill fit on the taper and a bit of out of balance could easily cause the wheel to wobble back and forth however many times per minute that it rotates at and a stress raiser/weakpoint at the end of the keyway easily caused by a chip in the mill tool that cut it could have started the whole story.

Was this the same side he lost the wheel off 3 yrs ago or the other side?

When the wheels come back from being reconditioned the keyway is very slightly rolled in on the bigger bore. I assume it's caused when they set the wheel on a mandrel and pitch block. It just takes a couple of passes with a file to insure that the key slides freely through the wheel. We had a piece of a shaft like that on the sales counter for years. It had broken all the way around and flopped like hell but the two pieces wouldn't come apart. I thought when part of the break is dull and part is shiny then it was cracked for a while, but I'm not a metallurgist.

Is the shaft the correct diameter and alloy for the boat and engine combination? From the tape it looks like less than 2" and with about 400 Hp per side ----??

If of marginal diameter or alloy, any poor fit of key or prop may be the straw that broke the camels back.

To me, when I hear the same shaft broke again 6 years later (and neither due to a strike), I have to wonder about a constant stress like allignment. As for SR build quaity, I've always felt that they're built with about a 10 year lifespan in mind. They expect their customer to trade up within about 3 years or sooner. So getting through warranty is all that matters. Like most things today, they're not built to take whatever comes at them. Instead it's more what's the minimum standard we can get way with. They could use a beefier shaft, but why? That would just take away from profits, and their buyers would never know the difference except in the purchase price. For many of their customers their previous boat was a car.

I have managed/maintained many older searays and currently manage/maintain 2-50' Searays a 1991 and a 1998 and they both have held up exceptionally well and have no inherent issues and have faired much better than many of the competitors in their class.

I think one can only judge a boat manufacturer or any manufacturer against their targeted use and purpose. On that basis, I think Sea Ray has a solid history. Yes, like any, they've had occasional issues, but they would have more just based on their volume. Their business was built on lake and river usage. Then some of that carried over to coastal cruising. My first two boats owned in my life were both small Sea Rays and I never had problems with either one. While they would be inappropriate for an Atlantic crossing, I'm trying to imagine a 99 meter Feadship on the lake. Other than not being able to go under any bridges, running aground regularly, not being able to turn around in any coves, having nowhere to dock, and no one having the ability to haul it out or service it, it would have looked cool I guess.