Bent prop shaft

[jumpjets]

I took my 1990 Wellcraft eclipse out for it's maiden voyage this weekend after finishing a pseudo-restoration. It was my first time ever driving a boat, and my buddy had only slightly more experience than me.

Long story short: upon post-flight inspection, I noticed that the prop shaft seems to be ever-so-slightly bent. When I spin the prop by hand, I notice that the prop spins in slight eccentric circles. If the prop shaft is bent, it's by less than 5mm; most likely its about 3mm. It's very very slight.

Is that something that I need to have repaired right away? It is going to vibrate the drive apart over time? Will a drive failure of that type cause me to sink?

 

[picklenjim]

Re: Bent prop shaft

I don't know where you are taking your measurement at but the prop shaft is supposed to be with in .010". 3mm is almost 1/8th of an inch. or .125". If you really think it is that much you should remove the prop and put a dial indicator against the shaft and turn it to find out.

 

[dn010]

Re: Bent prop shaft

What drive do you have

 

[jumpjets]

Re: Bent prop shaft

I don't know where you are taking your measurement at but the prop shaft is supposed to be with in .010". 3mm is almost 1/8th of an inch. or .125". If you really think it is that much you should remove the prop and put a dial indicator against the shaft and turn it to find out.

I was just spinning it with my hand and visually checking the trailing edge of the prop. I can definatley remove the prop and mic it, to see what the actual tolerance is. If it is out of limits, how much work/money is it to replace?

What drive do you have

Good question? It's a 1990 merc 5.7L with an alpha one drive. Is that a Gen one or gen II?

 

[Silverbullet555]

Re: Bent prop shaft

Before assuming the prop shaft is bent measure the runout of the shaft itself. The prop hub could be bent, the hub could be pressed in slightly off center, etc.

 

[Bondo]

Re: Bent prop shaft

It's a 1990 merc 5.7L with an alpha one drive. Is that a Gen one or gen II?

Ayuh,... 1990 Should be an Alpha 1...

 

[Brentathon]

Re: Bent prop shaft

Ayuh,... 1990 Should be an Alpha 1...

I think he meant should be a "Gen I".

 

[Bondo]

Re: Bent prop shaft

I think he meant should be a "Gen I".

Ayuh,... There is Alpha 1, 'n Alpha 1, Gen.II....

There is No Alpha 1, Gen.I....

 

[Brentathon]

Re: Bent prop shaft

Yes, you're right.........of course.
I just think it's more clear to specify the fictitious "Gen I", to clarify it's not a Gen II (in response to his question).
Maybe Merc could have named the Gen II's "Alpha 1.5"?

 

[jumpjets]

Re: Bent prop shaft

Yes, you're right.........of course.
I just think it's more clear to specify the fictitious "Gen I", to clarify it's not a Gen II (in response to his question).
Maybe Merc could have named the Gen II's "Alpha 1.5"?

That would also confuse me, since I have "1.5" stamped on the side of my drive!

 

[cr2k]

Re: Bent prop shaft

1.5 is the gear ratio. The absence of GEN II indicates Alpha one.