Alpha one bent prop shaft 40 thou

"so after blowing out a prop,

"so after blowing out a prop, we took boat in for servicing, they found the prop shaft had a bend in it (probably from hitting the rock?) and is out 40 thousandths of an inch.
I know 40 thou is a number almost undetectable to the human eye...
and he wants $500 + labour to fix it.
and we have been driving it for about a week since we blew the prop, with no problems at all.
is this an issue we can put off until the boating season is over? (2 months) so we dont have to have it sit in a shop and dump money into it, and wait and address this in the winter? what are your guys opinions?"

"Sure,........

The Rest of

"Sure,........

The Rest of your Outdrive will probably be Junk by then though.......

That much Wobble will Destroy the Seals in short order......."

"I'm with Bondo; 40 thou i

"I'm with Bondo; 40 thou is a lot.
I read somewhere that 15-20 thou out of straight its recommended to replace the prop shaft.
The concern I would have is what other hidden internal drive damage has been done to cause that amount of bend in the prop shaft. That would have to have been be a serious impact. I suspect that gear cracking is very likely, like we said in your other post.
I think the longer you let it go, the more it will cost you in the end.
Rod"

wel that blows! we're gonn

wel that blows! we're gonna try and run it through our insurance and get a new bottom end.

"<[img]"http://www.marineengin

" ooouullll.....Suddenly I'm not feeling so well. Messed up my prop pretty good, too (as posted in his other thread). Is there any way for me to tell if the shaft is bent when I swap the prop or is that something for the trained professional?"

"Alright, so then to completel

"Alright, so then to completely fix this repair, assuming cracks to gears etc, bent shafts etc. what are ALL the parts you would replace to make this as good as new? I havent taken a drive apart before, which gears are you referring to? could this damage have spread to the upper drive unit, or is it possibly contained in the lower unit?"

"no way to know without disass

"no way to know without disassembling, and inspecting. hence the big price tag. many insurance co.s cover collision damage. rocks count.
aside to Bill. if you can put a dial indcator on it, and get a reading for out of true, and side play, that will tell you. the spec. by the way, is .003"

"I'm with Scott on this on

"I'm with Scott on this one...
"Expect what you inspect."
If you don't look at it, measure, check it, you'll never know the condition.

While we're here, and there's been so much discussion on correct prop sizes, pitches, etc, there's another factor in considering the type of prop to go with. Stainless steel is much more rigid as compared to aluminum. From a performance perspective, stainless is better. From the standpoint of hitting something, aluminum is much more foregiving in terms of drive train damage.
In the cases where you put your boats against the rocks, not sure if it would have made much difference, but here's a tail of two friends:
Friend #1: Honda 250 O/B with SS prop (brass hub) just starting out, not quite on plane, hits a submerged object (never saw it so, don't no what it was, but it's not there now, so it wasn't anything permanant). Damage seen all the way to the crankshaft. About 2 months to get all the parts, and have it fixed. Total bill was over $3500.
Friend #2 (Me!) 5.7L Merc, Alpha 1, aluminum prop (rubber hub) cruising at about 20 knots, hits a log tangled up in lobster trap bouy on a stainless steel cable; the current pulled everything under water, not even a ripple was visible. Two of the three blades were cracked and bent, one had a 1/4" x 1" gouge cut in it from the cable. No damage to the outdrive or engine. New prop and hub kit... $150.
Not preaching one way or the other, just offering it up as something else to consider when you're trying to get every last mph out of your boat."

"Troy
Great point on the All

"Troy
Great point on the Alloy props.
Mark
I am with the other guys, 40 thou is a big bend in a rotating shaft it most certainly would infect the bottom end of the leg in a a very short period of time if it was left untreated.

See if your insurer will spring for a new complete gearbox assembly.

Cheers
Peter C"

Similar experience to Troys. A

Similar experience to Troys. AL props/soft hubs have saved us on two occasions. Submerged piling and flotsam.

"Well, just got back from insp

"Well, just got back from inspecting my boat. I did a masterful job chewing the prop up and managed to take a nice chunk off the skeg to boot.

$$$$$$$

Fortunately my insurance agent says I'm covered after $500."

"any internal damage bill?
we

"any internal damage bill?
we have the same $500 deductible, so we'll see if they'll set us up with a whole new lower (or maybe complete) drive unit.
would hate to have them want to rebuild it, and miss some broken parts in the upper unit.
which leads me to a question....with the bent prop shaft, I understand there would be damage to the gears. are the gears in the lower unit, or upper? if they are located in the lower unit...could there as well be damage in the upper unit? like a chain reaction of damage all the way up?"

"There are gears in both the u

"There are gears in both the upper and lower housings, and yes, they could all be affected.
Chances are the damage will be confined to the lower unit though. The lower gears seem to be the most fragile.
Upper gears are perhaps spared some of the shock loading due to torsion flexing of the vertical shaft, or maybe they are just tougher. Mostly the upper gears fail due to lack of lubrication.
I have never lost an upper gear set in 20 years with several boats, but I have had two lowers pack in due to previous prop strike damage.
Rod"

"Mark -

with how the prop

"Mark -

with how the prop and skeg look I don't see how there couldn't be internal damage. But then, I'm a contingency planner by trade, so I'm always planning for the worst and hoping for the best!

At least what Rod says about the upper probably not being bothered is encouraging.

Good luck with yours, Bro!"

"ok...so with my bent prop, an

"ok...so with my bent prop, and likely damaged gears....we are waiting for an estimator / adjuster from the insurance company to check out the damage (possibly tomorrow) and in the meantime, we have be driving the boat, in anticipation that we're likely going to get a new lower unit.
Mostly all I have been doing is driving it (slow take off, and cruising at about 3000 rpm) to a location, then just shutting it down and swimming. no tubing, or skiing or anything ot put stress on it.
Could this lower unit go at any time? like blow a gear? i have no idea what these outdrives work like, and assuming we're getting a new one, we're just going to keep on driving it. good idea, or bad idea?"

"Mark

( "we have be

"Mark

( "we have be driving the boat, in anticipation that we're likely going to get a new lower unit." )

I dont know that I would be putting any more hours on the drive untill it has been inspected.
If your insurer walks away from the claim you may be causing additional damage to the leg that you may have to pay for.

My suggestion is to park it untill your insurer gives you their decision.

The long and short of it is, that if there is enough damage done internaly it could fail by just putting it into gear once to often.

Cheers
Peter C"