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Old 11-01-2016, 02:45 PM   #21
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Pgitug - I don't think a spare shaft and prop is really necessary on a Nordic Tug. First, your prop is very protected, so little worry of hitting something. Second, I don't think you could change the shaft in the water. If your boat is like ours, you would need to drop the rudder or cut a hole in it in order to change out the shaft. Third, if you have a PSS seal like we do, there is a hose that pushes raw water through the cutlass bearings that keeps everything cool, and also prevents stagnant water. Finally, I have no idea where you would be able to store an extra shaft. I think ours is at least 10 feet, and yours would be a little longer. Finally, I've scoured the SENTOA owners forum archives and never saw a single instance of a shaft breaking on a NT. Possible, yes, probable on a well maintained boat, very unlikely. Just keep your towing insurance paid up.
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Old 11-01-2016, 04:43 PM   #22
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I carry spare props and tailshafts because I have them. Shafts are monel. Because my boat was built 70 years ago, any new shaft would be custom built. Tailshafts make good ballast and weigh enough that two men can barely lift one.
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Old 11-01-2016, 04:55 PM   #23
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Quote:
Originally Posted by Bacchus View Post
Sometimes it's useful to have contacts in large corporations with lots of technical expertise.

Here's the summary of a metallurgical analysis done on a failed SS shaft.
I would have guessed crevice corrosion was the culprit but the metallurgist ruled fatigue.
The shaft in the picture is made of 304 SS, not the recommended grade of SS for a higher speed vessel like the SeaRay. CMS summarized potential shafting issues succinctly. Not all shaft failures are due to CC, possibly very few.
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Old 11-01-2016, 07:13 PM   #24
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Quote:
Originally Posted by Carolena View Post
Pgitug - I don't think a spare shaft and prop is really necessary on a Nordic Tug. First, your prop is very protected, so little worry of hitting something. Second, I don't think you could change the shaft in the water. If your boat is like ours, you would need to drop the rudder or cut a hole in it in order to change out the shaft. Third, if you have a PSS seal like we do, there is a hose that pushes raw water through the cutlass bearings that keeps everything cool, and also prevents stagnant water. Finally, I have no idea where you would be able to store an extra shaft. I think ours is at least 10 feet, and yours would be a little longer. Finally, I've scoured the SENTOA owners forum archives and never saw a single instance of a shaft breaking on a NT. Possible, yes, probable on a well maintained boat, very unlikely. Just keep your towing insurance paid up.

Valid points.
My friend had a 30' Mainship. I am guessing some kind of corrosion on the shaft. He doesn't think he hit anything in the water at the time of the failure. Rudder looked fine except for a ding caused by the loose prop.
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Old 11-01-2016, 08:09 PM   #25
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Shoalwaters.
PVC tube with end screw caps can be cut to length and filled with old shot blast, sealed and glassed into position to correct listing or as ballast.
Insequent.
A handy wee tip.
If you use 2 hammers, give the prop base a sharp tap with both hammers simultaneously from opposite sides, rotate the prop and repeat, it will just pop loose. No need for prop pullers.
Just helpin..
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Old 11-01-2016, 09:36 PM   #26
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A friend has 2 spare props for his sportfish. He used them to create a really good looking base for a round salon table. One is on top of the other with a stained dowel through them and a nice top supported by the dowel. Looks great.
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Old 11-02-2016, 07:20 AM   #27
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Shoalwaters.
PVC tube with end screw caps can be cut to length and filled with old shot blast, sealed and glassed into position to correct listing or as ballast.
Insequent.
A handy wee tip.
If you use 2 hammers, give the prop base a sharp tap with both hammers simultaneously from opposite sides, rotate the prop and repeat, it will just pop loose. No need for prop pullers.
Just helpin..

I just hate the idea of banging hard into the transmission gears.
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Old 11-02-2016, 07:49 AM   #28
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Greetings,
Mr. P. I think Mr. IR is suggesting you simultaneously bang at right angles to the prop shaft on either side of the prop hub thus applying a percussive force that really should not be transmitted into the drive train. Whether or not one can get a good "swing" on a 3 blade prop is another thing. A 4 blade should afford a bit more room.
Now, I banging on the front or back of the prop hub will most certainly transmit forces into the transmission gears.
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Old 11-02-2016, 11:05 AM   #29
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Bang on Firefly, pun intended.
Obviously at right angles.
Were talking sharp taps here, rotate the prop, couple of sharp taps, rotate again, etc. and it'll just pop loose. No need for Redneck wallops..
After all it's your girlfriend, so treat her gently.
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Old 11-02-2016, 01:21 PM   #30
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Not sure if I am following you Cap'n??? I don't know if you read my entire post. But the shafts were almost gone....hence the "no surprise" when they finally did fail....if that is what you were getting at.
I was just thinking that it had to be at least a bit of a surprise to the person operating the boat at the time.
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Old 11-02-2016, 07:39 PM   #31
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I was just thinking that it had to be at least a bit of a surprise to the person operating the boat at the time.
Yes, I bet, but not as much of a ghastly surprise as I saw on the face of a newcomer to our marina the other day when I was down there. They had this new (to them) twin Bayliner, and were clearly a bit unfamiliar with driving a twin, and he was trying to back into the berth, as they feel they must if they have a twin for some reason. Anyway...to flick the stern to the right to clear the end of his finger, which was to the left of his stern, he put on too much reverse power to the port engine, and not opposed by putting the starboard engine in forward thrust, and it shot back and crashed into the stern of the boat in the adjacent berth. No major damage was done, and to his credit he reported it. (I checked)
I note he now cruises gently in bow first and with no dramas, just like most now do in our marina, as the fingers are plenty long enough for boarding by the swimstep.

Sorry, thread hijack over...
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Old 11-02-2016, 08:19 PM   #32
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Prop shaft failures

Just in case you want to think about a different very possible answer as to "why"....................................For the past 30 years dealing with these "unknown failures" this is what we have seen most shaft failures result from right at the beginning of the taper ........A poor install of the prop and key and /or keyway / proper fitting, it eventually comes loose, and the results are obvious.......I will offer one more thing to think about-- I am a very a qualified engineer & machinist and understand this stuff from "top to bottom", both on paper and in the field.

Take that for what s it's worth..


Tony
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Old 11-03-2016, 12:52 AM   #33
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I was just thinking that it had to be at least a bit of a surprise to the person operating the boat at the time.
Yeah it was. It was that girl captain again....haha. She recovered well and just jammed the thing into the slip bow first.
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