Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Sign in to follow this  
tccombs

Warning..please read

Recommended Posts

REW

Never have heard of this, I'll be checking.

Share this post


Link to post
GreenMan

I would be confident that this would only occur if there was some contaminant (sand etc) or a tuft of metal sticking out caught between the prop and shaft taper surfaces when the prop is installed. Such items can subsequently crush, work loose etc leaving a loose fit.

A neat, clean fit between properly machined tapers that are pulled together firmly with the retaining nut should remain tight.

I guess the ACME people are the most experienced experts but I've never heard of it.

Many, if not most of us, have changed at least one prop. I've done a bunch of them on several boats. Each one was fitted and tightened once and when it was time to remove it later, it sure needed some 'encouragement' to break it free from the shaft.

Share this post


Link to post
nutoz

I think this is a similar action as called "transient torque" in rotating shaft or electric motors. Where a electric power is interrupted in mili seconds then full power is reapplied. Causing a torque of up to 6 x normal on shaft causing breakages is what I have been told. So with a slight loose fit of the prop and internal combustion engine , I could see that but I believe manual calls for 30-40 ft lbs of torque on the shaft nut..I think the shaft key would shear first..???My 2cents. As long as prop is on tight,I do not see an issue. With that I am going to check my nuts

Share this post


Link to post
tccombs

I would have agreed until it happened to me... I've changed my share of props.. but this was a first.

Share this post


Link to post
TURNITRED

very informative post. Thanks for the info. Sorry that happend to your boat

Share this post


Link to post
TallRedRider

I think it would be hard to not have the prop mated tightly to the shaft with 40 pounds of pressure on it. IIRC 40 pounds is what they call for.

Share this post


Link to post
tvano

added a check of the prop nut to my annual lay-up proc

Share this post


Link to post
Punyelroo

Interesting post as it was only last weekend I went to change my prop and the nut on the existing one was not tight !!

Not sure how long its been like that....

:surprised:

Share this post


Link to post
GreenMan

I for one, am checking my nuts right now. If my shaft broke and fell off I would be quite sad.

Yes, you could be left somewhat idle with no means of thrust.

And someone might be pining that don't impress me much...

Edited by GreenMan

Share this post


Link to post
85 Barefoot

And someone might be pining that don't impress me much...

I like what you did there

Share this post


Link to post
saidainc

If this thread gets shut down, its Baddogs fault....

Share this post


Link to post
Baddog

If this thread gets shut down, its Baddogs fault....

How can a frank discussion of loss of propulsion be objectionable?

Share this post


Link to post
Woodski

The key can also be a cause for the prop not to mate to the taper on the shaft. The key can ride up in the slot thus keeping the prop from a proper seating, always check for that possibility.

Share this post


Link to post
JasonK

I got in some deep muck last week and now have a vibration. Figured it was just mud or the strut bushing. Maybe my prop is loose too. Thanks for the heads-up.

Share this post


Link to post
John I.

As the result of a recent discussion here about engine alignment and how freely the prop should spin by hand, I decided to check mine. Grabbed the prop, and it wobbled noticeably! I assumed something had happened to the shaft key, but when I put the wrench on the prop nut to remove it I was shocked to find that it was already loose by about afull turn. Same prop, nut, and cotter pin have been in place for many years.

Share this post


Link to post
saidainc

next you are going to tell us the key to a healthy shaft is to have a female mechanic inspect your nuts?

Share this post


Link to post
MLA

Not uncommon to have the newly installed prop not full seat on the tapered shaft. The worst ive seen from this is a buggered key.

Share this post


Link to post
oldjeep

Well, thanks for the warning. Poked my head under the boat and what did I see - a gap. Odd since I've never under tightened anything in my life.

post-22501-0-47709000-1443637567_thumb.j

Share this post


Link to post
Ndawg12

Well, thanks for the warning. Poked my head under the boat and what did I see - a gap. Odd since I've never under tightened anything in my life.

attachicon.gifWP_20150930_002.jpg

So did it snug up?

Share this post


Link to post
Baddog

Well, thanks for the warning. Poked my head under the boat and what did I see - a gap. Odd since I've never under tightened anything in my life.

attachicon.gifWP_20150930_002.jpg

That gap is typical. It is a tapered shaft and the prop will only go so far onto it. If the prop was in contact with the cutlass you would have metal rubbing on metal and that is a really bad thing. Almost as bad as when your shaft is broken and falls off.

Share this post


Link to post
oldjeep

So did it snug up?

I tightened it up as well as I could but didn't have a 2x4 chunk handy so I need to try again later. Prop didn't seem to move at all. The nut spun pretty easy - one of the reasons I hate nylocks.

That prop has about 75 hours on it since installed.

Share this post


Link to post
oldjeep

That gap is typical. It is a tapered shaft and the prop will only go so far onto it. If the prop was in contact with the cutlass you would have metal rubbing on metal and that is a really bad thing. Almost as bad as when your shaft is broken and falls off.

Talking about the air between the nut and the prop - the one that you could just about stick a dime in.

post-22501-0-51727300-1443639100_thumb.j

Edited by oldjeep

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...