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!

Forward to Reverse Bent Prop


Recommended Posts

I was out this weekend with my wife driving the boat. She was not paying close attention and passed me by when picking me up after a run. She was driving forward at idle speed or slightly above when she noticed she had passed me. Next she did something I that I couldn't believe. She slammed the boat in reverse at a very high throttle rate. The boat could have been going as fast a 15 mph in reverse. I got into the drivers seat to check it and sure enough, the dreaded vibration. When I took the boat out of the water the prop was bent on 2 of the 3 blades. I have a spare prop and I am going to install and water test the boat. My questions are, 1. Do I need to buy a new key for the prop/shaft or can I reuse the current key? 2. Do I need to buy a new prop shaft nut or can I use the current one? 3. What torque setting do I set the nut to? And last what indications am I looking for (vibration aside) that there is not further damage to the rest of the driveline? I am new to the forum world so please forgive me if this improperly posted or in the wrong format. B.T.W. the boat is a 2004 Malibu Response LXI with a Monsoon 340.

Link to comment

Most likely the rudder got pulled into the prop causing the damage. This can happen if you go hard into reverse with the wheel turned all the way to one side or the other.

Use the current key unless it is really worn.

Use the current nut.

Just get the nut tight onto the shaft. Use a block of wood to block the blades from turning as you tighten the nut. Also make sure you replace the cotter pin. You may need to replace this as they do break after being bent and unbent.

I would just put on the new prop and run the boat to feel for any vibrations. If you don't feel any, then you should be good to go. It would be very unlikely that you have any shaft damage with just a few bends on the prop blades and no other underwater gear damage.

Link to comment
Most likely the rudder got pulled into the prop causing the damage. This can happen if you go hard into reverse with the wheel turned all the way to one side or the other.

Use the current key unless it is really worn.

Use the current nut.

Just get the nut tight onto the shaft. Use a block of wood to block the blades from turning as you tighten the nut. Also make sure you replace the cotter pin. You may need to replace this as they do break after being bent and unbent.

I would just put on the new prop and run the boat to feel for any vibrations. If you don't feel any, then you should be good to go. It would be very unlikely that you have any shaft damage with just a few bends on the prop blades and no other underwater gear damage.

Thank You for the fast response. I have to drive 50 miles Round trip for the parts(if i needed them) and 100 miles round trip in the opposite direction just to get the boat to water so it is nice to have access to good people with good info.

Link to comment
forget buying a new key and nut, just buy a new wife!

I gave that a hard thought but the economy is not in my favor. I'll have to see how the rest of the year shapes up.

Link to comment
If you have a stainless steel nut make sure you use anti-seize or you could be in all sorts of trouble!

-Chris

Good tip. I think i should be set the shaft is SS but the Nut is Brass or Nibral with a nylon liner for lock.

Link to comment

Water tested today and it was silky. Only damage was to the prop and all is good again. As a side note I am not convinced that the prop came in contact with the rudder or any other object. Not a single nick or telltale sign on either of them. I spoke with a boat mechanic today who said he saw the same thing about 5 yrs ago on a sportster. Either way I am very happy and thanks for the info everyone.

Link to comment

I can't imagine how a prop would get bent purely because of high throttle in reverse. I'm not mathematician but suspect the forces during normal high rpm & high speed use would be way way higher than high throttle low speed. It had to have hit the rudder.

Link to comment
I can't imagine how a prop would get bent purely because of high throttle in reverse. I'm not mathematician but suspect the forces during normal high rpm & high speed use would be way way higher than high throttle low speed. It had to have hit the rudder.

If it hit the rudder then it should still be bent, those things can not bend that much and come back to normal position Whistling.gif

Link to comment

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.

×
×
  • Create New...