Prop damage, and more???

[strokeoluck]

I have three main questions: 1) what happened?; 2) how do I remove this prop?, and 3) can this prop be salvaged?

Long story, but I think I did two bad things to my prop and/or engine today. First, we were going slow through a channel and hit "something". I still don't know what we hit but it was a good solid thud on the lower unit. About 50 yards later I tried to open it up a bit and it felt/sounded like I had seaweed on my prop (high rpm, very little movement), even though I was pretty sure I had a prop issue. We moved slowly to some shallower water where I hopped out and checked out the prop. Sure enough, it was pretty chewed up (see pic below; this was a new prop - had seen water 3x). I had a spare prop with me, but my utility tool wasn't big enough to get around the nut to loosen it (yes, lesson learned). I already had the wife in the boat along w/my son and his buddy and all our stuff, so I decided to just slowly make our way to the beach and have a little fun. After all, at that time I figured it was just a heavily beat up prop but we still had power. There would be no tubing, but we could move.

Fast forward 90 minutes, I drop my wife off at the dock so she can take off and I head back out the channel to the lake to take the kids back to the beach. As we approach the beach I see a fisherman working on his outboard so I pull up and ask if he needs help. He does, so I haul him about 200 yards over to a dock in some very shallow water (only other option would be to haul him back through the long channel and I didn't want to leave the young'uns out of eyesight that long; they asked to be left at the beach). I cut him loose early enough, but by the time I get done screwing around w/unhooking the rope the wind had pushed me into the really shallow stuff. I raised the lower unit a bit and tried to gently power my way out of there, but the lower unit was in the muck and I know I stirred up some of the muck before I shut off the engine. The fisherman was kind enough to give me a shove out and I fired her up again and motored out carefully, again w/the drive somewhat raised (yes I know this is not good for the unit, but I don't know what other choice I had short of walking the boat out 100 yards in muck, and into the wind). I make my way over to the beach area and drop anchors and wait for the kids.

Fast forward 45 minutes and we start to head back to the channel to head home. I can't get her above 1300 - 1400 rpms or I get that same "seaweed wrapped around prop" feeling/sound. I stop several times and pull a bunch of seaweed off the prop. I'm still feeling like it's just a beat up prop, and seaweed. Because I have power, and no odd sounds, engine is not overheating, etc. But the fourth time I hit the gas a bit and we don't move; hit it again and don't move. I shut her down and go back to pull weeds off the prop and...there are no weeds. A few more tries but no luck, we ain't moving. So we drop anchor again until someone comes over to tow us to the dock.

My questions (sorry for the long message, but I felt the info was important):
1) any ideas re: what happened here? Why did I lose power? And what do you think I should do about it? My son thinks I should just replace the prop and give her another shot in our local pond/lake. Then again, he's just 9 years old.
2) how do I remove this prop? I loosened the tabs on the "cotter pin" star shaped thing around the nut, but when I go to turn the nut counter-clockwise the threaded bolt turns with it (???), so it doesn't come loose.
3) can this prop be salvaged?

Thanks everyone.

 

[TimBobCom]

Re: Prop damage, and more???

Is the entire prop spinning or just the shaft?

If it's the prop, use a small length of 2X4 between the cavitation plate and the propellor to stop the spinning. If it is just the shaft, you have done some internal damage, I'd be talking to mechanics.

 

[ralphy670]

Re: Prop damage, and more???

is the prop turning with the shaft when you are turning it?

 

[crxess]

Re: Prop damage, and more???

You have spun the prop. Center is loose.

place the motor in forward.
Get a short 2x4
Place the socket wrench on the nut Handle straight up.
Rotate left while placinig the 2x4 between the prop and lower unit.(this holds the prop still)
Now, Smack the ratchet handle HARD with a heavy hammer.

If all goes well, the nut will loosen enough to thread off.

Prop can be sent to a prop shop and rebuilt. Replacements off Ebay are about as cheap.

 

[strokeoluck]

Re: Prop damage, and more???

Is the entire prop spinning or just the shaft?

If it's the prop, use a small length of 2X4 between the cavitation plate and the propellor to stop the spinning. If it is just the shaft, you have done some internal damage, I'd be talking to mechanics.

When I attempt to turn the prop nut I'm bracing my leg against the blades of the prop. When I do that - and keep the prop from moving - and I turn the nut counter-clockwise, that's when the shaft turns w/the nut.

 

[Frank Acampora]

Re: Prop damage, and more???

With the constant use of a "spun" propeller, the condition gets worse. Spinning a prop hub refers to the rubber insert wearing or breaking down so it no longer has enough friction with the prop to drive the boat. Usually it first manifests itself at higher power setting and progressivly worsens.

By constantly causing the prop to break free of the rubber, you "spun" the hub so badly that there is no longer enough friction between the rubber insert and the prop to back off the nut. You don't have too many choices.

Put the engine in forward gear and turn the prop the wrong way to set the drive dogs against each other. Bend up the locking tabs on the star washer. Now, put a deep socket over the nut. With a rubber mallet, smack the driver a really good shot. Hopefully the engine resistance will be enough so that the nut breaks free.

While it is admirable that you were a good samaritan, remember that your first duty is to your family and rig. I personally have no qualms about towing a fellow boater in distress and will do it without thinking twice, HOWEVER: Knowing you were having engine problems, you were negligent in towing the other boater. If you lost complete power, then there would be two of you to "rescue" Didn't think of that, did you?

 

[strokeoluck]

Re: Prop damage, and more???

With the constant use of a "spun" propeller, the condition gets worse. Spinning a prop hub refers to the rubber insert wearing or breaking down so it no longer has enough friction with the prop to drive the boat.

Thanks! I'm still learning, so forgive any stupid follow-up questions. But what caused the "spun prop" in the first place? Was it the initial jolt when we hit the submerged thing? My simple brain is assuming that the main drive is being powered (spun) by the engine and transferring that power to the shaft of the propeller. When I hit the item the resistance stopped the actual prop momentarily, while the shaft continued to spin under power...so what had to "give" was this rubber insert?

By constantly causing the prop to break free of the rubber, you "spun" the hub so badly that there is no longer enough friction between the rubber insert and the prop to back off the nut. You don't have too many choices.

If I can replace the prop, am I good to go? Is it safe to assume I didn't do any other damage? Or do I also need to change the rubber insert? I have a replacement prop that's in great shape, but I haven't spent much time inspecting the inside of it. The only thing I noticed that was interesting about this new prop (well, it was a rebuilt; the owner gave me a beat up spare and I sent it in to be repaired) was that it had a metal-like silvery/grainy "stuff" slathered on the inside shaft of the prop.

HOWEVER: Knowing you were having engine problems, you were negligent in towing the other boater. If you lost complete power, then there would be two of you to "rescue" Didn't think of that, did you?

Ahhhh no. Why do I suddenly feel like I'm 7 years old and talking to my Dad?! It's a very good point. Trust me, I'm learning something new every day. On a side note, the boat that towed me in was a newer - and VERY nice - Malibu ski boat. There were two teenagers driving it (obviously Daddy's boat). They were so darn concerned about heading into shallow water w/their boat that I had to tie two lines together and drag my boat out to them and then toss them a line. Too funny. They have obviously been taught better lessons than me! And boy did that boat purr like a kitten; it sounded beautiful.

 

[MikDee]

Re: Prop damage, and more???

You probably did no other damage, thanks to the ribber bushing in the prop. The center hub, and rubber insert are professionally pressed into the prop,,, basically you are running on the friction between them at all times, and they are pretty sturdy, until overly abused. Your better off getting a new prop at this point, I think a Turning Point Hustler is the Best aluminum prop out there! and you can get it here at iboats for under $100 lately (a bargain).

But, if you ran the engine in the muck, you should check out your cooling system for muck, it sometimes comes in through the side screens by the water pump of the drive, maybe a backflush with a garden hose is in order.

The inside of the spare prop, probably had a (metallic) graphite type grease to keep it lubed on the shaft.

Those "inboard" ski boats, have a rudder, prop, & driveshaft, deeper under the boat, that's not very forgiving if it hits bottom, so they are more concerned then you. Yeah, you were mesmerized by that powerful smooth V8 sound

 

[strokeoluck]

Re: Prop damage, and more???

Ok, thanks guys. I'll see what I can do tomorrow. I have most of the weekend free and it's supposed to be pretty crappy weather here in the Twin Cities over the weekend. You'll likely see some follow up questions so stay tuned. Thanks again.

 

[MikDee]

Re: Prop damage, and more???

You have spun the prop. Center is loose.

place the motor in forward
Get a short 2x4
Place the socket wrench on the nut Handle straight up.
Rotate left while placinig the 2x4 between the prop and lower unit.(this holds the prop still)
Now, Smack the ratchet handle HARD with a heavy hammer.

If all goes well, the nut will loosen enough to thread off.

Prop can be sent to a prop shop and rebuilt. Replacements off Ebay are about as cheap.

Just do this, but maybe you can just yank on the wrench till it starts to come loose,,, or to help, put a small piece of pipe on the wrench as a lever, or do whatever you need to, to get it off.

 

[strokeoluck]

Re: Prop damage, and more???

Ok, I discovered that I don't have a deep well socket big enough to bit over the prop nut. I'm running to Northern Tools this morning to get a bigger set/socket.

Follow up question for you guys. Should I have the drive unit all the way down before I start rapping on the nut?...or can I leave it up (easier on my knees!).

 

[MikDee]

Re: Prop damage, and more???

I would say you could leave it up, the nut shouldn't be that tight (famous last words ) When putting it on, I guess you can torque it down, But I usually just grab the prop with a heavy glove, and tighten it as tight as I can, while holding it back with the gloved hand. Once you put the cup washer on, and line up the tabs to bend down, it will help lock it to the shaft anyway.

 

[crxess]

Re: Prop damage, and more???

If it won't pop loose find a friend with a compressor and impact wrench. One good pull of the trigger will remove the nut and your back in business.

I didn't see anyone mention it, but you will need to check the output shaft for out of round once have the new prop on.

Place a flat blade screwdriver very close to the edge of the prop cone. In neutral, have someone turn the prop. The gap should remain extremely close. No out of found movement.

A hard hit can bend the output shaft and hasten hub failure, internal gaer damage, seal failure.

 

[strokeoluck]

Re: Prop damage, and more???

Ok, some good news. I got the right socket from Northern Tool and managed to get the nut off (wasn't as challenging as I thought, I didn't have to hammer the socket). But now I have another challenge. After removing the nut and the "collar", I'm left with the larger brass ring-thing underneath it. How the heck do I remove this? I tried pulling the whole prop off, but it seems the brass ring is holding it on. I included a pic below.

 

[MikDee]

Re: Prop damage, and more???

That's the thick lockwasher, & nut collar, it should slip right off!,,, a little persuation maybe needed, so pry it up against the prop, or tap the prop off with a wood 2 by 4, the prop is shot anyway.

 

[crxess]

Re: Prop damage, and more???

^^^^^^^^.....Yep. You are all but there. Pop it a few times and install the new prop.

Hope all is good and Happy Boating!

 

[strokeoluck]

Re: Prop damage, and more???

Is this what owning a boat is like?...significant ups and downs?!

Ok, I got the lock washer (?) thing off; had to take two screwdrivers and pry it up from underneath. Then had to use the rubber mallet to hammer the prop off. Got it all off, cleaned the "broken" rubber off the shaft (yep, spun prop!) and put it all back together.

But now I have one more challenge. I can't get the nut to screw on. When I ratchet it on I can get about 3-4 "easy" turns, then a couple tougher turns of the ratchet, and finally it gets really tough to turn the ratchet handle. And when I say "tough" I mean really tough. I'm holding the prop with my hand (seems that I can hold it ok) and cranking on the ratchet handle and it barely turns. So I backed the nut off and took a look at things. The nut looks fine, but when I looked at the threads there seemed to be almost angel-hair-like metal threads coming off the inside part of the nut. Then I looked at the prop shaft threads (see pics below) and noticed that the first couple threads looked "flattened out" somehwat; the threads weren't clean and crisp like the ones below them (where I had yet to get the nut down to).

I took the nut into the local marine shop and asked them to check the nut out. The guy took it in back and threaded it on a similar prop shaft and he said it threaded just fine. I tell him my problem, and his reply is that it's a nylon (?) something-or-other nut (must be the black things at the top of the nut threads?) and it's going to take some elbow grease to get it on. I tell him what the top couple threads on the prop shaft look like and of course he doesn't have much comment because he can't see them. But he tells me I'm looking at about $1,000 if I have to replace the prop shaft.

Ok guys, I'm not super mechanical, but I've removed and installed my shair of nuts and I don't know how I could have possibly screwed up the REMOVAL of of the nut. But maybe when I screwed it back on I misthreaded it somehow? But geez, even if I did misthread it, are these things built so that I have to buy a $1,000 prop shaft because of that simple mistake?!

Thanks in advance for your help!

 

[MikDee]

Re: Prop damage, and more???

What do ya mean, you put it all together? With a new prop, or a different one, Right? Ok, next, the nut will go on tight, once it hits the nylon lock, but it should be super tight? You should be able to get it on all the way, till you get to the prop surface. If not, you better get yourself a DYE the proper size from the hardware store, or wherever, and run over those threads with it, until you can get the nut on fairly easily with a ratchet, untill it hits the nylon threadlock, and starts to get hard. Don't screw up the shaft! Although if it came off fairly easy, it should go back on that way. It's a brass nut, and a steel shaft, it really shouldn't be an issue?

If need be, put the Drive in reverse to help you hold back on the prop.

 

[strokeoluck]

Re: Prop damage, and more???

What do ya mean, you put it all together? With a new prop, or a different one, Right?

Correct, got her all back together with a new (rebuilt) prop.

Ok, next, the nut will go on tight, once it hits the nylon lock, but it should be super tight? You should be able to get it on all the way, till you get to the prop surface.

I know it's kind of hard to tell from a forum post, but I think it's going on way too hard. It came off relatively easy (nice, simple ratchet turns with slight/normal resistance), but when I get a couple threads down on the shaft I'm getting a h*ll of a workout.

If not, you better get yourself a DYE the proper size from the hardware store, or wherever, and run over those threads with it, until you can get the nut on fairly easily with a ratchet, untill it hits the nylon threadlock, and starts to get hard. Don't screw up the shaft!

I have no clue what a "DYE" is but I guess I'll be Googling it now. Sounds like I can "fix" the damaged (???) threads on the shaft without paying the repair shop $1,000?!

It's a brass nut, and a steel shaft, it really shouldn't be an issue?

I agree - still not sure what happened. There's a smaller, independent Mercruiser repair shop a little further away from the marine shop I went to today. I'll give them a call Monday if I can't figure this out.

 

[strokeoluck]

Re: Prop damage, and more???

Ok, no matter how I try to Google "DYE" along with metal thread/bolt repair I keep getting pages and pages of ink dye information. So I welcome more details or links. Thanks!