Idle speed, hit rock, small ding in prop, anything to worry about?

xxpilot

New Member
Apr 11, 2010
25
New Berlin, WI
Boat Info
2011 Sea-Ray 250 SLX 8.2L Mag HO, Bravo 3x, Bravo 3XR 27p stainless props - 2015 F-350 Diesel
Engines
8.2L Mag HO - Bravo IIIx Drives - 27p Bravo3XR props
Was on a new lake last Saturday. Going through a channel at idle/no wake speed. Had it trimmed up but not quite far enough. Found a shallow spot. Heard the prop hit a rock and then drag across a few others

Got to a gas-dock and raised the drive and checked the SS prop. One very small ding on the side of one blade. Skaeg was intact, just a little rough on the front side from dragging on the ground.

Got back to open-water and went WOT and didn't feel any vibration and the boat seemed to hit the same speed that it was doing an hour earlier before dinging the prop.

Just wondering how fragile the prop shaft/driveshaft are. Would a slow speed contact with a small rock that was just enough to put a tiny ding in the prop be likely to bend or put the shafts out of tolerance?

If the boat seems to run fine and you don't notice a vibration is there any reason to take it in and have it checked?
 
If the prop is not visibly bent and doesn't vibrate at all then it is probably OK for now but I would recommend it eventually be sent to a prop shop for balancing and to have the prop hub checked (if it has one).

Dave
 
Been there, done that. I believe you are OK.
 
I would grind the damaged place smooth for two reasons: 1) you don't want to cut yourself, and; 2) the prop will be less prone to fatigue if you smooth any sharp gouges. I agree you are fine. A prop shop can make it look like new if you want to send it off during the winter.
 
:thumbsup: Take the prop off and tap out the ding best you can. File it off so there are no sharp edges. Don't worry about gouges too much or even if a little piece is gone, it takes alot of missing material and/or a significant bend to throw it out of balance. Same goes for the skeg, file it off and just make sure it is still lower than the prop. While the prop is off, hold a screwdriver or something to your cavitation plate and make note of the center of the prop shaft. Rotate the shaft to see if it is spinning out of round. Our rule of thumb is that if it's more than 1/8" out than you should replace the shaft. If so, I wouldn't bother changing it until you're done your boating season, the worst thing is you will wear out the seals which will get replaced in the process anyway.
Good luck!
 
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Wow, 1/8" would be HUGELY bent. I can't remember what my marine mechanic told me when I ran over my own anchor at speed (long story, but make sure you have the anchor secured), but it was a lot less than 1/8 inch. In my case the prop shaft was fine, but the prop itself was not a pretty sight. It was aluminum so a prop shop rebuilt it and it was demoted to spare.

I would say that you could do a visual test as a "quick and dirty", but if you can see any bend visually, you should get the prop shaft replaced.
 
Having a bend of 1/16" on the shaft would show 1/8" of movement. When that prop is spinning at thousands of RPM that 1/8" becomes almost nothing on a +/-14" diameter. You can/will get that much variance on a brand new prop with a perfectly straight shaft. You can do the "measure from the cavitation plate test" while your prop is on as well. (Measure each blade tip as it comes around) I've even rotated the prop on the spline one notch at a time to get optimal centering. Slight imperfections of the blade and/or rubber hub can throw it out by 1/8" or more.
 
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took it in to the dealer just to have them check it so I'd sleep better at night. :)

They said the prop was well within spec. Said it was 3 thousanths off but factory margin is 7 thousandths.

They pressure tested all my seals while they were at it and everything checked out fine.

They did say I had a couple hundred feet of fishing line wrapped around the prop shaft. I'm not sure if that would have caused a problem or not but they cut it off.

From 10 feet away you can't even tell the prop has a ding in it, but I'll probably just get a new one.

The prop on their now is a quicksilver "OSS" 19pitch 3 blade.

I've been very pleased with that prop as far as performance. (my 2000 Sea-Ray 210 with 5.0 EFI) will do 54 (on the speedo) on light chop on the cold Lake Michigan harbor with that prop. (haven't gps measured it yet so don't know how accurate that speedo is)

Haven't been able to reference that same prop online. Anyone know whats the closest to it?
 
I did that once on a twin stern drive. No real damage to the prop but it chipped a tooth in the gears that eventually took out a seal. That resulted in a new leg. I would change all the drive oils and get them checked for metal content.
 
:thumbsup: Take the prop off and tap out the ding best you can. File it off so there are no sharp edges. Don't worry about gouges too much or even if a little piece is gone, it takes alot of missing material and/or a significant bend to throw it out of balance. Same goes for the skeg, file it off and just make sure it is still lower than the prop. While the prop is off, hold a screwdriver or something to your cavitation plate and make note of the center of the prop shaft. Rotate the shaft to see if it is spinning out of round. Our rule of thumb is that if it's more than 1/8" out than you should replace the shaft. If so, I wouldn't bother changing it until you're done your boating season, the worst thing is you will wear out the seals which will get replaced in the process anyway.
Good luck!
Hey I hit a small Rock but my boat wouldn’t move any more I had to get it towed back it doesn’t seem that bad hit it is leaking some fluid I have a Sea Ray Sundancer 240 can any one tell me what might be wrong is there a safety switch that will cause the motor to not work
 
If the prop is not visibly bent and doesn't vibrate at all then it is probably OK for now but I would recommend it eventually be sent to a prop shop for balancing and to have the prop hub checked (if it has one).

Dave
Hey Dave can u help me understand what has happen I am a new owner of a 240 Sea Ray Sundancer and I was in MIAMI I hit a small rock and my boat drag for a few feet and it stop moving then engine still works but it’s leaking some fluid
 
took it in to the dealer just to have them check it so I'd sleep better at night. :)

They said the prop was well within spec. Said it was 3 thousanths off but factory margin is 7 thousandths.

They pressure tested all my seals while they were at it and everything checked out fine.

They did say I had a couple hundred feet of fishing line wrapped around the prop shaft. I'm not sure if that would have caused a problem or not but they cut it off.

From 10 feet away you can't even tell the prop has a ding in it, but I'll probably just get a new one.

The prop on their now is a quicksilver "OSS" 19pitch 3 blade.

I've been very pleased with that prop as far as performance. (my 2000 Sea-Ray 210 with 5.0 EFI) will do 54 (on the speedo) on light chop on the cold Lake Michigan harbor with that prop. (haven't gps measured it yet so don't know how accurate that speedo is)

Haven't been able to reference that same prop online. Anyone know whats the closest to it?

The fishing line was what was really going to cause a problem. Hitting bottom might have saved you an outdrive.
 
Bill and Phil....this is an 8 year old thread.

Phil, you are asking several questions and none of them make much sense. I understand you hit a rock and had to be towed. What part of the boat hit the rock? The hull? the outdrive? The prop? Did the engine start? If yes would it go into gear? if yes would the boat move? We're going to need a bit more detailed info to help you.

When a boat hits a rock(s) many things can happen. Unfortunately, none of them are good. If you had to be towed in chances are you hit on the outdrive. If you are leaking fluid you may gave cracked the outer case and possibly damaged some gears. That would explain the fluid leaking and the boat not going. It's time to call your insurance company. That's what you paid for.

So why were you boating where rocks are present or boating in shallow water. It sounds to me like you need to take some time and get to know your boat a bit better as well as the area you do your boating. You can just buy a boat, stick it in the water and haul ass around a harbor. People can get hurt and you are the captain; you are responsible for all souls on your boat. Sorry to preach but your incident could have been much worse. Good luck to you.
 
Bill and Phil....this is an 8 year old thread.

Phil, you are asking several questions and none of them make much sense. I understand you hit a rock and had to be towed. What part of the boat hit the rock? The hull? the outdrive? The prop? Did the engine start? If yes would it go into gear? if yes would the boat move? We're going to need a bit more detailed info to help you.

When a boat hits a rock(s) many things can happen. Unfortunately, none of them are good. If you had to be towed in chances are you hit on the outdrive. If you are leaking fluid you may gave cracked the outer case and possibly damaged some gears. That would explain the fluid leaking and the boat not going. It's time to call your insurance company. That's what you paid for.

So why were you boating where rocks are present or boating in shallow water. It sounds to me like you need to take some time and get to know your boat a bit better as well as the area you do your boating. You can just buy a boat, stick it in the water and haul ass around a harbor. People can get hurt and you are the captain; you are responsible for all souls on your boat. Sorry to preach but your incident could have been much worse. Good luck to you.
Thanks for your reply the back of the boat is what hit the rocks I believe The propellers when I turn over the engine it’s a beeping noise and it’s appears the gears is up high
 
Bill and Phil....this is an 8 year old thread.

Phil, you are asking several questions and none of them make much sense. I understand you hit a rock and had to be towed. What part of the boat hit the rock? The hull? the outdrive? The prop? Did the engine start? If yes would it go into gear? if yes would the boat move? We're going to need a bit more detailed info to help you.

When a boat hits a rock(s) many things can happen. Unfortunately, none of them are good. If you had to be towed in chances are you hit on the outdrive. If you are leaking fluid you may gave cracked the outer case and possibly damaged some gears. That would explain the fluid leaking and the boat not going. It's time to call your insurance company. That's what you paid for.

So why were you boating where rocks are present or boating in shallow water. It sounds to me like you need to take some time and get to know your boat a bit better as well as the area you do your boating. You can just buy a boat, stick it in the water and haul ass around a harbor. People can get hurt and you are the captain; you are responsible for all souls on your boat. Sorry to preach but your incident could have been much worse. Good luck to you.

I feel like I got punked when I reply to one of these things!
 
A little punctuation would go a long way to clarifying this!

A few properly placed comma’s and periods would be a good start. Then, before you hit “post reply” read it back to yourself and see if it makes sense.
 

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