vibration at 22000 to 24000 rpm

I have a 34 Mainship trawler.I got stuck in soft bottom yesterday tryed to get out but failed. Sea Tow had to haul me out.

Ran the boat to check..... Starboard Engine ran good but found my Port Engine
had Vibration that started at 22000rpm and ended at 24000rpm. Never had any vibrations issues before

Any suggestion what to look for
Regards

The vibration between 2200 and 2400, did the grounding stop the engine?

Or, did you take it out of gear and turn it off?

jann said:

I have a 34 Mainship trawler.I got stuck in soft bottom yesterday tryed to get out but failed. Sea Tow had to haul me out.

Ran the boat to check..... Starboard Engine ran good but found my Port Engine
had Vibration that started at 22000rpm and ended at 24000rpm. Never had any vibrations issues before

Any suggestion what to look for
Regards

Click to expand...

I would suspect you dinged one of the blades. If you have someone who can run the boat for you, bring both engines up to speed and then go look at them. You will probably find the port engine moving on it's mounts more. Next step would probably be to have a diver pull the prop or haul the boat out, and take it to a shop to be checked.

Ted

Pull the boat and fix the problems due to the grounding. Check both sides too. It could be prop, struts, bent shaft, alignment, couplings, mounts or all of the above. Check the rudders too.

Check with your insurer first. Suggest you not run the engine hard to check it out. Something is buggered and you don't want to make it worse.

Pretty sure if I ran my engine at 22,000 rpm I'd get vibration too.

Probably dinged a prop. Did you hear or feel a hard hit? If so it could be more than a prop. I had a bit of vibration at higher speeds so I pulled the props and had them rebuilt at a prop scan shop. Had them take 1/2” off the pitch so I caould get a bit more RPMs. Just launched Tuesday and have not had a chance to try it and see if the vibration has gone away yet.

Why did you run aground? What will you do differently next time to prevent it?

Those are the questions I'd be asking myself so I would not have a preferred parking place at the prop shop.

So tell me if this is true: If you run aground, NEVER try and back off because that is when the damage happens. Just face up to it and call for a tow.

bluebyu said:

The vibration between 2200 and 2400, did the grounding stop the engine?

Or, did you take it out of gear and turn it off?

Click to expand...

The port engine shut down by itself ( In Gear ) when I hit around
What does that mean

Rats; I thought I would learn more about gas turbines...

jann said:

The port engine shut down by itself ( In Gear ) when I hit around
What does that mean

Click to expand...

It means there was enough force on the prop blades to stall the engine. Prop in that instance is likely bent. Even a little bend, which might not be visible, can cause a vibe.

Whether the engine stalled is one of the first question asked on a grounding. If they do not stall, good chance the props are ok.

If you ground, before trying to power off, go in the engine room and hand roll the prop shafts. If you can't move them by hand, just get towed off.

Get both props pulled and have them tuned up. A diver can do this, but if near time to do bottom paint, just go ahead and haul it for both jobs.

Tom.B said:

So tell me if this is true: If you run aground, NEVER try and back off because that is when the damage happens. Just face up to it and call for a tow.

Click to expand...

No that's not always true.
Depends on the situation.
I have been aboard other boats that went aground and we got off unscathed.
I have pulled boats off with my dinghy with and without the troubled boat's help that went unscathed.
These were soft groundings of course.

Tom.B said:

So tell me if this is true: If you run aground, NEVER try and back off because that is when the damage happens. Just face up to it and call for a tow.

Click to expand...

Lots of variables.
If you're aground in the stern there's more risk than at the bow.
Single or twins. Most twins have no protection below the props and rudders. Singles may have a skeg protecting the prop and rudder. Also, with a skeg, rudder and prop may provide more protection if the tide goes out.

Bottom material is a big consideration. I would be likely to back my boat off mud or sand. With stone or reef I would be very hesitant to back off if aground in the stern.

Lastly, sea conditions are a big factor. If you're aground in calm waters with a tow not far away, thats one thing. If you're in seas on rocks or reef, you have to decide if time could result in holing your hull, a decision may have to be made regarding sacrificing running gear to save the boat.

Lots to consider.

Ted

Yeah; few things at sea worse than putting on snorkeling gear and watching your hull pound into reef every 5 seconds with passing waves.