Rudder prop strike

[csoule13]

Gather 'round and here a tale sure to send shivers down your spines.

To back into my slip, I go rudder full starboard, shift into reverse, and give a good goose of throttle. Stern pivots to starboard, bow to port, and once aligned and a few feet into the slip, we're good. Today, I got as far as giving the throttle a bump. A vibration on the tiller that made me start to think "Huh, that's odd".

BANG.

The Yanmar YSM8 immediately shuts off, and my tiller, hard to starboard, is immobile. My black box thankfully has a little bit left in it, and I'm only 18 inches or so from the end of my finger pier. I manhandle the 27 into the slip and tie everything up. Inspecting where the prop enters the boat, I am getting one drop every 5 seconds or so. At least if she's sinking, she'll do so very slowly. And thus the good news ends.

Hypothesis - the rudder turned far enough and struck the prop, wedging the rudder in place. I've done this move many times before without issue. However, this spring, an engine shop at my previous marina replaced the engine mounts and realigned the shaft. I wonder if something went awry at that point.

End game, and where hopefully y'all can chime in. I'm in a marina with no ramp, no lift, no nothing. Just some floating docks in a pretty location. I now have a boat that will forever act like it's at a NASCAR race(yes, we're making left-turn jokes), with an engine that can't start. Can't dive on the boat for fear of getting fried up.

I'd assume the next step is to lower the rudder enough to clear the prop, and from there get a tow to someplace that can make sure I didn't just tear the guts of the engine to shreds. Not entirely sure how to do that without the rudder ending up on the bottom of Lake Chickamauga.

Chris

[mgphl52]

The engine won't start in neutral? Can you pop the compression release and turn it over?

[csoule13]

The engine won't start in neutral? Can you pop the compression release and turn it over?

TBH, once I realized the boat wasn't sinking and safely tied up, the mental circuit breakers sorta popped. We'll see tomorrow.

[Frenchy]

Chris, does your boat have rudder stops? If you could somehow back off on the stop a bit, releasing
pressure on the rudder, then hand turn the prop shaft as if the boat were going forward, you might be able to release it.
You might need a large pipe wrench on the coupling. - Jean

[ghockaday]

Could the prop have backed off with the sudden change of direction (sheer the carter key). I know the shaft is tapered and it should get looser as it moves back, but it could have jammed against the rudder some way. I have heard of boats actually loosing the prop this way. I just find it hard to picture a correctly sized prop getting into the rudder under any circumstances unless something either shifted or came loose. Dennis

[Walter Hobbs]

Following, I have a 27. Your engine mounts look nice.

[csoule13]

Chris, does your boat have rudder stops? If you could somehow back off on the stop a bit, releasing
pressure on the rudder, then hand turn the prop shaft as if the boat were going forward, you might be able to release it.
You might need a large pipe wrench on the coupling. - Jean

A fine question, which I don't have an answer to. The entire steering set up on the 27 is a black box. Tiller to post, which runs through a fiberglass tube under the cockpit and out the underside of the boat. If there are stops, they aren't visible or at least obvious hanging upside down in a locker.

Sounds like 1) In neutral, it may be possible to rotate the shaft enough to unstick the tiller and 2) the engine should still run in neutral.

We'll see what adventures await at the marina after work.

Walter - The mounts have a whopping 2 to 3 hrs of working time on them. And given labor costs where it was done, was a fairly high bang for the buck.

[ghockaday]

I don't see how rudder stops would serve a purpose on a tiller boat. There have been none on any boat I have owned. Dennis

[RC James]

I like the thought of turning the prop-shaft in the opposite direction that brought on this problem.
-if the propeller is jammed against the rudder, it should free up the tiller.

A second thought, since you said you had very little time on the new engine mounts is to check the tightness of the mounts where they:
- mount onto the bed and/or
- check for any vertical looseness between the metal legs of the engine block and the upper/lower engine mount locking nuts.

IF that does free up the rudder, a 3rd possibility is that the Shaft itself has loosened in the 'collar' that mates up w/the transmission coupling. Hitting reverse could have caused it to slide, or be pulled, backward a bit - causing the interference.
- perhaps check the bolt/s (I believe there are 2) that secures the shaft to the flange, and if it is loose, loosen it a bit more and use judicious
forward throttle to let the engine and prop 'force' the shaft forward, thereby regaining the original clearance from the last haulout.

[ghockaday]

You can just see the key way in your first picture and the shaft there does not look like it has slipped back. The seal appears to still be on the set screw it should not have backed out but it does look like it has a shinny tread or two. Could just be the flash on the camera. I missed the part somewhere about the new motor mounts.

Were new motor mounts put on with the boat in the water?
Is the motor sitting exactly where it was including height? It would not take much to shift the prop one way or the other or to tilt it to a higher or lower angle.
I still think if the prop was where it is intended to be, no amount of rudder turn would make it hit the rudder unless something shifted from the correct location.
Dennis

[RC James]

Ghockaday-- I should have paid more attention to the photos. Great analysis.

Csoule13-- one other thought comes to mind...... That lake is know to have a large number of 'snags' floating in the water.

Perhaps your marina has a few underwater floating treebranches that might have been sucked into the propeller aperture.
If the propshaft turns in the forward position (manually), it's worh poking around w/a boat hook to see if you catch anything.

Sure hope it wasn't one of those giant catfish!

RC

[ghockaday]

Ghockaday-- I should have paid more attention to the photos. Great analysis.

Csoule13-- one other thought comes to mind...... That lake is know to have a large number of 'snags' floating in the water.

Perhaps your marina has a few underwater floating treebranches that might have been sucked into the propeller aperture.
If the propshaft turns in the forward position (manually), it's worh poking around w/a boat hook to see if you catch anything.

Sure hope it wasn't one of those giant catfish!

RC

I think Occam's Razor may apply here (simplest explanation is probably correct) and you are probably correct about the snag, we'll see. Dennis

[sgbernd]

It is possible that the new engine mounts are softer than the old ones and allow more fore-aft travel. Thus when you hit reverse the machinery shifts back, particularly at higher rpms. I have this problem but there is not much to be done except remember to limit the tiller to no further than the coaming boards while reversing. If you push or pull against the engine as hard as you can, you can measure how much things move. That motion is transferred to shaft and propeller. In my case, I found a circular area on the rudder where all the paint had been ground away by the propeller. As it hadn't gone thru the gel coat, I didn't worry too much and now am careful to limit the tiller position while in reverse.

As you were at idle, the tip may have jammed which stalled the engine. Had you been running a bit faster, you would have felt a vibration as the propeller tried to eat into the rudder.

Softer engine mounts transfer less vibration to the boat (good) but also allow more travel (bad).

Steve Bernd

[csoule13]

Well, I never had any reason to get a GoPro, but since the easiest solution to all of this is to see what the heck is actually going on below the water line, what the hell.

I'll share the photos and the experience. The local shop, while primarily for powerboaters, seemed dubious about the wondering prop shaft hypothesis, and also suggested that I just managed to snag a chunk of tree.

So, we'll see. At least the weather has finally turned pleasant enough to putter on boat, functioning tiller or not.

[RC James]

May all your problems be small ones.
RC