spun propeller?

[Chickenbone]

I have a Maxum 1800 SR3 with Mercruiser 4.3L. Yesterday I hit a rock pile on the ICW in South Carolina. We were traveling just above idle speed. Engine seems fine, but after it happened propeller seemed to be slipping for a few seconds, then completely stopped spinning (engaging) in forward or reverse. Had to be towed. Marina guy says I probably sheared a pin, and I'm not sure exactly what he's talking about. I'm hoping the gears are not stripped. My prop is a little jagged but not very bad. The prop is aluminum. With the engine off, the prop spins freely in neutral in both directions. Have not tried while in gear. Any tips?

 

[alldodge]

Your drive does not have a shear pin. You might have spun the prop hub.

With engine off put it in gear and try to spin the prop, it should lock in one direction and click in the other. Will lock in the opposite direction when shifted in the other.

Let us know what you find

 

[FunInDuhSun]

Chickenbone-
I hope your luck is better than mine because when that happened to me, my shop discovered the pinion gears were missing a couple teeth.
I submitted a claim to my insurance company and the adjuster agreed it was due to an impact, so it was paid (minus deductable of course).

 

[Chickenbone]

No Title

Thank you both for your input. Last night, with the engine off I did the handspin test. Here are the results:

In Neutral: Prop spins freely in both directions, feel a little ratcheting but mostly free.
In Forward: Spins clockwise like neutral, but not so counter-clockwise. (Although I can turn it ccw with a little elbow grease)
In Reverse: Spins counter-clockwise like neutral, and spins clockwise but I can feel resistance (ratchet) every cw quarter turn or so.

So, I'm a little nervous to hear what ye experts will say about the likely culprit. Already spent a fortune on the tow this weekend and could use some hope. I'm not familiar with how this propeller/plastic hub/spline-sleeve/drive works, but I'm trying to learn. Anyone know where I can find a diagram? This has a Mercruiser Alpha-One drive but not sure of the prop model. (See attached pic).

 

[Sea Rider]

Before venturing assuming you have a gear problem, perform a simple hub slip test at wot. In a very short time period will definitely know if prop is spun, gearcase with issues or a combination of both, bad prop and bad gearcase which should be quite impossible to happen, but you never know.

Happy Boating

 

[Chickenbone]

Thank you. I'm not familiar with a hub slip test and I had to google WOT. I assume this needs to be done by a pro. I'll look into it.

 

[Sea Rider]

Anyone can perform that test. Remove prop, turn it upside down, with a proper marker mark a staright line as the upper one or 2 facing dots as lower ones.



Go for a one minute or less wot run, remove prop, check if upper line is misaligned or dots have moved from where originally were marked. If so, you have a spun prop. Will need to have it repaired, buy a rew one or install a new hub if it's a removable one, will depend on the prop model in current use. Good luck!!

BTW, WOT is Wide Open Throttle, Full Hammer Down..

Happy Boating

 

[Chickenbone]

Great! Thanks. I assume the WOT run needs to be in the lake under load, and not just with muffs on. Correct?

 

[alldodge]

Agree with the prop test but the last time the OP was in the water he had to be towed in and the prop was not spinning.

Since you can turn the prop in gear with effort my first guess is you spun your prop hub. When you remove the prop look on the inside where the rubber is. If it is not evident of the problem with the rubber, put it back on the prop shaft without the any fastening hardware.

Put drive in gear and turn the prop to see if the shaft stays in place and the prop does move. For this test you can even put the prop on backwards, you should not be able to move it.

If you can turn the prop and the shaft moves with the prop and there is no metal grinding of the like, I would remove the drive and look at the coupler

 

[redneck joe]

If you have a spare prop put it on and go for a spin (pun intended )

 

[Chickenbone]

No Title

Thanks for all the advice. I took AllDodge's tip and removed prop. Rubber is cracked and shaved to pieces. Look like a spun hub? With drive in forward gear, i can spin prop ccw. Shaft stays put. It looks like i have the replaceable flo torque hub but not sure. If so, i assume i can just replace hub. Prop blades need some attention too so maybei should just get a new SS prop with third party hub? See pic below. Hoping theres no chance of spun hub AND ground coupler teeth. Dont see how if hub did its job.

 

[alldodge]

Looks like an old prop and the rubber has just dried out. Also say the hub did it's job and protected your drive. If the hub was in good shape the aluminum prop would have taken the hit and save the drive also in most cases. If you have a stainless prop and hit the same thing it has a higher chance of breaking something in the drive.

Just something to think about when changing the material of the prop.

 

[Sea Rider]

Now the new bummer is, was current prop working spot-on on that combo ? that's revving near max wot rpm range stated for that I/B ? It's always a must tach current prop to see if performs good on your current boating application, if so can buy same prop new in case it's spun, broken, kaput or go from there maximizing a +,- pitch to suit best your current boating activity.

Was that prop tached running at lake before becoming spun while at wot and lightly loaded ? If so, which rpm was achieved, in it inside safe min-max wot range for current activity ?

Happy Boating

 

[Chickenbone]

I dont recall the max rpm achieved with that prop. However, I will say that it was slow getting to a plane with a 180 lb skier. I've heard I need to go froma 21P to maybe a 19P to help with that. At wot, it was always spot on.ot sure of the max rpm range for my prop.

 

[alldodge]

Your WOT rpm should be between 4400 to 4800

 

[Sea Rider]

With 2 less pitch will achieve faster hole shot for skier. Do you have an installed tach on dashboard ? Will need to tach new prop you alone and lightly loaded, check max WOT rpm achieved on that run. For top skiing need to have a fast hole shot for skier to stand up real fast above water level in the shortest possible term.

Make 2 wot test, first with just driver and skier, second same but with a back spotter if mandatory to have one on board. Jote down WOT RPM achieved on 3 independent runs to compare how weight affects RPM. The more weight you pull or add the more rpm will lose.

Besides skiing, which other activity do you plan doing with current combo, like speeding, having a family oriented combo, cruising far away distances ?

Happy Boating

 

[Chickenbone]

Actually just saw the number on my old prop. Its 832834A45p23 Mercury. Found on another forum here that it is a 23 pitch. Shopping for a new prop today so I'm thinking of around a 19 to 21 P. our trips are mostly family boating, cruising, tubing, and of course skiing. Dont do much long distance or speed running. Its an 18 ft, 190 HP V6 Runabout, usually with no more than 4 passengers. When I ski, I have to make all the kids get in the front of boat, which seems to help get on a plane sooner and get my 180 lbs on top of water. Reading other posts on here makes me think a 20P will fit our needs.

 

[Sea Rider]

Large props usually comes in 2 pitch increment/decrement, if with a 23 try a 21, a 19 probably will overrev excesively when lightly loaded and without a tach is bad music for I/B. In your case will need a starter prop to go from there maximizing one for your current boating activities if needed. Would suggest install a tach if you don't count with one...

Happy Boating

 

[Chickenbone]

Ok, Hopefully this is my last post about my ordeal, which turned out to be a pretty useful lesson about props and hitting rock bottom on the Intracostal Waterway. Bought a new Prop, same diameter but went down from 23P to 21P. Keeping the old prop (now fitted with new rubber hub) and socket wrench in the boat just in case. Took boat on the lake and it did great! Significantly faster takeoff and still tached WOT (just me in boat) at just under 4900 rpm. Haven't tried to ski yet but looking forward to not drinking a gallon water before planing. I appreciate the advice from all of ya.

 

[Sea Rider]

Congrats, you're there at max wot rpm lightly loaded, bear in mind that when skiing with more load, boaters, max rpm will drop acccordingly, if so, add max weight passengers for I/B not to rev less than middle (4600 rpm ) for hole shot to remain acceptable. Maximizing new prop with tach broadens your world of boating fun. Just for the record and when possible, will be nice to know rpm difference at wot as same previous run with re hubed 23 pitch to check rpm gain per pitch.

Happy Boating