Starboard prop not keeping "traction"
 

Hi all,

Had an interesting experience last night while coming home from some all-you-can-eat just down the river... We were cruising around 3k rpms when all of the sudden the boat seemed to come off plane or at least act a little funny - i turned around as I backed both throttles off and noticed a funny spray of water coming what I "think" was the starboard side.

I thought maybe I caught a crab pot rope... turned off both motors, raised the drives, and checked for missing out drives, props, bent skegs, wrapped around ropes, etc... everything seemed to be normal and in tact. However, I could never get back up on plane after that... I typically throttle both engines up to about 2300-2500 rpms to get on plane; this time as soon as I got both engines up to 2k rpms, the starboard engine would start to rev up much faster than the port??? I played around with it for several minutes, trying different RPMs, checked everything out back again, made sure fwd and reverse worked for both engines/drives at idle, etc... But I could never get the starboard side to "bite" again and get up on plane...

Fortunately I was only a few hundred yards out from my marina, so we limped back plowing water with both motors around 1500 rpm.

Could I have a bent prop? A buddy of mine said it could be a prop hub??? When I had both my out drives serviced this spring, the shop said that my input shafts were slightly worn, and would need replacing "at some point" but he didn't know when for sure... I'm sure hoping it's not the latter since that requires taking the engines out!!! :poo poo:

Boat is a 2000 Donzi 28ZX (Scorpion) with the 377 scorpion engines... Everything is factory stock. Both tickers have about 395 hours on them.

Any ideas? Thanks all...

- Justin

what props are you running?

Something is taking the water off that prop. Is the boat on a trailer or lift or is it in the water at the marina?

Bring the motor up to TDC and mark the outdrive shaft at the coupler.
Go for a ride and see if they line up after.

Do you have a solid or rubber hub?

I'm not 100% sure, but the previous boat owner just responded to my txt and said it's a (3 blade) Mercury Mirage... I wasn't necessarily feeling for nicks or dents last night, more just checking to see if all 3 blades were still there. And it was dark, so I didn't get a chance to examine them once I had the boat back up in the lift... but I'll head to the water this afternoon and check to see if there is anything obviously wrong with the prop.

It's in a covered lift slip... I can hang off the back this afternoon and examine the prop.

Ha, I'm a little afraid of what I might find if I mark the outdrive shaft! :) But I hear what you're saying... I know the teeth on both shafts are a *little* rounded, as my mechanic pointed out this past spring... but the shop tech and I were thinking/hoping I could still get a few more years out of them before they got too bad.

I'm not sure what the hub is made of; is there an easy/obvious way to tell?


Thanks for all the replies, fellas... I appreciate it!

The smallest piece of wood jammed up in the right place can do exactly what you describe. It has happened to me many times running at LOTO and on the Illinois river. If you don't find anything around the drive that could disrupt the water to the prop, then I would take a look at the prop hub and driveshaft splines/coupler splines.

A spun hub in a prop will do all of that too.

That's what it sounds like to me.

I'm a big fan of going for the simple stuff first.

I want to say it's a rubber hub, but I can't be sure yet... can I tell by looking at the back of the prop? Also, how hard is it to press the old hub out and press a new one in? Are the hubs prop-specific I would imagine? Sorry for the amature questions... I'm new to this :)

No problem. That's what we're here for.

Assuming you can access the prop and get some leverage on it, block the prop from turning with a block of wood. Now, with a heavy glove on, try to turn it with the boat in gear. (Be careful not to cut your hands here!) If the prop spins and the propshaft doesn't, you've got a simple hub issue.

You can tell if you have a solid or rubber hub by looking in the back (exhaust) side of the prop. A solid hub will be all metal in there. A rubber hub will be - well - rubber. Newer Mercury props use a Flow Torque system with either a solid metal or plastic hub. Again, this is vissible from the rear.

If you have a rubber hub and have spun it, you've got to take it to a prop shop to have it replaced. If you have the Flow Torque system, you can buy the parts and do it yourself.

Hope that helps.

Haha...
 

Found the culprit... It was wedged in between the outdrive and the transom... not sure how it stayed in place since I raised both drives all the way up twice. In any case, I'm ASSUMING that this was the problem... won't be able to take her out for a test spin until tomorrow...

https://lh5.googleusercontent.com/-H...0/P1010231.JPG

We did also mark the prop hub just to be sure - in the even that it does it again...

Thanks for all the input today, fellas... Again, much appreciated!

- justin

Yea, that'll do it. Glad it was something simple!

I'm assuming your on the potomac... There used to be a dock-n-puke I cant remember the name of just north of Quantico. The wife and I went there alot for hush-puppies. You should check it out!

I moved away from there in 2006 but I loved it while I was there with all the water around...

Glad your boat wasnt broken! hope thats all it was!

Hey, I missed this post somehow last year... We have a blast and only live about 3 minutes from the boat/water... I'm thinking you were talking about Tim's Ricershore just above quantico?? Good times for sure... not the best food, but I've yet to see a Ruth's Chris on the water... haha

And the boat was fine after the removal of the buoy! ;)