motor shaft vibration

[Jm2fly]

We did a sea trial on a 1975 C&C 33 on Saturday. The engine which is supposed to only have 150 hours on it vibrates badly at near full throttle. The surveyor said it is due to shaft alignment causing it to rub on the hull.

What should this cost to repair? Trying to decide what to take off our offer.

Thanks
Jessica

[hanleyclifford]

That depends on whether you plan to do the work yourself or have a yard do it. If it is simply a case of moving the engine into correct alignment most yards will charge 2 to 3 hours labor. But if the shaft and cutless are bad you are looking at a haul out and maybe $500 in parts for openers. The surveyor should be able to give more information from the short haul.

[Al Schober]

The chances of the propeller rubbing on the hull are slim to none. The worst cases of vibration I've seen have been due to a bad propeller. Second cause is a bend in the aft end of the shaft. A bad alignment will move the shaft and engine around a bit, but won't really shake the whole boat - bent shaft or bad propeller will!
Tough to tell whether it's a shaft bend or the propeller - usual approach is to check the shaft (fairly easy), and if that's good replace the propeller.
Shafts get bent often (and struts bent/broken) by poor placement of slings when hauling. Props usually get damaged by hitting things in the water under power.
I'd take $1000 off your offer. If the owner doesn't like that, have the owner fix the problem. There are lots of boats out there for sale - why buy a known problem?

[Jm2fly]

The Surveyor said the shaft and cutlass looked good. I think the prop was good also. The vibration was between 6000-6500 rpm. Correction: could have been 6-6.5 knots. I'm new to marine engines.

[Al Schober]

Fact - the boat has a vibration problem.
Looking good doesn't count. To check a shaft, you have to remove the propeller, remove the shaft from the boat (usually, there are exceptions), and use a dial indicator on the fwd and aft ends of the propeller taper (also checking intermediate points).
Is your surveyor working for you or for the seller? It's starting to sound like this is a surveyor recommended by the broker (if the boat sells, he gets a cut). Get your own surveyor!
Not getting a good feeling about this. Walk away from this one?

[Al Schober]

BTW, the Atomic 4 will self destruct before things hit 6000 RPM. More good info from the surveyor???

[alcodiesel]

self destruct.

I concur with that: 6 to 6500 RPM on an Atomic4??! That's way past red line in my book.

[JOHN COOKSON]

The Surveyor said the shaft and cutlass looked good. I think the prop was good also. The vibration was between 6000-6500 rpm.

I look good but I can't run worth a s**t.
Was the boat out of the water when this determination was made? Is there an Atomic four engine in the boat? It sounds like the tachometer is set for an 8 cylinder engine not a 4 cylinder engine. An Atomic four will self destruct way before it gets to 6000 RPM - somewhere just over 3000 RPM - as others have noted. IMO the surveror wouldn't know an A4 if it jumped up and bit him in the ass.
Buyer beware.

TRUE GRIT

[Jm2fly]

I could be wrong about the RPM thing. I haven't gotten the survey report yet. I'm a newbe at this. Maybe it was 6-6.5 knots. Sorry about the misinformation. I do remember we hit 6.6 knots and it smoothed out.

[Jm2fly]

I look good but I can't run worth a s**t.
Was the boat out of the water when this determination was made? Is there an Atomic four engine in the boat? It sounds like the tachometer is set for an 8 cylinder engine not a 4 cylinder engine. An Atomic four will self destruct way before it gets to 6000 RPM - somewhere just over 3000 RPM - as others have noted. IMO the surveror wouldn't know an A4 if it jumped up and bit him in the ass.
Buyer beware.

TRUE GRIT

No, this was during the sea trial. Sounds like we may need it hauled out. Do you really look good?😜

[JOHN COOKSON]

No, this was during the sea trial. Sounds like we may need it hauled out. Do you really look good?��

When you get the survey report post it. We would like to read it.
I think you are spot on when you say the boat needs to be hauled out. The only way to address under water issues is to haul the boat. After the haul out you will know what you are dealing with and if you want to continue with the purchase and what a fair price is.
BTW was someone up the mast to survey the rigging?

TRUE GRIT

[ndutton]

Any decent purchase survey includes a short haul for bottom inspection at the buyer's expense, generally scheduled the same day as the survey. If you are serious enough about this boat to invest in a proper survey, please take lots of pictures and post them here. We have many experienced members who can point out things others may have missed. In your pictures include the prop shaft, prop, strut and other things like the forward edge of the keel, hull to keel joint, thru-hulls, hull surface and rudder. Each of those may provide telling evidence of a problem or maybe even confirm no problems.

And depending on what is uncovered if anything, don't get emotionally attached to the boat just yet, there will be plenty of time for that later. Know when it's time to walk, it is your only power.

Another thing I do when pre-surveying boats for friends is open the bilge hatch and stick my nose in there for a good sniff. I did that on a C&C Cruising 39 and in 10 seconds advised the buyers there was a diesel leak, an engine coolant leak and the previous owners likely had a cat on board. They ultimately bought the boat, found and repaired a diesel leak, found and repaired a coolant leak and found a plastic shampoo bottle that had spilled its contents under the aft berth leaving fermented residue on the hull (the urine smell). All that after a 10 second sniff.

[Jm2fly]

When you get the survey report post it. We would like to read it.
I think you are spot on when you say the boat needs to be hauled out. The only way to address under water issues is to haul the boat. After the haul out you will know what you are dealing with and if you want to continue with the purchase and what a fair price is.
BTW was someone up the mast to survey the rigging?

TRUE GRIT

No one went up the mast. It seems in Superior they overlook a few things maybe.

[Jm2fly]

We took $3200 of our original offer. We'll see if they accept.

[sastanley]

jm2fly, As far as rigging goes, the corrosion of wire is 'usually' at deck level, and the top of the rig is pristine, except for all the bees & spiders. However, there can be failures at any point along the route, and I would want to check out spreaders/brackets, etc.

We also have salt water around here, which can rust even the best stainless to some degree (hence the issues with fittings at deck level..the rain keeps the others pretty clean and corrosion free.)

I am not a professional rigger by any means, but I've been up a few in my day.

Good luck and we'll be here to help you with the A-4!