Unsupported prop shaft....

[romantic comedy]

How far does your shaft stick out?

My shaft is exactly 4 feet long and I measured from the cutless to the prop hub. It is 5 3/8 inches. Wow, yes I know. I am running the Indigo 10X7.4 three blade. The blade tip to hull clearance is 1 5/8 inches. If I shorten the shaft by 1 inch the clearance would be 1 1/4 inches. It has been this way since 2001. I replaced the shaft with the current one, along with the prop and cutless back in 2001. I ran the ICW and did some sailing until 2008 when I pulled the boat. So it had been over 1000 miles of motoring. The cutless was very worn then. I checked the engine alignment and found it was off (my bad). I aligned the engine and replaced the cutless. I pulled the boat last month, after 9 years of use. The cutless was barely worn. (I had already ordered a new cutless, but could have gotten away with the old one). I have been thinking of shortening the shaft for years. But at this point I am thinking of leaving it alone. I know I have way more unsupported shaft then is recommended. If I shorten the shaft the prop gets too close to the hull. Years ago I ran a 12X6 with a shaft 1 inch shorter. Maybe the laws of physics are null under my boat? BTW the marina was not hit by a tornado.

[lat 64]

How far does your shaft stick out?

Hmmm.
How do I answer that?
I'd say mine is 4-5 inches. I believe its a 16 x 11. Zinc fell off four years ago.

[ndutton]

Well, it's certainly not a textbook installation but given the hull configuration I don't see what choice you have. I think your successful nine years drives the decision to leave it alone.

If you shorten the shaft to meet the standard clearances as close as possible (1 shaft diameter minimum clearance between prop tip and hull, same between cutlass and prop hub) you'll be committed to a smaller prop forever and between it and being closer to the cutlass it'll be spinning in more disturbed flow. Nah, I'd let it be. I wouldn't like it on principle but what else are you gonna do?

[JOHN COOKSON]

Well, it's certainly not a textbook installation but given the hull configuration I don't see what choice you have. I think your successful nine years drives the decision to leave it alone.

+1
Don't fix it if it isn't broken.
An improvement is a different story.


TRUE GRIT

[lat 64]

Yah, +2 here.

You proved it works and you have shown that prop alignment is more important than getting a more ideal (shorter) unsupported shaft.

Surely that jetski could be hauled off to the landfill

[romantic comedy]

Thanks guys. My thoughts too.

Just wondering if others have way too much shaft unsupported.

This boatyard is the place where dreams go to die. What a disaster!!

[JOHN COOKSON]

This boatyard is the place where dreams go to die. What a disaster!!

Looks to be a boat grave yard. How depressing. Maybe left there as a reminder to pay your yard bill?

TRUE GRIT

[lat 64]

My boat yard is a bit like R.C.'s.
But, I find it an asset. If I need a ladder or oil drum to stand on, there's always one laying around. My winter cover is made almost entirely of salvage from the shrink wrap garbage pile.
I guess Jet skis are useful too. The gas tanks make a good hazmat dump and the whole machine can be used for target practice.

[CalebD]

KISS and "If it ain't broke, don't fix it".

Here is a non-standard idea that I don't really like either.
Instead of shortening the shaft, make it longer and add a strut.

This would move the prop to more undisturbed water, which would be the only positive effect IMHO.
Adding the complexity of a strut violates the all important KISS principle.

I was on a friends recently purchased C&C 35' mk iii last summer. We were motoring from the Hudson River to the Long Island Sound with the intention of going to Block Island. In the Sound we noticed the prop/shaft making a kind of banging sound that would sometimes go away by adjusting the throttle. By the end of the day we had reached Huntington Bay but I had noticed that there was quite a bit of water in the bilge that was overwhelming the bilge pump. It turns out that one of the 4 bolts that holds the strut in place had vibrated enough to completely fall out, leaving a nice round 3/8" hole in the hull. We ended up calling for a tow and after perhaps a 2 mile tow we were in Huntington Harbor where an emergency yard hauled the boat out with their travel lift at about 9pm (after dark). Block Island would have to wait; all the planning and provisioning done for naught.
The silver lining in all of this was that we discovered the leak within 2 miles of a populated harbor with lots of marine services rather than further east where we could have been 30 miles (or more) from any harbor that could help us.
It was a pretty windless summer day so we were motoring the entire day with no chance of sailing into harbor. First time for me being on a boat that had called for a tow and boy did they show up fast once we called in. Good thing for me I had only had one or two beers as all the water LEOs from neigboring towns showed up.
I am sure this experience taints my appreciation for shafts with struts on them. My little Tartan 27' with the shaft exiting the deadwood of the keel in a cutaway before the rudder is the ultimate in simplicity (KISS).

My $.05.

[BunnyPlanet169]

I think we'd all probably agree you shouldn't hack away at your keel with a sawzall to mount a strut with a few screws....

I'm going to be a PO someday, and I don't want to be remembered like this.

[Hymodyne]

no unsupported shaft at all. That is the propeller I posted about...

James

[CalebD]

I think we'd all probably agree you shouldn't hack away at your keel with a sawzall to mount a strut with a few screws....

I'm going to be a PO someday, and I don't want to be remembered like this.

The "funny" part about that incident was that my friend was speaking with another member at our club who owns the exact same boat (C&C35' mk iii) and he told my friend that it was likely the strut as it had failed for him in a similar way.
I don't think some PO sawzalled the hull to install the strut, I think C&C did that originally. What was a PO "fix" was the Bondo covering at the base of the strut which was pulled off for my picture. The Bondo was limp like a sponge too.
I wonder what Neil D. might say about struts and C&C build quality. He is our resident expert from the builders point of view after all.

Nice propellor Hymo.

[ndutton]

I wonder what Neil D. might say about struts and C&C build quality. He is our resident expert from the builders point of view after all.

Based on very few C&C manufactured boats I've seen personally my opinion of their build quality isn't that great but that may be unfair due to a microscopic sample size. I think their designs are stellar however so I guess you could call it a mixed bag.

Studying the strut picture and reading the post-sortie debriefing, several problems are apparent:

1. The strut does not sit flat against the recess in the hull. The aft end of the base is slightly aft of the flat in the recess and is kissing the angle. That way it will never bolt up tight. The aft part of the recess should have been relieved with a grinder before the strut was installed.
2. Stainless machine screws on a cast bronze strut below the waterline is bad form for the reason everyone on this forum knows. Silicon bronze machine screws are what belong there. This may not be a C&C goof, probably a PO.
3. Never ever use Bondo or similar automotive body fillers below the waterline. A structural filler is required, usually made by the installer by mixing a fibrous thickening agent into polyester resin to the required viscosity. Back in the early to mid 70's we used powdered asbestos. Sure, it'll kill ya but it was strong like granite. Life's a trade-off.

For further information please read my Factory Driveline Installation thread.

[romantic comedy]

Russ we should compare yards.

Just the other day I had to avoid a falling mast. The boat next to me was being dismantled and dismasted. They were about to lower the deck step mast when it went its own way. (btw, I told them not to undue the stays until it was hooked to the crane)

The mast came crashing down and missed my boat by inches. Lucky for the mast that my scaffold broke the fall. The jet ski survived without an additional scratch. Even more fun was that the mast was wood and had a huge bees nest in it. We were dodging bees for days. I cant get used to those inquisitive bees. The yard boss was stung and started to swell. We got him to the er just in time. I nailed him with an epi pen, but it did little. The bee keeper was called and collected the cute little fellows. He estimated 30,000 bees were living in that hollow wooden mast.

Every day I arrive at the yard with a knot in my stomach, wondering what has happened over night. I have stayed on the boat about half the nights returning home only to eat dinner and shower.

[lat 64]

Oh cripes! this thread is off the scale.

We need some kitten pics just to pull out of this dive,

Re: "compare yards", You win. The bee story really made me laugh. Thanks for that.
I have eagles crapping on the boat and a great view of the airport; nothing like your Fort Sumpter though. Tom G. knows this place. I get to watch the Coast Guard C-130s do approaches and touch-an-gos. Always something fun to see while the paint dries.
Photo is a plane that parks about 200 yards awayDa comrade, Kool!