Thoughts please

[SideshowRob]

Alright, here's one for you to think about.
A little while ago we were out in the boat, I had the Volvo SS prop on, we went down the lake about 8 miles stopped a talked with some friends, turned around and came home. At the launch, came in slow, put it in reverse once. Bla, bla, bla. Pulled the boat out, and heh, the cone was gone off the prop. I pulled the prop off with no effort at all.
So.... where did it fall off? Is it possible the prop would stay on while we were moving? I don't think so. My buddy threw on his dive gear and looked around the launch... but, there's a pile of millfoil (weeds) there and you can't see anything. I have a big magnet (it will lift the prop) I figure it has to be at the launch. Any thoughts?
If not how hard is it to get a new cone?

And so continues my education as a Donzi newbie.

[Morgan's Cloud]

I have no idea where your locking cone is , but I'd say your one damn lucky guy

[gold-n-rod]

I believe Tony has a similar story to relate. Tony???

[Carl C]

I have a big magnet (it will lift the prop)

I was about to ask how a magnet can lift stainless steel but first went out to check and a magnet does indeed stick to a stainless prop. Magnets do not stick to most stainless steel; how is it that they stick to props?

[Morgan's Cloud]

Props are made of 'cheap' stainles steel.
Only the better grades are non-magnetic.

[SideshowRob]

Well I guess I had an ultra rare SS Cone
Left hand by the way.

[Ranman]

I was about to ask how a magnet can lift stainless steel but first went out to check and a magnet does indeed stick to a stainless prop. Magnets do not stick to most stainless steel; how is it that they stick to props?

Lower grade stainless alloy with a higher iron content. Props, cheap BBQ Grilles, SS car headers are some examples. Only the high grade stuff 304, 316, etc is truly non ferrous / non-magnetic.

[hardcrab]

it's the quantity of chrome that dictates the quality of stainless steel.

I believe a minimum of 11% chrome puts it into the "stainless" catagory

[Carl C]

Lower grade stainless alloy with a higher iron content. Props, cheap BBQ Grilles, SS car headers are some examples. Only the high grade stuff 304, 316, etc is truly non ferrous / non-magnetic.

And I would've thought a propeller would call for the "good stuff". Sideshow, good luck replacing your part.

[RedDog]

And I would've thought a propeller would call for the "good stuff". Sideshow, good luck replacing your part.

I suspect the composition of the SS used in a prop IS good stuff for a prop. The lower chrome level and higher FE content likely makes the steel more ductile, i.e., more likely to bend than fracture on impact.

[Ranman]

I suspect the composition of the SS used in a prop IS good stuff for a prop. The lower chrome level and higher FE content likely makes the steel more ductile, i.e., more likely to bend than fracture on impact.

My thought process is along the same lines. For some reason I think that the "good" stainless is actually more flexible than that with the higher FE content which would be stiffer/stronger.

Where's Root (resident engineer) to explain this...

[f_inscreenname]

IMHO the prop would have stayed on when in drive forever without the cone on it. You have to remember the prop pushes the boat. So as long as it was in drive there was no way for it to come off. As for reverse, you got lucky if you could pull the prop off easy when the boat was out of the water. I guess the force of it pushing it against the splines kept it on. Again very lucky.
Now for the prop cone, Like M/P said its aluminum and you can not pick it up with a magnet. Start looking for a new one as it could be anywhere over a 8 mile stretch.

[penbroke]

Actually, the prop would have to beat it's way past the exhaust outlet or trim tab (if either was installed) to come off in reverse.

Nice cone 'Poodle. Is that a Volvo part or custom?


Frank

[Team Jefe]

How about a note from a metallurgist.

200 Series SS - like props, etc is Ferritic Stainless. it is cheap in that is has a lower content of Chromium and Nickel. Being Ferritic it is Magnetic

300 Series - like most, parts you get at the Marine Store is Austinetic. Know as 18-8 SS 18% Chromium 8% nickel minimum. NON-magnetic

400 Series - Knife blades...at least the good knifes. It is Martensitic and is Magnetic (if your SS knife is not magnetic....throw it away)

then there is the Duplex Stainless Steels......

....I guess I lost you a long time ago.:lookaroun

[Tony]

I was at the far east end of Michigan's Inland Waterway, with my truck and trailer about 60 miles away. After dinner at the Hack-A-Ma-Tack restaurant, I am admiring my boat in the crystal clear waters of the Cheboygan River, when I notice that I have no prop cone!

I believe I lost it about 3 hours prior, when I remember thunking something as I entered Mullett Lake. Apparently, since I rarely used reverse on my old AQ200, the prop held itself on. An old salt searched his garage for about an hour before finding me a 5/8" (or so...) nut that I put on until I could buy another prop cone set. (see below...)

As others have said, drill your shaft and use the locking bolt and red loctite.