Propeller shaft vibrated loose, CD 30

[Stefan]

This is the kind of post where I confess to all kinds of mistakes in the hope that others will not have the same issues.

We were sailing our CD30 last Sunday in Santa Monica Bay. Sunny day, nice wind of 10-12 knots, little swell.
Then I hear a loud and distinct grating noise under the cockpit sole and I loose steering. We bring down the sails. I find the emergency tiller and try to open the cover in the cockpit. It doesn't budge. In fact, you need a special tool to open it and since it hasn't been opened in likely 30 years, it may not have worked anyway. Our first mistake, we did not know how to open the emergency tiller cover (in retrospect it would not have helped but still we should know how to use it).

We are now starting to drift. I radio the coast guard and vessel assist. The coast guard checks on us first and tell us to throw out an anchor because we were only in 50 feet of water. Good idea. We do this. This was our second mistake. I should have thought of the anchor right away.

We are towed into our slip. The situation is very peculiar. I can turn the steering wheel to port and then back but not beyond the halfway mark to starboard. I check the bilge but we do not seem to have water in it. That evening I check the CD board and find lots of post about eroded sheave pins and broken cotter pins. I go back to the boat but our sheave pins are stainless steel and the cotter pins are fine.

I talk to the local boat yard people. They send someone over on Wednesday and he says that the steering is OK. It probably is something with the rudder, maybe the zinc blocking it. I check the rudder and I notice that the zinc and the propeller are against the rudder, obstructing one side.

Concerned about a leak, I check the bilge again and it is full of water, almost to the cabin sole. Mistake number 3. We don't plug the boat into power because we don't have a refrigerator or anything that needs power. This time, however, the bilge pump emptied the batteries and if I hadn't checked, we would have had water in the cabin. I pump out the water.

Then I notice in the little reservoir under the engine three big bolts. They connected the propeller shaft coupling to the engine. The problem seemed to be that the bolts vibrated loose and the propeller shaft hit the rudder.

The boat yard had installed a new propeller shaft last year. They are going to realign the shaft to the engine and pull out the boat to check rudder and propeller.

In the end, no disaster but we came close several times.

[Jim Davis]

A few things I do to reduce this problem. I don't know if your shop did this.

1. The shaft should be dimpled to give the "bolts a place to set.

2. The "bolts" should be square head set screws with holes for a safety wire and be wired so they can't turn. Either "cup point" or "half dog".

3. I always put a shaft zinc collar on the shaft inboard of the stuffing box so if the shaft slips it can't go far. If there isn't enough room try a hose clamp. I leave about a half inch between the zinc and the stuffing box.

http://www.theindustrialdepot.com/squar ... 2-dog.html

[bottomscraper]

One of the things I do every spring is remove the "ETC" put a little
bit of grease on the threads and replace it. The first year we had
Mahalo I tried to remove the cover with the junky little bent rod
wrench that came with the boat. It would not move. I ended up
using an adjustable face spanner, Kroil and a hammer to get it free.
Not exactly something I would have wanted to try in an emergency.
Now I carry a decent wrench and grease it every year. Hamilton
Marine sells a decent wrench called a "Hinged Deck Plate Key" #732012
made of bronze and stainless for $20, it's a Seadog Line product,
but not bad! :


Picture of an adjustable face spanner like the one I used the first
time, made of steel, strong, rusts like crazy!

[Duncan]

...Then I notice in the little reservoir under the engine three big bolts. They connected the propeller shaft coupling to the engine. The problem seemed to be that the bolts vibrated loose and the propeller shaft hit the rudder....

That could have happened to me - I noticed one bolt in the same place, and eventually figured out that it came from the coupling. Like yours, they hadn't been wired.
My engine is a one-cylinder Yanmar that vibrates a lot, but I think the necessity of wiring these bolts applies to any engine. I've had other bolts vibrate loose (notably on the exhaust manifold, causing it to come completely detached).

Both those failures occurred when I first acquired the boat, and it had a newly reinstalled engine. I find it's worth:
1) checking any work done by anyone on the boat;
2) going over the whole engine once a year, tightening all the bolts

The boat yard had installed a new propeller shaft last year. They are going to realign the shaft to the engine and pull out the boat to check rudder and propeller.

I hope they are also going to absorb the cost? I would think that The failure to wire the bolts is the problem, and that it's their fault they didn't do it last year.

I had a rigging failure once on another boat, when the mast had been put up by the yard. They didn't tighten the locknuts on the turnbuckles, and I didn't check their work. One of the lower shrouds worked loose and detached on my second day sailing, singlehanded, about five miles offshore.

Nothing bad happened, but it could have.

so, "yard work" is not always done right, and needs to be checked.

[M. R. Bober]

One of the things I do every spring is remove the "ETC" put a little
bit of grease on the threads and replace it. The first year we had
Mahalo I tried to remove the cover with the junky little bent rod
wrench that came with the boat. It would not move. I ended up
using an adjustable face spanner, Kroil and a hammer to get it free.
Not exactly something I would have wanted to try in an emergency.
Now I carry a decent wrench and grease it every year. Hamilton
Marine sells a decent wrench called a "Hinged Deck Plate Key" #732012
made of bronze and stainless for $20, it's a Seadog Line product,
but not bad! :


Picture of an adjustable face spanner like the one I used the first
time, made of steel, strong, rusts like crazy!

Good points. I grease, with marine grade--whatever that means--white teflon every deck plate at least once a year (ETC, water fills, holding tank pump out and diesel fill). It is also good practice to put a bit of lube on the o-rings.

Mitchel Bober
Sunny Lancaster, (Where the rain has briefly halted.) VA

[marka]

thank you for this post. i checked my shaft coupling bolts this morning and they were loose. i installed them about 8 yrs ago and wired them but the wire wasn't tight enough and they vibrated loose.

[chase]

Rich, good call on the thread protection. I also do that with many fasteners I have problems with. They pay me the same whether it is difficult or not-

Jim, the zinc is a great idea, in addition to checking bolts routinely. There is a zinc just as you suggested on my new boat. Not understanding how that could help with electrolysis, I wondered if it was to keep the shaft in place.

Chase