1981 Hatteras 43c Prop Shafts

[Hat43c1981]

Good morning. I have a question about the prop shafts on our 1981 Hatteras 43c. I noticed there is a large (possibly a coupler) about 2 1/2' up from the props on the shaft. It is about 10" long and has 4 recessed bolts on it. Is this a coupler that attaches two shafts together? I am not familiar with this set up. At first I thought it might have been an anode, but if that was the case, it would be a very large anode!

I wanted to make sure I knew what this piece of equipment is moving forward. Attached is the best picture I could find that shows what I am referring to. Is this piece of equipment typical on older Hatts.
IMG_5194.jpg
Thanks in advance!

[oscarvan]

On my boat the shaft is in 2 pieces and there is a coupler. Right behind the strut. Zincs are off in this picture.

[Hat43c1981]

On my boat the shaft is in 2 pieces and there is a coupler. Right behind the strut. Zincs are off in this picture.

Thanks! I was wondering if my shafts were two separate shafts.

[oscarvan]

Thanks! I was wondering if my shafts were two separate shafts.

Not saying yours are, but mine are.

[jim rosenthal]

Most likely a muff coupling, and yes it is probably a two-piece shaft.

On some boats, it is possible to replace the two-piece shaft with a one-piece one; they are said to balance better and run smoother. If I'm not mistaken, the process of installing the single-piece shaft requires raising the boat higher up during the haulout, in order to slide the longer one-piece shaft in.

When I have heard of an owner going to a one-piece shaft, IIRC it was always in the context of having to do major service work down there and the one-piece shafts were a "while you're in there".

[Bob Bradley]

That is correct. I have a 79 43C with the same setup.

[Hat43c1981]

Most likely a muff coupling, and yes it is probably a two-piece shaft.

On some boats, it is possible to replace the two-piece shaft with a one-piece one; they are said to balance better and run smoother. If I'm not mistaken, the process of installing the single-piece shaft requires raising the boat higher up during the haulout, in order to slide the longer one-piece shaft in.

When I have heard of an owner going to a one-piece shaft, IIRC it was always in the context of having to do major service work down there and the one-piece shafts were a "while you're in there".

Thanks Jim!

[Hat43c1981]

That is correct. I have a 79 43C with the same setup.

Thanks Bob. I am experiencing a bit of a vibration at cruising speed on the port side. If I stand in the cockpit floor, on top of where the shaft would be, I can feel a decent vibration in the floor. Not sure if this coupling might have worked itself loose. I just had the props reconditioned as well. Cutlass bearing seemed to be fine. No play.

[Maurice]

I had such a coupling come apart once while operating in reverse to enter a slip ... not fun. They can come loose and come apart. Suggest it be investigated. of course, while operating in forward gear they are held together.

[oscarvan]

I had such a coupling come apart once while operating in reverse to enter a slip ... not fun. They can come loose and come apart. Suggest it be investigated. of course, while operating in forward gear they are held together.

Hadn't thought of that yet...... I've had a one piece shaft do that, pulled itself out of the coupling on the gears. Gets your attention, especially since I only had one of them.

PO left me with a spare short shaft. (The piece that the prop mounts on.) Hope to never need it.