Mechanical Woes

Stuart, FL

No LL

On Monday we're going to Fort Pierce to have Tarwathie hauled up on the hard. Here's the story behind this expensive and unexpected development. Warning: what follows is technical.

On our recent survey, the surveyor found that we had excessive wear on our cutlass bearing. That was coupled with a drastic increase in the amount of water leaking in around the shaft. What the H? The cutlass bearing was new 3 years ago when we repowered. It should last up to 20 years. How could it fail so fast?

I called Bud Taplin for advice and ideas. After describing the symptoms Bud said, "It sounds like your shaft log is vibrating." What the heck!!! How could that happen. Bud asked, "Are you getting any leakage around the shaft log?" As a matter of fact yes. Indeed, I wrote about it in a blog post last November including a blue print of the shaft log. Finally Bud asked, "Have you run aground or had any crab pot lines wrapped around the prop?" Bingo. As usual, Bud was brilliant. Just a few questions and he nailed it. I think.

Last summer on Lake Champlain we allowed the dinghy painter to wrap around the prop. It sank the dinghy and stopped the engine dead. It is possible that incident pulled sideways on the shaft so powerfully that it pulled the shaft log loose and elongated the bolt holes that hold it in place. Our current woes could be the result of undetected damage from that incident.

My first thought was to wait until we get to Deltaville, Virginia to do this repair project. Upon further reflection I conclude that would be really dumb. Deltaville is 1,000 miles from here and the severity of the vibrations and leakage could increase drastically converting a problem to an emergency.

So, what's the cure? How do we confirm the hypothesis and repair it if correct. It means putting the boat up on the hard, removing the propeller, grinding down the Marine Tex putty over the log. At that point the evidence confirming the hypothesis may be evident. Maybe not. Either way, I'll have to follow through the same way.

I'll remove the log. Then, I'll have to re-glass the bolt holes and bore new holes. Next I'll remove the Drive Saver flexible coupling, move the shaft forward, and re-bolt it in place. (With the Driver Saver in place, the shaft would droop and alignment is impossible.)

Then, adjust the engine mounts to align it so that the shaft passes exactly through the hole in the log. (I could do it the other way around; put the log on the shaft, then bore the holes to mount the log securely in that exact spot.) With the log firmly mounted, and the shaft aligned, install a new Drive Saver, put new Marine Tex putty over it to make it waterproof, and remount the propeller. That should do it.

We are allowing one week up on the hard to accomplish this project.

Comments anyone?