Tuesday, March 22, 2011

Just when you thought it was safe to go back in the water.

It was another gorgeous weekend in Houston with temperatures hanging in the mid-70s and big gusts of wind. I used to hate wind, but without it, sailing is very boring.

Perfect morning in Houston

After getting the alternator wiring sorted last weekend, I thought we were set for a nice long season of sailing every weekend through the entire summer. Unfortunately, the boat was not in agreement. My first weekend out in February, I noticed an occasional stutter and shake in the hum of the engine. I also could have sworn I felt the boat speed up and slow down a couple times. However, the tachometer wasn't yet working and I was in the cabin when it happened, so it was hard to judge. Then during our outing last weekend, we definitely felt more stuttering, but we thought it might be due to the choppy water. Unfortunately, this weekend we found out the real cause.

Upon leaving the slip Saturday, the boat suddenly stopped moving forward and the tone of the engine went from being under load to being in neutral. No longer did we have just a stutter. The transmission was full-on slipping. We would get 30-40 seconds in gear, 5-10 seconds out of gear, 30-40 seconds in gear, 5-10 out of gear over and over. Ben went below to check the linkage in hopes that maybe it had slipped and the shift lever wasn't pushing the transmission all the way into gear, but unfortunately, that wasn't the case.

I had finally started feeling confident enough to invite friends out sailing. You never know how people are going to react when a boat suddenly quits in the middle of the bay. I'm not one to panic, but that doesn't mean my passengers wouldn't. It also doesn't mean they would be thrilled sitting for hours waiting on a towboat.

Once upon a time in a previous life I had a lucrative Sunday afternoon gig playing guitar on the patio of a local restaurant. I had about 25 people turn out that first weekend. I thought I did a great job entertaining, but the bar staff managed to get hair in most of the food and then double bill half the crowd. Needless to say, none of them ever returned. I get the same fear when it comes to the boat.

Knowing it was just a matter of time until the transmission gave out altogether, we just sailed back and forth in Clear Lake for an hour or so. It was good practice. We also saw another sailboat get stuck over near our channel. They kept tipping the boat at precarious angles attempting to break free, but it never happened. Someone in a motor boat finally threw them a line and pulled them free.

When we returned to the marina, I sat moping in the cabin for a long time before I stirred up the energy to start pulling the transmission. Then I still took a nap before I started. However, I did have it off and was headed home with it by Sunday morning.

ZF Marine Hurth HBW-5 transmission

Upon disassembly, I couldn't find any broken gears, obvious signs of failure or even signs of wear. The clutch discs still looked new.

ZF Marine Hurth HBW-5 transmission

Since I already had a rebuild kit from the first time I'd done this last summer, I went ahead and put fresh clutch discs on just to be on the safe side. Then I made sure to shim the output shaft, so there was no forward/backward wiggle. My only theory was that the pressure of the prop shaft would slide the output shaft forward, which would reduce the pressure on the clutch discs, which would allow them to slip until the RPMs of the propeller dropped, which then reduced the forward pressure on the output shaft allowing the clutch discs to catch again -- and so on and so forth, which would explain why we'd have a few seconds of power, a few seconds of no power, etc.

I guess we'll see how it works Saturday when I reinstall it. While annoying, at least this breakdown hasn't cost anything.
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