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Repacing The Driveshaft... The Hard Way

We get lots of tips and real-world ways cruisers cope with the issues of maintenance and repair when they are out there enjoying this lifestyle. Resourcefulness is often a key to getting things done when traditional methods are either unavailable or financially excessive.

The following article does not portray the typical approach to solving a shaft problem, but it is a resounding example of the self-reliance and creative ingenuity that defines the successful cruiser. We would not recommend most people attempt this at home, but it is nice to know it can be done.-Bill P.

Stop! Stop! You're sinking the boat!" That got my attention-it's like your dive buddy yelling "Shark!" while you're in the water. Although I was in the water at the time, I knew it wasn't a shark attack that Judy was trying to alert me to-but I could tell by the sound of her voice that we were dealing with a serious problem.

We had just installed two new John Deere engines in a boat that we had recently purchased, an older 55-foot Hatteras that needed lots of work. The Hatteras, Imagine Me And You, was originally equipped with two large Detroit 8V71s, each producing more than 300hp. The Deeres were smaller, rated at 150hp, but developing a fair amount of torque for their size. We felt the Hatteras, now equipped with smaller and more efficient engines, would be an ideal coastal cruiser that would meet or exceed our needs.

We loved cruising under power. We had taken our old boat, Gracias, from Los Angeles to Panama and back. After that four-year cruise, we decided we needed a bigger boat, mainly because our two dogs required more room, and besides that, we wanted redundancy in the drivetrain, as Gracias was a single-screw DeFever.

After the Hatteras had been repowered, we discovered that the starboard engine had an alignment problem that may not have been present with the old Detroit, but we weren't sure. My wife, Judy, and I spent several days trying to align the new engine, but we could not eliminate a severe oscillation of the drivetrain whenever we engaged the gear. The engine and transmission would actually bounce up and down in forward and reverse.

Eventually, we threw in the towel and hired a professional mechanic to check our work and resolve the issue. He completed the alignment but didn't solve the problem; the severe oscillations remained. He determined that the problem was somewhere between the shaft coupling and propeller, but he couldn't pinpoint the exact source.

The propeller was the logical starting point, so I donned scuba gear, entered the cold water of San Francisco Bay and pulled the prop. The local prop shop examined the propeller and reported that the pitch was not consistent throughout the blade area, but the variation was slight and probably would not have caused the extreme motion we were experiencing.

If the prop wasn't the problem, then either a shaft was bent or the shaft coupling face was not true (perfectly perpendicular) to the shaft. In either event, we were advised that the shaft had to be pulled to determine the problem. Shafts, especially large shafts, generally are pulled when the boat is out of the water, but our boat had been pulled twice within the last six months. I didn't want to go through the expense of another haulout, paying for lay days while waiting for shaft repair or replacement, and dealing with all the problems associated with towing the boat to the yard-an approximate cost of $2,000. Years ago, I had pulled a small shaft from a 30-footer while the boat was in the water, and it had been fairly easy. The primary shaft on the Hatteras, however, was 13 feet long and 2 inches in diameter, and it weighed over 130 pounds. (There are actually two shafts per engine, coupled together for a total length of 19 feet.)

We were somewhat intimidated by the thought of pulling and replacing this size shaft while the boat was in the water, but it's a simple procedure. What could go wrong?


The prop shop gave us a short, stainless-steel plug the same diameter as the shaft to be inserted into the stuffing box as the shaft was pulled from the boat. The plug would fill the hole created by the absence of the shaft. The transition from shaft to plug, however, was cause for concern. This part of the operation had to be done quickly and without a hitch to prevent too much water from entering the boat. We had recently installed four new bilge pumps, but we didn't intend to find out if they actually could pump 1,000 gallons an hour. The plan was simple: I would go under water and pull the shaft, and as the shaft exited the boat, Judy would insert the plug into the stuffing box.

Pulling the shaft under water took longer than I had anticipated and was hard work. Over the course of two days, I burned four tanks of air removing the shaft. We used a come-along to provide the pulling power to extract the shaft, and we used lines to support and hold the shaft as it was removed from the hull.

With the plug safely in place, we delivered the shaft and the shaft coupling to the prop shop. After inspecting the two parts, the technician reported that the shaft was straight as an arrow, and the coupling was true to the end of the shaft. Now what? Frustration was building, as we still couldn't identify the problem.

The tech asked me to bring the shaft key (a rectangular stainless-steel bar that prevents the coupling from spinning on the shaft) back to the shop for a complete inspection. He discovered that the key and the keyway (the groove in the shaft and the coupling) had matching compression scars at the aft end of the keyway. This bit of evidence suggested that the key had migrated aft and up as the coupling was installed on the shaft. The raised key caused the aft end of the coupling to stand proud on the shaft after it was bolted together, meaning that the face of the coupling was no longer perpendicular to the end of the shaft. The out-of-position key was the source of the problem.

Earlier, after the old engines had been pulled, I had removed and reinstalled the shaft couplings so that they could be cleaned and painted. The technician was confident that the problem had been introduced at this point, during the reinstallation of the shaft coupling. We also discovered that the old shaft was pitted and probably needed to be replaced.

A week later, I found myself back in the water with 130 pounds of brand-new stainless steel, yards of line, and my old faithful come-along. We were hoping that it would be easier to install the new shaft than it had been to remove the old one.

It was going to be nearly impossible to communicate with Judy while she was hunched over the stuffing box in the engine room and I was under water trying to stuff a shaft back into the boat. We agreed on a simple tapping method: One tap from Judy with a rubber mallet meant for me to start the insertion process, and two taps indicated that I should stop. (Maybe there would have been some benefit to learning Morse code, but I doubt it.)

All went well as I passed the shaft through the two struts and one final cutless bearing, then into the hull. It wasn't difficult to align the shaft with the struts and slowly move the shaft into place using the come-along and the supporting lines. This was turning out to be a piece of cake, much easier than the removal. After spending less than 45 minutes under water, I had the shaft nearly in place, only about 2 more inches to go...and then disaster struck!


When the front end of the shaft was almost in place, I felt some resistance to the forward movement of the shaft as I worked the come-along. I wrongly surmised that this was caused by the end of the shaft making contact with the flax in the stuffing box. No problem, I figured-one more hard pull on the come-along, and the shaft would be in the correct position.

Not quite. The last hard pull caused the shaft to shoot forward about 4 inches. With this sudden movement, the end of the shaft knocked out the stuffing box, the prop shop-supplied steel plug, and the rubber hose that connects the stuffing box to the stern tube. Instead of the anticipated trickle of water entering the boat, we now had a 4-inch wide stream of water gushing through the stern tube and flooding the engine room.

Of course, being under water, I had no idea that Judy was dealing with a situation that could quickly overpower the limited capacity of the bilge pumps. She had the presence of mind to remember our simple method of communicating while I was under water. However, instead of two sharp raps against the hull-her signal for me to stop-I heard what sounded like a 50-caliber machine gun being fired in downtown Baghdad. This was my first clue that we may have had a problem. I popped to the surface and immediately noticed a stream of water being pumped from the engine room by the bilge pump. And that's when I heard Judy yelling (and she doesn't often raise her voice), "Stop! Stop! You're sinking the boat!"

I flew out of the water (it's surprising what a little bit of adrenaline will do) and raced into the engine room, dropping dive gear along the way. There was so much water coming into the boat that it seemed like a good place to have on a wet suit. I knew we had a problem when I saw Judy holding the entire stuffing box, hose and plug as one solid unit. First things first: We had to stop the flow of water that was overpowering the engine room bilge pump. I cupped my hands over the end of stern tube and told Judy to get several towels.

When she returned, I wrapped a towel around the protruding end of the shaft and stuffed it between the shaft and the inside of the stern tube, firmly holding it in place with my hands. It worked. The flow of water nearly stopped, and after a few minutes, which seemed like several hours, the engine room bilge was nearly empty of water. We still had a problem, however. The plug was locked into the stuffing box, as Judy couldn't get it out by herself, and my hands were full. We had to get the plug removed before we could attempt to get the stuffing box and the hose back on the end of the stern tube. Once the stuffing box was back in place, the flow of water would be cut off.

The automatic bilge pump finally shut off, which meant that most of the water had been pumped overboard; this had a genuine calming effect over both of us and gave us a chance to catch our collective breath and to slow down our heart rates.

We came up with a quick plan. Judy and I would trade places. She would hold the towel and I would work on the stubborn plug. On the count of three, I let go of the towel and Judy dropped the plug. The flow of water immediately returned the moment I released the towel, and Judy and I knocked each other down as we tried to maneuver around in a wet and slippery engine room. (This must have resembled a scene from an old Keystone Kops movie, and I got THAT familiar look from Judy that said, "This is another fine mess you've gotten me into.")

The good news was that dropping the stuffing box had helped to dislodge the plug. With the plug out, I could try to force the stuffing box and hose over the protruding shaft and back onto the stern tube. We waited for the bilge pump to stop pumping, counted to three again and traded places one more time. Water poured back into the boat, the bilge pump kicked on, and I struggled to get the stuffing box and hose back over the end of the stern tube. It finally worked. The hose went on, and the stream of water as wide as the Colorado River stopped flowing into the boat. I know, I may be exaggerating just a little, but it really did seem like a lot of water was trying to cover our brand-new engine.

We got the soggy mess cleaned up and relaxed, finally, over two stiff adult beverages. The next day, we attached the coupling, aligned the engine, installed the prop and fired up the little tractor engine that powers the boat. We both held our breath as we engaged the gear while the boat was tied to the dock. Ah...smooth as silk. We did it! We solved the problem.

Actually, Dave, the owner and technician at the prop shop deserves all the credit. His observation and analysis were right on target. His shop, The Prop Shop, is in Richmond, California, right on San Francisco Bay. He knows his trade, and I would recommend him to anyone who has a prop or shaft problem.

We plan to return to Mexico in the fall; the itch to cruise has flared up again, so we're off to another adventure. It will, however, be a long time before either of us forgets the day I almost sank the boat.