The Drivetrain

This weeks blog entry is partially authored by Captain Doug Gould who had a need for my assistance this past week. Following is his perspective.

After 6 seasons of operating the Safe/Sea Block Island, my ears are highly tuned to the sounds that normally rise from the large aft engine compartment of our turbo-charged jet propelled towboats. Most of the racket comes from the 315hp Yanmar Diesels. Indeed, over about 1600 rpm, I can barely hear a difference when the jet is disengaged. When you push the throttles up quickly for a fast acceleration, there is a satisfying roar as the boat gets up on a plane. The lack of rattles, groans or squeaks is a reminder that these are finely tuned machines. Driving a Safe/Sea jet boat is more akin to a Ferrari than a Mack Truck.

So, about a week ago, I noticed a sort of quiet grinding noise in reverse. Shifting each jet to neutral narrowed it down to the starboard side. I had to make an unwelcome call to Andy. I wanted to be precise and give him my most technical analysis of the problem," Hey, the starboard jet is making a bad sound."

"Yeah, maybe it just needs some grease. Load up that fitting behind the bucket pump and call me in the morning."

The following day, I had to make an even more unwelcome call to Andy; "Hey, the starboard jet is still making the bad sound, only a little louder." Andy was tactful when he suggested (albeit without any conviction) that perhaps there was "something snagged on the impeller shaft." The implication was that some idiot boat driver had just blindly crossed over a line or lobster pot, and now said idiot was looking for Andy to bail his sorry ass out and make the noise go away. Andy suggested that a short swimming excursion might be the next step, as opposed to his having to drag the big trailer down to Galilee only to find some line in my jet intake.

Did I mention that the water temp last week was 55 deg? So we lifted the back of the boat with ACE (the local mooring tender with an A-frame) high enough so I could open the shaft inspection covers, and I found them to be clean as my record for avoiding floating lines (my own towline excepted). I made one last call to let Andy know that the ball was now fully in his court. The only question left was whether the noise came from a bad main bearing (my diagnosis), or anyplace other than that (Andy's hope)....

Here's where I came in. Doug brought the boat over from Block Island in time for us to have breakfast together. Then I took the boat for a ride. I noticed a familiar hesitation while bringing her up on plane. It was the transmission slipping. So I had my morning project and I swapped the gearbox out with a spare.

About 4 hours later I was happy to find the slipping had gone. But the whining was still there. That meant it could only be the jet bearing. So now I had my afternoon planned for me.

I had the drive shaft and bearing assembly out and dropped at UPS just under the wire at 6pm. The whole thing was shipped to Atlantis Marine Gear in Topsfield, MA and they pressed the new bearing in and shipped it right back. The Safe/Sea Block Island was down for only 3 days. Luckily, it was Monday, Tuesday and Wednesday of a pre-July 4th weekend.

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It's official, the season is in full swing. By the time Memorial Day weekend was over more then a few boats were trapped by fishing nets, fouled in there own anchor line, and a couple of close calls with fires; but those were just the more interesting cases!

We also helped a number of members back to home port after they experienced simple malfunctions of some sort. But who wants to hear about that boring routine stuff?

Here are a couple of pictures of a boat that struck Mount Tom Rock off Prudence Island on Memorial Day. These folks were very lucky! Another inch or two and the strut comes through the bottom of the boat, sending it for a trip toward the bottom.

In 2007, the blue trawler below was not so lucky. She hit Mount Tom Rock and punched a hole in her keel under the generator and had to run it up on the beach just outside Potter's Cove. I removed the six passengers and transferred them to the Bristol Harbor Patrol who took two of them to be checked for minor injuries. The good news was that they were all ok, and the boat was saved after extensive repairs.

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It's not just our customers that have an occasional mishaps on the water. Remember the job Capt. Pete and Capt. Phil did last week, putting a 118' motorsailer to the dock in Newport? (If you don't you can read Capt. Pete's blog post about it here.) Anyway, during the job, Capt. Pete's starboard jet was mysteriously fouled by an unknown object or line. After some detective work, I've solved the mystery!

While transferring to a side tow of the 118' Knickerbocker around 2 am, Capt. pete's boat picked up a black line that, as it turns out, was hanging off a custom fender that had been deployed by Knickerbocker's crew. The line was invisible at night and had a stainless steel snap shackle that got sucked up in the jet and left its mark. Click on any of the photos at right to see the actors involved in the mystery.

Capt. Pete's boat was not disabled and he was able to help Capt. Phil complete the job successfully.  As you can see in the photo gallery at right, we did have a little work to do on Monday. I bent the grate back into shape and filed and grounded the impeller a bit. The boat runs at about 95% capacity with the damaged impeller. But we don't tow folks 95% of the way back to the dock, so we've ordered a new impeller and will have the old one reconditioned as a spare.

We love our jet drives. They have many advantages over conventional props for our type of business, but like anything mechanical in use around the ocean, they're not bulletproof. Stuff happens. I like to think of it as job security! ;-)

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