Prop Vibration & Replacing a Cutlass Bearing

On the Subject of Dealing with Prop Vibration & Replacing a Cutlass Bearing

Dear Dr. Motorhead,

Winter, it seems, has finally reared its ugly head. As I sit and write to you on this frigid morning, I am thankful that now we are closer to liquid water and longer days than further away. The Minneapolis boat show is behind us and we once again can revel in the thought – we soon will be boating. This pleasant thought is wrought however with concern and anxiety. I have, and must admit, been procrastinating. Oh, I am sure you find it hard to believe that one would procrastinate and be filled with anxiety over what to you would seem to be such an easy task. I have heard the term, “it’s as easy as shooting fish in a barrel.”

Alas, for me however, I would miss the fish and put a hole in the barrel. I am all thumbs. I have just recently learned which end of a screwdriver to use. At least I am making progress. At times, my children criticize me. Even my dog Sparky looks at me cross-eyed when I take out my official ACBS tool bag with the Dr. Motorhead seal of approval. I haven’t really used the tools yet, but it sure looks cool prominently displayed in my garage. A thought just came to me; if I have a bunch of tools that I don’t use, does this make me a “tool junkie?” Oh no, oh no, something more for me to worry about. I knew I should not have gone the route of the self-mechanic. Why did I throw away Tonka-Bob’s telephone number? I actually think I am starting to sweat on this 20 degree below zero day. I have three months to prepare myself for the tasks ahead. I must think positively. Remember the little engine that could. I think I can, I think I can. NO, I know I can, I know I can. I will, I will be able to use my tools. I am not a tool junkie. Each tool has a purpose and the handle fits in my hand. I am a self-mechanic. I can and I will make the repairs before the ice thaws. But first, tell me, how do you connect the battery cables to the battery.

After you have taught me how to master the task of
connecting battery cables, perhaps we can move onto
something a little more difficult. Ok Fred, if I may call you Fred. Here is my other dilemma. If my boat has a propeller, then why do all the cool guys refer to this propeller as a “screw” or even a “wheel”? And if this thingy, sometimes called a propeller is brand new to my boat, why do I get vibration when I am “under way”.

Oh by the way, did I tell you I also have a brand new propeller shaft. And oh by the way again, did I tell you I also have a brand new engine. And you know what else the guy who rebuilt my engine also said it was “balanced.” He said it was the thing to do. So, why do I get this vibration if it’s balanced? And why does this vibration happen when I am moving forward and not sitting still at the dock. Please let me know what I should do. Must I dig Tonka-Bob’s phone number out of the trash? Do you know who Todd Schultz is? Do I need to sell this boat and buy one that doesn’t vibrate? Or maybe keep this one and buy another boat to use. Is that why so many people own more than one classic boat? That’s got to be the reason; you never have to repair anything, just buy a new boat. That’s it. I could become a collector. Or perhaps I should sue someone. That’s the American way; it is always someone else’s fault. I could become a millionaire. I would never have to repair another boat again; just collect barns full of them. Do you know a good Attorney? Oh so many questions, the anxiety. Maybe summer will never come and I won’t have to take the boat out of storage. Is there a chance of this? I know, I’ll call Paul Douglas or maybe the Weather Channel, they can help with the weather. Maybe we can iceboat all year, they don’t have vibrations. I’m sure of it.

So what do you think Doc, what should I do? You have all the answers you know everything. I also heard somewhere that you even give advise to other mechanics. Are you are also an attorney? Where’s Mils Lord when you need him? Oh oh, I think I am starting to sweat again. Hurry. Write me back soon. I won’t do anything until I hear back from you. Standing by with baited breath, or is that something that fish just do?
Clyde Kaddinger

Dear Clyde,
Where do I start? What can I say? Who the hell is Todd Schultz? I can’t give advice to other mechanics because my business card doesn’t say “of council.” I went to law school but never passed the bar — I always went into it. If you need to get hold Mils, you can call 612-333-LORD. I like your theory of having a boat collection. I never thought of it that way, it makes some sense; you could throw away all your tools. I could toss out my sign that says, “Old Boat Repairs, Open Every Day”. Clyde, you’re a man of my liking, “cut from the same jib”. We could go into business together, or just iceboat all year long. It doesn’t matter. We’ll be rich and famous with barns full of boats. I can see it now, our names in lights, Motorhead and Kaddinger. We’ll be known around the world. No more articles in the Boathouse. Free at last. I love it, Kaddinger you are a genius.

Then suddenly, my dream was abruptly ended by the sound of the alarm clock. It was morning and the harsh realities of life were ever present. I hadn’t become rich and famous and the lottery was continuing to elude me. There were projects to tend to and I had to answer Clyde’s letter. Poor guy is always sweating. I can’t help him with his anxiety that’s Cousin Phil’s job, but I know where that vibration comes from. How do I break it to him, there is no such thing as ice boating all year long. He will have to fix his problem and become a true self-mechanic. I know his issues, and I can help. Yes, it is time once again to become Dr. Motorhead, benefactor to the tool impoverished, mechanically handicapped and repair disadvantaged. As soon as I finish my breakfast of Spoon Size Shredded Wheat, I will don my cape and attend to the indigent.

Dear Clyde,

Thank you for your nice letter and concerns for the vibration you feel while you are “under way.” Perhaps you can tell me when we see each other sometime this summer what “under way” really means. Until then, lets deal with the vibration. I am going to assume that there are no problems with your new propeller and or shaft. There are additional two factors that may be your problem I will address them both. The engine may be out of alignment with the shaft or the cutlass, also known as a bearing, may be worn.

Let me first address the cutlass. The strut on the bottom of the boat that holds your shaft in place has an insert or
bearing that keeps everything in alignment and properly
supported. If this is worn it may allow the shaft to vibrate or wobble slightly. You can easily determine if this is worn by a visual inspection. It is always easier to perform this inspection when the boat is out of the water. The cutlass is made of a brass tube that has a rubber insert. This rubber should not be cracked, chipped or allow you to move the shaft up and down or right and left.
If you have movement you need to replace it. The task is painless, however this is one area you will need some help unless you own a hydraulic press. You must remove the strut from the boat by removing the six bolts that hold it in place. The nuts are on the inside, in the bilge. Remove these and tap the bolts down through the bottom. With the “wheel” removed, slide the strut off the shaft and marvel at this thing for a while before you bring it to your nearest boat repair station. Tonka-Bob is an all right guy; he can help you if you live in the western suburbs. You need a hydraulic press to push this bearing out of the strut and the new back in. There are many different sizes. Few repair shops keep them all in stock, so you may need to order one. With the new cutlass in place it is time to re-install the strut. Slide the strut back over the shaft. Squirt a little bedding compound on the plate of the strut and in the bolt holes. Refasten the strut to the boat reinstall the “screw” to the shaft and you are ready to go.

The other issue may be the engine alignment. Here is my advice for you on this topic. Launch your boat and see if the vibration continues. If there is no vibration, you are done. If the vibration persists you are likely to have some alignment problems. Remember, your boat will have a slightly different shape on the trailer than when it is the water. This is why I like to align engines while in the water.

Are you ready Clyde? The flange on the motor must be in alignment with the flange on the shaft. Remove the bolts that hold the two flanges together. With these bolts removed, pull the shaft flange away from the motor flange ever so slightly. (See Illustration) Loosen the bolts that hold the engine to the stingers or bed. The wedges between the motor mounts and stringers allow you to move the engine alignment by sliding the wedges back and forth. This will make all sorts of sense when you see them. Now, tap the wedges fore or aft as needed so the two flanges line up with each other. Double-check everything with a feeler gauge. (See Illustration) Now you can bolt the flanges together and tighten the engine mount lag bolts. There are very small holes in each engine alignment wedge. They are there for a specific purpose. After the engine has been
positioned and aligned, install a wood screw through these holes into the stringer. This procedure helps hold the wedges in place keeping everything in alignment for hours of boating pleasure.

Additional Answers:

Todd Schultz? He is a fictional character written in the many books authored by Dickens. You may remember him as a short little guy with pointy ears. Judgmental and opinionated, he scurries about town while in constant trouble with his lovely wife.

As far as the terminology “screw” and “wheel” are concerned, here are your answers. Prior to the invention of the propeller there was only the paddle wheel and the common oar for boat propulsion. The invention of the screw propeller, by John Ericsson, was first used on the Merrimac, the iron battleship built and designed by Ericsson for the Union Army. You see the paddle wheel was too vulnerable to enemy fire as was the oarsman. The propeller or “screw” was underwater and worked quit well and was protected from enemy fire. It was called a screw propeller because that is what it resembled as it screwed through the water. Besides, the inventor gets to call his invention what ever he or she wants to. Hence, the term “screw.” The diehards who thought of this invention as a form of propulsion only, continued to call it a “wheel.” There ya have it, call it what you want, they all work for me.

If there are any technicians out there whom I can help, please send in your questions. Remember, the shop is open everyday.

And yes, only fish can stand by with baited breath.

Keep Dreaming,