Boatworks

Give your Running Gear an Upgrade

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We had no inkling that there was a problem with the running gear on our Pearson 323, Alma, until the diver we hired to clean her bottom told me the propeller was binding. Time for a haul-out! As soon as Alma was on the slings, I went right for the prop. Interestingly, it spun easily in reverse but locked up in forward. It was a “soft” binding in forward, not a mechanical clunk like a transmission adjustment. 

When she was blocked on the hard, I disconnected the shaft coupling from the transmission to eliminate any transmission or engine issues, and—clunk—encountered the same problem. I would have to remove the running gear to check the cutless bearing. 

Before removing the prop and shaft, I used a wire cup brush on a grinder to clean the bronze prop and bronze strut. I don’t use mild steel wire cup brushes on stainless steel—the bristles will deposit mild steel on the stainless steel and cause it to rust. I always try to use stainless steel or non-ferrous tools on stainless steel, even fasteners. Beryllium-Copper tools are available for marine use and they are also corrosion-resistant themselves. They will not ruin stainless steel and will not create a dangerous spark when banged around in an engine room or propane locker.


It can be a struggle to remove a propeller without the right tools. A nifty prop puller will make the job simple. If you can borrow one, perfect. I bought a bargain-priced three-legged bearing puller from Harbor Freight that I used to grab my ancient Michigan Wheel Sailor three-blade propeller. First I sprayed the shaft around the prop bore with PB Blaster and then left it to soak for a day or two. I soaked the transmission coupling bolts and propshaft/coupling with penetrant as well.

To use a three-legged puller along with a hammer to coax a stuck prop from its shaft taper, first orient the puller’s legs to grab the back of the prop’s hub. The three legs fit nicely between the prop blades. Loosen both shaft nuts, leaving one nut loosely in place to both help locate and trap the puller’s center bearing screw and to keep the prop on the shaft when it breaks free. Now, tension the puller slightly and check that the three legs are well engaged with the prop’s hub. Hold the puller (not the prop or shaft) and tighten its mechanism. If you hold the prop or shaft and try to turn the puller you might rip the puller from the job. Does the prop come free? If yes, continue. If no, STOP!

Now uncouple the prop shaft from the transmission or Vee-Drive inside the boat. The thrust bearings in the transmission or Vee-Drive are not made to withstand a hammer’s pounding so pull the shaft an inch or two away from the transmission, insert a folded magazine between the transmission and the shaft coupling, and duct-tape the magazine in place between the couplings.

Check to see if the prop has broken its bond to the shaft. Yes? Great. No? Give the puller a little more tension, then tap the front of the prop’s hub (or a leg of the puller against the hub). The goal is not to pound the prop off the shaft but to shock the stuck parts so the tension of the puller and penetrant can do their job. Remember that the shaft is floating unattached to the transmission aboard so do not keep pounding the shaft until something touches. If the shaft doesn’t come free with a few “bumps,” it is stuck.

Try some more penetrant. Spray on the penetrant and then lightly tap the prop’s hub all around its circumference to encourage the penetrant to wick in. If you have the time and patience, wait a day. The penetrant works 24/7 and I have seen stuck parts come free overnight. If the bearing puller and tapping of the hub don’t work you will need to either borrow or make a dedicated prop puller from steel plate and threaded rod. Some prop reconditioning shops lend/rent pullers. I don’t recommend heat. A torch could make the penetrant fumes start a fire or make you sick. I would hire someone with a proper puller before using a torch, even more so with an expensive feathering prop. Never use a torch inside the boat.
Once the prop has been removed, remove the transmission shaft coupling. Maybe it will slip free once the safety wire and locking bolt are removed. No safety wire? Make a note to get some for reassembly. If the coupling is stuck it is possible to use the coupling itself as a press to separate it from the shaft. Use a mechanic’s socket wrench slightly smaller than the shaft diameter and slip it into the back end of the coupling as a ram. Using the bolts that attach the coupling to the transmission flange, draw the shaft out of the coupling by using the bolts as a press. Resist the temptation to use the original bolts if they only engage a couple of threads with the socket in place. Buy longer bolts if necessary.

Next remove any stuffing box/shaft seal hardware that prevents the shaft from passing through the stern tub. You may need to clean the shaft in order to get it to pass through the cutless bearing. Grind a half moon shaped hole, matching the shaft diameter, into some scrap stainless steel plate and use it as a scraper. Remove any hard growth to prevent damage to the soft rubber cutless bearing before pulling the shaft out.

Once the shaft is free, check the cutless bearing for wear. This is where my running gear was fouled. Sea worms had made a home in the water-cooling ridges of my cutless bearing! A fine concrete-like coating had fouled my rubber bearing and made the shaft bind. I used a little wire brush that just fit into the cutless bearing with water to scrub away all traces of this thin coating. When cleaned, I could see my rubber bearing was good as new and there was no damage. And, the shaft had almost no galling from the abrasive hard fouling—great!

 

After cleaning the shaft with Bar Keeper’s Friend brand cleanser, I used Flitz brand fine polish on a long rag that was the hem of an old shirttail. Wrap one turn around the shaft like a shoelace and run back and forth to create a mirror finish. This mirror finish on stainless steel or Aquamet shafting helps postpone corrosion and hard growth. Bronze shafts can simply be scraped and cleaned with ScotchBrite. As a final treatment, I went over each machined area on the shaft with my Dremel tool and a stone to lightly chamfer the keyway’s top edges and transmission flange lock-bolt dimple edges, removing all burrs.  This insures I won’t damage the O-rings in my dripless-shaft-log rotor upon reassembly.

Once the shaft was cleaned and polished, I lapped the prop hub bore to the shaft. Experts lap the bronze prop hubs to the shaft to insure smooth running by insuring the prop is centered. Although more important on high-speed propellers, it certainly can’t hurt our “wheels” as well. Another benefit is the excellent electrical continuity the clean surfaces provide, allowing a shaft-mounted zinc to also protect the propeller from galvanic corrosion. I used a 400 grit, wet-dry sandpaper for this job. You can also use automotive valve lapping paste if you have a stainless or Aquamet shaft. 

If your shaft is bronze, work slowly. You only want to take away a little material from the propeller hub and none from the shaft. With bronze shafting, use the sandpaper’s grit side against the propeller hub. The paper side will not harm the shaft’s taper. When the hub has a pretty matte finish, you are done. With the shaft installed, I mounted the prop. Grease or anti-seize may block the electrical continuity between the shaft and prop, causing galvanic corrosion on props without their own dedicated zincs. You can see my 37-year-old prop has had some lapses in galvanic protection.

Experts disagree which thickness shaft-nut goes against the prop hub and which nut acts as a lock-nut. I have used both arrangements and have had no problems. The proper torque of both nuts and a properly sized cotter-pin in the shaft that is more noble than all your underwater metal components is more important than which nut goes on first. I used a stainless steel cotter pin. There is no need to wrangle the cotter into a pretzel shape. You will be pleased you didn’t make the job harder when you need to remove the pin in the future. 

Smooth-running and quiet running gear is long lasting and economical. It saves fuel and won’t let you down when you need it most.


 

Gene Smith is a photographer,
sailor and jazz musician
residing in New Jersey

 

 



 

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