Overhauling a Kenyon Boom, new reefing sheaves

After some initial sails and testing, I came up with a list of updates that I wanted to make to my boom.


1. Remove & replace the frozen reef line sheave at the aft cap end. (Replace both sheaves as they are of similar original vintage)
2. Remove & replace the small worn front reefing line sheaves.
3. Remove the after-market Harken single line reefing system mounted on the outside of the boom.
4. Cosmetically update (i.e. repaint) the front gooseneck cast piece.
5. Run a new second reefing line inside the boom (the frozen sheave side had been abandoned by a PO.
6. Make a reasonable estimation of the health of the outhaul and topping lift lines inside the boom.

The wear on the rear sheaves was pretty obvious (you know, obvious once I had paid for the boat and made it mine). One sheave no longer turned at all and the other was a chafing hazard.


The front sheaves also had some jagged edges. The paint finish on the cap was rapidly flaking off with oxidation. (The rear cap had no similar problem)


The bow end of the Harken single line reefing system is visible in the first picture. It’s a great idea (to be able to use one line to pull down the tack and the clew, but what kept happening is that I could put a lot of force on the tack, but very little on the clew. I would have to climb up to the mast to try to yank the lines appropriately, defeating the purpose of the single line reefing. My plan was to remove these add-ons and save them for an emergency.


For the rear cap, I followed, for the most part, another member’s explanation in the Ericson Yacht forum for his similar fix. To his forum entry I added my own explanation of knurled pin removal.  The boom extrusion number for my 1990 Ericson is Kenyon 3550.

There must be some variation on the Hippocratic oath when it comes to old boat repair. It’s virtually impossible to “first do no harm,” so one might be better off planning to do some harm and deal with the consequences. This thought occurred to me as I dealt with various steel-to-aluminum fastener connections that had corroded over the past 30 years.

I’ve seen a lot of references in sailboat repair to PB-Blaster as an effective assistant for removing stuck metal parts. I’ve had lots of experience with WD40, but none with PB blaster, so I bought some. I’ve learned that PB Blaster does an excellent job of penetrating the pores of my skin and fingernails. I’m not entirely sure about the corrosion removal, but I guess it all worked out okay.

I tried a variety of ill-advised hand tool combinations to unscrew fasteners. Crescent wrench tightened up on a square-shafted phillips screwdriver, grabbing a smooth screw head with a small pair of grooved channel lock pliers. Some thinking. Some “waiting for the PB Blaster to penetrate.” Some profanity. I sheared off the end only of two of the screw fasteners on the aft boom cap (with the channel lock pliers). Twisted them clean off. I had to drill out the screw shafts. This is a challenge with a hand drill in that the stainless steel of the small screw is so much harder than the surrounding aluminum of the boom extrusion, so the drill tends to walk away and massacre the aluminum. I knew replacement would involve wider diameter fasteners.

The other item that stymied me was removing the support bars for the Harken single line system. There were five large screws for the fore and aft block mounts. With patience and effort I was able to remove the entire rear support bar. But there were three particular machine screws on the front bar that foiled me entirely. They were installed decades ago, were no longer useful, and could only have been removed by an unwarranted act of violence. I also would have had to figure out something to take up the voids they would leave and that might be worse then what I had. I gave them appropriate names, left them installed, and got on with my life:



At least two sources for replacement sheaves are available: Rig-Rite and Zephyrwerks. I contacted both providers for parts requests.

I got an e-mail back right away from Ed Louchard at Zephywerks. His price was better than Rig-Rite and I had read a positive review of his stuff elsewhere. I sent Ed the Kenyon part numbers for the sheaves, which I got from the Rig-Rite web site. The rear/aft large sheaves are

Reefing Sheave for 3550 Outhaul Ass’y: K-10347:
Molded Nylon sheave w/ integral Bronze bushing is 1 7/8″ OD x 35/64″ (<9/16″) wide x 3/8″ ID.

The front/bow smaller sheaves are

Reefing Sheave for 3550 Gooseneck: K-11412:
Delrin sheave is 1″ OD x 1/2″ wide x 1/2″ ID.

The parts arrived to my great excitement. Old and new compared:


Unfortunately, the diameter of the bronze bushing for the rear sheaves was a hair too narrow.


I e-mailed Ed and politely asked if he had suggestions. I didn’t have a drill press and I didn’t want to mess around with my cordless. Sure enough, Ed asked me to send him back the sheaves with the axle pin and he would make them fit. No extra charge, no fuss, no muss, not even extra shipping. Ed is a good dude. If you order from Ed, you might consider sending your axle pin in advance to save yourself this step and to ensure fit.

Interior Boom Parts Analysis

I wanted to make a reasonable effort to determine if the outhaul and boom topping lift were in okay shape. Without disassembling the interior parts of the boom, it was very difficult to get solid information. From what I was able to retrieve of the lines, the rope portion inside the boom looked like they were in much better shape than the lines for the outhaul and topping lift that dangle outside the boom, which are perfectly serviceable. I was somewhat afraid of disassembling everything and fouling up the re-assembly. I decided to call those lines good and leave it at that.


My front gooseneck cap needed repainting. I went after the oxidation with a wire brush on my grinder and it was quick work.


The cast piece is very light. One can easily imagine how Christian William’s fatigued and cracked and was then was supported with his well-documented “Hunsicker (?) Plates.”

Did the Kenyon guys use the same casting for the gooseneck on a 38 with a 303sf main and on my 32 with a 207sf main? Hmmmmm. I think the neck on a 38 might be undersized, then. My gooseneck compared to the one in the video of the 38 is identical except that the diameter of the boom extrusion on Thelonius II is larger. I suspect it was less expensive to use the same aluminum cast piece.

Also, if I break something in an accidental jibe, the gooseneck piece seems a likely candidate.

I did not spend an excessive amount of time on an elaborate paint process for the gooseneck casting.

I washed the bare aluminum with soap and water. Next, I applied Rust Oleum self-etching metal primer and some semi-gloss topcoat.

It’s not the best out there, but compared to 30 years of neglect, I think I have made an improvement. Here’s how it turned out:



I mentioned that I massacred a couple of machine screws when attempting to remove them from the aft end of the boom. I have always understood conceptually tapping a new set of threads, but in my bicycle-repair upbringing never really had a reason to do so. I bought a little $30 DeWalt set from Home Depot and set about re-tapping larger diameter screw threads in the boom and the aft cap. It is remarkably easy to do in Aluminum. Just insert the cutting tap and twist. New threads, easy-peasy.

I wanted to avoid in the future the frustration I had in removing corroded parts, so I went to West Marine to purchase some goop. I had two choices, Star-Brite Anti-Seize thread lubricant for $14 and Tef Gel for $32. I have this deep system BIOS aversion to spending money, so I bought the chocolate-looking Star-Brite instead of the tidy, clear Tef Gel for twice the amount. I still haven’t decided if it’s worth it to avoid the wiping of Hershey’s syrup gunk off the boom.

I left in the cam stoppers for the in-boom reefing lines. Chris says they can be removed, but they haven’t caused me any trouble yet, and I have some hesitation about eliminating a capability built into the gooseneck. Maybe one will get jammed in the future and I will regret the decision. We’ll see.

Getting the knurled sheave axle pin knocked back into place proved to be quite easy, much smoother than the removal of the same pin during the disassembly process. With the free-spinning sheaves from my new friend Ed at Zephyrwerks everything came together nicely. Many readers will readily recognize that “India Pale Ales” were developed in England during the heyday of the raj for transport by sail to the subcontinent. This rich sailing heritage means that enjoying a West Coast IPA, such as Racer 5 from Bear Republic Brewing Company, is an extremely nautical thing to do while repairing one’s boat. That’s what I tell my wife.


Once you re-assemble your boom with all of the caps and screws and ropes and blocks in the right location, if you don’t have a stopper knot on your outhaul line, it’s entirely possible to pull the outhaul car too far forward on the boom and yank the outhaul sheet into the boom such that you will have to un-mount the boom from the gooseneck and disassemble the front cap to access the outhaul sheet. Can you guess how I learned this lesson? Use a figure 8, or a barrel knot.


Next up, some engine control re-assembly and then some more test sailing with hopefully, better reefing, better wheel braking and more fluid engine control.