Replacing lower sheaves on Catalina 30 with internal halyards

[acudavid]

I purchased this boat three months ago and have been working to get her to sea for a trial. The halyard for the jib is frozen. I ascended the mast expecting to see it wrapped, but it looks good on top. I was able to get slight movement of the halyard at the top. At the base of the mast, there is a dual roller clip with a frozen sheave. I ordered replacements for port and starboard from Catalina Direct. Each clip has six stainless screws that are frozen tight to the aluminium mast. I tried multiple coats of PB Blaster of the last three months, but it is frozen. I tried vice grips + phillips, and a manual impact driver. I think I need to drill and retap. Does anyone have any ideas? If I have to drill, is my 18V Dewalt drill a good choice, or should I get a larger 120V drill? I bought the best cobalt bit that my hardware store had, and oiled it every 30 seconds, but it stopped cutting as it barely penetrated the screw head. I hit the head once with a chisel and hammer, and the top came off. At this rate, it looks like about a dozen drill bits.
I certainly am no fan of drilling and tapping and welcome any other ideas!

 

[cymeyer]

Not sure PB Blaster is strong enough. there are several penetrating oils that may do the trick. I would try those before drilling out the screws.

 

[Ward H]

Also try a powered impact drill. Try a little tightening first, then loosening. A little back and forth may help.
When I pulled my mast exit blocks in 2018 I lost one or two screw heads. My mast was down so I could spray PB Blast on the inside and eventually got ended up with 5 good screws each when I reinstalled them.

Do the CD replacements have bearings or bushings?

 

[RitSim]

I did that job on my C30. I was lucky and was able to remove/drill the 4 outside screws. A few tips on drilling stainless. 1) use only a sharp drill, 2) use oil, 3) and most important- use as high a pressure as you can at the lowest speed. Once you spin up the drill, you finish hardening the screw which is already work hardened. 4) getting the drill in the screw center is the hardest part- so I always start fairly small. The drill usually walks so If you start at the tap drill size the drill will be foo of the screw into the aluminum in a hurry. One thought I had a the time was to add an aluminum spacer frame with a bolt pattern outside the existing mast pattern. The aluminum frame is tapped also to mount the new sheaves. This means that the existing screws only need to be flush so the frame fits flat. The new sheave screws can't penetrate behind the frame so either they are sanded flat or the frame is thick enough to handle the issue.

 

[acudavid]

Thanks for the advice! RitSim was right on with the power impact driver. I think you could have knocked me over with a feather when I saw the first screw turn! I thought for sure it would just strip--which is why I purchased the old fashioned manual impact driver so I could clobber it with my 20 ox dead blow hammer. What a waste of time. I was able to remove 10 of the 11 remaining screws with a simple Milwalkee power impact driver.

I do wish I had read RitSim's advice on the drilling technique. I made a mess of it, but will figure something out to reinstall the new sheaves, which were just delivered by Catalina Direct.


Thanks all! I am all set.

 

[Hayden Watson]

Also try a powered impact drill. Try a little tightening first, then loosening. A little back and forth may help.
When I pulled my mast exit blocks in 2018 I lost one or two screw heads. My mast was down so I could spray PB Blast on the inside and eventually got ended up with 5 good screws each when I reinstalled them.

Do the CD replacements have bearings or bushings?

The ones I got from Garhauer are bushing type. I would really like to find a ball bearing exit box. Short of that, I have considered abandoning the mast base boxes and installing traditional exit plates higher up the mast ±7' so that I can jump the halyard from the mast to help hoist. That is how I installed my spinnaker halyard and really like it. When single handing, I hoist the spinnaker in a sock tie a cleat hitch at the mast. I then go back to the cockpit and pull in the halyard to through the clutch and lock it with a bit of slack. I then go back to the mast and untie the cleat hitch which drops the head a few inches which I then raise back up from the cockpit. I will sometimes just do everything from the cockpit.
For at least the main sail this type of halyard would likely make raising the main much easier. I could then put a quality ball bearing block on my mast base plate.