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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

replacing "sheaves"? at bottom of mast?

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cayugaboater
1st Mate

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50 Posts

Initially Posted - 06/22/2013 : 21:32:54

apologies if terminology is off, but the plastic wheels that sit inside the bottom of the mast where my line comes out to hoist sail are badly chipped up and deteriorated. My questions are:

1.)Where and what do i get for replacements?
2.) Is this a big job or can I just pull them out and put in new ones, (the boat is presently in the water with mast up)

It is a wingkeel, 89 catalina 25

89 wingkeel;std rig.
Sail #5811

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trptelf
Navigator

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USA
113 Posts

Response Posted - 06/22/2013 : 23:32:53

Exit Block Single from Catalina Direct:

http://www.catalinadirect.com/index.cfm?fuseaction=product.display&product_ID=316&ParentCat=407

We found that we had to replace the entire part, and that we were not able to replace just the sheave. Easy fix, but there was some minor manipulation involved in making the new part stretch to fit the old screw holes.

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islander
Master Marine Consultant

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USA
4038 Posts

Response Posted - 06/23/2013 : 05:57:03

I used the same replacment block from CD as stated above, Easy replacement and work well.

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OLarryR
Master Marine Consultant

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USA
3521 Posts

Response Posted - 06/23/2013 : 08:49:01

Same here - I replaced with parts received from Catalina Direct. Only problem I had was I could not easily unscrew the old blocks. I was afraid I was going to strip the screws. But I had my standing rigging replaced this past winter and I asked the rigger if he could give it a try. He had an impact power drill/screwdriver and that did the trick. Easy replacement and we were able to use the old screws to install the new blocks.

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Lee Panza
Captain

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USA
468 Posts

Response Posted - 06/23/2013 : 09:51:08

I presume you know this, Larry, but for 'cayugaboater' (and others who'll read this thread in the future) your post highlights an issue that should be mentioned whenever we're discussing adding or replacing hardware on our spars. A stainless steel screw driven into aluminum creates the opportunity for galvanic corrosion to bind the two together, especially if there's salt present. In order to prevent extraction problems in the future (or, ironically, the exact opposite problem when the corrosion advances to such an extent that the connection is weakened and the screw fails to hold anymore), it's advisable to use a barrier compound like Tef-Gel on the threads and under the head of the screw. Tef-Gel is a bit of a nuisance to use (it's very sticky stuff), but it can eliminate the electrolysis that takes place between the dissimilar metals. I even use it to bed stainless fittings that I attach to the mast or the boom.

BTW, Tef-Gel (or any similar product) is also advisable whenever a stainless screw is tightened into another threaded stainless component (even machine screws into nuts), as it resists the galling that can weld the two components together.

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cayugaboater
1st Mate

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50 Posts

Response Posted - 06/23/2013 : 15:02:58

Thanks! I was looking at those but wasn't 100% sure I had the right item, so its great to get confirmation that I was on the right track, this forum is fantastic for those of us who don't know as much as we would like to know, I'm ordering them right now, are there any tricky issues involved with doing it while the mast is up, i.e, pressure/tension from rope? Can't wait to get the new ones, the old chipped up ones were barely working anymore!

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OLarryR
Master Marine Consultant

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USA
3521 Posts

Response Posted - 06/24/2013 : 03:38:53

Lee makes a good point when we discuss SS screws into aluminum due to the potential for galvanic corrosion to set up. "In order to prevent extraction problems in the future ...it's advisable to use a barrier compound like Tef-Gel on the threads and under the head of the screw.

My posting indicated issues with breaking the screws free and how an impact power scredriver did the trick. It was either that or having to drill the screws out. Okay, those screws were probably in there from original installation...eons ago but after removing them successfully, the rigger did put some type of lubricant on them but I am not sure what.

I believe you can also use one of the Loctite products commonly sold in Home Depot or Lowes...One of those products is "Threadblocker" but I do not recall if it provides galvanic protection or just a set to prevent loosening. So, best to read the instructions as to it's benefits/uses.

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redeye
Master Marine Consultant

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3478 Posts

Response Posted - 06/24/2013 : 04:16:27

I likes aluminum rivets.

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.