Replacing Cabintop Turning Blocks

[dave_ren]

Has anybody replaced the sheaves on the cabintop turning blocks that run the halyards from the mast back to the cockpit? I purchased the replacement sheaves from CD last fall. I expected them to be through-bolted with the nuts and bolts exposed inside the cabin near the curtain shown in the photo below. However, nothing inside. The blocks are inline with the mast on the cabintop and a little outboard of the mast supports. Looking at the two mast supports inside the boat, I assume there is some sort of beam structure spanning the two mast supports.

So, my question is, are these blocks threaded into a mast support beam sandwiched between the cabintop and interior liner? Or, is there a small gap between the cabintop and liner that I need to cut into to access the bolts? Thanks!!!

 

[jerrymlewis]

On my 1985 fin keel/std rig, there were threaded 'nuts' embedded in the liner for the new bolts to screw into. Nothing goes all the way through.

Good luck.

 

[jerrymlewis]

In thinking about after posting my reply, I think there is a 'beam' that has holes tapped for the turning block bolts.

 

[aviatorjames]

Later models (Mk II with the dancer's pole) have bolts that go all the way through.

 

[HERSH]

Re: Replacing Cabintop Turning Blocks + Jib Halyard block

I replaced them on # 297 and # 425 ( present boat). Both had the imbedded piece of metal. No through bolts. This time though I countersunk the holes a little so the 3M 5200 would seal better. Some one else on this site recommended that method and it seems like a good idea to me.

By the way, The jib halyard top exit block is held in place with stainless pop-rivets. The basic pop rivet gun will NOT be able to pop the rivets. On "Defender.com" they have a pop-rivet gun for stainless rivets -- ~~ $180. I decided to go with aluminum rivets. Should they fail ( I doubt) no major damage would occur ( Mast would not come down.)

Hershey

 

[dave_ren]

Hey guys, Thanks for the help. Do you suggest a drop of Locktite on the threads to hold everything tight?

 

[shnool]

I strongly recommend the aluminum rivets for holding in sheaves... the basic rivet tool works, and like was said, the rivets go before the mast does.

As for turning blocks going into embedded plates... If I were "replacing" them... I'd strongly recommend through bolting them with a backer plate. There can be a lot of force exerted onto those blocks.

 

[jepomer]

On #281 the 1/4" bolts attach to an embedded threaded area.

I replaced one of the bolts with an "eye". This location is just about right to attach straps to keep the mast from shifting while raising or lowering it using a gin pole (a whisker pole repurposed for that moment).

During the season, the halyards get attached there and don't bank on the mast.

 

[Chris Capri 22]

I replaced and re-bedded mine on hull #365. Old ones screwed out, new ones screwed in. They got tight and stayed tight. Used 3M 5200 which may have been overkill but no Loctite needed there. Hope this helps.

Chris