Changing Block on Cabin Roof

[HeaveToo]

I may have to change one of the blocks on my cabin roof that are where the halyard comes from the mast to the deck.  It looks like there are four black nut covers in the cabin that correspond with the block.  How do you remove the old block from the cabin top?

[HeaveToo]

It just dawned on me that I could possibly drill out the pin that holds the block in place and just replace the sheave.

Has anyone done this? 

I have the old Ronstan blocks, anyone know what size the sheave is in them?

[HeaveToo]

Oh, and if I can replace the sheave, what size sheave would I use?

The sheave replacement seems to be the most attractive option.  Drill out the old pin, put a new sheave in with a bolt and a lock nut and I don't have to worry about dealing with the block removal from the mast.

[brackish]

Is this what you have?



If so I think it is a series 40 all purpose standup block from Ronstan.  Here is a link to info on the block.  No info about how to change the sheave but they do indicate you can buy sheaves.

https://www.ronstan.us/marine5/product.asp?ProdNo=RF41140

[HeaveToo]

No.  I have the blocks with the 4 attachment points.  They are a diamond shaped base.

I just found a deal on 3 used blocks, should be the same ones I have on my boat, for $20 on ebay.  I went ahead and bought them.  These are slightly different because the sheave is removable.  I still may try drilling out the pin in the old block and putting one of the sheaves from the blocks I just ordered into it instead of messing with removing the entire block.  I need to get to the boat to see once the new blocks come in.

I still would like to know how to remove the old ones just in case.  Those 4 black bumps in the cabin roof make me think that they are thru bolted and those black bumps are covers for the nut.

I would also guess that the old blocks were bedded with 5200 (a.k.a the Devil's Glue).  Removing them may be a royal pain!  Avoiding that would be the best thing.

[HeaveToo]

Here is the best pic that I can find of mine: 

[brackish]

I would also guess that the old blocks were bedded with 5200 (a.k.a the Devil's Glue).

Doubt it.  I haven't removed the blocks but have removed a lot of other stuff that Hutchins installed and found them all to be 4200 or equivalent.  Very easy to remove. 

Mine have stainless acorn nuts holding them on the underside.

[HeaveToo]

I hope mine is too!  Thanks for the encouragement.

[Bristol14]

What's the U-shaped "bracket" that is attached to your mast step? Looks like it's used for your boom vang?  The reason I'm asking is that I'm going to set up my main halyard to lead the cockpit and I'd like to avoid putting another hole in my deck and am wondering if this would work to lead the halyard to the deck organizer?

[HeaveToo]

The U shaped thing is a bail for the vang.

You will probably have to add a deck organizer and some deck blocks for the halyards if you lead them aft.  The other place you are talking about would interfere with the boom if the halyard went back that far.

[Bristol14]

I saw a mast bail on-line that allows blocks to be placed to the side of the mast, almost like a mast plate. A mast plate that sets under the mast step may be a better alternative. Either way, I'd still use a deck organizer to make the 90 degree turn to a line clutch and winch.

[HeaveToo]

I think that the blocks are out further from the mast to prevent halyard slap when the wind blows.  If the halyards were closer they would slap the mast, causing chafe, since the halyards are external.

[Bristol14]

Do you think there would be more halyard slap and chafe using a mast bail or mast plate to mount the blocks than when halyards are cleated to the mast?

[HeaveToo]

Being that the halyards are lead externally, you are probably best having them beside the mast and a little out from the mast.  There is a reason Compac designed them this way and they haven't changed the design.

I do wonder, at times, why they didn't go with internal halyards at some point. 

[HeaveToo]

So the blocks I bought off of ebay were bigger than I thought that they were.  They are probably at least one size up from what we use on the Compac 23s. 

I am now thinking that I may remove my damaged block, fill the holes, and put one of the blocks that I bought off of ebay on it.  This is a pretty serious block with an aluminum sheave.  The sheave is removable too.  It might be a better block for my boat since I do use that forward block when I hoist up my mast. 

I would love to add one of the blocks as an extra block for the spinnaker halyard.  That would be a project for another time since it would mean adding another block, add a new deck organizer, and another jam cleat.

How would you fill the old holes?  Marine Tex?  Epoxy?