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How to replace "wheels" on single blocks??

10K views 16 replies 6 participants last post by  capngregg 
#1 ·
Am on my third boat and still dont know what to do when I have an old and melted -looking wheel on a block..in this case a single block..can I replace the plastic pulley?
 
#2 ·
Souljour-

It depends on who made the block and how it was designed. Some don't have user replaceable sheaves, others do. It would help if you posted a photo of the block in question.
 
#3 ·
Okay thanks.... I dont know if the photos will come thru but here are the two culprits....is a mounted single block and what i will probably erroneously call a tethered single block...these both have major warp issues with the sheaves..do u think they can be manually replaced by someone like me or do I need to buy new blocks altogether??? Thanks.. Morgan
 
#4 ·
Again... only an idiot would expect anyone to be able to give any advice based on the little information you've provided. You haven't mentioned the brand or model of block. Without knowing what brand and model of block, or at least a decent photo of the blocks in question, there is no way to know if the sheaves are user replaceable.

The "mounted single block" could be a cheek block, which looks like this one from Lewmar:



Is the "tethered single block" a block on a shackle? A block on a shackle looks like this:



The sheaves on the bottom block in these two photos are replaceable IIRC, the sheaves in the block in the top photo are not.
 
#6 · (Edited)
No, I don't believe you can. Those appear to be riveted construction, which means you'd have to drill the rivets out. Blocks with replaceable sheaves are bolted together. The blocks you've posted photos of are low-end models, which generally need to be replaced as a unit.

Unfortunately, your hand is in the way and I can't tell what the end on the second block looks like. It would help if you said what boat it was. It would also help if you said what kind of line it was used for. For Halyard and other relatively static lines, I'd recommend using Lewmar Synchro blocks. For more dynamically loaded lines, like sheets, I'd recommend using Harken Carbo Air Blocks.

Garhauer also makes some good blocks.

I'd also recommend you read the post in my signature.
 
#7 ·
Thanks very much Sailingdog...I suspected they were not going to be replaceable either after having another look...they are the jib sheet blocks from an old 1983 hunter20 ...I dont have alot of funds for much at the moment so would I might consider drilling out the rivets though they look pretty tough...and running a pin/shackle arrangement through instead...or something to that effecet if it looks like it could work...thanks for all the help...I will be trying to get better at posts in here......Morgan
 
#8 ·
Given the prices for the smaller Lewmar Syncro blocks, I think you'd be better off buying them, rather than trying to cobble something together. THink about the cost of the replacement sheaves, pins and such, and you're pretty much at what the Lewmar Synchro blocks are going to cost.
 
#10 ·
read the post in my signature...
there's a fair bit of advice there on how to maximize your time on sailnet...
 
#12 ·
Hey Max-ON...you signed a non-disclosure agreement about that part...I'm going to have to sic a lawyer on yah... ;) Wait...damn... you are my lawyer.... Can you sue yourself for me... :)
 
#13 ·
One other point... buying new Lewmar Synchros means the blocks are far less likely to fail than are re-built home-made cobbled blocks that you'd have after drilling out the rivets.
 
#14 ·
Souljour,
Nice lookin' boat there. You can replace those blocks for $40 or so. West Marine has some Ronstans (Series 30) that take up to 5/16" line that'd probably do the trick. If your line is a bit heavier you might get all the way up to $60 to replace-and that's at WM-there's better deals out there.

Good luck to you. And you posted just fine, you were asking a question that you probably thought had a single correct answer. I'm sure that SailingDog did not mean it when he implied idiocy and I'm surprised he has not aplogized yet. One of these days I may even read that new to sailnet forums post, or swallow a bullet, it's a toss-up.:)
 
#15 ·
Soul-j, Yes, you actually can replace the sheave in almost anything. But, usually it's not really practical.
The blocks in the photos are riveted and while the rivets can be drilled out and replaced with a bolt, it probably wouldn't be worth it.
When you are talking about a larger more expensive block, then it would probably make more sense to replace the sheave.
Having said that, it really depends on how handy you are and how much your time is worth.
 
#16 ·
Thanks for the good advice...I may "give it a go" with a carbide drill bit and see if I can get into those rivets without a struggle...afterall..they are worthless as they are so its not like I am out anything except some time and expensive drill bits...and then the cost of the sheaves and the new pins in their place...the blocks are in great condition .(other than the 25 cent pieces of plastic each of them has...also known as sheaves...lol...If drilling out the rivets doesn't work l will have to check a local surplus sailboat supply depot called "Nautical trader"..been looking for a reason to go back there anyways...well see.....Thanks so much guys...
 
#17 ·
Souljour

The sheaves are replaceable but the block was not designed or intended to allow the sheave to be replaced. I have replaced sheaves on identical blocks in the past (for friends on a budget) but it took a while to find just the right sheave. On top of that I had to manufacture the replacement rivets. If you have all the right tools it's no big deal but for the # of manhours you would consume it would be better (and depending on your motor skills and replacement materials) safer to purchase a replacement block.

West Marine has a good assortment of replacement sheaves in their catalog with all the dimensions and composition materials noted.

Good Luck!
 
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