Trying to find what I think is a cheek block

[ProDave]

Like this one.



Crucially it has a plastic backing plate shaped to match the curve of the boom.

The new one we want is for use with 10mm diameter line.

I have found lots of blocks, very few are 4 hole mounting like this, and none yet with a matching backing plate. Any ideas please?

 

[nrcoyle]

Looks like a Barton Cheek block
#
Barton Size 4 - 58mm Block 12mm Rope Single with Cheek Block

Don;t think you can get preformed backing plates, I assume someone must of sanded it to fit.

 

[ProDave]

Thanks, that's the thing. Plastic back plate looks to be included. Just need to spend some time with a file or sander.

 

[nrcoyle]

tell a lie, you do get curved backing plates

Barton Curved Backing Plate for Cheek Block, Size 3

But I would have thought the chances of it being the perfect curve for a specific application is slim although it may be a better starting point

 

[DinghyMan]

Looks like a "Ronstan #RF1379 Curved Base Cheek Block"

 

[jamie N]

You could try making the backing plate from Polymorph.
Cheap & simple.

 

[Aja]

You could try making the backing plate from Polymorph.
Cheap & simple.

I've used Polymorph in the past for taking moulds and shapes. Don't think it would be strong enough in this application.

 

[Daydream believer]

Is that block on back to front?

 

[Sandy]

I'm about to remove something like that from my boom. Let me know if you want it, otherwise it is going in the skip.

 

[B27]

You can shape the block by taping some sandpaper to the boom and rubbing the block on it.

But really it's much better to get a 4 sheave end fitting for the boom and run the lines internally.

That avoid the nonsense of the blocks always being in the wrong place as shown in the photo, where someone has fudged the issue by turning the block the wrong way around running the line outside the block. An arse-about-face cheek block or arsecheek block for short?

 

[Aja]

You can shape the block by taping some sandpaper to the boom and rubbing the block on it.

But really it's much better to get a 4 sheave end fitting for the boom and run the lines internally.

That avoid the nonsense of the blocks always being in the wrong place as shown in the photo, where someone has fudged the issue by turning the block the wrong way around running the line outside the block. An arse-about-face cheek block or arsecheek block for short?

I don't see why the block can't just be reversed

 

[ProDave]

I'm about to remove something like that from my boom. Let me know if you want it, otherwise it is going in the skip.

Yes please, I will pay postage. PM me.

Yes the existing block is indeed the wrong way round. That is how it was when we got the boat, and it was not in use. We have been experimenting with alternative reefing ideas this morning as the existing arrangement with the lines running inside the boom is unworkable, way too much friction. We have tried all sorts, different lines and just can't get it to work. The basic problem is lines inside the boom do not exit via blocks but plain sheaves = more friction. Line exiting at front of boom exists downwards so has to go over another block on the deck and back up = yet more friction. We are trialling ideas with the reefing on the outside of the boom = 2 simple blocks low friction no unecessary blocks.

 

[B27]

I don't see why the block can't just be reversed

It then wouldn't pull the reefed clew back enough?
And the screws are probably seized in the boom...

 

[dunedin]

Is that block on back to front?

Yes, ProDave that block looks to be the wrong way round for the rope direction

 

[William_H]

Yes, ProDave that block looks to be the wrong way round for the rope direction

Note the load on the outer end of the axle of the sheave is supported by the mount and flat plate to the right in the picture. It is mounted back wards in the picture such that the support to the outer end of the axle is in compression. Much better around the other way in tension. (pull support) However probably still ok in service depending on loads on reefing line. Just not as intended. ol'will

 

[ProDave]

I did mention in a post above, that original block was not fitted by me, that's now it came on the boat. It will be turned round and another the same fitted to the other side of the boom.

 

[Daydream believer]

I would not be worried about the way the load was distributed but more about the line locating on the sheave as the reef was applied. it would be a nuisance if it kept shaking off as one was at the mast trying to take the line in.

 

[ProDave]

My new cheek block arrived today.

Slight issue. Yes it does have a plastic backing plate that I could sand to match the curve of the boom, BUT un the centre of the SS back plate is a protruding boss on the back. The plastic back plate appears to exist just to level that up, with the plastic plate having a hole in it to clear that. So no chance of sanding that plastic plate or else the boss will protrude in the middle.

So separate back plate?
Or just a couple of washers under each fixing screw? (yes that sounds like a bodge I know)

 

[Daydream believer]

2 narrow strips of plastic each side, so a channel is formed in the centre.
Plastic could be from an old 5 gallon plastic container as the material would likely have a less harsh surface to surface contact with the boom.