Changing Blocks on the Mast

[Time Theory]

I have a 16 foot O’Day sailboat and I need some guidance on the best way to change out two of the blocks located on the mast. The “wheel” on both blocks are deteriorating and need to be replaced. The blocks are used for my main halyard so I need them to be in excellent working order.

The first photo shows the deterioration of the wheel. The second photo shows how the block is attached to the mast. The third photo is the other block “wheel” on the mast fastened in a different configuration.

I have searched YouTube but have not found any videos that address how to do this. Your help would be greatly appreciated.

[Dsanduril]

The "wheels" are properly called "sheaves". You can frequently find replacement sheaves many places. Both blocks are made by Schaefer and you may be able to find the exact replacement sheaves for them.

The hard part is that both the axle and the mounting hardware are not intended to be disassembled. The rivets have to be drilled out to remove either the block from the mast or the sheave from the block. The mounting rivets look like aluminum and will be much easier to drill than the axles. In that size the blocks are not expensive, it may just be simpler to drill out the rivets, purchase new blocks, and then put it all back together.

[Time Theory]

Dsanduril,

Thank you very much for the information. I greatly appreciate it!! I will check out the sheaves that Schaefer Marine has to offer. Thanks again for your help.

[roverhi]

The axle will be welded to base on the cheek block. Not going to be easy to remove so wouldn't buy a replacement sheave till I'd gotten the block apart without destroying it and figured out how to get it welded back together without melting the sheave. Will probably need an impact driver to get the fasteners out. A cheek block with a becket is kind of a rare bird, btw.

You'll need to drill out the rivets on the pad eye for the other block. Source monel or SS pop rivets to put it back together. The riveted axle should be able to be drilled out and replaced with a bolt. Still by the time you source a new sheave and do all the work would probably be money ahead to replace the block with a removable pin block. Then you wouldn't have to mess with the pad eye if you needed/wanted to remove it in the future. The sheaves on Harken blocks seem to have way less problems with UV damage than Schaefer's.