Masthead assembly (pulley wheel)

jssailem · Feb 1, 2022

Hello
See this is you second post since joining the SBO Forum. Welcome.
Not to worry about the technical labels. They are extremely helpful but sometimes the issue is understood.

The term for the "pulleys" is sheaves. The are made of a plastic material that eventual wears out when exposed to constantly to UV rays.

There are a number of companies that have replacement sheaves and mast parts. It would be helpful if you posted pictures of your mast head and sheaves. I suspect they are white and breaking on the edges.

As an example. Here is a website with sheaves for a variety of mast heads.

Sailboat Sheaves | RiggingAndHardware.com

sheaves

www.riggingandhardware.com

Leeward Rail · Feb 1, 2022

The grooved wheel in a block or pulley is called a "Sheave"

Sheaves - Marine Outfitters - Ontario Canada

Discover the best Sheaves at Marine Outfitters at competitive prices

www.marineoutfitters.ca

A quick Google search came up with this site specifically for "MacGregor yacht corporation" sailboat owners.

MacGregorSailors.com

Likely a good source for info.

I seriously doubt that Tattoo yachts will be any help.

Replacing the whole thing will need to be a used part which will probably be in the same.condition.

Parsons · Feb 1, 2022

As noted above, you want a halyard masthead sheave.
This link seems like a similar problem with solutions, mainly around getting it rebuilt, not ordering a part: venture 25 mast sheaves

Welcome aboard SBO!

rgranger · Feb 1, 2022

jssailem said:
The term for the "pulleys" is sheaves.

Uh oh! We are heading for that "terminology" rabbit hole.

If you want to get picky (doh! It is a sailboat forum) the sailing term for a pully is a "block" and the wheel in the block is a sheave. But what you have at the mast head is not technically a block. Blocks are stand alone hardware. The mast head "pully" is just called a masthead and the wheels are still called sheaves.

dLj · Feb 4, 2022

It's definitely winter ....

dj

Leeward Rail · Feb 4, 2022

dLj said:
It's definitely winter ....

dj

Only in the northern hemisphere.

dLj · Feb 4, 2022

fjcattleco said:
I have a 1981 Macgregor Venture by Newport (23). The pulley wheels for the mainsail on the masthead have deteriorated to a point where the line slips off and binds up when I am hoisting the mainsail. I can't seem to find a replacement assembly or even the pulley wheels. I would prefer to replace the entire assembly as it all appears to be press fit into the assembly. I admit I may not be using the proper terminology which may be limiting my search. Any help would be appreciated.

@fjcattleco - do you have pictures? I'm not understanding your statement "entire assembly as it all appears to be press fit into the assembly" - I'm getting confused as to what assembly is appearing to be press fit into what assembly... In the past I've replaced these sheaves without having to replace the masthead. I've often changed the material to be more UV resistant that the original sheave

Leeward Rail said:
Only in the northern hemisphere.

Indeed, and right now in the Northern Hemisphere, specifically on the East Coast we are really getting winter! Where I"m at right now we are getting an ice storm that is putting down potentially a couple of inches of ice.... Yikes! Here's to hoping in the near future these months will be spent on my boat in the southern hemisphere!

dj

rgranger · Feb 4, 2022

That is a very helpful photo. I think you could drill that out and replace it with a bolt and lock nut.

rgranger · Feb 4, 2022

fjcattleco said:
Copy that. That was my original thought, but wanted to check and see what the "experts" say. Enjoying this forum and all the help and support.

I love the lines of the Venture 23. I have owned two V21 sailboats and a V22-2. I always envied the look of the 23. I especially like the wooden rails on the cockpit coming.

dLj · Feb 4, 2022

Question
Is the line I'm pointing to all the same line? (Sorry I should have used a different color) If so, the pin where I have my ? - is there a sheave there also? or just a pin? Looks like this line has some funky travel up there in your mast head....

dj

Joe · Feb 4, 2022

Yes, and Yes. It's your mainsheet. You can remove the masthead fitting and do a thorough inspection and refit, by loosening the tapped fasteners.

Leeward Rail · Feb 4, 2022

Joe said:
You can remove the masthead fitting and do a thorough inspection and refit, by loosening the tapped fasteners.

Joe's suggestion should come with a warning.... when you remove stainless steel fasteners, that thread into aluminum, in a boat of this age, the corrosion often causes the bolt to snap and then you have a big hassle of drilling out the old fasteners.

You need to slowly work the bolts out, often with some penetrant or even heat. There is a recent thread in the forum's discussing the various options.

dLj · Feb 4, 2022

fjcattleco said:
Yes, the same line. There is a second sheave but it is further to the left in the picture. It also has some pretty good sun rot and needs to be replaced, but not as bad as the first. Where your mark is, is just a pin. I'll double check the travel as well.

Yeah, looked like there was likely two sheaves in the head for that line. Definitely if you are going through this work, fix 'em all...

I would not be surprised if you have to build, or get built, the replacement sheaves. Have you thought about what material you want to make them out of?

dj

jssailem · Feb 5, 2022

dLj said:
Have you thought about what material you want to make them out of?

If long term use is expected then suggest Delrin as a good choice.
Here is a link with many options.

Sailboat Sheaves

Order online Sailboat Sheaves.

www.velasailingsupply.com

Masthead assembly (pulley wheel)

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SBO Weather and Forecasting Forum Jim & John

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