Sheaves too old or too wide?

[DinoKanuck]

Hello All

The main sail's reefing lines are routed through the boom. One set of shives is missing and the others set needs replacing. It is very difficult to turn. The reefing line sheaves have an outer diameter of 1 and 1/2 inches, inner diameter of 5/16 inches, and width of 7/16 inches.

The remaining reefing sheaves are very difficult to turn. The sides of the sheaves are rubbing against the boom.

Based on the pictures and what you may have seen on your boat, do you think the difficulty turning is something related to age or are the 7/16 inch wide reefing sheaves too wide for the space available?

 

[CalebD]

You owe it to yourself to take off the end cap on your boom and service or replace those sheaves this winter.
When they all spin freely you will be a much happier sailor.
McMaster.com sells some off the shelf "sheaves" ("sheaves for rope").
I used some delrin sheaves from McMaster to rebuild my in-boom out-haul.

You could even try sanding the old sheaves down a bit if you think they are binding.

 

[Apex]

use spacers on the sides, same diameter as the hubs for the sheaves.

 

[Joe]

Change everything out... replace with a higher grade line, smaller diameter... say 5/16... there's not a lot of load on reefing lines.. think about it, 7/16 is way too big for anything on a 28 foot boat.

 

[Chris Patterson]

That's what I was thinking, that's a hog of a line in there..

 

[Ron20324]

Uummm, guys, he did not say the lines were 7/16, just the thickness of the sheave. You can see from the picture there is some thickness to the sidewall of the sheave, so maybe he has 3/8 or- hopefully not- 5/16 line?

 

[Steve Dion]

Depending on the type of line they can absorb moisture and swell.

I would also suggest that you just replace all of the sheaves and get line that is appropriate for the sheave.

 

[DinoKanuck]

Thanks All:

I'm now shopping for reefing line sheaves with a 5/16" width or 1/4"width so I can add spacers.

Dino

 

[Steve Dion]

Dino:

I do not think you need spacers. You can use the smaller lines on the larger sheaves.

I would check to see if there are any specs for your boom/mast before you purchase anything.

I would check with Rig Rite or Rigging Only and see if they can help you out.

 

[DinoKanuck]

Just zipped off a request to John Mast in Danmark

 

[DougM]

The sheave in the foreground of the photo appears to be a replacement already, and may be too wide for the opening. All it takes is one of them to cause the whole system to bind. The line does appear to be oversize, and as suggested, may have swelled over time. if you measured it at 7/16, it may well have been 3/8 when new. You can certainly use an even smaller diameter on a boat like yours.

Another thing to look at is if the line is rigged properly inside the boom. Some boats have a double block arrangement for purchase, and in rigging, the line can get twisted around itself.

 

[Bosman]

All major players in the marine equipment game carry replacement sheaves:
Barton:
http://www.bartonmarine.com/products-shackles-sheaves-springs-and-v-bolts.asp

Harken:
http://www.harken.com/productcategory.aspx?taxid=393

 

[DinoKanuck]

Friday night dinner benefitted from 2 guests... Paul M and Boeshield T-9®

 

[DinoKanuck]

Friday night dinner benefitted from 2 guests... Paul M and Boeshield T-9®

We used some 400 grit sandpaper to clean up the sides of the sheaves, the bore holes, the pins, applied the Boeshield to the works and the system is turning effortlessly.

Appreciate the advice... I have an email into John Mast for specs on the system and will use the links to order a set of sheaves for the lower reefing point.

Dino