Masthead main halyard sheave?

[PlaneTom]

Catalina 310, hull #73, built Dec 2000.
I'd like to replace the sheave at the masthead, the main halyard is hard to pull when there is tension on it. Before I go up (or send someone up) I'd rather have the parts in hand and do it in one pass.
I called Catalina Support, they referred me to Charleston Spar (Sparcraft), saying they built the mast up. Charleston Spar said last week they would research it and get back, but I haven't heard from them as yet.
Does anyone have a part number or specs for that sheave?
Thanks,
Tom

 

[sail sfbay]

You did not say whether you have a furling mainsail mast. If you have one (or it might be the same for a slab sail), attached is the manual. See page 3 for the part number.

 

[PlaneTom]

I forgot that the furling main was an option. I have the slab sail.
Since it is a different mast, it could likely be a different masthead.
I'll look through that manual, but will hope to hear from Charleston Spar with a part number.

 

[PlaneTom]

I just looked in that manual, completely different masthead fitting.
I find it funny that the cover picture for their furling mast handbook is a regular mainsail with battens and a sincle reef point.

 

[sail sfbay]

Hard to believe the sheaves would be different. The 320 mast "standard" manual attached shows the same sheaves.

 

[berner73]

Not sure how the masthead on a 310 goes together, but I'd be hard pressed to attempt replacing a sheave with the stick up - let alone in one trip. I realize it's possible, but having done a bit of work at the masthead myself (replace lighting, secure windex/anemometer, add bird deterrents, etc), I can say I didn't find it easy working up there.

Have also pulled our mast to replace the sheaves as we had a similar issue as you describe above. Turns out that over the years, the shaft had worn the sheave bore into a slightly oblong shape due to halyard tension. While swapping sheaves is not a difficult task to do on the ground, I wouldn't want to try disassembling the cap and managing all the parts while swinging 40' to 50' in the air. But we all have different comfort levels/skill sets, that's just my experience.

Is there anyway you could repurpose another halyard/topping lift for the mainsail until the mast can come down? Which halyard would you send the rigger up on if you were to try and replace the sheave?

BTW, got our sheaves from Rig-Rite. Not the easiest place to order from, but they fit perfectly.

Good luck with whatever path you choose.

 

[PlaneTom]

This is our masthead. The fitting is different. It is possible that Charleston Spars used the same shea

 

[PlaneTom]

I have changed a mainsail sheave at the masthead on the Catalina 27 we had before the 310. I went up the stick with a Mast Mate- a web ladder that goes up the mainsail track. I hoisted it with one of the other halyards and got it high enough to do the work at the top.
That Mast Mate isn't long enough for this stick, I can get to the spreaders but not a lot higher. And after a knee replacement earlier this year it doesn't flex quite enough for this climb.
I do have the name of a young energetic crew from a nearby boat who does mast work. Once I have all the parts I want I'll contact him.
There is a spinnaker halyard that could be used to hoist someone.
The other project up there is replacing the arm with it's sensors for the Raymarine wind instrument. They indicate but the vane for the wind direction is mechanically stuck, you may be able to see that it's bent in the picture.
In a few weeks we have a haulout for a bottom job scheduled. My plan B for the mast work is have the yard do it. They use the travelift crane to hoist a worker to the mast top before hauling the boat. I already talked to them, they figure doing both jobs should only be 1/2 hour or so if I already have the parts in hand.

 

[PlaneTom]

Research continues.
Still no response from Charleston Spars.
After discussions with Catalina tech support and Catalina Direct support, it's looking like the sheaves can't be replaced with the mast on the boat! The masthead fitting has to come off to access them.
Look at the picture in post #7. I can't see any sheave pins that could be reached from the outside. Both tech lines told me that it is likely the same stick as the 320, and that one with a hanked on sail needs the masthead fitting removed.
More fuss and expense to replace something that should be accessible more easily.
I still want to verify all this before I have the mast removed for the repair.
On the plus side, there is no benefit to doing it at the same time as the bottom job. They would pull the mast and replace it with the boat in the water, so I can just as easily bring it over to the hoist anytime and put it back in the slip while I mess with the mast.

 

[berner73]

Maybe I'm misinterpreting your comment, but not sure I buy that the masthead "fitting" has to come off the mast (yes, the cover will need to be removed - same as other mastheads I've worked on). If it's the same as the 320, then we can reference post #5 above, item 7 - the cover will lift off and you "should" be able to access the sheaves and pins inside the masthead. The pins will be nestled in castings within the masthead that are oriented athwartships. Without halyards installed, the pin/sheave assembly would simply lift out (simple is a relative term - Murphy predicts that the pins will fall down the mast, so maybe a good idea to have spares on hand). As mentioned before - there are a lot of parts involved and some are awkward to move around, making it difficult to manage in a bosun's chair. If you can get someone on a crane/bucket lift then the process would be far more manageable than in a chair. For my $, I'd ask the yard to try it with the bucket/crane before dropping the mast - unless of course you have other work to do on the mast or want to inspect it on the hard.

While not your boat, here's an example of what I mean relative to the cover. This demonstrates access and orientation of the sheaves/pins with a masthead cover removed. With the cover off, one can see how a halyard (white with blue tracer) has 'jumped' the sheave and is partially riding against the pin while also being pinched between the sheave and casting. This can be one cause when feeling friction while trying to raise/lower a halyard. The sheave material deteriorates over time and will fail at the thinner, outermost edges - allowing the halyard to 'roll' off the sheave valley (eventually, this can chafe to failure depending on the integrity of the sheave and how it's in contact with the halyard).

Cover Installed

Cover Removed

 

[valcour]

I had some hard to hoist halyards when I bought the boat and thought it was the sheaves. Turned out to be tangled/twisted internal halyards that were fouled. In order to replace the sheaves on the boat you would need to disconnect both the forestay and backstay, tie yourself off up there below the fitting, and relive all tension on all the halyards (or use an aerial lift).

 

[valcour]

one more photo from another 310 owner's masthead crane

 

[PlaneTom]

Maybe I'm misinterpreting your comment, but not sure I buy that the masthead "fitting" has to come off the mast (yes, the cover will need to be removed - same as other mastheads I've worked on). If it's the same as the 320, then we can reference post #5 above, item 7 - the cover will lift off and you "should" be able to access the sheaves and pins inside the masthead. The pins will be nestled in castings within the masthead that are oriented athwartships. Without halyards installed, the pin/sheave assembly would simply lift out (simple is a relative term - Murphy predicts that the pins will fall down the mast, so maybe a good idea to have spares on hand). As mentioned before - there are a lot of parts involved and some are awkward to move around, making it difficult to manage in a bosun's chair. If you can get someone on a crane/bucket lift then the process would be far more manageable than in a chair. For my $, I'd ask the yard to try it with the bucket/crane before dropping the mast - unless of course you have other work to do on the mast or want to inspect it on the hard.

While not your boat, here's an example of what I mean relative to the cover. This demonstrates access and orientation of the sheaves/pins with a masthead cover removed. With the cover off, one can see how a halyard (white with blue tracer) has 'jumped' the sheave and is partially riding against the pin while also being pinched between the sheave and casting. This can be one cause when feeling friction while trying to raise/lower a halyard. The sheave material deteriorates over time and will fail at the thinner, outermost edges - allowing the halyard to 'roll' off the sheave valley (eventually, this can chafe to failure depending on the integrity of the sheave and how it's in contact with the halyard).

Cover Installed

View attachment 200202

Cover Removed

View attachment 200203

Thanks for the pictures.
Between yours and the ones in post #11 I'm getting a better idea of what is likely to be up there.
Yours has a removable cover, and as I read your post that is from a 320. Useful, as I had been told it could be the same fitting. On my old 27, the halyard issue was also the line jumping the pulley, but the pulley was old and breaking up, so I changed it.
The shots in #11 are the first I have seen from a 310 like mine, and it does not appear to have a removable cover, the fitting was removed from the mast to access the sheaves. It looks like that is likely my setup.
The halyard was not stiff when I bought the boat 7 years ago, so not likely to be a twisted lines issue.
If I need to have the mast pulled, it's not the end of the world, just more time, fuss, and expense. But knowing that at least some of that type masthead fittings have a removable cover leads me to think it's worth asking around to find a friend with a camera equipped drone to take some pictures of the top, or get someone to climb it.
Many thanks to all for the info.

 

[PlaneTom]

I had some hard to hoist halyards when I bought the boat and thought it was the sheaves. Turned out to be tangled/twisted internal halyards that were fouled. In order to replace the sheaves on the boat you would need to disconnect both the forestay and backstay, tie yourself off up there below the fitting, and relive all tension on all the halyards (or use an aerial lift).View attachment 200205View attachment 200206View attachment 200207View attachment 200208View attachment 200210

Thanks for the info, as much as I can tell from the ground, that appears to be the same as mine.
Do you have any part numbers or size specs on those sheaves? Were all three identical?
I'd bet they are available from various sources, but if possible I'd like to have them ahead of time. Otherwise it's remove the old ones and look for matches.

 

[valcour]

all four are identical. I got the sheaves from Catalina for a standard mast a few years after the hull was commissioned as a (gratis type) warranty item. I will look for part number in my records. it still have them somewhere as spares. Mine is hull 218 circa 2003, these pics are from 2006 when I bought her. If you have a std mast with slab reefing there is a no chance (in my opinion) you have a removable cover on top of your mast like the photo from poster #10 with a boat from another manufacturer The photo from my post 12 was within a year or 2003 model I believe. It would be very hard to replace aloft unless you have access to an aerial lift at your marina.