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Misaligned jib car traveler sheave
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Author:  AntonLargiader [ Mon May 27, 2013 9:17 am ]
Post subject:  Misaligned jib car traveler sheave

Long title I know...

Anyway, I was hoping to find a different problem when I removed the rivet from my port sheave but I found that indeed the axis is wrong. The problem was that the sheave kept binding; it spins freely enough when the traveler line isn't there but the line binds between the sheave and the aft part of the casting.

The casting seems to be mounted to the crossbar in the same way as the starboard side, although it looks twisted in the photo. And the starboard sheave is level.

Any ideas how I should go about fixing this? Does anyone know, is this hole pre-drilled in the crossbar or is it drilled when the sheave is installed? I'm trying to figure out where this went wrong, in case it means there is another problem elsewhere that I should be looking at.

Image

Author:  MBounds [ Mon May 27, 2013 3:02 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

The hole is drilled after the casting is installed on the crossbar.

A way to fix it would be to put a plastic spacer underneath the sheave (a piece cut out of a mast chip might work) to keep it from slipping down and binding. Mast chip might be too thick / soft. Sheet Delrin would be ideal. If you really wanted to do it right, shape the spacer to match the curve of the crossbar, leaving a perfect rectangular hole for the sheave.

I wouldn't try to "straighten" it, since the new hole in the crossbar would almost certainly overlap the old, and the rivet wouldn't hold.

Author:  AntonLargiader [ Mon May 27, 2013 3:19 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

Thanks for the info, Matt. The problem isn't the angle of the sheave, it's the side clearance. There isn't enough room on the left side of the picture for the line to fit. The line rubs the casting. Well, I guess I could use thinner line, but the line that was on the boat is already thinner than what the Hobie dealer sent me as replacement. Maybe some shimming upward, thinner line and shaving the top of the sheave would give me what I need.

I was thinking of having a welder zap the old hole in the crossbar so I could drill a new hole into solid metal. Not sure if anyone can get in there, though.

I hate careless s**t like this. Not that it matters, but is this hole drilled at the factory or at the dealership who assembles the boat?

Author:  MBounds [ Mon May 27, 2013 5:07 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

AntonLargiader wrote:
Is this hole drilled at the factory or at the dealership who assembles the boat?

Factory.

Author:  mmiller [ Tue May 28, 2013 8:23 am ]
Post subject:  Re: Misaligned jib car traveler sheave

Yes, factory error, but maybe you use too large a line diameter? Has always been an issue for you? How old is the boat? Looks like the crossbar is not quite aligned with the casting... gaps / twisted?

Author:  AntonLargiader [ Tue May 28, 2013 8:35 am ]
Post subject:  Re: Misaligned jib car traveler sheave

Bought the boat (2000) last fall and it was jammed then. I was hoping it was just a broken rivet or sheave.

As I said, the picture makes it look like the extrusion is twisted in the casting but it's not really; that is mostly an optical effect of the casting bevel (or lack thereof) around the perimeter. The starboard side has the front of the sheave cavity lining up with the jib track exactly the same way. At any rate, I would think that the crossbar and casting were riveted before this part was even drilled.

If it had been noticed at the factory, how might they have fixed it?

I'll get you line diameters when I'm home, but I have let the Hobie dealer (Backyard Boats) dictate that.

Author:  Tim H16 [ Tue May 28, 2013 12:45 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

Could you mount a cheek block on top of the casting?

Author:  mmiller [ Tue May 28, 2013 1:54 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

I'd guess the line diameter is too large if jammed. Likely would have been working when new or we would have heard about it.

Author:  AntonLargiader [ Tue May 28, 2013 5:12 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

The line that came on the boat was 3/16". The new line that the dealer supplied was 1/4".

Here's how it looks with the old line. I think it was binding up in the lower left of the picture, when the sheave dropped to the bottom and shifted to the left.

I think I will follow MattB's suggestion and shim the bottom of the sheave to keep it up. It seems to function OK there with the 3/16 line.

Image

Author:  MBounds [ Tue May 28, 2013 7:33 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

3/6" is the proper size line for that application. 1/4" is too big.

3/16" = 4.76 mm - Try a 4 mm line. You only need ~ 25' or so. Check the APS Sale Bin - http://www.apsltd.com/c-4751-line.aspx (the selection varies from day-to-day)

Or just buy what you want from their small diameter control lines - http://www.apsltd.com/c-1499-smalldiame ... raids.aspx

Author:  AntonLargiader [ Wed May 29, 2013 4:40 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

Thanks for the input. I shaved the top of the sheave a bit and shimmed it from below, but there's another problem. Either the supplied rivet was too thin, or the holes are too big. The rivet mandrel pulled through, past the hole in the crossbar.

The starboard sheave is pretty snug on the rivet, so I'm thinking I have the wrong diameter rivet.

Author:  Tom King [ Wed May 29, 2013 5:00 pm ]
Post subject:  Re: Misaligned jib car traveler sheave

I'd tig weld the hole and drill a new hole.

Author:  AntonLargiader [ Fri May 31, 2013 3:16 am ]
Post subject:  Re: Misaligned jib car traveler sheave

What's the correct size and type for the rivet? The dealer and I reviewed the part numbers and the length is correct, but the diameter (3/16") is considerably smaller than the 1/4" hole in the sheave and smaller than the holes in the aluminum. Seems the diameter should be at or just under 1/4".

Author:  rattle 'n hum [ Fri May 31, 2013 10:52 am ]
Post subject:  Re: Misaligned jib car traveler sheave

AntonLargiader wrote:
What's the correct size and type for the rivet? The dealer and I reviewed the part numbers and the length is correct, but the diameter (3/16") is considerably smaller than the 1/4" hole in the sheave and smaller than the holes in the aluminum. Seems the diameter should be at or just under 1/4".


http://tinyurl.com/aunqqj7

Part No. 8011251 (RIVET 6-16 PH HD-ALUM) See the bottom of the H14/16 front crossbar detail on Page 52 of the catalog. The rivet should be 3/16" diameter and ~1 1/8" long (very long for a rivet). The stock rivet is aluminum. I bought a few of them this winter from http://www.sailandskiconnection.com/. Fits and operates perfectly.

Maybe you could use a rivet cap on the crossbar hole. Or, if not tig weld ala Tom King, fill and drill with JB Weld? Wouldn't be out much if it didn't work!

Good luck, man!

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