Replace telescoping beam shims

[davefarmer]

Anyone care to comment on the best way to replace the shims/bushings on the telescoping beams on the SC20? Thanks!

Dave Farmer 509 276 6355

[Matt Haberman]

Dave,

It has been a long time since I have had to replace the beam buttons, but here are a few thoughts.

Start by taking the boat apart, remove the beam from the hulls, remove the dolphin striker post and the bushing sleeve, then remove the cross bolts from the beam.

With the post, sleeve and bolts out of the beam you should be able to slide the beam out far enough to remove the first row of buttons from the outside of the 4" beam. You can also rotate the 4" tube and try to fish them through the dolphin post hole in the 4.5" tube.

You could also try removing the nuts from one end of the striker cable. This would allow the cable to slide in the beam (until the swage hits the slot) and probably get the beam completely apart. Before you take the nut off here are a few things to remember: count how many threads you have showing past the nut, you MUST get the cable back to the same position. Also be careful getting the nut off, the cable and swage are expensive not to mention it is swaged IN the beam so it isn't something we can really ship you. We have to swage it in the beam if it needs replacing.

One more tip for putting the buttons on the inside of the 4.5" tube. We used to put a piece of masking tape over the hole on the outside then stick the button in from the inside. The tape would hold the button in place while you inserted the 4" tube.

Good Luck

[davefarmer]

Thanks for the prompt response Matt! I disconnected the aft beam on the port side (4.5" dia tube) this evening. The boat is collapsed on the trailer. Needed to disconnect both ends of the traveller cable to get the tubes to completely separate, but that was relatively easy. Had to pop off one end cap to get at the cable so I could grip it while unscrewing the cap nut.
Three of the shims on the inside of the larger tube are either damaged or missing. The remainder look to be in good condition, and are still well attached. I'm somewhat reluctant to remove them, even thought the previous owner kindly provided me with a complete set of new shims. Seems that keeping them in place while reassembling could be tricky. I like your idea of using the masking tape, hope it will work. What do you think about reusing the existing shims? Recommendations on a suitable lubricant for the reassembly? The same waterproof grease that I use on the beam bolts and mast post ? Silicone spray? McLube? There was a black gummy substance on some of the original shims that I had to work at a bit to remove.
I sure like the high quality of the components of this boat every time I have to mess with it, even as a 25 year old boat. Thanks again for all your help!

Dave

[Matt Haberman]

Dave,

You could use a dry lubricant, but I would avoid silicone or other similar lube that will attract dirt...

Regarding the exsisting shims. If you have the beam apart this far I would personally replace them on the basis that I wouldn't want to have to do this again any time soon.

[efinley]

Matt you said this:
> count how many threads you have showing past the nut, you MUST get the cable back to the same position

Why is this so important? The nut on my cable has come loose so it has moved. How do I determine the correct length to fix this now?

Thanks,
Eric
SC 20 #113

[Matt Haberman]

Eric,
The cable length is more important on the forward beam then the rear beam. If the dolphin striker cable is improperly adjusted the mast has the chance of bottoming out on the beam and causing some damage.

To adjust the dolphin striker cable the beams need to be on the boat, but you need to have the mast down and off of the boat. Next you have someone push down on the ball/post while lifting up in the middle of the cross beam. While doing this you tighten (or loosen) the cable until you can just slip the Avibank pin through the post below the beam. After you have sailed the boat a few times and take the mast down you will probably find that the cable needs to be adjusted again (Avibank pin too low). Usually after a few adjustments of the cable everything settles down and it probably won't be necessary to adjust the cable more then once a year or so.

Just remember that when the mast is up the post will move down and the avibank will be away from the beam, this is normal. When you take the mast down and off the boat the post will move back up and this is when you should check and adjust it if necessary.

[efinley]

Thanks Matt, that is basically how I have been adjusting it.

[davefarmer]

So my dolphin striker cable is secured on the outside of the beam end caps with cap nuts that are fully seated. So to adjust , (shorten cable) I would need to cut threads off the swaged fitting. Is that what you're doing when you adjust the dolphin striker?

Dave

[Matt Haberman]

Dave,
Check both ends, you might have some adjustment room at one end versus the other. If you are out of room at both ends, then yes you will have to cut some of the threads off. I have also seen people add a jam nut, then the acorn nut in leiu of cutting the swage.

[efinley]

That is how mine is done, it has the following parts going from the inside of the beam:
nut->end cap->nut -> cap nut (acorn nut)

I can tighten the 2 nuts up against the end cap and lock it in place. However in practice the 2 nuts always works loose so when assembling I just readjust each time, only take 1 minute.

-Eric

[davefarmer]

Thanks guys! Helpful as always.

Dave

[SC20 808]

Hi Matt,

do i understand you right that it is actually not possible to pull the frontbeam cable out of the beam when loosening the nut?

I sourced a new one piece frontbeam for my 1980 SC20 and have been in communication with Tom for a while discussing the need updating to the new strap system or not. Finally decided to keep the old wire system with the new beam. I haven't tried yet to take the cable out of the old beam, but if you tell me that it is actually not possible I would be more than surprised... and stucked!

Dirk

[Matt Haberman]

Dirk,

No, it will not be possible to remove the cable from the slot in the front beam. The roller swage on the end of the cable is much larger then the slot cut in the front beam. You could always cut the beam, but then you have the issue of getting the cable back into the new beam.

[SC20 808]

Thanks Matt for the (surprising) news. Seems it would have been a better idea talking to you than to Tom He forgot to mention this little detail .

Not sure how many of the old SCs are still floating around but what would make sense from a boats owner perspective is to have a detail pic gallery available on the web where one can see all these details and original parts. It could be combined with the order numbers for the new parts and so it would be very easy for boats owner to check if their boat is original or what parts are needed to return back to a safer design specs environment. With an online catalog this could be easily solved. Featuring older and newer boats it would also help when thinking of updating to parts from the newer models.

In my case I found out that my frontbeam has a much larger wall thickness than original but also large holes where the cables run through. I was thinking these big holes are a (weak) stock solution and was going to make the same cuts into a smaller diameter replacement beam with a thinner wall thickness... which would have probably failed quite soon. I ordered an owners manual now in hope it will show enough pics to get a grip on what other strange modifications my 27 years old boat has 'enjoyed'...