What Is This Called

[David]

Anyone, please jump in.  I am about to order some parts, and I need to know what the broken part in the picture below is called.  From the Compac parts list, my best guess is:   S Gooseneck Casting.

Next question.  Do I just use a standard pop rivet for hole size, or as I have read in other posts sail hardware is stronger than regular hardware.  Are the rivets used on the compac boats a certain standard that I need to seek out also?

Thanks in advance.

David

[mrb]

You have the right part name, gooseneck casting.  About the rivet, why not get one from Compac or at least get their recommendation.  I am not a big fan of pop rivets but they do seem to work and have their place in the overall scheme of the world.

[BamaSail]

I have to repair my gooseneck too.  The type of rivet Hutchins uses is called a drive rivet not a pop rivet.  I contacted them about getting some when I ordered the replacement gooseneck and he suggested that I just use sheet metal screws.  The drive rivets, he said, were used to speed up the manufacturing process.  I'm a little reluctant to do so.  I'm sort of anal in using the exact same types of fasteners and parts that the boat came with.   So, I searched for drive rivets.  Have yet to order some.  The place I contacted had a minimum of 100 per order.

[RCAN]

I bought my 1976 Com-Pac 16 in May, 2010 and it needed some repairs, including replacing this cast aluminum part.

I ordered it from Hutchins. The guy in their parts department is easy to talk to and will help identify any part you describe to them and even help you find it in their price list.

I do not have a work shop of any sorts but was able to do this myself. After the part came in, I carefully drilled out the manufacturer's rivets so as not to enlarge the holes on the boom. There are several springs and other components on the inside which all come apart pretty logically. Since I do not have a riveter, I took the boom to my local True Value Hardware store which has a small shop to repair aluminum screens, etc. They were kind enough put the three rivets on for me for a nominal fee of about $ 5.00. They enjoyed doing it because it was an unusual request.

The part is replaced and you would never know it. It looks looks the original.

[Bob23]

Anytime I've had to do such a repair or modification which involved drilling holes in boom and/or the mast, I've drilled, tapped and used stainless steel machine screws with Never-Seez graphite grease. They can always be removed and it's a very strong connection...better than sheet metal screws although they and rivets work just fine.
Bob23

[David]

Bob23,  Did you glue a nut to the inside of the boom or just let the machine screw cut some threads in the aluminum boom and use the never-seeze?

Thanks to all.
David

[Bob23]

David:
  I drilled and tapped out the hole for the thread of the particular screw. It holds pretty good. You can buy taps and dies at Lowe's or even HD. I have some on hand from my old days as a VW mechanic. The Never-Seez is a must as you are using SS screws on aluminum parts. Helps to prevent some sort of galvanic corrosion.
Bob23

[brackish]

Yep, called a gooseneck casting.

All parts and descriptions here.  This is the 23 boom.  16 is probably on this site too.  Dwyer.

http://www.dwyermast.com/items.asp?cat1ID=30&cat1Name=Booms&familyID=5&familyName=DM-275+Boom

[BamaSail]

Bob23,

Sounds like a good solution.  I was concerned about the sheet metal screws because of the corrosion problem, but it sounds like you have a fix for it.

[curtisv]

I have had rivets pull out of aluminum, but so far never a machine screw (that I remember, let me think now...).  On the Yahoo Compac list a number of years ago was a long thread on which is better.  I don't think the long thread was conclusive.  It depends on what you are doing.  The argument for rivet was an aluminum rivet doesn't give you dissimilar metals and they can be quite strong.  Machine screws are only as strong as the thin bit of metal that you screw them into if you tap a hole.  Some claimed rivets are stronger.  Some thought machines screws were as strong or stronger.

Like Bob, I prefer to use a tap and die set and put some threads in the boom aluminum and then a SS machine screw that can be removed later.  For something where the load is trying to pull the rivet or machine screw out, like a padeye, through bolting is the only way to go.  But its hard to through bolt anything on the boom other than installing a bail.

In the case of the gooseneck, the force is trying to sheer the rivet rather than pull it out so it should be plenty strong enough.

Curtis

[CaptRon28]

I've used rivet-nuts on some jobs in the past. They work like a pop rivet, but you wind up getting a real nut behind the surface that's held in place by flanges on both sides of one of the materials. You can get them in both aluminum and stainless steel, and you need a special rivet tool to install them. The tool can be used to install regular pop rivets or these nuts by changing the head. They are somewhat stronger than either pop rivets or machine screws especially in soft metals like aluminum, and they can be dis-assembled many times if necessary.

In general, stainless pop rivets are significantly stronger than aluminum. and any machine screw in aluminum is limited by the tapped threads in the soft metal. Best to use a fine thread if you can - more theads will yield more strength. Self tapping is not a real option here.