Rivet specs

I need to replace the rivets on my 21SE wings. I have tried using aluminum and they don't last. Are the Monel rivets stronger and do they prevent corrosion at aluminum and stainless contact points? The rivet guide with the boat manual does not mention rivet specs for the wings, only the spars and deck hardware. Some are spec'd as "csk aluminum" what's that?
I'm getting corrosion at the diamond wire tangs and want rebuild that joint. What material is normally used to insulate the aluminum from the SS?

csk - countersunk
Monel is stronger than aluminum.
http://en.wikipedia.org/wiki/Monel

To quote: "It is commonly used in applications with highly corrosive conditions."

I believe Monel alloy has a decreased tendency towards a galvanic reaction with the aluminum alloys typically used on sailboats.

Since the 21SE wing structure is similar to the 17, I'm betting you can use the corresponding 17 rivet call out.

Wing
End Cap 8010051 - qty 1
Castings 8010131 - qty 8

Brian C

Thanks Brian but I had a 17 and the wings are nowhere near as hefty. I believe the 21SE wings are the same as the 21SC if those specs are still available.

Perhaps... I seem to remember some of the 21SE wings looking more like the 17 wings than the 21SC wings. I thought there had been a change during the production run. But I've slept since then.

Neither my 21SC nor SE part guides have rivet listings for the wings. My SE part guide is actually a marked up SC guide (not sure who marked it up).

I pinged Matt via email a few minutes ago with some other questions, but asked him to review this thread. Hopefully he's still got a BOM for the 21SE.

So yeah... I may not have the correct rivet numbers. I'm confident on everything else.

Brian C

The 21SE and 21SC are the same hulls with the same wing sockets and very likely the same wings. They have a 450 lb. load rating I think. The 17's were nowhere near as stout and I beieve the rear stanchion or both were bent right into the seat area and welded as opposed to the 21 having cast sockets and rivets. The 21SE came with wings assembled I think. The 21SC guide shows the customer needs to rivet the wings together, surprising they don't spec the correct rivets.

3/16" stainless rivets (available from your local Worst Marine, Fastenal) or 3/16" monel rivets (available from your Hobie dealer) will do the trick just fine. Be sure to put a little sealant on the rivet when you put it in the hole, and you'll be fine.
Email brad@sunjammers dot com if you want to go the route of monel rivets.

_________________
Trey Brown
www.velocitysailing.com
2006 N20 1017
1998 H16 102698
www.sunjammers.com ftw!

"Worst Marine" ... There's actually a guy who worked here who's out at the West in the east side of the County. That particular West is pretty good.

But I think the question is more to do with what length. When in doubt, too long is better than too short. If the wing is apart, get a caliper and measure. That's all I have to offer till Matt gets on the scene.

Brian C

Rivet materials:

Aluminum. Low shear strength. Should not be used anywhere that is structural.

Stainless... Best shear strength

Monel... is a stainless alloy with less galvanic corrosion issue in aluminum.


Lengths:

Too short... Does not expand inside the drill hole and may "pop" prematurely without actually connecting the two parts.

Too long... Friction during the pulling process may cause the pin to "pop" before the expanding inner meets the inside surface of the object being riveted.

Best... the inner expands and pulls tight against the inside surface of the object, pulling the two items together tightly, before the pin "pops".

Hobie 21 Parts guide with partial rivet chart: http://static.hobiecat.com/2010_archive/support/pdfs/H21SE_Parts.pdf

The wing Bill of Material calls out 16 rivets and caps per wing. The part numbers are 8011291 Cap and 8010131 Rivet.

The 8010131 rivet is 3/16" diameter and 3/8" grip length. The seal caps are 15/64" diameter.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

This is excellent, thanks Matt. I had the rivet guide.
Now, one last question. What is the 8011291 Cap?
I'll definitely get these from my favorite Hobie Dealer, Worst Marine is notorious, with me at least, for poor quality stainless products.

The caps are an aluminum "plug" if you will that goes in the hole before the rivet. Hobie has them made special and is the only place to get them (I know, I looked forever and day for them). Net result bought a 100 through my hobie dealer.

Rivet caps are actually thin stainless. They seal the rivet hole from leaks as rivets have a hole through the middle. They are normally used on areas that need to be sealed. The look a little like an Abe Lincoln hat. They are deep enough for the longer rivets to slip in and not bottom out. The do cause a bit more friction when pulling as the cap has to expand along with the rivet. The length of the rivet used would be more critical then as the risk of a rivet popping prematurely is greater.

We don't make them, but not many people use them I guess, so they are harder to get.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)