H17 - How to remove the mast base

Are you talking about the casting riveted on the bottom of the mast or the ball the mast sits on on the front beam?

Quarath wrote: Are you talking about the casting riveted on the bottom of the mast or the ball the mast sits on on the front beam?

The casting (50416011)

It should slide in the mast and have a few rivets through the mast into the casting. It also may have a bunch of silicone sealant inside holding it in place but it still should have rivets. I'll have to go look at mine tonight.

Stainless Steel or Monel rivets.

Gonna need an Armstrong Rivet Tool to replace those bad boys.
I think its four rivets, and if some holes are stretched out, you may want to drill new holes.

(note: ART is slang for a really big rivet gun- either long handles, compound action or an air tool.)

All you really need is aluminum rivets. The mast base is held in place by compression.

As always, if you do this replacement, please photograph and put the pictures into an album in the Technical Help gallery to help the next guy with the same question.

I have never seen a mast base from the factory with aluminum rivets, always stainless steel in every model cat that I have came across. I would replace with SS. They are normally 3/16, if the holes are enlarged go to 1/4 using the same holes. Drilling more hole will weaken both the bottom of the mast and the mast base. It is really a simple job with the proper tools. If there is a Harbor Freight Store close by, they sell a long handled rivet gun for about $20.

Thanks for the info! I'll document the replacement as soon as I locate a used base or spring for a new one!

stainless steel

I'm about to install a new mast base on my 5.2. What's the best way to remove the old rivets without damaging the mast? Drill out the centers?

If you drill centers just take I slow and easy using the exact same size bit as the hole. You want to avoid enlarging the hole.

You can also use a larger bit and and just drill carefully and slowly until the cap comes off then use a center punch to knock the rest back into the hole.

I have tried both either can work if your careful. A drill with variable speed trigger would be best.

Hey Dustin. Thx for the tip on Rick Whites book. I love the way the 17 sails and the 1 up sailing.. Just got one more for my fleet however. A H 18.. 80's.. Nice shape and has been raced but still want to be out there. Not giving up on the 17 however.. Are you coming to CA this summer.?? Was IMing Mr Tahoe about a sail in June - July.. Be great to have a few boats there.. Hal

halliske wrote: Hey Dustin. Thx for the tip on Rick Whites book. I love the way the 17 sails and the 1 up sailing.. Just got one more for my fleet however. A H 18.. 80's.. Nice shape and has been raced but still want to be out there. Not giving up on the 17 however.. Are you coming to CA this summer.?? Was IMing Mr Tahoe about a sail in June - July.. Be great to have a few boats there.. Hal

I'd really like to get up Tahoe just not sure if/when I can make it happen. I was thinking most likely scenario might be in August. I got a lot of local weekenders planned in June - July but we'll see. I told the wife maybe I'd need to tear off and just run up there myself was told hell no if I'm going we're all going.

What's the best way to remove the old rivets without damaging the mast? Drill out the centers?

An aerospace engineer showed me the "proper" way to drill them out. Those guys were always bashing tin, & used clecoes(little gizmos that go into the rivet holes to hold multiple pieces of sheet metal in close tolerance) by the hundreds on some jobs. They were also fanatical about not enlarging the holes, as that compromises the design strength.
You do not actually want the drill to eat into the material, only the rivet itself. Drill straight in , using a bit the same size, or preferably 1/64 smaller than the rivet shaft, & STOP, just when you get the depth of the rivet head. You do not need to drill til it falls out.
Now, using a suitable tool, ie the blunt end of the bit you just used, insert the end into the hole you drilled, & with a small sideways motion, pop the head of the rivet off. You will quite often be left with the shank of the rivet still in the casting, & a small "donut" on the end of your tool. If needed gently drive the shank through with a small punch.
Maybe it isn't as critical with our boats, but it takes the same effort to do it right. If the holes are enlarged at all, you are now depending on the rivet holding the pieces together by compression, & friction to prevent movement. These will always loosen, the effect is like having a bolt that is to small a diameter, the sloppy fit will allow the pieces to "work". Proper rivets act like a very close tolerance bolt, allowing zero lateral movement. Not only the head expands, the shaft also expands a few thou, making a very tight fit.