Mast Step Base

While stepping the mast the other day, the mast base fell out. Upon inspection, the holes in it are cracked and the rivets were no longer holding it in. I feel as I can repair this myself. My question is I noticed grease looking stuff all along the edges. Is this a sealant of some kind? I already know where I can get a new base and rivets, but I'm not sure what this sealant grease stuff is. Any insight?

It may be sealant but I doubt that it is sealing anything. The mast gets sealed by foam plugs that are inserted in the mast and then sealed into place. I wouldn't worry about resealing the mast base.
My 1980 H-16 only had 2 rivets holding it and it failed in a similar manner where the base had cracked around the rivets. The new mast bases do not have rivet holes pre-drilled which made it easy to convert to a 4 rivet configuration.
It is an easy job, but make sure you have a heavy duty rivet gun since SS rivets will destroy a cheap rivet gun.
Good luck!

_________________
Eric Weller
2006 F18 Capricorn
1980 H16
Keep the pointy side up!

Yeah, I saw the foam plug inside. I'm not sure if its still good or not, but when I tipped over once, I never turtled and the boat was on its side for a good 45 minutes. I just wasn't sure if it was a grease or sealant or what.

Your break sounds similar to mine, with the 2 rivet design. Where do I drill to convert to a 4 rivet pattern like you mentioned? Also, is there a significant difference between Monel and SS rivets (I only sail in fresh water if that makes a difference)?

It sounds like your mast is water tight but the only way to really be certain is to put your mast entirely under water and look for air bubbles.
I removed my old mast base and taped the new base into place. I drilled holes at the 1, 5, 7 and 11 o'clock positions in the mast. Make sure your new holes are no higher than the old holes. Also, use a drill punch to indent into the mast prevent your drill bit from walking across the curved surface. Then drill the mast and the base at the same time.
I am not certain about the difference between Monel and SS rivets but I know that Monel is a proprietary SS, so technically, both Monel and SS rivets are SS. I don't think it makes a difference on the mast base since the only real stress on the rivets are when the mast is being raised. I put SS rivets in my mast and I have not had any problems for almost 2 years now.
Thanks!

_________________
Eric Weller
2006 F18 Capricorn
1980 H16
Keep the pointy side up!