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Mast base separation - What to do?
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=54741		 Page 1 of 1
Author:  janek.w [ Fri May 15, 2015 11:49 am ]
Post subject:  Mast base separation - What to do?
Hello!

I've recently taken my Hobie out of storage and noticed that the mast step has become separated from the front crossbar. It appears that the rivets have pulled out. When I raise the mast the step appears to compress back down but I'm not sure if it's safe to sail like this.

I'm wondering what would be the proper course of action to go about repairing this? Do I need a new mast step? Do I need larger rivets? (If so what size should I use). How do I go about replacing/reattaching the mast step?

Thanks so much guys.

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Author:  mmiller [ Fri May 15, 2015 1:16 pm ]
Post subject:  Re: Mast base separation - What to do?
Larger rivets or alternate locations.
Author:  janek.w [ Fri May 15, 2015 5:43 pm ]
Post subject:  Re: Mast base separation - What to do?
Alright so I took the mast step off and there seems to be another problem - Part of the hole for the dolphin striker rod has sheared and enlarged.
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Is this a problem? I imagine when I rivet the thing back together it won't be much of an issue, but I want to be sure.


On a side note - do you know if there's any way to make 3/16" rivets work? Maybe some kind of bushing? I don't have to tools to use 1/4" rivets and I can't find 7/32" rivets (do those even exist?).
Author:  mike11787 [ Fri May 15, 2015 6:12 pm ]
Post subject:  Re: Mast base separation - What to do?
I think the best solution to the pulled-out rivet holes would be to get someone to weld the holes shut and re-drill them. A skilled welder should be able to tig-weld the holes shut in no-time, and for pretty cheap. If the forward holes are not too reamed out then you can (after welding the rear holes) rivet the mast step back in place with those holes to align it, and then match-drill the rear holes and install the new pop-rivets.

Alternatively if you don't want to weld it, you can use washers on the back side of the pop rivets, but I would be concerned with them interfering or damaging the trampoline as it looks like the holes go into the groove.

Also as was already mentioned, you could just re-locate the rivets to new holes all together.
Author:  Fxloop [ Sat May 16, 2015 9:49 am ]
Post subject:  Re: Mast base separation - What to do?
Looks like perhaps the dolphin striker was too tight? I'd loosen it all the way before re-riveting. Also, I've seen 80's front crossbars for hobie 16's used on craigslist for $50-$100 that were in excellent condition. You could swap it out quickly to keep sailing while you get your current one fixed up. There's a lot of discussion on here about welding anodized aluminum and the consensus is that it makes the metal MUCH weaker. That seems like a high stress area to have weakened metal. Rivets with SS washers on the backs might be an idea if you can find a way to keep them in place before riveting.
Author:  MBounds [ Sun May 17, 2015 4:41 am ]
Post subject:  Re: Mast base separation - What to do?
mike11787 wrote:
I think the best solution to the pulled-out rivet holes would be to get someone to weld the holes shut and re-drill them.

Heat-treated aluminum extrusions should never be welded - it will reduce the strength of the material by a factor of 3 in the heat-affected zone. All the extrusions on a Hobie Cat are heat-treated (6061-T6 aluminum).
Author:  janek.w [ Sun May 17, 2015 11:53 pm ]
Post subject:  Re: Mast base separation - What to do?
Just thought I'd update what I ended up doing - I slipped washers into the crossbar and then riveted using the standard size 3/16" rivets. It seems to hold very well and doesn't interfere with the trampoline at all. To get them in there I used a magnetic flat head screwdriver and (very carefully) slipped the washers in through the trampoline track. I then inserted the rivets in through the holes while holding the washers in place with the flat head.. It was a rather tedious process which would be made much easier with another set of helping hands.

I expect that it will get me through the season but I think I'll end up buying a new front crossbar at the end of this season as a permanent fix.

On a side note, Exactly how tight should the dolphin striker be? I tightened the bolts on the sides until they provided a decent bit of resistance, and as a result the dolphin striker feels very tight and has minimal movement in any direction. Is this too much?

Thanks for all the help by the way! :)
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