I just bought an 86 Hobie 16. I was raising the mast, and had it almost up, when the base came apart. Luckily it was almost up, and I was able to get it seated without losing control of it. I managed to get it more-or-less back together and get it down safely.
Here's a picture:
http://s159.photobucket.com/albums/t131/jpwu/Hobie%20Cat%2016/?action=view¤t=IMGP0113.jpg
As you can see in the picture, there's a BOLT holding the mast base into the mast. You can't really see it in the picture, but the aluminum below the holes that the bolt goes through is ripped out (C's instead of O's).
A couple of questions:
- Looking at some other threads on here, I see people describing similar problems, but they describe it as having RIVETs popped out, rather than a bolt. So, I'm guessing that a previous owner had already damaged the mast, ripping out the rivets, and replaced them with this bolt. Should it be riveted in?
- I was thinking of cutting off half an inch or so off the bottom of the mast, drilling new holes, then replacing the bolt. I saw a thread where someone else suggested this solution. Will this work? Should I use rivets (I'd have to buy a rivet tool) rather than the bolt?
- In addition to riveting or bolting the base together, what about the idea of using epoxy? It should make it very strong. Would it matter that I'd never be able to take it apart again?
Any help appreciated!
Thanks!
Hobie 16 mast base ripped out.
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Posted: Jul 12, 2009 - 10:45 PM
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Posted: Jul 12, 2009 - 11:16 PM
The mast base on my nacra has about a 1.5" flange that fits up into the mast. This flange is the same shape as the inside of the mast. If the hobie base is like that you could use 4 rivets, one fore and one aft on ether side of the bolt hole. -
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Posted: Jul 13, 2009 - 12:38 AM
That sounds like a good idea. I'll take the base apart and see if that will work.
Now that I think about it, aluminum rivets are probably a better idea than a steel bolt, to avoid electrolysis and corrosion.
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Posted: Jul 13, 2009 - 07:32 AM
Not aluminum rivets (they will not hold), you must use 3/16 Stainless Steel Rivets. Do not forget to use silicone when you put the mast base back in after you cut the bottom of the mast. -
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Posted: Jul 13, 2009 - 07:43 AM
i removed the mast cap and base this winter to clean up corrosion and paint then paint them
i used alloy rivets on the top cap and haven't used any rivets on the bottom cap as it was such a tight fit
perhaps it's because i don't have a captive base but i couldn't see why i would need hugely strong monel or stainless rivets when the loads on both caps are pushing them in to the mast and not trying to pull them out
my mast is well sealed from the lower diamonds and mast rotator up, as that's where water could enter if it was on it's side but for the 1st yard/meter above the base it isn't sealed at all so the inside can breath etc. -
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Posted: Jul 13, 2009 - 09:44 AM
If that boat turns turtle you will see why it is important to have the base sealed. There is a reason why the factory puts stainless steel rivets in the mast base.
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Posted: Jul 13, 2009 - 09:55 AM
As for Nacras, the factory does not use SS in the mast base. . . not sure about the H16.
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Philip
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Posted: Jul 13, 2009 - 10:02 AM
Cut as little off of the mast as possible, the mast base has a lip that fits into the mast tightly, it most probably also has holes drilled from previous rivits, trying to line up on these holes to drill new holes in the mast is very difficult but has to be done as you don't want to drill new holes, this will weaken the mast base, remember, it's made of aluminum. Once you have the holes lined up, get out the silicone, calk/seal mast base, using stainless steel rivits, attach the mast base to the mast, my mast base has 8 rivits around the base, and don't forget to seal the rivits when finished. The mast will be shorter and you will have to adjust your shrouds accordingly.
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TurboHobo
H14T
H16
P18
G-Cat 5.0
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Posted: Jul 13, 2009 - 03:12 PM
Turbohobo is right.........
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and other toys.......
~~ I live in NY state on the north shore of Oneida lake in
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Posted: Jul 13, 2009 - 03:55 PM
Thanks for all the tips.
Now I think the best plan is not to cut the base of the mast, but rather to drill new holes through mast and base, two on each side of the existing holes (4 in total), then pop-rivet the assembly together.
I do question the advice to use stainless steel rivets. After all, the mast itself is aluminum, and what failed was not the rivets but the mast material itself. Can anybody verify that the original rivets were steel, not aluminum? Does putting steel fasteners into aluminum create a corrosion issue?
Nobody commented on my idea to use epoxy, in addition to the rivets. This might not only make the whole assembly very strong, but might also help seal against leakage. Anybody see any problems with this idea?
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Posted: Jul 14, 2009 - 09:46 AM
OK, did more research. Here's more info on rivet material:
The answer is NOT stainless steel. This will cause corrosion problems.
Rather, where rivet strength is an issue, the answer is to use Monel rivets. Now I just need to find a source for these and a rivet gun that can place them.
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Posted: Jul 14, 2009 - 10:31 AM
I just took a look at your picture. Interesting... I have never seen someone use a bolt to hold the base onto the mast. The other thing is there are no previous rivet holes in your mast. This leads me to believe that the mast has already been cut, and the bolt through the mast is a repair job already. If you cut your mast more you might have issues with your shrouds and forestay being to long. Just my .02
If you do cut and rivet, as suggested above, which is the best plan, I wouldn't epoxy. I dont think you will get that much bang for the buck with the epoxy. Just seal it with silicone. -
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Posted: Jul 14, 2009 - 10:43 AM
The reason why it is not a good idea to epoxy the mast base is that sometime in the future the mast base might have to be removed, for example, if the link pin hole snapped off and you had to replace the the mast base. If the base is epoxied it will make the job that much more difficult. I'm glad to see that you're doing the research though, I would have just used rivits from my local ace hardware store, they're aluminum.
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TurboHobo
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Posted: Jul 14, 2009 - 11:03 AM
I was looking at your pics, nice boat, I did notice someting though, your pic of the gooseneck (where the boom joins the mast) shows missing parts, the u-shaped bracket needs a clevis pin with split ring, pull the clew plate on the sail down into the u-shaped bracket and slide clevis pin through connecting the sail foot to the gooseneck assembly, attach rope to the downhaul ring, this allows you to apply tension to the sail after you have hoisted and secured the sail using the halyard hook by hauling down on the downhaul.
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TurboHobo
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Posted: Jul 14, 2009 - 12:26 PM
Thanks, you're very kind. But it's not a nice boat - YET. (Hopefully it will be before I'm done with it.)
Yes, very observant. Those were pictures I took to remind myself of all the things I have to fix!
Duncan
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Posted: Jul 14, 2009 - 12:44 PM
Yes, that bolt is something I didn't notice when I bought the boat. It's just one of the many wrong things I'm discovering that need to be fixed. I expected this was going to happen - I just hope I don't find something fatal or too expensive! Never having owned a Hobie before, I'm now groping forward into the vast unknown world of the Hobie fixer-upper.
It's possible the mast has been cut before, but on inspection the bottom of the mast doesn't look like it has been cut - it's completely straight and fits flush with the base. If it had been cut by hand I'd expect to see some imperfections.
Question for you: You point out that there are no previous rivet holes in the mast. Where would you expect these holes to be? When I looked at the mast base (the cast aluminum piece that goes inside the bottom of the mast) I only saw holes that the add-on bolt runs right through. How many rivets should I expect to see on a stock Hobie 16 mast of that vintage?
I think you're right. Others have pointed out the disadvantages of the epoxy idea.
Right now I think I'll not cut the mast, just put the mast base into the bottom of the mast, drill additional holes through mast and base, rivet, and seal with caulk.
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Posted: Jul 14, 2009 - 03:39 PM
Once you remove that bolt, keep in mind that the bolt hole becomes a weak point, if there are no holes in the mast base then it has never been rivited before. I would use 3 rivits each side and maybe even a couple around the leading edge of the mast. If you don't cut the mast above the bolt hole, you might want to consider leaving the bolt in when you rivit and caulk the base, there would be no compromising of the structual integrity of the mast around that area, just don't forget to caulk that area as well.
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TurboHobo
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P16
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Posted: Jul 15, 2009 - 10:37 PM
HObie does use stainless steel rivets with cups (you can check the parts list and order from murrys) and yes stainless to aluminum can be an issue but I think they get around it by coating the cups. you drill a 13/64 hole for a 3/16 rivet and insert the cup in the hole first. This also provides some waterproofing
As far as rivit guns go, the ONLY way to go is a hydraulic\pneumatic rivert gun (harbor freight is my hero!!!)
most hand powered riveters do not have the balls to do stainlesssteel rivets and the ones that do are so big you are wobbling the rivet around while you are trying to compress it which is not good
If you are in the tampa area, drop me a line and you can come by and use mine. I just replaced my mast cleats and it was a piece of cake not to mention only taking a few minutes.
Air tools rock!!! (pds624 at gmail.com)
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Posted: Jul 15, 2009 - 10:46 PM
P.S. from Murrys
| Item No Description Qty BackOrder Qty Ship Price/Unit Ext.Price |
|______________________________________________________________________________|
19-5023 RIVET MSP 6-10
2 0.65 EA 1.30
19-5020 RIVET CASING 6-10 (3/16 X 1/2)
2 0.70 EA 1.40
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Posted: Jul 15, 2009 - 10:54 PM
I've looked for an easier rivit tool... couldn't find one, went to Home Depot, Lowes... so I guess they never made one... Harbor freight HUH !!! Wish I knew that a few yrs ago......hand rivits suck, especialy with SS rivt's, then to top it off with the 'sleve' thingy...
Maybe I'll stop there on the way home from work tomorrow
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~ Vietnam Vet 69-71~ 17 Hobie w/big jib, ~18 Hobie mag,~DN Ice sailor,
and other toys.......
~~ I live in NY state on the north shore of Oneida lake in
Bernhards Bay. ~~~~~~
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