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 Post subject: More Rivet Quandries
PostPosted: Sat Apr 18, 2009 9:20 am 
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Joined: Wed Mar 12, 2008 8:10 pm
Posts: 48
More questions...I go to bed and awake with a head full of mysteries. I build timberframe homes and teach art. This metal "joinery" is sort of new to me. I really want to do this right...measure twice, cut once...ha ha. Again, thanks for bearing with me.

1. Does a new tang come with the new shackles? If not, what sizes do I need to order? I think I need a shackle for the standing rigging and one for the traps. What sizes? How are they sized?

2. The tang rivets, that came with the comp kit, are 7/32s in size. Is that the size of rivets in the mast step and base as well? Do I need to drill out the old rivets with the same size (7/32s) or can I use a 3/16 to knock em out? Are all the rivets everywhere stainless?
3. When I drill new holes for the new tang, what size of hole do I punch? Is my pre-drill the same size as the finish rivet diameter or do I drill smaller and stuff it? I could drill 1/32 larger than rivet diameter and have a 1/4 in hole?
4. Can I use thickened West System to glue the tang on? I noticed my old tang has some sort of glue residue around it. Do I finish it out with a dabble of marine silicone on each rivet?

I think I'm going to cut my mast today and drill out the old tang. There is sort of a "point of no return" on the horizon...I can't go to the sawmill and conjure another mast! Thanks folks (MBounds)!!


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 Post subject: Re: More Rivet Quandries
PostPosted: Mon Apr 20, 2009 9:37 am 
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Joined: Mon May 09, 2005 10:25 am
Posts: 2553
Location: Jersey Shore
- The new tang doesn't come with any shackles. The proper sizes should be called out in the Hobie catalog illustrated parts list, otherwise, call you Hobie dealer, they can get it for you no problem.

- I thought all the rivets were 3/16", but I could be wrong. You should drill out the old rivets with an oversized drill (like 1/2" or so) and you should only drill off the head of the rivet and then drive the remaining shank into the mast with a puch. If you try to drill through the entire rivet, you will most likely end up oversizing the existing hole.
The rivet material is monel which is better than stainless at resisting galvanic corrosion when used with aluminum.

- Drill your new holes the same size as the rivet or one drill size larger. The rivet should fit snugly into the hole (although with the large number of rivets used to hold the tang, you may have to allow a little extra tolerance to get everything lined up). If you use a smaller drill than the rivet, there's no way you'll get the rivet in the hole. I suggest doing a trial run on some scrap metal.

- Epoxy is not necessary to hold the tang on. The 12 or so rivets are more than adequate. I believe the residue you are seeing is from an insulating tape that Hobie puts on to prevent galvanic corrosion between the aluminum mast and stainless tang. Probably not a bad idea to do something similar. And yes, use liberal amounts of silicone to seal everything.

sm


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 Post subject: Re: More Rivet Quandries
PostPosted: Mon Apr 20, 2009 11:57 am 
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Joined: Wed Mar 12, 2008 8:10 pm
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Well...I've passed the point of no return.

--the mast is cut down, the old one-holed tang has been removed
--I've pre-fit the comptip to the mast...took a little shaping and sanding...I "snuck" up on it in order to get a tight fit
--I've inserted the foam plug to a depth of 12 inches
--the comptip inserts to a depth of 6 inches (leaving 6" for foam)
--I drilled a hole at 9 inches down from cut to fill with foam (not done yet) and plug

The next step is to glue the stainless plate (it's in the shape of a cross section of mast) against the foam plug with plenty of marine silicone?? The spray foam will fill the void between the plug and the inserted comptip. What would happen if I put ping-pong balls in that 6" airspace, glued up the comptip, and then foamed through the hole allowing the foam to fill around the balls? Would I have created a space of added boyancy to the mast ...or at least a permanent section impervious to leakage with the added benefit of boyancy?? I'm guessing the answer is: "follow the directions...they don't call for ping-pong balls, just spray foam". It seems like trapping an air-tight object inside the to-be-foamed 6" void would encourage more mast floatation. Is it a silly idea??

My Aussie style halyard comes with a small stainless halyard "keeper" (fairlead?) for which there are no layout numbers or instalation instructions. Does this small keeper just perswade the halyard from getting hung up on the battens? I was all set to install it about 3 feet below the yet to be installed tang...it looks like that in the illustration. At the last second, I felt bad putting 2 more holes/rivets in a space that may be airtight already. Do I really need to install that little halyard keeper?? If so, it seems like placing it on the side would direct the halyard out of the way of the battens as apposed to installing it on the front of the mast like the illustration showed.
Also, is my jib halyard cheek block, on the bottom of the mast, rendered unnessessary by the Aussie style jib halyard??
Thanks all you commenters for the input...I want to do this right the first time! bones.


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 Post subject: Re: More Rivet Quandries
PostPosted: Wed Apr 22, 2009 8:47 am 
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Joined: Wed Jul 21, 2004 7:46 pm
Posts: 1468
Location: Santa Cruz
This might help with the rivets:

http://www.youtube.com/watch?v=J9Af7Q58FRk

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