Catastrophic Mast Exploding Through front beam (averted)

I just happened to be at the beach early yesterday to run some new bungee under my tramp. Looked over at my dolphin striker and saw the rivet was sticking out about 1/2". Closer inspection shows my dolphin striker mostly cracked and about to fail...

http://www.asnstudios.com/images/striker-bar.jpg

My last 2 sails included some pretty heavy pounding waves and then this sat had some strong easterly gusts... glad i saw this before it cracked all the way through...
Is there any real need for that rivet Andrew?
A round hole is the best,(the larger the radius, the better) as far as stress propagation goes, but no hole is better yet.
Is that rivet only there to hold the DS pad in place? I have 6 Nacra front beams, only the early 5.2 boat had a screw to hold the pad. The others had a layer of adhesive silicone, one looked like 3M 5200. They were all stuck on pretty tight, no chance of losing the pad when removing the V strap.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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it goes "BAM!!!" WHEN IT BREAKS! inspect the crossbar where the bolts attach also...

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Check out "Prindle Sailors" on Facebook!
bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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Ha! Nice topic title, glad your boat didn't explode.

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Damon Linkous
1992 Hobie 18
Memphis, TN

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QuoteIs there any real need for that rivet Andrew?

it does go through the shoe, which has a small stud in it to hold the tube in place...

Quoteit goes "BAM!!!" WHEN IT BREAKS! inspect the crossbar where the bolts attach also...

yes, i head my friends mystere 5.5's pop. Lucky his ddn't kill the boat

Quoteglad your boat didn't explode.

Thanks
http://www.asnstudios.com/images/striker.jpg
If your DS is 9/16" I can send you a Nacra pad. They have a depression in the top of the pad that the DS rod sits in. As long as the whole thing is not sloppy loose, it cannot come out.
A quickie measurement shows the V strap to be 1 1/2" wide.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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the v braces stretch out i have found...at least you didn't have yours overtightened. the old prindles d/s rods seem to seize up in the mast step thus making adjustments tricky, we ended up using ss washers to shim to get more tension. i tried to tension the rod one time and sheared off the rod in the base, had to drill and tap out and made a new rod. i replaced the rod, base, ball, step, and stuff last year but the new d/s rod didn't come with the screw in the bottom. this allowed the rod to loosen itself in stiff winds/seas and eventualy led to me overtightening to compensate. if there is any way to have the perfect catastrophy, this is it! brace snaps, cross beam collapses, mast comes straight down, hulls toe in and rear beam gives...oh yeah, break your mamas back.

--
Check out "Prindle Sailors" on Facebook!
bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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Edchris177If your DS is 9/16" I can send you a Nacra pad. They have a depression in the top of the pad that the DS rod sits in. As long as the whole thing is not sloppy loose, it cannot come out.
A quickie measurement shows the V strap to be 1 1/2" wide.

Thank you for the offer
I can't see the advantage of using yours vs mine...
my bar is 1/4 inches thick by 1 1/2 wide .

my "shoe" has a "nub" in it the round bar sits in so it can't slip but i have to think the rivit is a "fail safe" measure so the shoe can't slip around...

I could 5200 or similar, but i dont see much advantage (my cat is 19 years, old... i can almost guarentee it wont last another 19)



Edited by MN3 on Jul 17, 2012 - 07:01 AM.
Andrew,
The newer boats don't have the rivet(97 and later). The base just sits on the dolphin striker and the compression holds it in place. Where did you find a replacement dolphin striker?
Jeff



Edited by beachsailor on Jul 18, 2012 - 07:20 AM.
haven't found one yet. catman and i are probably going to purchase the bar and bend it outself... still looking at options
UPDATE:
I fabricated a new one from 1/4" alum sheet:

I had it sheared to lenght and width - $32
Then had to un-twist it (that was created with the shearing off the sheet)
bent it into shape (using my old one as a guide)
drilled the 6 holes, used a counter-sink on the 4 holes that need it (2 other holes are for beam bolts)
got the bar anadiized -$80

after I removed the beam, the 4 (socket head) screws that attach the striker to the beam were frozen inplace, so i had to drill them out
re-tapped the 2 holes that still had some threads.
used a washer, nut and nylock behind all 4 screws (that sit in an alum block backing plate)
NO RIVET hole drilled nor used

the front beam bolt threads were shot, so I drilled out all 4, tapped and put in hexi-coils while i had the boat apart
also got the tramp repaired

Tef-gel'd the heck out of everything along the way

tested fri, sat, sun. - all good


In the end, fabricating isn't all that hard, but it took more miles and trips to ACE than i ever expected and i would probaby pay some shop next time


BIG Thanks to Mike from Ellie's Sailing Shop in Clearwater 727 442-3281 (and brian, steve & stevie)



Edited by MN3 on Aug 13, 2012 - 03:03 PM.