Front Beam prebend

I'm sure I read about pre loading the front beam,on a Nacra 5.7, by adjusting the DS bottom nut.
I know how to do it, by stretching a masons line along the bottom of the beam & measuring displacement at the DT, but how much do you bend it?
I can't find the photo, or am I hallucinating?


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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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Ed,
No need for the masons line. Just hand tighten the nut with no bend and then add 3/8" to the threaded rod. So easy a cave man . . .

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Philip
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Thanks Philip, I didn't know how critical that setting was, obviously it falls into the 'bout there category.

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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
--
Note to everyone, don't try to tighten more than that!! I wasn't thinking and did that over the weekend, managed to strip the dolphin striker and the bolt. Then tried to undo it and really made a mess (should have left it where it was). Hey EC you happen to have another one of those kicking around... :)

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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A load from the beam didn't cause the DS rod to strip. More likely the compression tube was corroded to the rod. If your boat has the original alum V bar, you might want to look carefully where the attachment bolts it to the beam for galvanic corrosion. Failure can happen here due to age and the results are catastrophic.

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Philip
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Nope, I stripped it by trying to put too much load on... it was a new rod that I was putting on. :) I had just finished cutting the old rod off (that I bent last year) and was putting the new rod on when I screwed it up. Wish I could claim your reason, but I can't darn it all. $68 plus shipping mistake (yep, I'm a moron).

Now I have one on order from Murray's, hopefully it will get here before next weekend.

Now here's a stupid question, I jarred the compression sleeve loose so it's isn't lined up with the holes. Is there an easy way to realign it?

D.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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I just tape it to a stick, or batten. Done.

The stripping thing . . . weird. I can collapse/break a beam, break the rod, etc. by over-adjusting the nut. Something ain't right, bro.

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Philip
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Yeah, might have been a flaw in the threads or a bad batch of stainless. No idea. Suffice to say I'm going to pay more attention this time.



edited by: Wolfman, May 16, 2010 - 10:05 PM

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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any stainless bolts must have lube (nickel anti seize is best) before putting any tension on them or they will bind up and resist any adjustment - take note all sailers
when i did the pre-bend on my 5.2 i worked it out to be about 5mm

about half the 3/8" that some have mentioned....
That would explain it! That's what I did wrong! Forgot to grease the damn thing, knew it was something simple.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Thank goodness for Murrays Marine! 1 dolphinstriker rod and hardware, 1 day delivery from California to Winnipeg, Manitoba, Canada! Unbelievable! I will be striking dolphins all weekend now. :)

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Sorry Dave, I only made one of 'em. When I chnaged mine, I realized it would be way easier to push a stick through the tube, as I withdrew the rod, in order to prevent dropping it in the beam. I think it would be pretty easy to tape it to a stick, but you would need two people. Your arms are not long enough to manipulate the stick, & look to see if it is lined up.
I don't buy needing lube on the threads. We used a lot of SS bolts/fitting in a mill I worked at many years ago.(West Coast Vancouver Island salt environment)The mill wrights never used anything on them.
I was concerned the threads of one nut might have been compromised, so I replaced them when I changed my rod. As an experiment we double nutted the cut piece of rod, put it in a large vice, then tried to twist the old nut past some bent threads. Using a 5/8 box end wrench, almost 18" long, it took all the torque I could apply before the nut/rod stripped. The nut was actually hot from the friction. I think there was a bad thread on the rod, or some filings got caught in there, or the rod was not straight. Check for trueness by rolling the rod on a glass table top, it will "click" if it isn't true. You shouldn't be able to strip it without applying a good deal of force, that is a pretty heavy duty rod.

--
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
--
No problems I'm sailing this weekend, that's what counts! I'll probably never know exactly what happened, but live and learn eh.


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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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happy sailing wolfman great pic here