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PostPosted: Mon Sep 19, 2005 2:27 pm 
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Joined: Mon Aug 09, 2004 9:35 pm
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Location: Northern Texas
Hobie Nick,

I keep my bolts, all eight, TIGHT. I really crank them down. However, I do this on the water. If you do this on the ground, the hulls can not tilt, or cant as I refer to it in this post:

http://www.hobiecat.com/community/viewtopic.php?t=2154

I use this method to set up the "chassis" on my boat and I end up having to retighten the bolts after about two regattas. I have learned the hard way that you can not get the bolts as tight as they need to be on land. Actually, you stand a good chance of cross threading the bolts if you try it on land. It is a real bear if you completely disassemble the boat and go back together with it and cross thread a bolt.

The inboard bolts screw into a casting that is riveted to the crossbars. If you crossthread a bolt and are lucky enough that the bolt breaks off flush with the hull, consider yourself really lucky. Normally the bolt threads will get trashed and the threads in the casting will stay good. I still run a tap through the casting to clean up the threads before installing the new bolt though.

If you are a poor soul that has the crossthreaded bolt break off flush with the interior casting, good luck. I had to drill out the rivets for the end castings, drill out the rivets for the interior casting, and fight for four hours to remove the remaining piece of bolt. Then rivet it all back together. NOT FUN!

Hobie Nick, be careful with that 12" SCH40 pipe. If you break the bolt, you might be in the same situation as mentioned above. AND IT SUCKS!!
I use a 3/8" ratchet that is about 10" long and tighten until I can't tighten anymore. I would rather the bolt fall out than break off. Much easier to replace.

Also, the lock washer idea is a must have. Only problem is that you must use the Hobie supplied washers or find a place to find thin walled lock washers. If everything is installed correctly, the lock washers you find at most hardware stores will be too wide when installed. I found out the hard way.

One more thing. I run a bead of silicone sealant on the threads of the bolts before I install them on my non race boat. It helps keep them in place, seals areas around the through hull connection, and helps to fight off corrosion.

Hope this helps, just DON'T BREAK THE INBOARD BOLTS OFF!


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 Post subject: Re: Good story
PostPosted: Mon Sep 19, 2005 5:14 pm 
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Joined: Mon Sep 19, 2005 5:05 pm
Posts: 9
Hi guys,

I spent many years sailing H18's before moving onto the Tiger. With the trampoline the rule of thumb has always been pull it as tight as you can, and then a bit tighter.

The 18 is somewhat better than the H16 but the curved beams will always cause drama (the rear acts like a spring always moving to some degree). With a tight tramp it produces a stiffer platform giving the hulls far less chance of moving relative to one another.

We used to pull ours drum tight with a pair of vice grips and then pliers for somebody to hold the rope in place while you moved onto the next hole. Then you have to re-tension them every now and again because the rope does streach.

Modern mesh trampolines last quite well with the biggest problem being the sun - keep them covered wherever possible. Don't worry about the hulls - a tight tramp will help if anything by reducing movement between the beams and the hulls.

Michael

BLOW ME II wrote:
That is an intersting story. I never thought the tramp would effect hull stiffnes on an 18. But clearly, it must. I think I will be buying a new tramp soon, and maybe some of those dodads that go in the track because I intend to get that sucker real tight for now on. Thanks for sharing your experience.


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 Post subject:
PostPosted: Mon Sep 19, 2005 7:15 pm 
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Joined: Fri Jul 15, 2005 10:43 am
Posts: 779
Location: St. Louis, MO
Has anyone tried Locktite? Not the permanant stuff but one of the other formulations.

BTW that's good to know about tightening on teh water. Never would have thought about that.

Are the bolts Grade 8 bolts? If so I woudl think the threads in the Al casting would strip before th bolt breaks.

I don't mean to be a pain, but since the bolts are a pretty integral part of the boat's structure I would like to make sure I am finding the best solution to keeping them tight.

Even on a boat without a motor there a lots of things to tinker with :)

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Mon Sep 19, 2005 9:31 pm 
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Joined: Wed Sep 07, 2005 10:37 pm
Posts: 38
Locktite 242 I love this stuff. It holds the bolt, stops corrosion, prevents galling and actually make it easier to remove the bolt when you want to. http://www.loctite.com/int_henkel/loctite_us/binarydata/pdf/LT3770v2_ThreadTreatments.pdf
I don't sell it, just use it. :D

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Jeff
Hobie 18 "Blue Jeanne"


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 Post subject:
PostPosted: Mon Sep 19, 2005 10:38 pm 
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Joined: Mon Nov 22, 2004 7:18 pm
Posts: 73
Location: League City, Texas, USA
Raced a hobie 18SX for a while with some success - and this is the same platform as the regular 18. We seemed to pick up quite a bit of speed with the following:

Take hulls/cross bars apart and bed them with 3M 5200 compound (could use mould release and epoxy with filler as a substitute that is easier to take apart). When bolting the rig back together again measure the distance between the bows, and between the center of the gudgeons for tow in/tow out. Don't measure the diagonals - this tells you nothing about tow out or in. The bolt holes in the hulls have enough slop to correct most misalignment. Our rig started at 1.5" toed out and we got in within a 1/4". We found tightening the tramp afterwards did not alter this measurement significantly.

Now when you have the whole boat back together again with the mast rigged and sails up and you sheet in the main hard you will end up with some toe in. Some folks tried to tell us we should set her up with toe out to compensate for this - but we ignored this: When the main sheet is cranked in hard the wind is blowing good and the windward hull is just kissing the water - hull alignment is not a big deal. When it is light wind the main sheet is loose and hull alignment is critical - both hulls are pretty much equally submerged and misalignment will hurt you.

We installed an extra set of grommets in the center lacing of the factory mesh tramp, then laced the tramp with skinny spectra line (yale pulse). This costs about the same as the regular line, is cheaper than shock cord and is much easier to tension than either and seems to hold up well. Be careful how much you tension it - my tramp side track rivets were loose to begin with (the holes in the hulls had wallowed out) and when I really went to town tensioning the tramp I pulled a couple of rivets out.

This wasn't a big deal - we filled all the holes in the hull with west system epoxy and high density filler then re drilled the holes. Important point: the rivets need washers underneath them, and these are a little akward to install but if you skimp you end up doing the job again (don't ask how I know this).

The end result: A very stiff platform that impressed even I20 sailors when they took it out - a big improvement from when we started out and the hulls used to 'walk' in chop.

I didn't use a torque wrench on the allen bolts that hold the cross bars to the hulls. Just an allen wrench and the box end of a 1/2" wrench for additional leverage. (I used to do a lot of work on bikes so have a reasonable feel for what torque these kind of fasteners can stand). I think we used loctite (but not one of the super strong grades).

Good discussion on this thread btw,

Chris.

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 Post subject:
PostPosted: Tue Sep 20, 2005 1:33 pm 
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Joined: Fri Jul 15, 2005 10:43 am
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Location: St. Louis, MO
These are all great tips on how to tighten up the 18.

Has anyone tired to line up the hulls by supporting the crossbeam only and letting the hulls hang from them? Will this allow the hulls to seat properly on the castings?

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Tue Sep 20, 2005 2:41 pm 
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Location: Northern Texas
Hobie Nick,

I tried this, but I had problems starting the inboard bolts and seating the crossbars. You almost have to seat the crossbars completely before starting any bolts. I can tell you what I did to help set everything up on land. A long time ago my wife was given one of those Denise Austin workout things where you put these little booties on your feet and slide from one side to the other like a speed skater on this hard plastic looking mat. Since it never got used for this purpose, I just guessed that it would work good for setting up my boat and it was. As I tightened up the bolts, the hulls side across the plastic. You might be able to try something like this.


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 Post subject: Aligning the hulls
PostPosted: Tue Sep 20, 2005 4:02 pm 
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Joined: Mon Nov 22, 2004 7:18 pm
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Location: League City, Texas, USA
Hobie Nick wrote:
These are all great tips on how to tighten up the 18.

Has anyone tired to line up the hulls by supporting the crossbeam only and letting the hulls hang from them? Will this allow the hulls to seat properly on the castings?


I had the hulls on the grass, got the bolts started and use a couple of assistants to push/pull in the relevant directions while I rushed around with the tape measure and allen wrench. Wasn't a big problem.

A friend of mine sat his on saw horses and dropped strings and shot lasers and all kinds of funky stuff. He applied the entire contents of the Hobie 18 performance manual (including sail draft measurement and adjustment) over a couple of days and it really paid off in straight line speed (he won class in a Ruff Riders - a 2 day distance race up a coastal canal in Texas). Hard work pays dividends - plus time on the water.

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 Post subject:
PostPosted: Tue Oct 04, 2005 8:55 am 
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Joined: Sun Jul 25, 2004 4:46 pm
Posts: 159
Location: Bakersfield, CA
I use shock cord to lace my tramp but it sounds like the majority here prefer non stretch rope. Any thoughts?


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 Post subject:
PostPosted: Tue Oct 04, 2005 9:17 am 
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Location: St. Louis, MO
From what everyone here is saying about the importance of the tramp tension I would think that shock cord is not the way to go. It offers no diagonal bracing and does not contribute to the stiffness of the boats structure.

But for rec sailing it will probably be more comfortable than a drum tight tramp. A little easier on the knees

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Tue Oct 04, 2005 12:27 pm 
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Joined: Tue Jul 05, 2005 8:45 am
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Location: Clinton Lake Lawrence, KS
Definitely small diameter. We've got an old 16 (just purchased) with like 5/16" or 3/8" lacing that is so "memorized" in place there is no way to get any slack pulled up. We're going to try two smaller diameter, low stretch yacht lines. Our 18 has relatively new 1/4" low stretch that moves when needed.

I'd agree that the bungee would allow to much angular reflextion for my liking. :wink:

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