I am tuning up the platform of this new to me H17.
The boats seem very tidy and in excellent order. I am surprised how much play there is n the platform.
When I lift the port bow there is 6 inches clear before the starboard lifts. The reverse sees ten inches when I lift the starboard. : (
Is this normal?

The bolts were loose but I have tightened as for as I would like. The tarp is off getting stitched so if I need to do anything to stiffen it up now is the time.

Any other things to look out for greatly appreciated.

Keep in mind the tramp is part of what makes the boat stiff. In addition rigging plays a part too. You might consider a foil between the bows which was stock on some 17's. Someone with more experience can chime in on which ones had it.

That sounds like an enormous amount of flex, even for much bigger cats. You really need to talk to some Hobie 17 experts.

Maybe it has something to do with the wings?

Yeah, What Flash said. It's all about the tramp. I've seen worse than 6" for sure. Get your tramp back and crank down on it, should make it way better. Use a good quality low stretch line. If saving every ounce is not that important, just use a 1/4" pre-stretched Dacron, it works fine and is easier on the hands while stringing up the tramp. If it's still bad, I've seen people shim the x-bars using various methods. BTW the bow spreader is for the 'turbo'. By adding the jib, the forces want to pinch in the bows.

Hope that helps!

Remove play from hull to beam joints.
Cover the beam joint area with parcel tape/polythene/food wrap and bed each beam into a layer of resin in the beam box. Place a washer over each bolt between beam and hull to allow a uniform layer of resin to remain in the joint and tighten the bolts lightly. Wipe excess resin whilst wet and let cure. Once cured undo joint and remove beam tape film etc. and clean up joint. Also, if you remove the washers at this point you are left with a convenient recess for sealant when you reassemble the joint. Repeat on all four corners. Once done properly remaining flex should come from lack of stiffness in actual beams/hulls. This should be done regardless of what else you try and should make a noticeable difference.

Cheshirecatman

first time I sailed a 17 I was gobsmacked at how wobbly it was ! compared to my Unicorn A class at the time (and everything else I've ever sailed before and after ) , The 17 was near new , they sailed with slack rigs then , prob because rig tension was unobtainable !

trapezing of the wobbly wings with the trapeze wire moving as the mast flexed added to overall effect of sailing a lump of jelly ,with hulls moving independant of each other , rig wobbling about and a fibreglass tiller extension which was soo bendy to be near useless , it was an experience I thought I had forgotten in the dark past .

to draw ALL the different oscillations in a 17 would keep wouter busy for a while <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

By far slackest boat I've ever sailed , there were quite a few at the time on our circuit and thats how they seemed to go ! and in right hands back then competitive , but certainly an aquired taste !

Those that had aquired the taste seemed quite happy , guess thats what the early hobbies were about .

I agree - I've sailed a 17 a few times and it was the wobbliest (word?) boat I've sailed. It's just how it is with those curved beams and narrow hulls. You can probably seat the beams to fit the hulls better and gain some stiffness. It was still a very enjoyable boat to sail - trapping off those wings was pretty awesome.

I owned a TheMightyHobie18 with lots of play (Hobie wobble). Tramp tightness was critical. There is a Hobie tightening tool that works very well for the tramp.

I found the beam bolts often worked themselves lose. I even had a bolt completely fall out at 1 time.

We removed the rear beam for some reason, only to find cracks in several places where the beam and bolts met. A quick trip to an alum welder handled that.

I would check that if all other "fixes" dont handle the "wobblem". - I think i just made up a technical word <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Bed the cross beams to the hull sockets using a thickened mixture of epoxy or polyester resin (high density filler and a touch of colloidal silica to stop it running). Wax the cross bars well and keep this stuff away from the bolt holes. When you tighten up the bolts measure the hull spacing between the center line of the bows and the centerline of the transoms and set it up square (you may be suprised how far out this can be). Use antiseize on the bolts and recheck the tightness once the resin has cured and after the 1st sail.

Check the rivets that secure the tramp tracks on the hull are tight and the tramp tracks are secure. If the holes in the deck lip have wallowed out the you'll have to drill out the rivets, fill the holes with resin and filler, redrill and re-rivet (using washers under the lip).

Then if there is room on your tramp panels to add more grommets (double grommeting) do so - easily done with a grommet kit and a hammer. Then double lace the tramp with skinny high tech line. This has less stretch and friction than the stock lines used for this - resulting in a tighter tramp and hence stiffer platform.

These handy boat stiffening tips were brought to you by Viagra.

Chris.

Get a 1/4" long T-handle hex head wrench. I had to tighten the 4 bolts ever few sails. Keep the shrouds just tight enough so you can rotate the mast. And YES if you have jib/spin or reacher, YOU must have a foil.
They are great fast boats!!!

Doug

One thing I noticed with my H-18 with respect to the curved beams was how the end caps played into the structure of the beams and boat. I think the H-17 beams are similar.

On those beams, the cast aluminum end caps are pop-riveted onto the end of the aluminum beam extrusion. The bolt for the beam to the hull then goes through the cast end caps. I found on my boat that over time the end caps work loose. You don't have a single stiff structure between the inner and outer hull bolts. I believe this also plays into the cracking you might find, as things can move around a bit. You can tighten the bolts and bed the beams all you want, but if those end caps are even a little loose the stiffness of the platform will suffer. On an older boat if that joint has worked a little bit probably the only way to get it solid would be to bed to the end cap into the beam with epoxy and then rivet it. On mine I simply re-riveted - it stiffened up for a bit but then worked loose again. On the 18 Magnum the problem is made a little worse by the fact that the supports for the wings push down on that end cap.

I always figured a way to make the boats better and cut manufacturing costs would have been to eliminate the end cap design for the beams. Anyway, no matter how tight the tramp on all of my Hobies I used to refer to them in my mind as Flexible Flyers. When I moved to the 6.0 I thought that was a stiff platform until sailing the N-20 with bedded beams - very nice...

X2 on that. Pretty much every trailer session, tighten the xbar bolts. Use some Lanocote or the like to keep from galling the threads.

I'm unclear how tightening the tramp would improve platfrom stiffness. I tried to draw a force diagram, but I still don't see it. Where's Wouter?

D. Ho
H 18 1067

Think of Pre-Stressed concrete beams ... it is a similar theory w/ tramp tightness. By tightening the tramp you are placing the "Whole" platform structure under a compression load. This makes it harder for the platform to flex torsionally ... but note it will not eliminate the flexing completely just reduce it.

Now I'll throw an idea out ... 7/16" or 1/2" Bungie cord. That is waht I have used for years to lace my Double Grommeted tramp for years. No matter how tight you lace a tramp quess what happens ... it loosens up (they ALL do). So I made mine "self tightening", and believe me it stays tight. I hate a loose tramp and sitting in water getting diaper-rash!!! And I have more beer drinking time ...

I bet a case of beer that my tramp is tighter on any given period over a tramp laced w/ non-stretch

And I do have "good" boat speed, you can ask any of the H-18 sailors in Div11 ... now if only the "idiot" on the stick could make the correct decisions!!!

Hint: Think "Needle-Nose Vise-Grip Pliers (2) pairs w/ (2) people to lace a tramp ... just once a season.
HarryMurphey
H18mag/#9458, Fleet54/Div11
P19mx w/spin /#86, CRAC

The really, really, tight trampoline was tried in the Tornado class, and it did not work. They even had trampolines cut so the threads was running diagonally to try and align the loads with the threads. Did not make much difference at that time. I dont see why it should be different on boats with curved beams?
I also dont like a loose trampoline, and that is why I tighten the lacings as much as I dare. Could you elaborate on your bungee lacing setup?

Go up to the Hobie 16 that comes in first at the next regatta and check out their tramp. You better bring a case of GOOD beer too.

DHO:

Tool bottom middle of pages 34 make it really easy to tighten tramp.

http://www.murrays.com/archive/34-35.pdf

Doug

Thanks guys, I don't know that I think any of that news is very flash. Any reason I should not just glue the beams?
Also, is there a reason that I can't just screw a lock nut on from the lower side to stop the bolts undoing?

Yes! Unglueing the beams if/when needed to make a repair is very tricky

Doug, That's a great looking gadget. I was just about to say that you can tighten a tramp solo with the right tools. My method (learned from Billy) involves two combination wrenches and three pairs of vice grips. Same result, and you can drink a beer at the same time.

If anyone is interested, come to Madcatter and we'll show you.

Mike