Cross-bar slop tech-pics for discussion

My 03 H17 was very loose a few years ago, so I had a local glass expert route out a pocket and install a block of a hard glass substance I believe was called G10 in order to firm up the connection between the cross-bar end casting and the hull. It was an okay solution. The epoxying of the cross-bar beds would have made it better, but if you study the geometry of the situation, you will see that even that is not going to last in areas where there is heavy chop.

I wanted a permanent solution, so I got a guy (?Lentz? of NC, from this forum) to cut-out and send me hull sections from a 17 cadaver so I could study the problem and come up with a fix that was both DIY and tightenable over time. I came up with a fix (the general idea is represented below) , but never tried it on my boat.

Here are some pics with some quick and dirty annotations and a funky representation of the fix I mentioned.








Other ideas include adding structural brackets to the top-side. Or, a cable/bolt affair which would attach the same way the shroud chain-plate anchors do (under the lip), come up through a hole through the hull lip, and anchor via a cable over the end-cap "hump" onto the top of the cross bar. All of these are major projects with too much sailing down time for me to even think about.

Enjoy the pics!

Peace,

Dan Peake
Campbell, CA
2003 H17
2005 FX1

Looks like a good solution, though I might substitute saturated fiberglass wool for the epoxy to anchor the bolts (the wool adds a huge amount of strength to the situation and a fiberglass to fiberglass interface would seem optimal). I sail my 2000 in pretty heavy chop, but haven't had that problem yet. Each spring I do disassemble my boat and tighten where needed. I will take an extra close look this year to make sure I not heading for the same problem.

Typical solution is to add resin / epoxy and chopped fiber to the holes and re-seat the castings. Never heard of more than that being needed. The loads are all transmitted into the glass that makes up the structure the casting is bonded to. The loads are primarily vertical (upwards).

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Thanks for the comments guys. Having sliced the structures for a better view, there are two things that jump out at me and seem important from a materials strength and maintenance stand point.

(i) the stuff above the ".280" layer is not load bearing, it is a soft foam covered by the decorative half dome shell. If the .280 layer has been breached by the casting pins, a butt joint of new reinforcing glass/ and resin may eventually give way into the soft stuff above. While the new reinforcement may be as strong as new, the problem has simply been moved from directly above the pins to an edge outside and above the span of the two pins - My opinion is not settled on whether or not this is an improvement over new, but please bear in mind, I have never done it or seen it done.

(ii) the hull's shear plate (flat, oval, vertical surface against the casting) gets sawed by the motion of the loose cross bar end over time. If you look closely at the section pics you can see that this saw slit leaves the casting retained vertically by the relatively thin shell of the half dome. See in the pics above how the dome has fractured above the shear plate. I am guessing that there is no effective way to restore strength in a confined "saw" slit like this.

I believe that the various resin/glass fixes, and my bolt fix, will eventually creep into a loose state. Where I believe that I have an improvement is in the ability to periodically tighten things back down. I bet it works well for the 18 and the many other boats that use bolts.

Peace,

Dan Peake
Campbell, CA
2003 H17
2005 FX1

Yes this is a very old thread, but it is exactly on-point for me. Is it possible to get copies of the no longer attached images?

Sorry Peter - i did some digging through old archives and was unable to find those photos. i will keep an eye out.

Dan

The H17 crossbar attachment system is, shall we say, less than ideal….

There is a lot of potential for a sloppy connection to develop. For the most part, I would suggest just accepting it for what it is and living with it. The two main things would be to ensure that the crossbar end castings are firmly attached to the hulls. Keep the screws tight. If they keep loosening up, you’ll need to either fill in the holes for the little pegs with thickened epoxy and/or just bond the entire casting to the hull with epoxy.

The other thing is to make sure the inboard bolts stay tight. I recommend keeping a T-handle allen wrench in your tool box (I believe it’s a 1/4” hex) and tighten them periodically.

Then there’s the issues with the crossbars themselves, but that’s a different subject….

sm

If I remember correctly the tightening of the bolts just compresses damaged material resulting eventually in no available holding strength from further tightening of bolts. In order to fix this, you really need to add new material. I wish I could find those pics - I owe it to a gentleman from GA who cut the cross beams ends and hull anchor sections out of his destroyed 17 and sent them to me for the purposes of publicly exploring solutions to this problem! At that time, Hobie would not host pics, so I hosted them on my company website, which is now gone. I am hoping the location of those pics comes to mind as I am falling asleep!

If you can find the pictures that would be great. I'm replacing the tramp and buying a new sail, so the timing is right. It all started though when I saw how much twist I had. I've seen that there is much less torque if I use the trap instead of sitting on a wing, which makes sense when I think about it, but stiffening the connections is still a good thing. One more question, is it possible to mess with this stuff on the trailer?

It’s easier to remove the crossbars with the boat on the ground. You need to be able to slide the hulls outward to remove the crossbars, and that can be difficult on a trailer, especially if your trailer has hull cradles. Also, once you remove the crossbars, the hull will want to roll over onto its side, so this is best done on grass. Easiest way to remove/install crossbars is to get one side out, then rotate the other hull so the crossbars are pointing straight up and then slide the crossbars up out of the hull pockets.

If your boat has a lot of slop, you will also want to check the ends of the crossbars for longitudinal cracks which have a tendency to form right along the bottom side of the tramp track.

sm

I was able to find the images. See Below.

The pictures are perfect. Now I just have to decide just what I'm going to do. The inboard bolt that is there already, does it screw into fiberglass? I would expect that to fail eventually too.

By the way, I built a catamaran many years ago. I guess it's a 1/12th scale A-class cat - made from balsa. It's surprisingly fast when sailed in ponds between sandbars at low tide. But, when I first built it I learned something that maybe everyone knows, but I thought it was interesting. I tried it first with just the front beam. Adding the rear beam, even though it is less substantial, probably made it more than 10 times stiffer. If you assume that the hulls are stiff torsionally, for the whole platform to twist the beams have to bend in sort of an s-shape. Anyway, having the connections on the 17 beams tight vertically at the end does seem important as does the bending stiffness. The torsional stiffness of the beams matters less - or so I believe.

Cool model - interesting interaction between that bars that you have pointed out.



Inboard bolt? Do you mean the purple one depicted in my blocky looking diagram? That is just a proposed fix, there is no bolt there. Note: I sold the boat and moved on to F18 before tackling this issue to my satisfaction.

Sorry, I didn't mean the suggested added bolt - I was referring to a previous recommendation:
"The other thing is to make sure the inboard bolts stay tight. I recommend keeping a T-handle allen wrench in your tool box (I believe it’s a 1/4” hex) and tighten them periodically."

I'm wondering if this screws into metal threads and can be tightened forever, if you use the right anti-seize, or if it screws into fiberglass. Great spot for semi-permanent loctite if it's metal to metal so it won't loosen, but can still be removed. Maybe loctite works on metal to fiberglass too? I've never tried that.

Not having disassembled anything, the pictures were a revelation. I now understand this other earlier comment too:
"The two main things would be to ensure that the crossbar end castings are firmly attached to the hulls. Keep the screws tight. If they keep loosening up, you’ll need to either fill in the holes for the little pegs with thickened epoxy and/or just bond the entire casting to the hull with epoxy."

This is an old boat that I'm just sailing for fun, so the solution doesn't have to be perfect and last forever and the end castings don't really have to be removable. "Perfect is the enemy of good" and all that. I'm wondering though if using something like these in stainless might make some of the attachments to fiberglass more durable with a metal to metal thread:
:

The inboard bolts thread into a 1/2” diameter stainless bar that sits under the hull lip. It is the same type of connection as the shroud anchors. You can tighten these indefinitely, but be sure to use a dab of antiseize on the threads. I would not recommend loctite here, just snug up the bolts periodically.

For the outer castings, I would not monkey around with some type of wall anchor or other bolting method. The original design is what it is and there isn’t a lot you can do about it. Just make sure the casting is tight to the hull by keeping the screws tight and bonding the casting to the hull with epoxy if things get really loose. Also, in the pictures of the cross-section, you can see at the bottom of the hull saddle, the edge of the crossbar has worn through the fiberglass, allowing the entire section of the deck that the casting is attached to fail and break away from the hull. A little filing or sanding to deburr the bottom edge of the crossbar probably would have prevented that failure.

sm