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Structural integrity questions.
http://www.hobie.com/forums/viewtopic.php?f=15&t=60992
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Author:  WindyCat [ Mon Jul 31, 2017 10:07 am ]
Post subject:  Re: Structural integrity questions.

I have one more concern. (Fingers crossed). Inner side of the port hull forward of the crossbar I have what appears to be a bulge in a horizontal line approx 2' long. Tapping on it provides a nice solid sound. No visible crack through the gel coat. Can't even really see it when you sight down the hull. Only when running your hand vertically. I'm assuming this is probably from standing on the inner hull when capsized to get the boat to rotate head to wind. If pushed on it hard enough it does give but I really have to lean on it. So on to my question. Is this a fatal flaw. And are these hulls prone to this weak spot?

Author:  srm [ Mon Jul 31, 2017 2:32 pm ]
Post subject:  Re: Structural integrity questions.

I have seen this before on several boats, including my own. In extreme cases a crack from nearly bow to stern. I think it is a design flaw and the boats are not quite strong enough in this area. I was able to catch it early on with my boat.

My solution - I added 5" access ports behind the front crossbar and then added a couple layers of glass inside the hull. The outside of my hull was similar to yours in that it had a slight "buldge" maybe 6" long. Inside the hull, the inner layer of fiberglass had visible crazing marks in the buldged area. In addition to reinforcing with fiberglass, I also changed my setup process so that now I step the mast with the boat on the ground and supported at the tip of the bow and under the rear crossbar, rather than on the trailer. I suspect that somehow with the trailer bunk being almost directly under the front crossbar, the load from stepping the mast is concentrated right in the front crossbar area and causes over flexing of the hull leading to a bulge and eventually cracking.

Securing the boat to the trailer with heavy duty ratchet straps or letting heavy snow accumulate on the boat are other possible causes of this damage. I tie my boat to the trailer with basic line using a trucker's hitch and store my boat inside in the winter.

In any case, since I made these changes (more than 5 years ago), my hull has not gotten any worse.

sm

Author:  WindyCat [ Mon Jul 31, 2017 7:26 pm ]
Post subject:  Re: Structural integrity questions.

Nice to hear. I was thinking about adding the port and adding glass to the inside as well. I have never stepped the mast on the trailer. That's always been a big no no. I'll be adding hull cradles as well.

Author:  WindyCat [ Sat Aug 12, 2017 9:11 pm ]
Post subject:  Re: Structural integrity questions.

After tearing her down and inspecting everything and letting it sit for weeks (it's too dang hot) I figured I have to put it back together before my neighbors start complaining. I did end up going with 5/16" SS lag bolts for the 4 stripped corner casting screws I had. I just about lost my mind putting the castings back on. Why do they bother stamping L and R on them? Or maybe I'm just too dense to get it (I've been guilty of that before). She's back together and waiting for me to assemble a parts list (Now to break the news to the wife).

Author:  srm [ Sun Aug 13, 2017 3:14 pm ]
Post subject:  Re: Structural integrity questions.

The R and L refer to the side of the boat each casting goes on in the front. They are reversed in the rear since the tramp track on the rear crossbar faces forward.

sm

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