Very nice modeling work Gunnar!
Yup, it makes sense that the cracks occurred at the location of greatest curvature.In fact, the cracks formed directly under the jig blocks that I used to bend the sides. A recommendation for the future would be to use more jig blocks so that all of the force isn't concentrated into a small point. I would also follow your suggestion to smooth the curvature. Now the plan is to go ahead and fix the top longerons, because they are accessible. For the bottom longerons, looks like the best option would be to cut out a section of the bottom skin. The longerons would then be accessible for a repair. I'll splice in some new 5/8" material and then replace the plywood skin that was removed. It all sounds good in theory, but the real question is to see if it's "doable!" I'll be moving houses in about a week. So It will probably be 3 weeks before I can try any repairs. Thanks for the reply's Sean Duggan Vero Beach, FL KR2S - http://n394ja.com/ ________________________________ From: Gunnar Olsen <gun...@online.no> To: KRnet <kr...@mylist.net> Sent: Tuesday, July 19, 2011 4:57 AM Subject: Re: KR> Progress Report & Another Cracked Longeron Story Sorry, but I don't have a good solution for replacing the longerons, but I can show you why you have the cracks in the place you have them. If you look at the two bottom images on this side http://go-design.no/images2.html, you can see that the curvature on the original drawings is high in exact that area. I have tried to smooth that out on my redesigned KR. One builder in Norway have used the new dimensions without problems. Gunnar Siljan, Norway Sendt fra min iPad Den 19. juli 2011 kl. 05:14 skrev sean duggan <seanjuly1...@yahoo.com>: > It's good to see some progress being made by fellow builders. I'd like to > contribute to the progress reports with my update. Today I managed to flip > the > "boat," and unfortunately, I will be adding to the list of cracked longeron > stories : (. > > Upon inspection of my boat structure, I found 5 cracks! Two cracks in one > longeron and one in each of the rest. They all reside in the bay directly > behind > the aft spar. I already knew that this could be an issue after seeing the > problems run into by other builders. The cracks in the upper longerons seem > reasonable to repair, a splice joint like the one shown in Darren Crompton's > build log should fix the problem. It is the lower longerons that have me > worried. > > > Since the lower longerons are already glued on two sides to plywood, I have > no > idea how I will cut out a section for replacement. Also, the area that these > cracks occur are in close proximity to a vertical stiffener. Too close to get > the proper splice length. > > So at this point what are my options? > > -Attempt repairs and hope for some luck on the bottom longerons? > -Cut my losses and start a new boat. (I've only used about $900 worth of wood > and glue and spent 100hrs building)? > -Look for someone selling a boat, toss mine and continue forward... > > Any suggestions/comments would be appreciated. My motivation is dwindling. > > Some photos are updated on my site. > > Thanks! > > Sean Duggan > Vero Beach, FL > KR2S - http://n394ja.com/ > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
