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CS-17 #121 is now 3D


Ken_Potts

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Last night my friend Mike and I unfolded my CS-17. We got the stitches and the temporary frame in place and now I get to take my time snugging things up.

There was only one hitch - The tape joint between the port bottom and side blew out - Completely. I think there were two contributing factors: 1. Although the tape was nicely saturated, I think the butt joint with the thickened epoxy was too dry and 2. I didn't get the temporary frame in place early enough and ended up pulling the sides into too vertical a position while installing the stitches. I think I would have been alright if either of those two mistakes hadn't been made.

The good thing is that the joint failed entirely in the tape. No wood was damaged. It should be easy enough to repair.

I'll try to pull the joint back to its original flat shape by installing some boards across it on the inside and the outside and pulling them together with screws. If that doesn't make things symmetrical enough I will take one of two actions. I'll either remove the stitches, retape the flat panels and reassemble OR - and don't yell at me for this :) - I'll break the other joint to make the bow symmetrical. The port (broken) side is actually almost as attractive as the starboard side, it just doesn't have that neat little area where the chine fades to flat just shy of the bow. If I break the other joint (I probably won't) I'll have to fair the bow again as there will be a dimple in the stem profile where the chines end.

So here's my warning: Be sure you have a good butt joint when you put the panels together - The tape alone may not be strong enough to hold. Also follow Graham's advice and work the temporary frame in early.

And here's the anti-warning: If (when) you hear a heart-rending "pop" and one more unplanned for challenge arises in your boat project relax, you just added a custom feature to your boat :) Remember, boatbuilding is all about enjoying yourself...

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You are not alone in this problem. The assembly design is very clever and makes for a real nice bow, but there are a number of ways to have "unexpected" results. I actually used four layers of 5.6 oz.tape on both sides of each joint since I wanted to carry the flat area a couple of inches aft of the designed joint (14" of flat). Thus the bow joint held fine but the next joint back started to tear where the 1/4" bottom ply meets the 3/8" bottom.

This was quite easy to fix by taking 10" 1x2, laying it on the outside of the curve on the damaged joint, then screwing drywall screws through the ply into this batten. Once I had flattened the joint back out I added more layers of tape and epoxy, next morning it was good as new.

I really think you should to try this first as the vertical area in the bow adds alot to the unique looks of the coresound, and will also keep the pounding down in a chop.

If you look back in some of the posts you will find variations on this theme for others who have had similar "incidents".

Good luck and let us know how it turns out.

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I learned about making custom features out of unplanned-for-challenges long ago. I was building a teak companionway ladder for my boat. I was routing slots into the the sides to receive the steps. I layed out guidelines and ran them though the table saw with a router blade to make the slots.

Suddenly I realized I had made the slot on the wrong side of two of the guidelines. I was about to trash a nice piece of teak and start over when the boatbuilder suggested I make it a feature. I routed all the slots double size and added a contrasting piece of ash above the steps.

Some months later, a regional sailing magazine (Carolina Cruising, long since gobbled up) did an article on the builder and featured my boat since she was the first of a new line for him. The contrasting strips were specially mentioned as the kind of feature you get on a "Custom" boat like this.

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Ken here are a few pictures of how I reinforced the joint on my Belhaven. I know its a little late but maybe it will help someone else. I used 10 oz cloth 10" wide and 14" long on both sides of the panels. Also I used a reinforcement block made from plywood in two different places. The pictures show one of these but I didn't get a picture of the one I had close to the tape joint. The joint held up very good despite some rough handling.

I have often wondered if a heavy biaxal or triaxle tape 10 or 12 inchs wide would save a lot of pain for us that don't do a lot of these. These tapes are supposed to be a lot stronger.

Scott

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Ken, congratulations on going 3D! I hope you enjoy every hour in your shop buidling the boat to completion. Every boat seems to offer its own challenges, but that is all part of the fun. And sailing the boat built by your own hand is a great experience.

---Brent

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Good news.

I had no problem pulling the joint flat again. So far I haven't re-taped the joint at the front but it looks like I'll have no problem with it.

Mustangermatt:

Before I saw your post I cut a few pieces of wood to brace the joint. The pieces are leftover ash from making the seat stringers so they are approx 3/4"X1". I put the longer piece on the inside of the boat oriented across the failed joint and ran one screw through a hole drilled in the smaller piece. I put the smaller piece on the outside of the boat with the screw going right through the joint between the side and the bottom into the longer piece on the inside of the boat and tightened it until the piece was pulled as flat as I needed.

I'm not sure how well all that description conveys the fix so I'll post a photo after the weekend if I can.

Garry:

That was a great anecdote about the article on your boat. I like the look of the ash on the ladder too - It really appears to be the kind of visual touch that makes a custom boat custom :) It's really the little things that make the boat yours...

Scott:

Interesting - I was very afraid of moving my panels once they were taped because of all the possible leverage acting on them so I ended up nailing a brace onto the side/bottom pairs in order to allow me to move them about prior to unfolding. That joint really made me nervous but like I said before I think I would have been okay if I had gotten the butt joint (between the tape joints) properly set up.

Thanks for the pics of the proven method.

Brent:

Thanks for the encouragement. I am making sure to only be working on the boat while I am enjoying it. The moment I get uneasy about something or other I retire to the living room to play my banjo or I go fishing. I'm all about having FUN building this boat.

Kudzu:

I've seen your posts as you've been trying to decide between the 17 and the 20 etc. You're going to have fun building that boat. The one good thing about having lots of other things to get done before you start the boat is you'll have plenty of time to familiarize yourself with the plans. By the time you get started you'll have already built the boat severeal times mentally so you'll have a few less hiccups along the way. Enjoy! Oh yeah, watch those side-to-bottom tape joints too :)

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