CS 17, #218

[SUKIE]

OK, I've got the hull panels glued up, done easily due to the step scarfs cut by Graham's CNC machine. I think this kit will be a snap to put together - all the pieces (except the seat tops and deck, left oversized for later trimming to size) are perfectly cut. Plus, the cockpit sides have tenons to fit into mortise joints in the fore and aft bulkheads, should make everything true and strong. I'm hoping the whole process is foolproof!

Now, for my question: do I epoxy the side stringers to the sides before or after doing the butterfly joint? It seems like the construction photos I've seen show it done both ways. Any thoughts?

[wkisting]

Hi Sukie,

On the CS20, the plans specify gluing the side stringers on before folding the boat into shape, and it seems to me that someone building a CS17 mentioned the same process on a thread awhile back. The butterfly joint at the front 12-18" can probably be done first or second, as long as the stringers get attached before folding occurs. I suggest doing the butterfly joint first so that you can lay both halves on top of each other and ensure you get an identical side-to-hull angle at the butterfly joint (i.e., glass both halves at the same time, stacked on top of each other with plastic between them). It's important that they be perfect mirror images to get a fair hull, but with Graham's kit, this may be fool-proof thanks to the cog design of the parts.

One caveat: When I attached my side stringers, I followed Graham's measurements to the letter and made sure everything was perfect. What I didn't count on is that when I drove the screws to pull the stringer flush to the sides, the torque of the screw must have upset the natural curve of the stringer, pulling it out of fair. At least I think that's what happened. Because after the boat was folded into place and the cockpit stringers (the fronts of the seat faces) were also attached, I noticed that my seat stringer was out of level. It was dead on level at each place I placed a screw (per Graham's measurements), but between screws in some sections, it was out. So something must've upset the fair curve. The lesson is: Be careful not to torque the screws down too tight when you attach the side stringers... partly because it may upset the fairness of the curve, and partly also because it can starve the joint. I watched out for these problems, but they still showed up.

My solution was to cut another (tapered) piece of stringer to ride atop the old one and then I glued it in place and chiseled / block planed it down into a perfectly level alignment.

[PeterP]

We had the discussion about the stringers b4 when Wes asked about leveling the the boat. Those stringers can be pesky and usually are. In my opinion glue them on before you butterfly. Here is why: the best way to make sure they end up about where they are supposed to be is to run screws through the ply. This is best done when you can flip the sheets. Weights will not do all of it on account of the sharp bend in the bow section so screws it must be. Pull them out later and fill the holes. 1" dry wall are perfect. In fact get an assortment of dry wall screws -boat builders best friends. None of those stringers ever glue up perfect. So don't feel bad - you will have to spend time fillin' and shavin' just like the rest of us. The reason for inaccuracy is just that plus the fact that every sheet of ply will bend differently to a certain degree. Graham's program could not possibly allow for such a range of variables. PeterP

[Ken_Potts]

  I paid careful attention to the tapering of the stringers at the forward end (per plans) and attached the stringers before I unfolded the boat - It worked great.

[SUKIE]

Thanks Wes, Peter and Ken. Well, I attached the stringers before the butterfly join - it was a little bulky because I did do right sides together, and the stringers were stacked up,but it appears to have gone together flawlessly. Those puzzlepiece notches Graham cut are fantastic! And Peter , you're right about the dry wall screws to hold the stringers in place, it worked perfectly except for the forward end which I had planed to 1/4" so the screws would have split it. But, close enough to the edge to get a few clamps on. I guess the next step is to unfold it, I guess I'll have to ask my husband to help for that part. I'm sure he'll have all kinds of advise of how to do it differently! 

Once it's 3D, do I install the inwales next, or work on the rest of the hull parts? I'm a little confused about sequence of construction.

[SUKIE]

Hello all, sorry I've shown an apparant lack of progress, but I've had to take the obligitory trip to FL (to play golf!) with my husband (Pat). Now I'm back and eager to proceed.

The butterfly joint has been done (and had lots of time to cure), and when Pat and I started to lift up the whole thing it made such cracking and groaning sounds that I chickened out and laid the whole thing down again. Tonight I have a friend coming over to help, thinking that an extra set of hands will lessen the strain on the joint.

Does anyone have any hints about how to make this process go smoothy? Of couse, I'll be telling 2 guys what to do, so that's another whole set of problems. (Of course, saying that to a whole forum full of guys is probably shooting myself in the foot!) But you are such a helpfull and supportive group, I'm throwing out the question. Thanks in advance. Sukie (ps, I promise photos soon, as soon as there's some progress to report)

[SUKIE]

WOW, it works! I had a great crew today, husband and friend, and together we made the pile of plywood look like a boat. After all my worrying, there was really nothing to worry about. Now I'm starting to wire the chines, it's really taking shape nicely. What beautiful lines she will have!

I'm trying to attach a photo, but not having any luck. Will try again later - can't wait to get back to that boat!

[Ken_Potts]

  Congrats!  It feels great when you've suddenly got something boat shaped, doesn't it?  All that worrying and bending and then - A boat!

[SUKIE]

Hello again to you all,

Well, summer's over here in New England and the leaves are doing their special show for all the tourists, the kayak's been put away, and it's time for me to get back to boat building!

I have a problem with the epoxy resin: it seams to all have coagulated into one large white lump. I think I remember reading something about heating it, but can't seem to find any answers with a search. Does anyone have any advise?

thanks!

[Terry Dunn]

I had that problem with some system 3 resin.

I put the container in hot water to warm it up. Worked for me.

[SUKIE]

We're through the Holiday season and I'm on to making this boat look like it will float. Right now I'm charging up my camera and will post a photo soon. I have the seat tops installed and ready to coat the whole inside of the cockpit with epoxy before installing the deck framing, but there's been a problem gnawing at me. The seat tops are not very rigid, giving when stepped on. I've seen some comments on this forum regarding extra framing under the tops, but I didn't do that. Now, if I apply 4 or 6 oz fiberglass on the tops, will that add the additional strength? My husband is about 230 lbs and I'm worried about the consequences of his step on one of the weaker places. Also, what about the foredeck? Should I do something to make that stronger too?

Thanks for your opinions/experience/whatever!

Sukie

[PeterP]

Nobody seems to be taking the bait on this one and I hate to think you are sitting there worrying. The glass will work. You could also snake a doubler to the underside through the inspection port in the side of the seat. About 10 -12 in long. For this to be effective it needs to go stringer to stringer or close to it width wise. Then again your port may not be wide enough to allow this. But if you can work it in it will be a beauty. The stiffness goes up as a square of thickness so you will get the biggest bang for your effort. Even a simple 3/4 x 1 1/2  epoxied in will add considerable strength. The glass will definitely stiffen it up but not as much. For maximum benefit it should, also, be on the back side. As to your fore deck: it will be fine-the camber pre-stresses the plywood. It is plenty strong. PeterP

[PAR]

On the CS-17 fore deck, I elected to make the forward portion of the hatch frame a full width deck beam, rather then just a stretcher between the two longitudinal stringers. I also didn't use an aft frame for the hatch, having it land directly on the forward bulkhead beam instead. This made the hatch nearly square, saved the weight of the aft athwart frame piece, which was added back with the addition of the full width beam.

I too had a client that was "well fed" and my seat top concerns were similar. The seat tops were made of 3/8" Okoume, rather then 1/4" (this change added about 5 pounds to the weight of the boat). The internal bulkhead arrangement is also quite different, as I made substantial changes to the shape and width of the cockpit seating. Essentially, I curved the seat risers, complementary to the sheer (in plan), which made the seats wider at the aft and forward sections of the cockpit. I also didn't use the partial height, aft bulkhead. This is because I've got a lot more "purchase" with the wider seat boxes aft and a big transom frame to support the curved transom (a lot more triangulation). The seat box, internal bulkhead spacing is 45" from the transom, then 45" to the thwart, another 45" to the end of the centerboard case. This makes four compartments on each side. The two middle ones are hatched, the forward and aft compartments are sealed flotation chambers (with deck plates). Total flotation per side is 300 pounds, not counting what is trapped in the lockers or forepeak.

The seat tops were also glassed (8 ounce) for abrasion resistance. This will not stiffen up the panel any significant amount. Now biax would, but I used regular E 'glass.

I've stood on the seat boxes and didn't notice any flexing (I'm only 150 pounds), but I suspect there will be a small amount of movement when a 230+ pound person does.

[SUKIE]

Gentlemen, thank you for your good advise. I'll add the doublers when I cut the hatches out. I'm assuming that I should complete the deck framing, then flip the boat to finish the outside of the hull, the flip back to finish. Is this right?

[PeterP]

I see you did the smart thing and painted the forward part of the footwell and your bow compartment. If your keel is on then finishing the outside first is a reasonable approach. Leaving the foredeck off as long as you possibly dare is something to consider which ever way you go. It is amazing how much that thing gets in the way. If you have a trailer and finish the outside now then you would be able to move the boat in and out of your shop for extra space without worrying about scuffing things up during flips etc. Good luck -PeterP