CS17 #315

[cprinos]

Finished up the bottom panels, beveled the inside edges, and then scarfed up the seat stringers and also the inwales since I was already ripping fir. Once those cure, I'll put the seat stringers in place on the side panels and then tackle the butterfly.

QUESTION: As I was making the inwales, I realized it's not clear when to install them. The plans show that bulkheads are pre-notched for the seat stringers, but there aren't notches for the inwales. Do you stitch (not glue) in the bulkheads first, then try to fit the inwales, or do you do the inwales before the bulkheads? On my kayak the inwales were put on the side panels before the stitch-up of the hull, but I haven't seen anyone doing that for the CS hulls.

[Scott Dunsworth]

I haven't built a CS, but on my Belhaven I installed the #1 bulkhead ( glued in ), the temporary bulkhead ( wired in ) and the transom ( glued in ) first. Then I installed the inner sheer battens.

I am sure someone who has built the CS will chime in here soon.

Scott

[Joe Kaney]

Finished up the bottom panels, beveled the inside edges, and then scarfed up the seat stringers and also the inwales since I was already ripping fir. Once those cure, I'll put the seat stringers in place on the side panels and then tackle the butterfly.

QUESTION: As I was making the inwales, I realized it's not clear when to install them. The plans show that bulkheads are pre-notched for the seat stringers, but there aren't notches for the inwales. Do you stitch (not glue) in the bulkheads first, then try to fit the inwales, or do you do the inwales before the bulkheads? On my kayak the inwales were put on the side panels before the stitch-up of the hull, but I haven't seen anyone doing that for the CS hulls.

I'm just a little bit ahead of you with my CS17 (#304), but I can tell you what I did with mine. I affixed the seat stringers in place to the side panels just before joining the two bottom/ side panel pairs together. I know it seems like it might make everything too stiff to bend them after that, but the planing you do to seat stringers forward of the forward bulkhead position gives them enough flexibility.

I put the inwales on after I had the hull 3D, squared, and the forward bulkhead and temporary bulkhead installed. It just took a little flexing to get them in to place. I chose to epoxy the inwales in and also threw in some 3/4" bronze screws on 8" centers from the outside for added measure. The screws might have been overkill but it seemed to me that since the inwales are the foundation for several attached structures, better safe then sorry.

You will be amazed at the difference the inwales make. The overall shape of the hull didn't seem quite right to me after I went 3D and wired everything together. The bow seemed too sharp and maybe even a little crooked. The inwales made the hull take on it's perfect "boat" shape.

[cprinos]

Thanks Joe, the sequence you describe makes sense and I remember reading a post at some point where Graham was describing exactly what you mention about the inwales playing a key role in setting up the shape.

I got the seat stringers on tonight, so I'm slowly closing in on the butterfly stage.

[cprinos]

Just to catch up a bit on the photos, here's some stuff from the past week. Bottom panels were cut, trimmed and beveled. In the first photo below, you can see the tell-tale "double scarf" on the port panel that was a result of me misreading the aft bulkhead location for the panel-join. With the extra scarf, all is well.

Next I needed seat stringers. It seemed silly to waste a batch of epoxy on two scarfs for the stringers, so I also ripped and scarfed a couple of lengths of fir for the inwales. This should have been a fairly quick affair but I somehow measured by 12:1 scarfs wrong and had to recut. I lost a bit of stock length in the process but still had enough (barely) for the stringers and inwales.

[cprinos]

To locate the seat stringers, I had to transfer the stringer position from the first lofted side panel to the mirror image and use a batten to mark the curve. For this part I got a hand from my 12 year old daughter. My kayak was done before she was born, so it's taken me a while to get around to my second boat, but I've wanted a sailboat for a long time, so it's nice to finally get started on it.

The seat stringers were positioned on the side panels, set in thickened epoxy, and fastened with drywall screws every 6 inches. This was a bit messy because the stringer has to be positioned along a curve and I got epoxy all over the panels until I was able to screw down enough of the stringer to hold the curve. I did make sure to clean that up so I wouldn't have to scrape & sand the drips afterward. I'll take the screws out when the epoxy is cured. The forward portion of the stringers is supposed to taper down to 1/8" -- I did that before putting the stringers in place.

That's all for now. Butterfly taping is next, and a few hours of garage-cleaning this past weekend has cleared enough room (I think) to proceed with the rest of the build so it's all-ahead full.

[Lombard]

Your build is inspiring me to finally purchase my plans for the CS15. Thank you for taking the time to post.

Dave Lombard

[cprinos]

Thanks Lombard, glad I could feed the boatbuilding addiction.

Here's some more....

I layered & stacked the sides and bottom panels to set up for the butterfly. I started to clamp them, but ended up just putting a small scrap of ply on top and screwing right through the panels to hold them in place.

[cprinos]

When I built my kayak I remember making a little spacer jig to ensure that the stitch holes were evenly spaced. On the back side of this little piece of wood is a block recessed 5/16", so it keeps the depth from the edge consistent too.

I let the butterfly sit for a couple of nights, my garage is inching below 70 at night, but i'm still using SLOW hardener. After I unscrewed the top ply and took off the release film, this is how the butterfly looked. The other side came out almost perfectly smooth, but even the side you see here won't need too much fairing. I also trimmed and faired the rest of the bow, trying to get a nice looking bow profile.

[cprinos]

Well, you guys know what comes next. Buh-bye to Flatland.

Now I've got some more stitching and tweaking to do on the hull. I'll dry fit the inwales to to help with the shape.

This is the part where it becomes hard to walk past the garage door without peeking in and "checking" on my boat.

[cprinos]

Forgot to mention...before unfolding I forgot to add the reinforcing pads at the end of the glass tape that some people have found to help keep the butterfly from breaking. As it happened, that wasn't necessary. The butterfly held perfectly, no creaking or cracking.

[cprinos]

Question for you guys: After stitching all the seams, the keel is still about an inch or so low at the (projected) bottom of the temporary center bulkhead. I'm just supporting the hull at two positions (forward bulkhead and aft bulkhead) to allow the rocker to form naturally, but how much should I worry about tweaking for a tight fit on that temporary bulkhead? I have no big gaps in any of the panel seams, nothing more than 1/8" and most areas are touching edge to edge. The picture in post #30 is pre-stitch, but the gap is similar, I don't have a more recent photo at the moment.

[John Burritt]

Two questions. How does the transom fit? And, have you fit the inwales? I presume you've rechecked the dimensions of the bottom panels.

[cprinos]

Inwales are in (clamped for now, and not shown in the picture above obviously). Aft bulkhead fits very well. I have not cut the transom yet but the "opening" seems to match measurements and I can't imagine it could be too different given how close the aft bulkhead is. I'll recheck the bottom panel width at the bulkhead when I get home tonight.

[cprinos]

Well I rechecked dimensions of the temp center frame and the bottom panels and everything seems ok. I can't really check to see what the bottom panel width is supposed to be precisely at the center frame location because that is not indicated on the plans. I suppose there's some variance possible at that point depending on the lofting batten. Rereading the plans, I saw that it was advised to screw the temp bulkhead to the bottom panels before wrapping the sides and I didn't do that obviously. Also the hull assembly sheet shows a diagram indicating the sides resting on top of the bottom panel with an inset of maybe a 1/2" or so. RIght now my sides are right at the edge of the bottom panels, so that could account for a bit of the discrepancy as well.

I will probably take a step back and loosen things up so that I can get the bottom of the temp frame secured to the bottom panels and then restitch everything with the side panels a touch more inboard. This is going to eat up a good chunk of time since the wires are breaking pretty easily from fatigue if I adjust them too much, and reaching under the hull at this point is a pain, but I want to try to get this part as correct as possible. This is probably my least favorite aspect of stitch 'n glue construction, where the hull is in shape, but still sort of loosey-goosey and you have to watch out for twist and assymetry.

[John Burritt]

Take a good look at the bottom panels. If the curve is "fair" (continuous curve w/ no dips & hollows from front to back), I'd leave it alone. Just a wee discrepancy on measurements can make a noticeable change in the way it fits the temporary frame.

[cprinos]

Thanks John. I traded some email with Graham on this too and he basically said the same thing. I have to trim the forward bulkhead a tiny bit to get it to it's lines and will get the transom fitted as well, and after that as long as the panels look fair I'm not going to sweat any differences on the center frame.

[ecgossett]

Hey, Graham told me the exact same thing on my build... And it eventually turned out looking pretty nice!! I did wind up using high strength marine line in a couple places and a piece of wood to twist the top around until it was tight.... That really held a couple places together where the wire was shearing, but I did have to drill bigger holes. In a few other places or semi-stress areas (corners, bottoms of bulkheads), I doubled or tripled wire for strength.

[cprinos]

Been a little while since some updates... I decided to change jobs so between the new job search and wrapping up the old one, I had a dearth of boatbuilding time. The good news is that I've got this week off before I start the new gig, so I'm hoping to make up some lost ground.

I sorted out the issue with the mid-frame fit... the bottom panel angles match nicely if I let the sides spring naturally instead of being screwed to the center frame. My boat is about 1-2" wider at the center frame as a result, but everything looks nice and fair along the sides and sheer.

Earlier I mentioned that I had not put on the transom (just the aft bulkhead). So I went ahead and started on that:

The picture above shows a "temporary" luan doorskin transom. It's slightly inset from the aft end of the boat. The bottom panels extend 2 or 3" past their cut lines (side panels are per plan). There is a good reason for this....

Here's a second luan transom being fitted. The first one made sure the aft end had the right shape. This one is to develop the proper expanded shape for a curved transom:

By using luan again for the curved transom, I was able to fine tune and scribe the fit. It bows out 2 inches or more at the bottom (basically to the end of the extended bottom panels) and at the top, it curves out about 4" more than a straight transom at the peak of the curve. After some trial fitting and trimming, I got the curved doorskin to where I wanted and then used that as a pattern for the Okoume stock.

[cprinos]

Here's what the initial fitting of the Okoume transom looks like. The picture is a little deceiving due to the angle of the shot (and the top of the transom is also not trimmed at all at this point), but it gives an idea of the rear curve.

Here's a closer shot looking down at the aft port quarter. You can see the curvature a bit more clearly. I'll trim those bottom panels after the seams are taped.

And from the inside here's the fitted transom. The bracing beam at the top is inducing the 4" curve and I'll leave that in place until everything is stitch & glued and I fitted a permanent reinforcing piece on the transom.

While the luan was easy to bend to this curve, the Okoume just barely made it, it was pretty stiff. The curved transom looks subtle on it's own and kind of hard to show really well in these pictures, but when I compared to the flat temporary transom it is quite a difference. My wife gave it the thumbs up, says the curve makes it look less like a rowboat (not sure how to take that comment, I think she likes it ).

I have to mention that Paul Riccelli (PAR) inspired me to try the curved transom (I saw he did that on one of his builds) and was generous enough to give me some instructions on how to tackle it. Working out the fit definitely caused a bit of head-scratching and time in the moaning chair, but I'm glad I spent the extra hours and gave it a shot.