If you remember, at the end of last week we steamed the first broad strake for the starboard side. As a bit of an insurance policy, we also backed up the end with a bit of carbon fiber to prevent our nib from breaking off. The carbon fiber worked out well on the garboard, so we thought we'd use it again for the broad since it also has a lot of shape to it. You can see the carbon fiber at the end of the plank in the following picture where Tim is backing-out the plank at station two. Because there is a lot of shape across the width of the plank here, it would be nearly impossible to bend the plank to fit the frame, so instead we fit the plank to the frame by carving out the backside of the plank, making it concave. This is what's called backing-out a plank.
With the plank backed-out, the fit is already looking pretty good. Now there's just some final fitting to be done.
Back aft, the fit is looking great.
It will be a little more fitting before we see a broad strake on the starboard side, but Tim's pattern looks like it fit nicely.
Over on the port side, we're ready to try fastening our garboard again. If you remember last week, we had the plank crack as we were fastening it down so we had to do a little repair. With the fix in place, we've re-applied the bedding compound...
And we're ready for a second try.
Unfortunately this piece of red cedar just didn't want to be a garboard on our catboat. We had it crack again as we were clamping it into position. We won't try fixing this plank a second time, instead will cut our losses, literally, and scarf a new end onto this plank.
To scarf on a new piece, we'll first cut off the cracked end, then we'll plane the end to a wedge. The new piece we're scarfing on will have the same wedge so that they'll fit perfectly. For a scarf like this the ratio of length to thickness is usually around 8:1, so for our 3/4" planking, the scarf is about 6" long.
Before we scarf on the new end, we'll steam it and fit it. Here we've got the piece clamped into position after an hour in the steambox.
Lots of clamps help hold it tight to the back rabbet.
It's a good idea to leave the steamed piece clamped into position for a while so that it retains most of it's shape when the clamps are removed. In our case we've decided to leave it there for three months or so. It wasn't really much of a decision, since we've reached the end of week 11. We'd love to keep right on working, but we've run out of time, so we'll leave it for fall quarter.
And when work does resume on the catboat there should be a few new faces about. Jonas will be back in the fall to see his catboat through planking and beyond, but for Tim and & I the end of this quarter means graduation. For Tim, graduation means starting full-time at SAFE Boats International where he's been working part-time during school. And for me, it means a summer (and maybe more) at The Center For Wooden Boats on Seattle's Lake Union.
Thank you to all of you who've been following along with our project. It's been an amazing experience.
And check back this fall when (fingers crossed) Jonas will be taking up the reins of this blog and bringing all the rest of us along to completion. I don't know about the rest of you, but I can't wait.
Hello,
ReplyDeleteGreat progress so far! The Fenwick plans call for steamed frames as well - 2 per sawn frame. Is it ok to omit those?
Joe - Cohasset, MA
Hey Joe
ReplyDeleteThanks for your interest in our project. In answer to your question (a great one, by the way), we haven't omitted the bent frames. They'll be installed once the hull is planked. In typical bent frame construction, the shape of the hull is defined by molds taken off the loft. Ribbands are fastened to the molds and the frames are bent to these ribbands. Once the hull is planked, the molds and ribbands are discarded. By using sawn frames to define the shape of the hull, we can eliminate a lot of waste since they are part of the finished hull. And the bent frames can be easily installed on the inside of the planking to supplement the sawn frames and strengthen the hull.
Fair winds...
Martin
Martin,
ReplyDeleteSo, after the turn-over will you make temporary molds from the lofting? If so, will you have to "create" new stations to fabricate the molds or can you use a neighboring station? For example, can you use station 4's lofted lines for the frames between station 4 and 6?
(I am lofting this same boat as we speak and this steamed/saw combination had me a bit confused - (where would the ribbands go?) - So , you shed a lot of light on this issue for me!)
Thank you in advance.
Joe
Hey Joe
ReplyDeleteAsk three boatbuilders how to do something and you'll get three different answers, all of which are correct, so your confusion is understandable.
To clarify a little, on our project, we began by patterning our sawn frames off the loft. These frames were set up on the building jig along with the stem, keel, transom, etc. Once we established the fairness of the hull using battens, we lined out our planking and began hanging planks. Once the hull is completely planked, we'll go back and install our steam bent frames using the existing planking to determine their shape. The bent frames are installed basically in the same way they would be if we were replacing the frames in an existing hull.
If you wanted to install your bent frames before planking, you could do so by fastening ribbands to your sawn frames and bending the frames to the inside of the ribbands. When planking you would then remove the ribbands as you went.
There are a lot of excellent books out there that detail different approaches to this. Two that I would recommend are "Building the Crosby Catboat" & "Building the Herreshoff Dinghy" both by Barry Thomas. These books describe in excellent detail the methods employed by two renowned boatbuilding companies. The Crosby method is basically the one that we are using on our project, but both approaches maximize efficiency and minimize waste materials. In addition, both of these books give a wonderful glimpse into these shops at the pinnacle of wooden boatbuilding.
Fair winds...
Martin
Hi,
ReplyDeleteCan't wait till you start posting new pictures and details of this boat. I've been following since you began and I really love this boat and its design. I would ultimately love to build one in the future.
Dom
Hey Dom
ReplyDeleteThanks for your interest in our project. Since graduating I haven't been able to keep up the frequency of these posts, but stay tuned, there's one in the works. And once the catboat is flipped and moved out of the school's shop, I hope to be back working on it (and the blog) on a more regular basis.
Fair winds...
Martin