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Email This Page to a FriendPreview: Laminating Wooden Boat Frames on the 68′ Sloop ISOBEL
January 24, 2012
Strong, light weight epoxy laminations are surely the wave of the future for many boat building projects. Even though your current task in the shop could be less than 68', you can learn a lot from watching the pros at Brooklin Boat Yard laminating wooden boat frames with speed and accuracy. Your joints will be cleaner and the job will be cleaner too. Who knows, after a big glue job, your spouse might not have to call 911 to get you unstuck from the shop floor.
– [Narrator] Today we’re at the Brooklin Boat Yard looking at the process of laminating frames on the 68 foot sloop ISOBEL. Designed by Stephens Waring and White. Laminating frames has become a popular way to frame boats for many reasons. Good quality bending stock has become more and more scarce. The very high strength-to-weight ratio, and the reliability of the frame to hold its shape once it sets is quite remarkable.
– The first thing that comes down from the design office is your construction plan with a description of each station, bulkhead, and frame up here. This tells you how thick its molded, if there’s any other information. You know, the dimensions. If it has a floor. Various little things. It differs from boat to boat. And, really the first process that’s the, the next thing that comes down from the design office are the Mylars. And the Mylars are the full size lofting of this boat.
– [Narrator] Full size Mylars allow us to set up a mold for the frame by placing clamping brackets along the inside line of the frame to bend against.
– I’m simulating the three inch backing board just with a key that will fit over the top of this. That way, once the backing board’s screwed to the brackets then I’ll be right on my inside line for the lofting to lay the frame on.
– [Narrator] There’s a backing board that runs along the jigs inside the frame and laminations to give you a line to sight fair and to protect the frame from getting marred by clamps.
– [Andy] And you can see that the front edge of the backing board is on the same plane as my inside line for the frame. So, I’m right on the money there.
– [Narrator] A little clean up of the brackets ensures the frame sets square and even as it dries. Once the glue is mixed, it all happens pretty fast. So having everything in place is the key. You can never be overprotective around epoxy. It sticks to everything. The stock we’re using here is quarter inch thick. Andy cuts it to width on the table saw, and it’s ready to scarf to the length needed.
– So I’ve got 16 foot lengths here, and I need 22 feet, three inches all together. So I’ll cut, this is quarter inch material, cut 11 of these to give me my sided dimension. And then I’ll have to cut 11 more at eight feet and a few inches to scarf onto the ends of them.
– [Narrator] This is a handy little set up to make scarfing veneer go faster. The stands keep the stock in place while the jig is set up to cut the ends at an eight to one scarf ratio.
– [Andy] That gives me a nice feather edge right there.
– [Narrator] We coat both ends with a quick setting epoxy, join them together, and then clamp a few up at a time with plastic film between them so they don’t stick to one another. After about five or 10 minutes, they’ll be ready to take apart.
– Take ’em off one by one. Clean up the scarfs, and they’re ready to laminate. Taking little pieces of wood and making big pieces of wood out of them.
– [Narrator] Rolling on the epoxy with three inch rollers makes the job go fast. Once the laminates are glued, we wrap the frame in a thin plastic and tape it up tight so the glue doesn’t get all over our clamping brackets or our loft floor. The floor timbers are incorporated into most of the frames on ISOBEL. So we add laminates at the centerline of this frame for the floor timber.
– [Narrator] As we start the process of clamping the frame around the mold, as you can see, it goes fast. And it works better with two people working as a team. The floor laminates get bent around last and clamped up tight.
– We just mark the top of the boards and the centerline. That way, for whatever reason, if we have to lay this frame back down, we have a spot that’ll set it back exactly the same spot it came off the floor.
– [Narrator] After the frame cures overnight, we’ll pull it up, unwrap it, and clean off the excess epoxy with a power plane. Plane just enough to remove the excess epoxy and square up the stack. It’s key here to get one side square so we can run it through the planer and bring the frame down to the thickness called for on the plans. Remember I said the floor timbers incorporated on the bottom of this frame? So we need to get that shape marked on the frame before we hand it off to Keith and Steve who’ll do the final shaping and beveling. We create a pattern for the floor timber on the frame by sliding a piece of lauan under the Mylar and punching holes into the lauan along the appropriate lines on the Mylar. Then we put nails in the holes we punched and lay a batten on it to create fair lines. Once it’s marked and fair, we cut out the pattern, clean up its edges, and mark the pattern onto the frame. With the floor timber area marked clearly, Keith can quickly cut off the extra bits and use a power plane to get close to the line. Then it’s time to cut out the slot for the keelson. At this floor, the keelson is exactly eight inches wide. Keith cuts the slot to receive the keelson as well as its bevel.
– [Keith] We’re gonna make an inch and a quarter radius limber hole. So we want it to be based on this point right there. Gonna make the line.
– [Narrator] Cutting in the limbers also requires fine hand work. Which Keith does here with a gouge.
– We’ve turned the frame over. Now we cut the frame to the line that we’ve made on the other side from the plywood pattern. I’ve planed it up to the line, but I’ve made no attempt to make this square. I’m gonna use a router with a pattern cutting bit and a bearing. We’re gonna run the bearing on the area that we cleaned up to the line, and this will square the frame up with the other side. This will get me this side the same as the other side.
– [Narrator] Once Keith has the edge of the frame square, he can begin to bevel.
– [Keith] This is a bevel board. We have bevels and angles from zero up to around 30 degrees.
– [Narrator] The bevel board is used in combination with the tables from the design office that show the angles of the bevel at one foot increments from the top of the bulwarks down to the centerline of the hull.
– [Keith] Along that side of the frame. And these will be our station marks. I’m gonna call that 9/16ths.
– [Narrator] Keith marks the amount of bevel on each station all the way down the frame.
– Now we have to connect these marks. I’m gonna clamp a block of wood at each mark. And we’ll spring a batten across these and pare it all in. We always need about three hands to do this. These marks all along this edge, so that I can see when I’m getting too close. When we’re done, we want these still to be just like that much left. All right, the last thing we need to do to this frame other than sanding, is to put a quarter inch roundover on the inside edges.
– So once we get all the frames all shaped and beveled and epoxy coated, and then we sand them. Then we bring them down and we leg ’em up. We make a jig so we can stand them all up in sequence. All the stations will be marked on this strongback.
– [Boatbuilder] I can actually build the boat on. You probably can’t see it, but they have the centerline down there with all the stations where every frame is supposed to go and a line squared off. And we’ll put two by sixes all the way across to nail those legs up. When we leg up the frames, they’ll go on there.
– [Boatbuilder] As the frames get legged up and stood up on our strongback, it really gives you an opportunity to walk around and see how the planks are gonna lay on and how the boat’s gonna fair up, as you can see nicely from this angle.