Boat Repair, Restoration, Building
With the major project of fixing the staple rot out of the way (see earlier post here), it’s time to start re-assembling the interior of the boat. Some of the old parts could be re-used, but many had to be made anew. New fuel tank saddles, engine beds, seat supports, etc., etc. If there was a doubt about whether new part would last another 60 years, it was re-made. The picture above is just a fraction of the parts that had to be made, painted and assembled to get this baby back in the water.
Anytime you have ferrous metal and water, you’re going to get oxidation. This oxidation causes rot in wood. In our case, the ferrous metal is the staples used to hold the upholstered “crash pad” around the perimeter of the cockpit. In the picture above you can see that the planking around the edge of the cockpit has turned black and is crumbling.
You can see the upholstered crash pad in this early post before I disassembled the boat.
There’s no way that it would hold new staples for the new upholstery we’ll order soon. Take a look at the detail picture here. So how do you go about fixing something like this? Cut out the bad and put back new! It’s really that simple. But it’s a rather involved process. I decided to make a template of the cockpit opening, and using a template guide for my trim router, I was able to cut away the rotten wood so that I had good wood to glue new pieces to. Continue reading “Fixing Cockpit Staple Rot”
A layer of fiberglass on the bottom serves two purposes. First, it provides a tough protective layer for rough treatment on a trailer or accidental grounding. Second, it holds a nice, thick epoxy layer that makes the bottom more water proof. Nothing is really water PROOF. But epoxy is pretty close. It takes a long time for water to migrate through unbroken epoxy.
It only takes a few days to add this beneficial protective layer, and now is the time!
We used 6 oz. 0-90 bi-axial woven roving. Let’s break this down. Six ounce means the fiberglass cloth weighs 6 ounces per square yard. 0-90 bi-axial means the threads in the cloth intersect at a 90 degree angle. Woven roving means the fabric has a simple over-and under weave to it. This cloth drapes well and will conform to the shape of our bottom.
When you apply fiberglass to anything, it’s held there with some form of resin. In our case, we use epoxy. If you do a good job, the resin fills the weave and displaces the air, making the cloth essentially invisible. It’s really cool how this works.
While the epoxy is still “green” (partially, but not fully, cured), it’s time to trim the edges of the cloth with a sharp knife.
After the first coat of epoxy cures, we can 2-3 more coats to fill the weave and the cloth will disappear completely.
We still have over 1000 screw holes in the bottom that need to be filled somehow. We’ll use two methods, depending on whether the screw hole will eventually be under paint or varnish.
I use a wood filler called Famowood for any screw holes that will be under paint. It’s pretty waterproof, dries quickly, sands easily, and won’t shrink. It’s been around for years and is superior to most other wood filler putties you can get at the big box stores.
For those screw holes that will be under varnish, the traditional approach is to fill the hole with a bung cut of the same wood, glued in with varnish or some other fairly un-tenacious glue so that the bung and screw can be removed later if repairs are necessary. Boats do run into things occasionally, and it’s best to be kind to the poor person who may have to replace a plank later on.
After all holes are filled and sanded smooth, we’ll add a coat of clear epoxy as a sealer and to provide something for our fairing filler to adhere to. Then we trowel on the WEST System 410 fairing filler to the low spots. Let it cure and sand it smooth.
A lot of preparation is required for steam bending wood. You need a fair amount of specialized equipment. I covered that a couple of weeks ago here in Getting Ready for Steam Bending Wood. Now it’s time to put that equipment into action.
The first piece I bent was the lower transom bow. I chose it because it was short, and I figured it would be easy to handle without the help of another person. You have to get the piece out of the steamer and onto the form quickly, before it cools. So if it’s long or cumbersome, it helps to have more than one person.
This boat has a curved transom with an 8 ft. radius to the curve. There aren’t enough pieces in the actual transom framing to support a smooth, even clamping surface, so I had to build a form. For everything else, we can use the boat framework as our form (i.e. keel, chines, planks).
Here’s the lower transom bow clamped to the form. I tried 3 times to bend a piece I could use. But alas, because the oak was about 1-1/2 inches thick, and because the bend was so severe, I got too much springback. The bent piece could be clamped to the boat framing, and forced to the proper shape, but this isn’t really what you want. Particularly with the transom, you want the bow to describe the curve and hold that curve. Forcing a piece to a tighter curve here runs the risk of having the bow stress some of the joints and pull them apart. I guess that’s why the original transom bow was sawed on a curve.
I didn’t like the idea of sawing this piece on a curve. It gives you too much short grain at the ends of the curve, which can split. Of course, it worked for 60 years. We have the original transom bow to prove it. But there’s a better way. I finally chose to laminate oak strips to the correct curve, using the form I’ve already built. I’ll post some pictures of the laminated transom bow later.
For now, it was time to move ahead and bend in the keel and chines. I was able to use the framework of the boat for my form for these pieces. They’re much longer (they run the whole length of the boat), and you need two people to get them out of the steamer and onto the boat quickly. So I enlisted the help of some good friends. This picture is of the crew that helped with the starboard chine.
Finally, after the chine was bent onto the boat frame, it was wrapped in wet towels to let it cool and dry slowly–over several days. Here’s a picture of it without all the people in the way. Not much to see really. But it’s there under the rags.
It will soon be time to start steam bending some of the parts we’ve been fabricating over the past few weeks. See The Board Stretcher a.k.a. The Scarf Joint. The keel will need to be bent to the curve of the bottom. At least the forward part of it will be. The aft 8 feet is supposed to be “straight as a string”. Also, the inner chines will be bent into their chine landings on the frames of the boat. And the lower transom bow will be bent to an 8 ft. radius curve per the original design drawings. To get ready for this, I needed to build some very specific equipment.
The steam generator pictured at the beginning of this post is a nice design I got from Don Danenberg’s excellent book, The Complete Wooden Runabout Restoration Guide. The main tube is a piece of 2 inch black iron pipe fitted with a heating element for a commercial water heater in the bottom end. Note the electric cord running to the bottom of this unit. Off the main tube, there’s a secondary tube, to which a sight glass is plumbed. The sight glass let’s you monitor the water level so the heating element doesn’t run dry. Water is supplied through a garden hose to the bottom, and regulated by a gate valve to maintain a constant water level. This is easier to do than it might sound as the secondary tube calms the water level fluctuation caused by boiling at the heating element. Steam is delivered through a piece of automotive heater hose attached to a nipple at the top of the primary tube.
Needless to say, you don’t want this unit to hold pressure. And you want to make very sure you have it properly grounded. It gets hot– 207 degrees by my measurement at the external of the primary tube near the heating element. Hot steam, water and electricity can be a bad mix if not managed well. I always keep a close eye on this piece whenever I’m using it.
Steam bending wood allows the wood grain to follow the curve of the finished piece, making for a much stronger part than if you were to simply cut a curved piece out of a straight board, thereby cutting across the grain at the ends of the curve. Also, it’s much more economical. Most lumber comes in straight pieces. You waste much less by bending a straight piece to the curve you want.
When we steam bend wood, we use the heat of steam to soften the cell walls and the lignin in the wood structure (the natural glue that holds the wood cells together). According to Webster’s dictionary, lignin actually makes up one-third to one-fourth the weight of wood, and after cellulose, it is the most abundant organic compound on earth.
Once the wood cools, the lignin re-solidifies and the wood retains the curve without wanting to spring back to its original shape. The water in the steam does not add water to the wood. It’s just a way of transferring heat to the wood. The rule of thumb is to cook the wood 1 hour for each inch of thickness. Then take it out and see if it feels rubbery like it will bend in to the shape you want it to. If not, put it back in and cook it some more.
We’ll need a box for soaking wood before bending, which can double as a steam box. So, I put together a box out of 2x lumber that is 18′ 1″ long, 9-1/2″ wide, and 13″ deep. This should accommodate all the pieces for this boat and future projects as well. The box is lined with 6 mil plastic from the local hardware store, which can be removed when it’s used as a steam box.
What do you do when you can’t get lumber long enough to fill the need? You go get the board stretcher! Any neophyte woodworker has heard that one. But the board stretcher I’m referring to really does exist. It’s called a scarf joint.
Boatbuilders have been scarfing together lumber for a long time. It’s a method of joining two boards so they have continuous sides as if the two boards have grown together to form one long board. Before the days of the great glues we have today, the scarf joint was made by overlapping the boards with a long diagonal cut, and then pegging a backing block to the joint. But I’m using epoxy. And if done properly, the glued scarf joint is stronger than the wood fibers themselves, obviating the need for a backing block.
In this case, I’m scarfing together two planks to make a blank that is 16 ft. long by 6 inches wide by 1-1/2 inches thick. That’s a serious piece of white oak! But it needs to be, it’s the backbone of the boat.
So I start with an 8 ft and a 10 ft plank. The scarf joint will be a diagonal overlap at a 12:1 ration. This means that since the planks are 1-1/2 inches thick, the joint will be 18 inches long. The joint needs to be so long in order to provide plenty of faying (glue-able) surface. The more faying surface, the stronger the joint. A structural joint like this one requires a 12:1 ratio.
I first line out the part of the board that will be cut away. Look closely in the picture at left, and you’ll see the diagonal line I’ve drawn on the edge of the board.
Then I stack the two boards on top of each other, offsetting them so I can make one long slanted cut with the power plane at the angle I want. I finish the cut with the hand plane to make for a good fit.
Then wet out the glued surfaces with straight epoxy. This lets some of the epoxy soak into the pores of the wood so the joint won’t be starved of glue. Then slather on a nice thickened mixture of epoxy and clamp, leaving overnight for it to partially cure.
When the joint is set, but the epoxy is still “green”, it’s time to plane it down to the finished thickness and clean up the joint.
Then lay out the outline of the new blank from measurements taken from the old keel. Since the edges are a curved taper, they have to be lined off with a batten as shown in the photo.
Finally, the blank is cut out on the bandsaw. And there it is.
The next step is to cut the rabbet (the groove along each edge where the bottom planking rests. That’s another story…