28.) The Hole in the Boat

The photo above shows what may be the single biggest challenge I face in restoring #48. See the big hole in the boat?  That's right where the mast is supposed to be supported.

Holes are almost never a good thing in a boat.  But this is truly the last place you'd want one.  So....how did it get there?

This area of the hull probably absorbs the most stress of any spot in the Interclub. The mast in anything more than a light breeze pushes down into the boat, especially when the crew is hiking over the side. I found this out on my first day of racing, when the mast step on my virtually new fiberglass Interclub cracked and collapsed, forcing me to stop sailing for a month while I repaired it.

I don't think the original Sparkman and Stephens design fully recognized how much stress this area of the boat must handle (nor, for that matter, did the builder of my fiberglass boat: Karl's Boat Shop).

When I began working with #48 I realized I was going to face this problem. The area was cracked and showed lots of evidence of rot. I started chipping away at the bad wood and the next thing I knew I went right through the bottom. When I had finally removed all the unsalvageable material, I was left with the very un-hydrodynamic void you see in the photo.

There are several factors that make this especially challenging to fix.

First, the repair has to be super strong.  That should be obvious because this was the part of the boat that held up least well over time.

What's less obvious is that the repair area is a very complex shape. The keelson—or backbone of the boat that joins the starboard and port halves—starts at around two inches wide at the bow, gradually widens to 5 inches at midships and then tapers to four inches at the stern. The angle of the hull changes as it intersects the keelson, from around 90 degrees at the bow to something like 160 degrees three feet back from the bow. And, of course, the whole piece has to bend to conform to the shape of the bottom of the boat. So we're talking about a patch that constantly changes form through three dimensions.

Finally, the damage also extended into the planking, making matters even more troublesome.

For months, I have been tempted to remedy the problem in a radical way. I'd saw the boat in half right down the middle, remove the entire keelson (also ok to spell it "kelson") and make a brand new one from stem to stern. Then I'd join the two halves to it.  I was convinced that this was not only one of the easiest ways to fix the problem (the keelson is cracked in other places as well and has another big hole back where the skipper must have stomped his feet a lot) but also would create the soundest repair.

Here's what a keelson looks like when a wooden boat is being built (upside down).  It is, for all practical purposes, the spine of a ship.  And mine has a big chunk of its backbone missing in probably the most critical area of the boat.

What stopped me, though, was that I realized that by the time I had finished removing the keelson, the remaining two hull halves would weigh less than a total of 70 pounds. To reduce the hull to less than half its original weight (minus spars and racing equipment) seemed to me to violate the whole spirit of a restoration project. I would, in effect, be building a new boat using little more than scraps from the original one. I decided this would run afoul of the spirit of the class rules prohibiting construction of new wooden boats (something I wrote about earlier in this blog. See Holes and Loopholes).

So....what to do instead?  

I've got another plan. And you can see the first stages of it if you enlarge the picture at the top and inspect the keelson just in front of the hole. There, I have started roughing out what looks like a flight of stairs that gradually ascend toward the bow.

I'll explain more about how (I hope) this is all going to work out in upcoming posts.

Below is a photo of what the area around the mast step looked like before I started chopping away at it:

Some people might have try a different, quicker approach than removing the rotten, cracked wood. They'd undoubtedly use a penetrating epoxy product that is supposed to infuse the wood with its original equivalent strength. I don't believe the hype and think diluted epoxy is a half-assed fix.  I am only up for complete-ass fixes.

27.) Battening Down the Hull

 

I've been doing most of the fairing inside the hull with a flexible spruce batten wrapped in 60 grit sandpaper. I don't always try to cover the whole batten, but use different lengths of sandpaper depending on the size of the spot I am smoothing out. The bare parts of the batten don't remove wood I want to stay on the boat, but help bend the batten to the shape of the hull. I thought of this technique on my own for fairing an inside curve. I highly doubt I am the first to come up with the idea; I won't be applying for a patent anytime soon.

The photo above shows the third and last coat of fairing material (epoxy plus filler) on the inside of the hull. It's much thinner than the first two coats and went on very smooth.  The density of the epoxy paste can be controlled by adding more or less filler to it.  For the first coats, I aimed for a thick peanut butter-like paste that wouldn't run. For the final coat, I mixed the epoxy to the consistency of mayonnaise.  I had to throw out one batch because I didn't like the way it turned out.  It's far better to make this call early than end up having to remove a big mess later.

Nobody asked about it (I don't have that many readers), but if you thought the little hand plane I showed in my last blog entry was as small as it gets, think again. This one is an instrument maker's plane sold by Lee Valley.

26.) Highs and Lows

>>>>>  I've been using this Lie-Nielsen convex sole block plane to help make the inside of the hull fair. This is a tiny tool, but it works great so long as the blade is sharp. The bottom of the plane is rounded from side to side and front to back for working on an inside curve.

I'm using it to take off high spots, feeling them with my hands, circling them with a pencil, and then taking some shavings until each bump feels mostly gone. (In woodworking, it's amazing how touch is often much more reliable than eyesight.) I don't yet want to remove the highs completely because I know from experience that sometimes a high spot just feels high if it's surrounded by low spots. The black squirrel tail of the plane rests in your palm as you wrap your fingers on the body, giving you more power and control.  I do wish the plane was a little bigger because I developed an ugly blister after a couple of hour using it. It was one time I have been glad the Interclub is only 11 and a half feet long.

For the low spots, I used the same method—feeling them with my hands and circling them with a pencil. I mixed West System epoxy with a combination of mahogany sawdust saved from sanding the boat (I have a whole gallon paint can full of it) and microfibers.  The saw dust colors the mixture and microfibers thicken the epoxy so it doesn't run. I made the first coat pretty thick and will make the next coat much thinner. The best way to apply is with a plastic spreader. Plop a small batch on to a piece of cardboard or plywood and use just like a painter's pallette. I don't usually worry too much about getting the first coat down perfectly smooth, but I also try not to put too much on—because that means I'll end up having to sand more off.  It takes practice to find just the right balance. In the very upper right corner of the bottom photo, you can see that the rail is completely gone.  (Click on the photo to expand.)

25.) Can't Wait to Plank

I can't wait to install those beautiful mahogany planks the Timesaver helped me make. It will be a real boost knowing that the work of rebuilding the boat has begun—as opposed to just removing material from it (which I have been doing for a long time).

Problem is, there's still stuff to do before I can start planking. I still need to remove the highs and lows inside the boat. The interior surfaces are very bumpy. I'll need to make them smooth and fair using a variety of tools and sandpaper, and I'll also need to do some fairing with epoxy putty.  The planks need to be able to go in with no air voids or bumps below them.

I also need to clean up some edges along the kelson—the piece that runs along the centerline of the boat and to which the planks are joined. This edge has been banged up, stomped on and battered from decades of racing, and is not straight enough right now for the new planks to fit flush.  Some of it is broken and in a few places missing entirely.

I am expecting this to take about a week.

And, yes, I blew it, because to do this work I have to remove all those screws and washers I painstakingly applied to get the boat to conform to the cradle. They can't go back in until the new layer of mahogany is applied.

Postscript: Friday was a fun day in the shop. Work was kind of slow so many of the woodworkers gathered outside with a homemade slingshot to try to shoot pigeons. The pigeons were not in great danger because the ammo consisted of large caliber wine grapes (courtesy of the Red Hook Winery's trash bin). I didn't join in the war against pigeons, but heard the groans and verbal jabs that accompanied many missed shots. It also sounded like the pigeons were laughing.

24.) Milling Strakes

I used the word strake in the headline because it's part of boat building vernacular. But it has a much easier to understand synonym: plank.  

The deeper I have gotten into this project, the more I've wanted to learn the skills required for building an Interclub 60 years ago  So, even though I could get by without installing new planks in the interior of #48, I decided not only that I would, but that I'd mill them myself.

I used wood from a supply of 5-inch wide, 7/8s-inch thick, 8-foot mahogany boards I ordered awhile ago from Chesapeake Light Craft in Annapolis. CLC's mahogany now comes from sustainably-harvested sources in Fiji, where vast tracts were planted just after World War II using seeds from Honduras.  It is genuine mahogany* but it isn't on the CITES protected list or illegally harvested in the rainforests of South or Central America. 

I used a bandsaw to resaw the boards into thin strips just over 1/8th inch thick. This is not hard to do if you set the saw up correctly, taking extra care to make sure that the blade is parallel to the fence. After a few attempts that didn't turn out as well as I hoped, I realized it's more important to focus on applying even pressure to the bottom of the board (like I am doing in the photo below) as I pushed it through the saw. I could easily see the top of the board (and take corrective action if the saw blade began to drift), but the bottom where the blade exits is hidden. I also cut slowly, giving the saw time to clear out waste. Each board yielded five planks and a lot of sawdust.  (Tool note: the blade on the saw was a Lenox 1/2 inch carbide tipped blade with 3 teeth per inch. It's specially made for resawing.)

Some readers who see the photo of the final step below may groan and throw up their hands because it's sort of cheating. Our shop is equipped with a powerful Timesaver sander. It is a great device that sports a three-foot wide sanding belt and automatic feeder. All I had to do was insert my rough-sawn planks into the machine; they'd emerge on the other end with one side sanded flat. I had to flip the board and make multiple passes to get the dimensions I'd set my calipers to, but it was a fairly quick and relatively foolproof (big plus for me) process. The Timesaver controls the tension the sanding belt applies to the wood with precise pneumatic pressure that is regulated by sensors. Check out the control knob wheel on the bottom left corner of the machine. Each full turn of that knob lowers the sanding belt to remove exactly 1/32-inch from a board. But a quarter turn is as far as you want to go for each new pass, removing 1/128-inch of thickness per pass. For the final pass, you put the board through twice without touching the knob. This achieves an effect similar to switching to a finer grit sandpaper.

The photo above shows a stack of finished and unfinished mahogany strakes, er, planks, on the cart.  I marked each with chalk before feeding them into the machine. When all the chalk dust was removed I knew they were fair.

Even though Interclub was originally built with 1/16-inch thick planks, I made these a little fatter: sanding down the 1/8th rough board to 3/32s.  This gives me an extra 1/32 of play when I sand them again after they are epoxied or glued** into place. If some are too stiff to bend into the right shape, I can always put them through the Timesaver again.

I don't know if the guys at Zephyr Boat Works had a contraption like this in the 1940s, but it's a good bet they would have used it if they did.  It also would be possible to do this work with a set of jointer and smoothing planes or a hand-held sander, but that's obviously a lot more time consuming. (The fastest way would be to buy pre-cut 1/16th-inch veneer.)

The cart in the photo holds enough finished strakes to plank one side of the
boat.

*There are many types of woods classified as mahogany, but not all are "genuine" mahogany. The label refers to the type that has been historically preferred by shipwrights for its beautiful grain, stability, light-weight for its strength, resistance to rot, and because mahogany trees can yield enormous boards (the trees grow as high as 150 feet tall and six feet in diameter). The specific species is Swietenia macrohylla and, in addition to the genuine label, also can be called Honduras, Peruvian, Bolivian, American and bigleaf mahogany. Genuine mahogany can vary greatly in quality and care needs to be taken when selecting it. Until recently, there were both political and quality issues associated with mahogany from Fiji. Most of these seem to have been cleared up with the launch of something called the Fiji Pure Mahogany initiative. Gibson Guitar was one of the first companies to switch to using mahogany from Fiji.

***I am still deciding whether to use epoxy or glue to laminate the new planks to the hull.  There are arguments for and against epoxy when it comes to joining wood. I'll be discussing these in a future post.

23.) Off with the Rails

I pried off the the first couple of plies of the rails using a hammer, chisel and saw (I didn't try to take them off in one big chunk).  After that, I began going after the remainder with the Lie-Nielsen scrub plane in the photo.  The scrub plane takes nice chunky shavings and removes material quickly.  It has a rounded blade that cuts deep into the wood.  Once I have gone a bit farther,  I'll switch to a finer plane or a power sander.

Why remove the rails?  Partly because they are cracked in a few places and show signs of dry rot in others. But the bigger problem is that they've changed shape over time in a way that has adversely affected the geometry of the boat.  In fact, after I finished attaching the hull to the cradle, I noticed the cradle itself was being pulled inward by a 1/4 of an inch or so and was tilting on its base.  The boat was literally rocking the cradle.  How amazing is that?

Once the rails were removed, the cradle settled back down flat.  This shows what a crucial part of the structure of the boat they are and where an Interclub derives most of its strength. (Interclubbers also refer to the rails as the "decks" because it's where you sit most of the time when you are sailing.) Some builders of fiberglass Interclubs underestimated the importance of the rails and made them too weak.  Consequently, many serious racers with fiberglass boats have commissioned boat shops to re-enforce or "box" them.

22.) A Bow to the Bow

One of the things I appreciate most about the way this boat was built years ago is the craftsmanship that went into the construction of the rails at the bow. The photo above gives a bird's eye view, looking straight down at it.

The detail of how to build this part of the boat was specified on the architectural plans. But it's different than the end result. So it might be that the woodworkers at Zephyr Boat Works came up with a better way to do it.

I want to document it here--and note how great it is--before I destroy it. Unfortunately, I am not going to be able to preserve this part of the boat.  There has just been too much damage and stress on this area over the past 65 or so years (some of that presumably from hitting other Interclubs on the race course).

Check out the construction, though.  As the rails come around the starboard and port sides, they need to be connected somewhere.  The method employed avoids having them all joined at one point, which would lead to a potential weak spot at a place in the boat that can't afford to be weak.  Instead, the rails are split and interconnected so that some parts of them wrap all of the way around the boat to the adjoining side.

You can see this better in the photo below, for which I removed the center fitting and sanded off the finish.  Note how only some of the strips meet in the center; the rest continue all of the way around.  Two types of wood were used in the construction of the rails: mahogany and spruce.

The final photo is a shot of the starboard rail about 24 inches back from the bow. It shows the starting point for the thin strips of mahogany that wrap around the front of the bow.  The two larger strips that continue toward the bow are gradually tapered to the points you can see in the photos above.

Pretty groovy, huh?

21.) Success

The photo below shows how the bottom of the boat now conforms to the cradle (and therefore its original designed shape).  The reason it doesn't look perfectly snug is that I beveled the face of each frame piece so that only the very center of each one would touch the boat at the station line described in the plans. (Without the bevels the curved shape of the hull would cause the hull to touch the cradle at the wrong place and throw off the shape.)  The bottom photo is a top-down view showing how the frames pieces are beveled, each one depending on its position in the cradle and the curvature of the hull at that spot.  I know this is repetitive, but it's important to be clear that the hull needs to touch the cradle at the exact center of each plywood frame piece.

20.) Wood Wrestling

Forcing the hull back into it's original shape was more of an epic battle than I anticipated. It took a lot force and I had to endure a lot of scary creaking and cracking sounds. A couple of times I thought I was going to break the whole thing.  The photo below shows how I finally got the stubborn craft to yield. First, I used lots of Bessey cabinet clamps to push the hull down into the cradle. Then, I used screws with large fender washers to secure it.  I put the screws in (sometimes just a turn at a time) from the middle of the boat up and out.  I had to frequently fiddle with the clamping pressure as I went along.

I believe most of the resistance was coming from the mahogany and spruce rails that frame the boat (the dark brown wood the red Bessey clamps are attached to). I am going to remove and replace these rails as part of the project and I'll explain why later.  But I didn't want to cut them off before the hull was fastened to the cradle because I was terrified the whole vessel would just open like a flower and leave me with a big piece of fancy curved plywood.

Before I put any screws in I spent a lot of time making sure the boat was perfectly positioned in the cradle.  This included measuring the fore and aft positioning as well as running a string down the center line of the hull to make sure the boat was centered and straight.

And yep, I drilled all those screw holes right through the bottom of the boat. When I was done, there were more than twice as many as shown in the photo.

The picture above also better shows the sanding I did on the interior.  You can see I sanded through the mahogany planks a little more than halfway up both sides.  I did this to remove evidence of damage, dry rot and other problems.  I will be adding new mahogany planking inside the boat.  I haven't been able to identify the wood used to construct the inner planks of the boat.  The Sparkman and Stephens plans specifically call for all five of the layers to be constructed of 1/16th-inch mahogany, but that is definitely not mahogany.  It could be soft maple, red birch or even pine.  I am going to ask an expert to look at it who can identify wood species better than I.  (Update: we have a positive ID: It's birch.)

The only woods mentioned in the plans are mahogany, spruce and white oak. Was the boat so popular initially that the builder ran out of mahogany planking? Did they pull a fast one?  Or was there another reason?  The boats were built shortly after World War II and there might still have been materials shortages.

19.) 90 Pound Weakling

Before attaching the hull to the cradle, I thought it would be a good idea to weigh it. The photo of the digital scale to the right reads 97 pounds, but that includes four pounds of equipment I used to lift the boat.

One reason it is so light is that it has been drying out in the indoor shop for more than a year.  The moisture content of the wood is extremely low.

I am going to want to bring the finished boat right in on the class minimum weight of 230 pounds. That weight includes the mast, boom, centerboard, rudder, and all the fittings and racing equipment (though not the sail and a few other odds and ends).

At some point, I am going to have to know what all those items weigh so I can subtract that from 230 to calculate the optimum weight of the finished hull.

The challenge is to make the boat as strong and stiff as possible, but not to go an ounce over 230 pounds.  The more rigid a boat is the more efficiently it transfers energy from the sail (or movement of the crew) into forward motion.