Repairing Wooden Rubrails and Toerails

Thanks to the high cost of marine lumber and a growing aversion to brightwork maintenance, fewer new boats these days have wooden rubrails or toerails. This is understandable—wood is pricey to install and, if finished bright, is a lot of work to maintain.
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The author and father, Nigel, attack the many wooden bungs covering the fasteners

The author and father, Nigel, attack the many wooden bungs covering the fasteners

Thanks to the high cost of marine lumber and a growing aversion to brightwork maintenance, fewer new boats these days have wooden rubrails or toerails. This is understandable—wood is pricey to install and, if finished bright, is a lot of work to maintain. Still, wooden rails give a sailboat an admirably classic look, even when left unfinished to weather naturally, and can be a lot less work to maintain than people realize. Repairing wooden rubrails and toerails is also very simple, requiring nothing more than a couple of hand tools—as I learned when I repaired some sections of rail on my long-neglected 1975 Cape Dory 28.

Gathering the materials

Often, the hardest part of the job is finding suitable lumber. If you can afford it—and are, hopefully, willing to source it sustainably—nothing beats teak. However, there are a dozen other woods that will also make great rubrails, particularly if you plan on finishing them with paint, oil or varnish, including ipe, iroko, cumaru and purpleheart. The repair stock must have a straight close grain, because twists and whorls will likely split the wood, exactly what happened to the original on my boat.

Fortunately, small repairs don’t require much lumber. The teak for my repair, for example, came from the heavily weathered, splintered remains of an old cockpit coaming that I cut up and laminated together to get the correct dimensions. After a sanding it looked as good as new.

We had to laminate salvaged teak to make repair stock

We had to laminate salvaged teak to make repair stock

I got my dimensions from the old rail, adding 1/8in to the height so I would have some extra material to practice on when planing the top of the rail around. In all, you will need a length of repair material equal to the length of the damaged rubrail, plus the length of the scarf joints. It’s good practice to get some extra material, just in case there are some bumps in the road.

The rest of the supplies were easy to track down. These included glue of some kind (I used epoxy resin—far and above the best choice for the job), some bungs to plug fastener holes, a drill, a sander, a hand plane and a saw. Cuts can be made with a circular or table saw and a jig, or with a sharp fine-toothed handsaw.

Before starting, I had to decide whether to make the repair on or off the boat. Repair work is much easier on a bench, but removing a rail is a lot of work and is not strictly necessary. I ultimately did my rubrails off the boat, but also fixed a portion of the toerail without removing it.

Removing the rails

Most rails have fasteners that are countersunk into holes plugged with wood bungs. There’s no point in salvaging these bungs, but the trick is not to damage the rails when removing them. The simplest way is to carefully split the bungs with a small chisel and a rubber mallet. Another technique is to drill a pilot hole in the center of each bung and then drive in a self-tapping screw, so that as the point of the self-tapping screw hits the head of the underlying fastener it will push out the bung. Scrape off any heavy varnish first, or the bungs may rip some surface fibers as they separate from the rubrail.

The repair stock is clamped to the damaged piece and cut to ensure a close fit

The repair stock is clamped to the damaged piece and cut to ensure a close fit

With the bungs out I then removed the fasteners securing the rails, and then, working carefully from one end, peeled the rails themselves off the boat. As I did so, I tried, without success, to keep the existing scarf joints intact.

Cutting repair stock

When making the repair, the new material should be glued in with some type of joint. There are lots of ways to do this, some stronger than others. But the easiest, most reliable method is a scarf joint.

There are many ways to cut a scarf, including using a jig for a table or circular saw to make an extremely accurate cut. However, I prefer to use a simple handsaw. It’s not the most exacting method, but it works well in practice and requires no calculations or fancy tools.

To cut my scarf, I laid my old rail directly next to the repair stock and then clamped both pieces down to a work surface. After that I took a sharp handsaw and made an angled cut through the old rail and the repair stock, at the same time. Clamping them together and making one cut ensures a good fit in the joint between the two pieces. The good news is, it’s even easier to do than to describe! The same technique can be used when making a repair in-situ. But take care not to cut into the boat.

 The scarfs match perfectly

The scarfs match perfectly

A note on scarf joints: conventional wisdom holds that there should be a minimum 8:1 ratio between the thickness of the stock and the length of the joint. On a typical 1 3/4in rubrail, this means a 14in cut, which is no easy feat with a handsaw, and why it is rarely seen even in the original rails. In practice, by using epoxy glue and fastening the rail close to either side of the joint I have found the ratio can be reduced significantly.

An easy way to strengthen a joint is to drill a 3/8in hole into the center of your rail on both sides of the scarf and pin them with a dowel when you glue up the joint. It is easier to make these holes precise if you drill them before cutting the scarf. The dowel should have a flat shaved into one side to allow air to escape when it is pinned into the hole.

Gluing it all together

With my scarf joints cut, I was ready, after a quick sanding with 80-grit, to glue the repair stock onto the undamaged rail. Thickened epoxy is the preferred glue, but take care, because epoxy resin sticks to almost anything and is highly toxic. It is also important to cover the work surface with plastic, so that the rail doesn’t get glued to the bench, and wear the proper safety equipment. Disposable gloves are a must. A respirator is essential when working indoors and is highly recommended outdoors as well.

Put plastic under the joins so you don’t glue your repair to the workbench

Put plastic under the joins so you don’t glue your repair to the workbench

When working with epoxy the first step is always the “wet-out,” in which neat resin (no filler) is brushed onto the surfaces to be glued. Teak, especially new lumber, contains a lot of oil, which can make it difficult to glue. I’ve never bothered, but some people recommend removing some of the oil by wiping the surface down with acetone and applying the epoxy as soon as the acetone fully evaporates.

Once the joints are lightly covered with neat resin, it is time to thicken the epoxy with a structural filler. I used West System 406 Colloidal Silica. Another technique, which results in a nearly invisible glue line, is to use fine sawdust as a filler. Add enough filler to create a “peanut butter” consistency—the epoxy should not be runny.

With thickened epoxy on hand, the scarf joints are glued together one at a time, clamping each piece in turn. Start by clamping one side of your original rail. If you’re pinning your joints with dowels, now is the time to coat them in thickened epoxy and insert them as well. Don’t forget to wet out the holes with neat epoxy first.

Pinning a butt joint with a dowel;

Pinning a butt joint with a dowel;

After that put your first scarf joint together, fitting the new stock and clamping it down onto the original rail you’ve already clamped in place. Because of your scarf joint, the rails may try to slide against each other, so this will take a bit of care. Epoxy resin does not require pressure to set, so there’s no need to clamp the joint directly; it is better to place the clamps on either side. Indeed, clamping the scarf directly may squeeze out the epoxy and leave you with a glue-starved joint.

With the first joint done you can continue to glue and clamp as many joints as you have clamps and workspace for. Rather than wiping away excess glue, let it begin to set first and then trim it with a shop knife after it has become rubbery.

Once the glue has dried it is time to shape the repair stock into a rubrail. On short repairs up to a couple of feet, this is easily done by eye with a sharp hand plane, using the intact rail as a guide. For a beginner this may seem difficult, but it is surprisingly easy and intuitive—you simply shave down the repair stock a little at a time until it reaches the level of the existing rail. Just bear in mind that you must always plane down the length of the rail from your higher stock to your lower stock. If you try cutting the other way you are liable to splinter the wood. For very long repairs you may need to use a router and a bit that fits the shape of your existing rails, or have your stock milled to order.

It’s easy to get a smooth transition with a hand plane

It’s easy to get a smooth transition with a hand plane

With your repair glued and planed down to match the existing rail, you’re ready to put the rail back on the boat. If you’re going to do any sanding, now’s the time. This is also the time to drill your fastener holes in the repair stock. To re-use the existing holes in your boat hold the rail just under where it will be fastened, line up the existing holes in the boat with those in the unrepaired rail, and mark where the holes in the repaired section(s) need to go. After that do your drilling on the bench. Most rails are plugged with ½in bungs. In a pinch you can countersink holes for these with a regular drill bit, but you will get better results with a Forstner bit. Drill your bung holes to match those on the existing rail and then drill pilot holes for your fasteners.

The repaired rails are ready to go back on the boat

The repaired rails are ready to go back on the boat

Install the rails as you removed them, starting at one end and working along the curve of the hull. Unless you have a very good reason not to, you should use a marine sealant here. A semi-flexible polyurethane or polysulfide sealant (3M 4200, BoatLIFE Life-Calk, etc.) is a good choice. Be sure to dry-fit the rail and mask off the area first!

Install the rail by turning in all screws just three-quarters of the way and then tighten them one at a time, starting in the middle and working toward the ends, alternating fore and aft. Trim away excess caulk after it has dried.

When making repairs without removing the rail, the procedure is the same but the order is different. After cutting the scarf joints, the damaged rail is thrown out and the repair piece is marked and drilled. The scarf joint is then glued up at the same time the piece is installed, using fasteners instead of clamps to hold the joint in place. Then plane the new piece to shape right on the boat after the glue has dried. Don’t forget to use caulk when you install the repair.

With the rail in place it’s time to attend to the fastener holes. These are plugged with properly sized wood bungs of the same material as your rails. You can buy bungs or cut them yourself with a tapered plug-cutter. They are installed with a wood or rubber mallet and a small amount of varnish on the plug. Don’t use epoxy resin or wood glue here. Varnish is best because it creates a seal and allows you to pull the plugs out later if you need to do more repairs.

Installing the teak plugs

Installing the teak plugs

Before knocking in, be sure to orient the grain of your plugs with the grain of the rail. Trim the excess bung with a sharp chisel, making sure to cut along the grain. A kiss with a sander will leave your bungs nicely flush with the rail, and your repair is complete. Now, if you choose, you can apply a finish to your neatly repaired rail.

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