The rub rail on your boat serves two important purposes: As its name implies, it provides a durable outer edge that's not easily damaged by coming into contact with other objects. It also serves as a decorative and protective cover for the seam where the deck and hull meet. It's a sacrificial edge that protects the nicely finished hull sides from damage, but it can end up looking like it's taken a beating. Replacing the rub rail can help restore the appearance of your boat and provide an opportunity to upgrade while getting a nicer-looking rub rail in the process.

Rubber-like vinyl railing is the most popular choice. It's available in flexible and semi-rigid forms and usually comes in two pieces, a base that's attached to the boat with screws and a flexible insert that snaps in to cover the screw heads and provide a finished appearance. It's relatively inexpensive and easier to install than metal rails. Some vinyl rails are available with a metal insert that provides extra protection as well as enhanced looks. Metal rub rails are available in both stainless-steel and aluminum versions. Stainless steel is more durable, but aluminum is easier to cut and form around corners.

Most marine suppliers' catalogs offer a wide selection of rail types. TACO Marine, a major supplier, offers a free Replacement Selection Guide, available at (800) 653-8567 or downloadable at  www.tacomarine.com . Once you've chosen a style, the most important consideration is size. The job will be much easier if you choose a rail that's the same width or slightly larger than the original.

Measure Before Ordering

Vinyl rub rail material is available in single, long lengths that will seamlessly cover the entire perimeter of the boat. This means that you must measure carefully before ordering. The length you'll need will be equal to the width of the parts of the transom that are protected, plus twice the length of the sheer line. Remember that the sheer line will be slightly longer than the boat length because it curves inward at the bow. Measuring twice and ordering a bit extra is a good approach.

Begin by removing the old rail. If its fasteners aren't visible, they're probably covered by an insert, which can be pried out with a large screwdriver. Most rails will be attached with screws and are easy to remove using a screwdriver bit in a reversible electric drill. 

Some rails may be riveted in place using "blind" or "pop" rivets, which will need to have their flanges drilled off. Use a drill bit that's slightly larger than the diameter of the rivets' shank, often 3/16 of an inch. Wearing safety glasses or a face shield, drill into each rivet just far enough so that its outer flange is removed. When all of the rivets are done, the old rail can be pulled away, although the original adhesive may make that a chore. Use a hammer and punch to drive the rivet bodies in so they're slightly below the surface, rather than pushed through, since they could end up in undesirable locations. They'll be held in place and sealed by a later application of sealant.
 
Clean, Seal and Replace

The exposed surface must be thoroughly cleaned and any old adhesive removed before applying the new rail. Be careful not to damage the gelcoat while scraping. This is also a good time to do any minor repairs in the area.

This installation description assumes that you're using a two-part vinyl replacement rail. The installation of rigid or metal rails will require the same hole-drilling and screw-installation routine but may require custom connectors or fittings at the bow, butt joints or corners where the material can't be bent to conform. 

Although the job of applying the new rub rail can be done alone, it'll be immeasurably easier if you enlist the aid of another person. Begin by heating the new rail material in hot water or laying it out in the sun so it'll be more flexible. Mark the location of original screw holes or rivets on the hull by applying masking tape just below each one. You'll want to avoid them when installing new screws. Measure to find the exact midpoint of the length of new rail material, and mark it.

Place the rail up against the bow so the midpoint you marked is aligned with the peak of the bow. Drill a new screw hole a few inches back on one side, and attach the rail to the boat. Stretch the material around the bow to eliminate gaps, and repeat the attachment operation on the other side. For particularly stiff material, carefully use a heat gun to soften it up to make the bend easier. It's important to drill a properly sized pilot hole for the screws, which must be the same length as the old ones. The pilot-hole diameter should be at least 1/32 of an inch smaller than the screw diameter but large enough to prevent excess chipping and cracking of the fiberglass when the screw is driven in. If screws weren't included in the kit, be sure to use only panhead or trusshead screws instead of flathead, which will distort the material. Don't overtighten the screws.

Once the new rail is anchored at the bow, stretch the free end rearward, and fasten it near the transom with one or two screws. Then drill new holes about every 6 inches along each side, beginning at the bow. Ensure that the rail is properly positioned vertically before drilling each hole. It may be easiest to do a 4- or 5-foot section at a time. After drilling the holes along a section, pull the rail away, and place a single bead of marine adhesive such as 3M's 4200 Fast Cure behind the rail, making sure to cover old holes before installing the screws. Go back occasionally and check along the entire length of the newly installed rail to make sure that there are no gaps caused by untightened screws or deformations caused by some that are too tight. Once both sides are done, the rail material can be pulled around the corner (if required) and fastened to the transom, in which case, the two ends should meet at the center of the transom in a butt joint. Cut the material a bit longer than necessary to ensure a good, tight joint without a gap.

In cases where a flexible insert is used, heat it to make it more flexible and install it, but leave the ends untrimmed for a day or two to allow for any shrinkage that's going to take place, and then trim to fit. If the rail ends don't meet on the transom, finish them by applying the caps that are normally supplied with the rail material.

For detailed instructions covering all types of rail installations, TACO offers (through dealers) a reasonably priced DVD that's loaded with useful information. Replacing your rub rail is a fair amount of work, but it can do wonders to improve the look of your boat and ensure continuing protection from the bumps and scrapes of everyday use on the water.


Quick Tips

1.     Choose a rail that's the same width or slightly larger than the original.
2.     Thoroughly clean the area, and remove old adhesive before applying the rub rail.    
3.     Drill properly sized pilot holes the same length as the old screws.
4.     Use only panhead or trusshead screws, and avoid overtightening them.
5.     Ensure that the rail is properly positioned vertically before drilling each hole.