Repair the Cap Rail on a Sailboat




Introduction: Repair the Cap Rail on a Sailboat

Do you have a nice old sailboat with plenty of teak trim, say 1970s vintage, and there is the odd cosmetic repair that has been nagging you?

It may be a big deal to replace the "cap rail" that runs along the edge of the deck, but you might find that it's not such a big deal to replace a few useless rusty screws.

Step 1: Get Organized & Set Up

You'll need the following:

cordless drill / driver (NOT an impact driver);
bits to match the screws and screw heads;
"vice grips" or equivalent;
C-clamp (4") or equivalent
paint scraper or pocket knife.

screws (#8 (or #6) stainless steel or brass ONLY) - length depends on where you will use them.

Step 2: Remove the Bad Guys!

First you need to remove the rusty screws that are not doing their job and will be in the way when the new screws are used to hold the trim back in place.

This is where vice grips (or maybe needle nosed pliers) will help grab these bad boys and back them out the point they can be unscrewed.

Scrape dirt and old caulking from the space between the pieces of trim.

Step 3: Make a New Home for the Good Guys!

Rather than using the old (and now empty) screw holes, you'll likely be happier drilling new holes for the new screws. Be sure to mark the bits with a bit of tape so that you do not drill too deep and come out the top of the upper piece of trim! It is tedious but it is worth it to drill first for the screw and then use the larger bit to drill just a little depression in order to counter sink the head of the screw.

Use the C-clamp (or perhaps vice grips GENTLY to avoid marking the soft teak trim) to hold the pieces of trim together while you drill and screw upward from the BOTTOM side.

Be careful and patient - it's easy to split the trim...Screw the new screws up from underneath

- careful not to drop them into the water!

Again, be careful and patient - it's easy to split the trim.

Congratulations - You're done - it looks better, and you've prevented the damage from getting worse!

Step 4: Send in the Good Guys!

Screw the new screws up from underneath - careful not to drop them into the water!

Again, be careful and patient - it's easy to split the trim.

Congratulations - You're done - it looks better, and you've prevented the damage from getting worse!

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    Tip 2 years ago on Introduction

    Check the wood below the cap rail, it can turn to compost over thirty years. Carve it out and replace with a good hardwood. For small pockets just around the screws, just drill a 1/2"/2 cm hole and glue in a wooden dowel, then drill for appropriate screw size. A non-shrinking, sand-able silicone based chalk will seal out water and protect stainless screws. Bolts that hold down the deck plate can hold the nuts inside the hull by bending a stainless washer about 1/4"/1 cm from the hole in the washer. This prevents the nut from spinning when tightening the screw from the topside. Or hold nut in place with Visegrips.

    You may have to remove interior paneling to get to the bottom side of caprail screws. Stainless is pretty soft are sometimes can be broken off or drilled out - but you have to get the rot out around the screw.

    Don't let cap rail gaps go unchecked: repair them and seal them. They can leak through the hull - and at 45 min to an hour or more a piece, for 75-80 long screws, these can become a reason people 'scuttle' an otherwise nice sailboat to the scrapyard.

    Old fiberglass repair books for sailboats, 1970's vintage, offer many caprail designs. This seemingly cosmetic wood or rubber holds the boats deck to the hole - a non-trivial function that is not cosmetic. My 1966 Ericson alternates between screws into wood, and 4 1/4" long bolts that have washers inside the hull. If the stainless screws get rot around them they can corrode, allow water to leak behind your panelling, usually into the bilge, but sometimes to the floor boards if drain paths are clogged.

    Great project - puts hair on your chest. And helps you understand quite a bit about the structural design and accessibility that your sailboat was designed to. Fun stuff.

    Finally, an old hand drill (like a small augwr) using the tips from an impact driver, is invaluable in backing out the old screws, and seating the new ones. (Tie a string between the hand drill and the boats safety rail - they sink fast if dropped. :) )

    And use Marine-grade stainless. Hardware store stainless is not suitable for salt water. Galvinized steel screws when they rust expand, then rot away, and create a water path in every single hole. Wet stainless screws are marginally better.

    Good luck! - a Seattle Mariner