As we enter the time between seasons and most boats head north to south in search of perpetual summer, it’s likely most of us will be doing our usual shipyard routine. Whether it’s a 10-year refit or a month to tick some repairs off, no doubt some caulking is on that list. Look around on deck and just about every fixture will begin and end with caulking — from windows to decking. It’s essentially the final piece of waterproofing and weatherproofing on a vessel.
Caulking itself has come a long way — traditionally being fibrous plant material driven between the cracks in decking. Nowadays, there’s quite the selection between caulking, sealant, and adhesive and their different grades; however, for outside, you’ll most likely be working with caulk.
As we work on what could be considered floating artwork, caulking must be as flawless as its surroundings. Take care when removing old caulking and use plastic scrapers and alcohol or adhesive remover. Only use metal blades if they’re absolutely needed — they are especially unforgiving on paint. If removing caulk from deep grooves, you may need a reefing tool. Make sure to remove all the old caulking as the new bead you lay won’t bond to the surfaces otherwise. Caulking while on charter can be quite the adventure if you have to redo it weeks later.
Similar to varnishing, tape the edges of where you want the caulk to end with masking tape, or if working with a lot of curves and corners, flexible electrical tape can work even better. Take your time with taping as it will reflect the line of the caulk, especially if set against white paint. It’s best to make caulking a one-day job — or at least a section at a time — as leaving tape overnight can lift slightly due to the temperature change and moisture.
Once you’re done taping, take a step back and proudly inspect the straightness of your line. Next, if you’re laying the new bead in direct sunlight, work as quickly as you can (as it will set or “skin over” much faster) and pull the tape as soon as possible. You’ll need your caulk, caulking gun, rags, and a mixture of water and dish soap to swipe the bead after you’ve laid it. Reef out the out-dried caulk from the end of the caulking tube and cut the tip at a 45° angle so it’s oval. The size of the hole should be slightly smaller than the seam you’re caulking into. When ready, have some alcohol or solvent nearby and begin laying the bead. More often, it can actually be better to “push” the caulking gun along the seam rather than pull so there’s a small ball of caulk in front of the gun. The pace of you pushing the caulking out of the tube and the speed at which you lay is the true art of this whole endeavor.
After you’ve laid your bead, dip your finger in your soapy mix, and pull your finger along the caulk with moderate pressure to get a smooth finish and seal it within the seam. Afterwards, pull the tape up and towards the caulking, being mindful of the residual caulking on the tape.
This article originally ran in the December 2021 issue of Dockwalk.