In summer 2002, we began the major project of recaulking all the seams of the teak deck. Actually, we started with a small test case in fall 2001, the seams around our key planks. These were badly cracked and needed immediate attention. In spring, we started again with a small piece, which was the deck pad at the base of our mast. Pictures can be found at the end of this post
The job of removing the original 17 year old caulking was simplified by our discovery of a neat little tool made by a German company called Fein. The Multimaster is a versatile tool that supports multiple bits. Instead of rotating, the attachments oscillate at high speed, thus helping to prevent "runaways". The truly nifty thing about the Fein is that in addition to the standard sanding, cutting and scraping attachments, you can buy a bit specifically for the removal of teak seam caulking.
Once the old caulking had been stripped, we did a final cleaning pass on the seams to remove any residual caulking. On the deck pad, this was done by hand with sandpaper, but for the longer sections of deck, we found a small circular saw worked well for this phase. We put enough blades on the saw to span the width of a seam. Curves and smaller pieces were still done by hand.
Any old bungs that looked suspect were removed and replaced. On the deck pad, we removed all the bungs and screws. This was a precaution necessitated by our discovery of a small interior leak. The screw holes were injected with epoxy before all screws and bungs were replaced. As it happens, our deck leak was not at the pad, but rather at another bung on our teak trim "eyebrow" rail. However, the preventative maintenance on the deck pad can't hurt.
On the deck itself, we also rebedded any planks that had lifted. This was done using 3M 4200. In certain cases, we replaced planks that had warped too badly or cracked, such as key planks or curved planks around hatches. Any deck fittings, like water and fuel inlets, were also removed and rebedded.
Before applying the new seam caulking, all teak was painstakingly taped. We originally used the 3M blue tape, but found that if tape was applied, caulking done and tape removed all in one day, regular masking tape worked just as well, and was far more cost effective.
Once the teak was taped, sealant was then applied using a standard caulking gun. The sealant was then evened out using a small plastic scraper. We had to take care in some sections to avoid leaving gaps or bubbles in the sealant.
Timing of the tape removal was a bit tricky. The sealant must be cured enough not to leave a stringy mess when the tape is removed, but not so hardened that the tape tears and stays behind with the caulking. We found that removing the tape within a couple of hours of sealant application worked best.
We also found that it was important to inspect the seams after the sealant had cured to verify that no bubbles had formed. Areas where this had occurred were quickly retouched, by removing the portion of sealant containing the bubble and recaulking.
When we did our small test areas, we used 3M seam sealer as our sealant. However, we discovered that the key plank portions done in fall 2001 had already started cracking by summer 2002. We've since switched to Sikkaflex one-part for the rest of the deck. We'll see how it holds up in comparison. We debated using two-part polysulfide, but after much hemming and hawing decided to try one-part first. Opinions seemed to be split in this area, and the two-part was harder to find, and apparently more difficult to mix and use correctly.
We made the conscious decision not to use bondbreaker tape at the base of the seams. One opinion on the 3M failure is that the lack of bondbreaker contributed to the cracking. However, the cracking appeared widest at the top of the seam, which doesn't appear to support the above conclusion. We feel that in all probability, we had a bad or expired batch, that had already started curing in the tube before application. This would seem to be supported by the fact that the Sikkaflex was much easier to apply through the caulking gun than the 3M was.
The overall deck project was started in July, 2002. We tackled one portion of deck at a time, starting from the bow and working our way back. By mid-July, we'd completed the entire starboard bow portion, and half the starboard beam. The work schedule includes 2 to 3 hours of seam removal per day (which is all our knees can stand) for 2 to 3 days, followed by an evening of final clean and prep, and an afternoon of sealant application. This seems to equate to about 1/7 to 1/6 of the deck area at a time. We finished the entire exposed portion of deck, excluding the cockpit, on the Labour Day weekend.
We found the following links extremely helpful when doing research for this project.