During my time restoring my decks I learned alot of do's and don't's. I won't say that I have it all figured out, but I'm further ahead than most folks that have teak decks. Here I will just state what has worked for me and some of the info I have gathered from other knowledgable people. In the end, after reading up, picking peoples brains, and contemplating you just have to experiment on your own. Because one thing is certain; you will hear alot of erroneous advice from know-it-alls who don't know anything. Maybe you're thinking that about me right now. But all I'm offering here is what I've done and seen. Take it for a grain of salt and make up your own mind.
I think one of the most exasperating things about restoring a boat (or maintaining it) is to hear so-called "pros" bluster about how they know what should be done because they've been doing it for 25 years. Unfortunately I have found alot of these people to have been doing it -WRONG- for 25 years. I have literally seen more than one of these "pros" using 3M 5200 on teak seams!!!
Without drifting too far off, let me say one thing; even though it often iritates them, you, as the owner, must keep a very close eye on anyone doing work on your boat that you have contracted out. It is absolutely shocking to see some of the things that "pros" will do to your boat. You have to know what you want done and how to do it even if you hire someone else.
CORING: Unless the deck is solid glas (Nauticat) it will be cored with balsa, foam (such as Divinycell or Airex), plywood, or worse (see my rant on Hans Christian). I would try to stay away from a wood-cored deck, but I know that is difficult to do since most decks are made that way. Eventually it will lead to problems that are a pain to correct. Solid glas is great but heavy because it has to be thick not to flex. The best core to me is foam. There is virtually no downside that I know of. It is lite, makes for a stiff sandwich, doesn't rot, doesn't allow water to migrate laterally, and provides some insulation from heat and cold. Very few boats, however, are foam-cored. It must be a cost thing. I don't really know why.
The thickness of the outer layer of glas in the sandwich is very important. Ideally it should be thick enough so that the screws holding the teak down don't even penetrate into the core. Let's face it.....sooner or later water WILL get under a teak deck. There are too many seams to be that perfect. Just imagine your wood core, with thousands of entry points into it. With foam it is still not a disaster since foam is closed-celled, meaning it doesn't absorb or transmit water. You can literally have an entry point but nowhere for the water to go. Better yet, don't have all those penetration points to begin with. This is just one of the beefs I have about Asian boats; they tend to do teak decks very poorly. (see my rant about Asian boats. I didn't start off prejudiced but now I am.....it's just what I've seen, sorry.)
CAULKING: This is where you get it right, do the job once and forget about it for 10-20 years, or get it wrong and grind your teeth until you have to do it again. It begins and ends with the sealant you choose. Whatever you do, don't use these products; any one-part polysulfide, 5200, 101, or 3M Teak and Wood Seam Sealer. These will be at the least a waste of your time and worse.....the ruination of your deck (5200).
I tried in vain to find out what the Swedes used on my deck because the material was still perfect after 20 years!! It is extraordinary.....flexible like a rubber band, very adhesive, and no UV damage. This was by far the best stuff I had ever seen and it made no sense to me to recaulk with anything else. I called people, talked to everyone, sent emails to Sweden. No luck. I still don't know what it is. It was probably taken off the market because it worked too well. That or the EPA found a molecule in it they didn't like. So I still had to find something worthwhile to use.
I called Stone Boatyard in the Bay Area. They have a reputation for teak decks going back decades. The manager there was very gracious and allowed me to pick his brain for a half-hour, even though I wasn't bringing him any business. They have been through everthing over the years and had two very good pieces of information for me. (but they didn't know what the Swedish sealant was either) After dismissing every sealant on the market they told me what they were using exclusively these days; a caulking material from a small manufacturer in Florida called Teak Decking Systems. I got some, tried it, and after 2 1/2 years I like what I see.....no sidewall delamination, flexible. But you really can't know what it will be like in the long term. This and another product are the best recommendations I've got at the time. The other product is a real surprise
I got tired of all the bullshit marketing in the "marine" industry and decided to look elsewhere for solutions to many boat topics. This led me to an industrial supply store where I found my little secret......DOW 795. They should give me a royalty if it catches on. It is a 30-year exterior skyscraper window sealant, very adhesive, extremely flexible, and tough. I use it for literally all my caulking jobs on the boat, everything. (but NOT below the waterline!!) It is terrific stuff. I have only used alittle of it in the deck 2 1/2 years ago as an experiment because it was just a gamble. So far I like it, but I haven't ripped it and the TDS caulking out yet to see how the adhesion has held up. You learn alot about a sealant when you remove it. The best part about DOW 795 is the price; $4.89/tube!! Anymore I just cringe when I see people using one-part polysulfide for anything. It truly is worthless stuff. But I don't say anything. People don't like to be preached to.
Regarding 2-part polysulfides, I don't have personal experience with it. Apparently it is a step up....maybe you'll get 10 years out of it, but the examples I've seen were too hard for my liking. Stone Boatyard has a dim view of it as well.
BOND-BREAKERS: Here is a relatively new buzzword, at least to me. (told you I didn't know it all) This is where you use a 3M Fineline tape on the bottom of the seams to prevent the sealant from sticking. The idea is to create a 2-dimensional bond rather than a 3-D one. Stone Boatyard and Teak Decking Systems both are big believers in this technique. I understand it in theory and I think in many situations it is sensible. For instance; if you have deep grooves then you have alot of sidewall surface area to adhere to. I can see how making the sealant stretch in one plane like a rubber band would make sense. But say you have shallow grooves like on an older deck.....not alot of surface area on the sidewalls. What happens if you use a bond-breaker and have sidewall delamination? Water goes down the sidewall separation, through the joint at the bottom of the seam, and then under the deck (because the Fineline tape sure as hell won't stop it!!). To me this technique places alot of trust in the sidewall NOT separating.
Now, what happens if you don't use the bond-breaker and the sidewall delaminates? The joint at the bottom of the seam is sealed so the water still can't go under the deck. The key to me in this situation is the quality of the sealant used. It must be very flexible and adhesive. This is all voodoo science. Nobody knows how alot of this stuff is going to play out over 20 years. This is why I wanted so much to find out what the original sealant on my Bostrom was because it HAD proven itself over 20 years.
RE-CAULKING: Rip out the old material (I made my own tool out of a narrow wood chisel), clean the grooves with your tool and sandpaper wrapped around a small square-ish item, acetone the groove, tape it with 3M blue, caulk it, and level it with a flexible plastic paint scraper. Remove the tape 30-90 minutes later depending on the weather or it will "pull" at the edges if you wait too long.
If you use a bondbreaker it will make the job quite bit longer. It's kind of tedious. Put it in after acetoneing the grooves.
If you feel you have to sand alittle, do so before caulking. Afterwards you'll just screw it up and very likely cause some sidewall delamination. I would only use 180 grit or finer. I've seen people using 80 grit on their decks and I can just feel the wood crying.
CLEANING AND MAINTAINANCE: Stay away from any kind of bristles; you'll eat out the soft cellulose and end up with peaks and valleys. I use a sponge if I clean at all, and I don't do that often. When I do clean I use a diluted orange citrus concentrate from Home Depot. This stuff is fantastic on most anything.....engines to Sunbrella. (but be careful when using it full strength on plastics, Lexan, decals. It nearly took the "Autohelm" off one of my instrument covers!)
There are two approaches to a deck; let it go natural or actively protect it. Saltwater is widely recommended for that silvery/grey look. The salt also attracts moisture which reduces the amount of expansion/contraction. If I understand correctly, wood submerged in saltwater is well-preserved if not for the worms. So I guess the salt acts as a preservative as well, but I'm not knowledgeable about this.
Since my teak is 20 years old I take a pro-active approach to protecting the wood from further UV damage. After I replaced missing bungs and lightly sanded I had a nice deck, but I knew that the teak had lost some of its' natural oils and was alittle ridge-y. I didn't want to sand enough to get back to a totally smooth surface. So I compromised. There is a product called Semco that I played with and have found satisfactory, if not perfect. I use it year round. It is a semi-transparent, pigmented, penetrating stain that offers teak-like color, UV protection, water repellency, and retains the non-skid feel of teak underfoot. Two coats twice/year does the trick (about an hour/coat on my boat). I mix one-part each of the three colors; natural, golden, and clear for a pretty decent teak imitation. The one drawback is that it somewhat covers the seams as well. If you're really picky you can take the time to wipe it off with a rag before it sets up and then it really is nice-looking. The pigment settles in the valleys, preventing the UV from degrading the cellulose there even further. I like it.
Whatever you do don't use a hard finish such as varnish or Cetol. You might as well rip the teak off and non-skid.
One thing I would like to know; is there a product that actually can return lost oils to the teak? Not petroleum-based products with mineral spirits in it, but real, natural stuff. All the "teak oil" I've seen is just hyped-up mineral spirits and it turns teak dark. Is there such a thing as 100% teak oil that could be thinned to penetrate back into the wood?
BELOW: This shows the deck before sanding and finishing. The Swedes had some sort of caulking which was indestructable; it was still very flexible and secure after 20 years. I have tried in vain to track it down but with no sucess because it is the best I've ever seen. Most caulking is severely deteriorated in 5-10 years.
I was halfway through the job of recaulking the foredeck when I realized that most of the caulking was still good!! It just needed to be shaved down a hair because over time the teak had eroded slightly, leaving the rubbery caulking standing too tall. So I went ahead and finished the job and replaced alot of bungs. A slight sanding and presto!
Hans Christian Deck Coring.
I have started to get emails about the site. Guess the search engines have picked it up. One guy wanted to know what I found in the HC 38, so here goes...
OK, this is NOT a cheap shot at Hans Christian. This is only a story about what we found in a mid-80's HC 38. How they built the boats since I wouldn't know. Hopefully they made changes.
By all accounts the HC hull is bomb-proof, the vessels are very salty, the interiors are superb, and they will take you anywhere. However, like most Asian boats the wiring and fasteners are questionable, and God forbid you have black-steel tanks. Other than that, hey, if you don't mind the vast horizon of brightwork they are great sailboats.
BUT.....listen to this. On this particular HC 38 there was an apparent leak around the windlass into the deck core. It spread from the foredeck down the sidedecks and the core and upper fiberglas sandwich had to be removed. What came out of there was shocking!! The core material was not marine plywood, it wasn't plywood, it wasn't balsa, it wasn't foam. Particle board, wafer board, chip board.....take your pick. That's what it was. And if you have worked with this material in construction you will know that it has NO moisture resistance. It was simply used because it was cheap. (that's my conclusion) Apparently all the builders wanted was a filler material between the sandwich in order to make a deck. What happened to that deck down the road didn't seem to matter. This deck had to be rebuilt using marine ply. That's alot of very expensive work.
Don't be afraid of buying a Hans Christian. Just use this knowledge to be aware of what to look for before you buy, and then be proactive in preventing the kind of leaks that might damage your deck. Because there are alot of other good reasons to sail an HC......
COMING SOON.....This will be my take on what I've seen in Asian boats.....the good and the ugly. I initially thought the criticisms of Taiwan/Hong Kong boats was just sour grapes, and I was determined to keep a clear head. After all, I almost bought one. But, after you have seen firsthand what others have been talking about it is clear that much of the criticism is accurate. Not that they can't be dealt with and used as great cruising boats, but there ARE lapses in quality that will cause you grief.....later.