Do you know if your model of boat was ever sold without teak decks? If a none teak deck was never an option then its possible the deck construction relied on the teak for some stiffness. I do however, think this is unlikely
I use a Protimeter ’sonic’ style damp meter on my balsa cored deck very successfully to find damp areas. As you say, it is relative readings that are important
Again agreed. If the "Professional" you are using is a "teak deck fitter" he is not going to give a fart if you have delamination as long as it looks pretty and he gets paid. You need to get a proper moisture survey of the deck first. Frankly if its very bad and flexing underfoot even that may only give you a general idea of the problem areas. I have in my time repaired quite a few dodgy decks. If it has an obvious area of deflection its almost certain there is a problem. Frankly I would remove headlining in that area and start by removing a small area of inner skin if you can. (like about 2" square) to examine the core. Usually the best plan is to test areas like that to determine the extent and nature of the problem. The repair necessary will depend on what you find. Sometimes its just a localised problem but while not wishing to frighten you I have seen at least 4 boats where the only solution was to remove most of the inner skin, remove the crap, thoroughly clean the bottom of the outer skin and replace the foam on crestomer paste or some other suitable paste adhesive before relaminating the inner skin. Of course if you are planning to replace teak deck in the areas affected you could reverse the process and work from above leaving the inner skin intact. The advantages here would be that working downhand is much easier, you will get rid of all the holes in the outer skin and the "new" outer skin will be covered by teak so you won't see it. Don't worry about gel coat. you only need that for cosmetic reasons. For my money I would then replace with imitation plastic teak and glue the stuff down rather than screw it. Either way its either an extensive DIY project or a job for a good yard professional with experience in this kind of repair. Sorry to be the bearer of bad tidings but amateur bodge ups rarely last long and it wont be solved by half measures......
I couldn't agree more. I knew a guy that had a Jeaneau that had a soft deck once the yard removed the old teak deck. The yard drilled some cores and the whole deck was saturated although the deck was only soft in a few spots. They ended up removing the whole outerskin of the deck and replacing the core. It was a big job. You wouldnt want to put a new deck on top of a soaked core. Its needs proper investigation first
That may have been true of your old boat, but this is a GRP boat which had options of plain or teak laid deck - look at the photos. The teak deck is thin planks glued on. No structural value at all. Nothing like the construction you describe. The concern here is that water has got into the sandwich deck which may be causing the springiness.