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I also believed that the grooves were there to prevent slipping. Apparently this is not the case. In the case of grooved boards, there is less wood in contact with the foot than with a smooth surface. In fact, having visited other countries (some where there is often a great deal of rain), and that use deck a great deal, None of them have used grooved deck. And, every ship I have ever been on (many), has smooth deck boards. Removing water and dirt is very much easier from a smooth surface. In my opinion all deck is slippery when wet.
Having done quite a bit of research into this subject, it would appear that the manufacturers of deck made one side grooved in order to improve moisture removal from the underside, and the fact that grooves made slipping less likely was a misunderstanding. It is not a matter of being trendy. My previous deck was grooved and was extremely slippery as it was so difficult to keep clean, and it was treated wood.
I will take a look at the link relating to fastenings and see if this is something I could use. When I say I don't want to see the screws, I don't just mean I don't want them standing flush with the deck surface, I don't want to see them at all if possible.