The teak deck leaks. A 7mm layer of teak screwed down onto white silicone from 1983; then a grp sandwich with a vinyl foam in the middle. It’s hardly surprising it leaks.. So, replaced the sikaflex black strips (and deepened grooves) this summer. I omitted the edge sealing and the more difficult curved sections which I will replace shortly. In the meantime I will fit these small drains into the deckhead (the inside of cabin, mounting onto the bottom layer of grp in the “sandwich”. This should reduce any water build up inside sandwich, make a catchment for any water and, crucially, allow me to measure ingress proving the effectiveness or otherwise of further deck remedial work. We shall sea.