I have built a Night Heron Single, a Night Heron Double, a 4.5 metre single of my own design and a 5 metre single of my own design.

I have used one layer of 125 gsm (4 oz) glass inside and outside on all of them with a couple of extra layers on the inside of the deck behind the cockpit and where my heels rub on the hull.

I have had all of them except for the double on the ocean a few times and they all survived. The NH single is about 6 years old and would have been used for an hour or two every week in that time.

For my 60kg weight and the way I use them, I would not consider anything other than just one layer of 125gsm everywhere.