I'm not sure what gross tonnage has to play with it as that is not really associated with displacement, nor solar power or abacuses but as I'm interested in this in the background I also worked out from curiosity beforehand it was somewhere about 30kg from what I could glean on-line from the model dimensions or the real thing but I might have been a bit high on guestimate block co-efficient. Never the less, a very impressive model it will make. I continue to watch in the background thanks! It reminds me standing watching the big boats moored at Peterhead (Denholm), while I was a few minutes quayside mobbing my adjacent DSV on the north Breakwater.