The way that fire spread so quickly does make me wonder if there was some "accelerant" involved.
Fibreglass burns rather well.
In the 70’s, my parents bought a 16’ cabin cruiser to see if canals and boating could be the family holiday and hobby. It was soon apparent that:
1) We all enjoyed canals, rivers and boating
2) A 16’ cabin cruiser was way too small for a mainly of five
The next step was to sell the plastic boat and use the cash (plus some) to buy a 40’ steel narrow boat hull. We sold the cabin cruiser locally and the new owner kept it at the same place. Soon afterwards, it was stolen and taken 200 yards up the cut and set alight. All that remained was the stainless steel sink - the fibreglass hull just burnt to nothing very quickly - including the parts below the water line.
The next day, we viewed the sad remains and my mother (always the tactful member of the family) announced in a very loud voice “The idiot didn’t have it insured”. There was silence. Of 30+ boats at Longwood boat club (including some nice 50’ narrow boats), ours was the only one that was insured.
