Those things were dreadful, we had two when I was at Bosham Sailing School in Sussex as an instructor during the summer and boat repairer/maintainer during the winter. No one like sailing them during the summer and yours truly found them hard to repair during the winter. Back in the 1970's surplus US drop tanks were readily available and bought by the hundred for floating jetties, houseboat floats and even boats proper. Trouble with them, and those Tod built dinghies, was that the resins of the day did not key with the glass fibre, no matter what we tried to do thus permanent repairs and conversions proved to be next to impossible.