If its the 'Select' mortise lock, rectangular in shape, wide flat lock bolt, black plastic knob on inside, key outside, secured with 4 bolts in the corners, then that is the same as the one fitted to my FP
Maldives and FP Athena and several other FP
boats. If this is the case, then there have been several posts on this forum to locate
replacements and get spare keys. To be honest, these locks are pretty poor and fall apart internally, once causing me to break into my own
boat. The only thing near I have found similar but of much better quality in the UK is below
SMALL MARINE SURFACE MOUNTED / RIM LOCKS