These guys are just across the Channel:
Marine Engines. Sales, Spares, Service and Repair, French Marine Motors - UK
Here's a list of European Yanmar distributors:
Yanmar Europe | List of distributors
Though there's a French listing, their site only mentions Cummins.. Good luck!
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)