Hello.
Show players cannon compatibility before purchase. This means if player is in Lynx and he selects 32Lb carronade, it should show in red text on the bottom of selected item(item is not compatible with your ship class). Player can still buy it, but message would ask Are you sure? I had few cases like this when I first started, made wrong purchases and ended up with useless cannons and money wasted. Don't let this happen to new players.
Thanks.