Sail Skills - ColRegs Free Guide to ColRegs (the International Regulations for Preventing Collisions at Sea, the IRPCS or Collision Regs).  Guidance covers all aspects with animations, pictures and diagrams.  Aimed at small vessel users but suitable for professional mariners.  Especially recommended for RYA examination candidates.
Every penny helps!
Boating Books
Rule 25 Sailing Vessel Underway  Animation:  under 7m and maximum design speed 7kts ColRegs Home>ColRegs>Lights & Shapes>Animations>Sail and Oars>Sailing Vessel Under Power Under 7m & 7kts Sailing vessel under sail and power based on sailing vessel under 7m & design speed of 7kts “propelled by machinery” of sailing vessels under sail and power back to top A sailing vessel under sail and power - displaying a cone, point downwards Vessels under sail and power Vessels under oars A small boat under oars Sailing vessels under 7m A sailing vessel (a dinghy) under 7m Sailing vessels under 20m A sailing vessel (a sloop) under 20m Sailing vessels optional lights A large vessel under sail showing optional lights on her mast Sailing vessels general A large vessel under sail