IRPCS stands for the International Regulations for Preventing Collisions at Sea. Getting the exact meaning of the acronym wrong is a common error - don't beat yourself up if you clicked the wrong answer by mistake. The important thing is that you have a strong working knowledge of which rules apply to you and others, and how to act on them in real life.

This is actually true! IRPCS sit below the authority of local governments and port authorities. Therefore, those organisations can lay down their own set(s) of byelaws to govern how we navigate our vessels. Really common examples are requirements for VHF check-ins by larger vessels or increasing the rights of ferries restricted by timetables. The key thing is to always check local laws and regulations before transiting a new port.

This is a tricky one: all of the answers are broadly true for dinghy sailors, and may be taught as a good rule for sailors when learning basic IRPCS. However, under IRPCS Rule 12B, the windward side of the boat is considered to be the side opposite to which the mainsail is carried - essentially opposite the sail.

Understanding your responsibility when in command of a give way vessel is crucial. You must, according to Rule 8 make a 'positive' alteration to course in 'ample time' while observing good seamanship. According to Rule 16 (governing give way vessels) you must make 'early and substantial' action. In reality, this could mean altering your course considerably or reducing your speed. Whatever action you take, it must be apparent to the vessel you are avoiding so as to avoid confusion.

Rule 17 states that stand on vessels must maintain her course and speed, allowing the give way vessel to take avoiding action. If it becomes clear that the give way vessel has not taken substantial enough action to avoid a collision, then the stand on vessel must take avoiding action herself.

The key thing to remember is that you are a 'stand on' vessel. You do not have right of way over anyone else, at any point. Failure to observe your responsibilities as a stand on vessel could land you in hot water - in the same way as failing to observe your responsibilities as a give way vessel could.

This is a sailing scenario, and both boats are on different 'tacks' meaning their mainsails are carried on different sides of their boats. The boat on the right has its sails on the port side of the boat, and is therefore said to be on 'starboard tack'. The boat on the left has its sails on the starboard side, and is therefore on 'port tack'. Under IRPCS, sailing boats on port tack must give way to boats on the starboard tack.

This is a classic trick question. We're all familiar with the rule that power gives way to sail, and that the overtaking boat keeps clear. However, when the two situations combine with a sailing vessel overtaking a powered vessel, people get themselves in a twist. Rule 13 clearly states that regardless of whether the vessels concerned are sail or power-driven, the overtaking vessel is the give way vessel, and must therefore keep clear. This makes sense with the advent of really fast sailing dinghies and catamarans, many of which will travel faster than the average cruising powerboat!

The difference between a vessel being 'under way' and 'making way' is all about fastening and propulsion of the boat. Any time the vessel is not tethered to the surface of the Earth (via an anchor, mooring line or being aground) it is considered to be 'under way'. Once it has begun to propel itself it can then be considered to be 'making way'. Beware - a vessel making way is not necessarily the same as a vessel under command.

1100 yards is the maximum distance for poor visibility, which is equal to 1.01 kilometres. Therefore, if you have 1 kilometre or less of visibility on the water, you are operating in restricted visibility conditions.

Traffic separation schemes keep very large vessels apart from one another at safe distances. In small powerboats and sailing craft, you should, as a general rule, keep well clear. However, should you need to cross one, and you cannot navigate around it, you must do so at right angles to the scheme, even where this is disruptive to steering your course.

Lights, other than the specified night lights in the rules, may not be used on your vessel between sunrise and sunset. HOWEVER, there is an exception for: "lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper look-out." (Rule 20B).

This means you can have lights on other than your navigation lights, but must be aware of their effect on your ability to navigate your vessel safely (back scatter) AND the potential for confusion for other vessels. If you are concerned about either of these, consider switching extra lights off.