Rules of the Road at Speed

Prerequisites

You should know the International Regulations for Preventing Collisions at Sea (COLREGs) at the level expected for Powerboat Level 2 and Intermediate Powerboat: the steering and sailing rules, basic lights and shapes, and sound signals. The Night Pilotage lesson in this course covers recognising vessels by their lights, and the Radar and AIS lesson covers collision avoidance by radar and Rule 19 in restricted visibility. This lesson focuses on how the rules apply when you are the fastest vessel on the water.

Learning Objectives

By the end of this lesson you should be able to:

Calculate closing speeds and the time available to act when a fast boat meets other traffic (RYA syllabus: collision regulations, application at speed).
Apply Rules 5 to 8 (lookout, safe speed, risk of collision, action to avoid collision) on a planing boat (RYA syllabus: collision regulations).
Apply Rules 13 to 17 (overtaking, head-on, crossing, give-way and stand-on) when your speed is much higher than other vessels (RYA syllabus: collision regulations).
Navigate safely in narrow channels and near traffic separation schemes under Rules 9 and 10 (RYA syllabus: collision regulations, pilotage).
Comply with local speed limits and control your wash (RYA syllabus: passage planning, local regulations).
Show the correct lights for a powerboat at night, and recognise the lights of others (RYA syllabus: night passage, lights).

RYA Syllabus Map

Syllabus item	Section
Collision regulations: application at speed	Closing Speeds
Collision regulations: Rules 5 to 8	Rules 5 to 8 on a Fast Boat
Collision regulations: Rules 13 to 17	Who Gives Way: Rules 13 to 17
Collision regulations: narrow channels and TSS	Narrow Channels and Traffic Separation Schemes
Local regulations: speed limits	Speed Limits and Wash
Night passage: lights	Lights for Powerboats

Closing Speeds

Why speed changes everything

Most collision situations at sea develop slowly. Two yachts at 6 knots on converging courses, seen at 2 miles, give each other about ten minutes. A powerboat at 30 knots closing head-on with a 15-knot ferry closes at 45 knots: 2 miles in under 3 minutes.

The quick formula: time to meet (minutes) = distance (miles) × 60 ÷ closing speed (knots).

Your speed	Other vessel	Situation	Closing speed	Time to close 2 miles
30 kn	Yacht 6 kn	Head-on	36 kn	3 min 20 s
30 kn	Ferry 18 kn	Head-on	48 kn	2 min 30 s
30 kn	Ship 12 kn	Crossing at right angles	about 32 kn	3 min 45 s
30 kn	Yacht 6 kn	Overtaking	24 kn	5 min

At 30 knots, you cover a mile every 2 minutes, a cable every 12 seconds, and a boat length of 8 m in about half a second.

The consequence: decide early

A fast boat has two advantages: it can change course and speed almost instantly, and it can move out of the way of almost anything. The danger is that the time to see, decide and act is short. The response is to look further ahead, to decide earlier and to act boldly in a way the other vessel can see.

As a working rule on a planing boat, identify all vessels within about 3 miles ahead, decide by 1 mile at the latest whether any risk of collision exists, and complete your avoiding action well before half a mile.

Rules 5 to 8 on a Fast Boat

Rule 5: Lookout

Every vessel must keep a proper lookout by sight and hearing, and by all available means (radar, AIS, VHF) appropriate to the conditions.

On a fast boat:

Look all round, not just ahead. Faster craft (other RIBs, ribs on sea safaris, personal watercraft, fast ferries) can overtake you.
The sector ahead is hard to see when the bow rises coming onto the plane. Trim the bow down and slow down if necessary.
Spray, wind and vibration blur vision. Wear eye protection if needed; clean screens and goggles.
Engine noise means you cannot hear sound signals. Look for whistle steam, flashing lights or a vessel turning.
Allocate a lookout on longer passages, as in the Preparation for Sea lesson. The helm is concentrating on the sea and cannot also scan 360 degrees.
Low objects such as kayaks, swimmers, divers and pot buoys are almost invisible at speed in waves. Slow down near beaches, harbour entrances and dive sites.

Rule 6: Safe speed

Every vessel must proceed at a safe speed, so that it can take proper and effective action to avoid collision and be stopped within a distance appropriate to the conditions. Rule 6 lists factors to consider, including:

Visibility.
Traffic density, including concentrations of fishing vessels.
Manoeuvrability, especially stopping distance and turning ability.
Background light at night, such as shore lights.
Wind, sea and current, and the proximity of hazards.
Draught in relation to available depth.

Note that safe speed is not a fixed number. For a powerboat, 30 knots may be safe in open water in good visibility and very unsafe in a crowded harbour, in fog, or at night near unlit pot markers. Reduce speed whenever you cannot see far enough ahead to stop or turn in time.

Rule 7: Risk of collision

Every vessel must use all available means to decide whether risk of collision exists, and if there is any doubt, assume that it does.

Steady bearing, decreasing range means risk of collision. Take a compass bearing of the other vessel, or line it up against a fixed part of your boat (but only if you hold a steady course and speed).
Large vessels and close range: even with an appreciably changing bearing, there may still be risk. A ship's bow may pass clear while its stern does not.
At 30 knots, you may have only seconds between bearings. Using the radar EBL and AIS CPA (closest point of approach) helps, as covered in the Radar and AIS lesson.
Do not assume on scanty information, especially scanty radar or AIS information.

Rule 8: Action to avoid collision

Any action must be:

Positive: clear and decisive.
Made in ample time.
Large enough to be readily apparent to the other vessel visually or by radar. Small, repeated course changes are not.
With due regard to good seamanship.

A course alteration is often the most effective action if there is enough sea room. A reduction in speed, or stopping, may be needed to allow time or avoid a close-quarters situation. Check the effectiveness of the action until the other vessel is finally past and clear.

On a fast boat, a turn of 60 degrees or more is usually needed to be obvious. A planing boat altering 10 degrees is invisible to a ship's watchkeeper half a mile away. Similarly, coming off the plane drops your wash and bow, which other vessels see clearly.

Who Gives Way: Rules 13 to 17

Rule 13: Overtaking

A vessel coming up with another from more than 22.5 degrees abaft her beam (so that at night she would see only her stern light) is overtaking and must keep out of the way. This applies whatever the type of vessel: a powerboat overtaking a sailing yacht or a fishing boat must keep clear.

On a fast boat you will be the overtaking vessel most of the time.

Give the boat being overtaken a wide berth. Your wash can capsize a dinghy or knock a yacht over.
Do not cut across the bow of the vessel you have passed until you are well clear.
Overtaking does not end when you are alongside: you remain the give-way vessel until finally past and clear.

Rule 14: Head-on

When two power-driven vessels meet on reciprocal or nearly reciprocal courses, each alters course to starboard so they pass port to port. By day, you see the other vessel's masts in line or nearly so; by night, you see both sidelights or masthead lights in line.

At high closing speeds, alter boldly and early. A small alteration to starboard by you and a small alteration to port by the other vessel (which happens when a watchkeeper misreads the situation) can lead straight into collision.

Rule 15: Crossing

When two power-driven vessels are crossing with risk of collision, the vessel which has the other on her own starboard side keeps out of the way, and should avoid crossing ahead of the other.

As a powerboat with plenty of speed, the usual way to give way is a bold alteration to starboard, passing astern of the other vessel. If you choose to slow down instead, do it decisively so the change is obvious.

Rule 16: Give-way vessel

Take early and substantial action to keep well clear.

Rule 17: Stand-on vessel

The stand-on vessel keeps her course and speed. She may act once it becomes apparent the give-way vessel is not taking appropriate action, and must act when collision cannot be avoided by the give-way vessel alone. A power-driven stand-on vessel taking such action should, if possible, not alter to port for a vessel on her own port side.

For a powerboat, standing on is harder than it sounds. A fast boat that holds its course must judge the moment to act with very little time. If a ship is not giving way, act early: alter to starboard, or turn away and stop. Use five short blasts if you can (and if the other vessel can hear them), and VHF if you can identify the ship by AIS.

Rule 18: Responsibilities between vessels

Remember that as a power-driven vessel underway, you keep out of the way of vessels not under command, restricted in their ability to manoeuvre, engaged in fishing and sailing vessels, except where Rule 13 (overtaking), Rule 9 (narrow channels) or Rule 10 (TSS) say otherwise. Also avoid impeding a vessel constrained by her draught.

Narrow Channels and Traffic Separation Schemes

Rule 9: Narrow channels

Keep as near to the starboard edge of the channel as is safe and practicable.
A vessel under 20 m and a sailing vessel shall not impede the passage of a vessel that can safely navigate only within the channel.
Do not cross a narrow channel if this impedes a vessel which can navigate only within it.
Avoid anchoring in a narrow channel.
Use the overtaking signals (two prolonged blasts followed by one or two short) in a channel where the overtaken vessel must take action to allow you to pass.
Approaching a bend where other vessels may be hidden, navigate with particular alertness and caution, and sound one prolonged blast.

Most powerboats are under 20 m, so you must not impede large vessels in channels. In practice, that means staying out of the deep-water channel, crossing it at right angles quickly, and running outside the buoyed channel where depth allows. Many harbours, such as Southampton and Portsmouth, have local rules creating moving prohibited zones around large ships; for example, the Southampton Moving Prohibited Zone extends 1000 m ahead of large vessels and 100 m to each side. Learn the local rules from the harbour authority before you go.

Rule 10: Traffic separation schemes

TSS are found in busy areas such as the Dover Strait. They divide traffic into lanes separated by a separation zone.

Use inshore traffic zones where available: vessels under 20 m, sailing vessels and fishing vessels may use them.
Avoid crossing a TSS if possible. If you must, cross on a heading as nearly as practicable at right angles to the general direction of traffic flow. Note that it is the heading that is at right angles, not the track over the ground; this gives ships the clearest picture of your intentions and minimises the time you spend in the lanes.
Do not impede a power-driven vessel following a traffic lane (vessels under 20 m and sailing vessels).
Keep out of the separation zone except in emergency, when crossing, or when fishing.

On a fast boat, a TSS crossing is quick, but the traffic is fast too. Before crossing, look for gaps in the AIS picture, call the VTS if required, and cross briskly on the right heading without stopping in the lane.

Speed Limits and Wash

Speed limits

Many UK harbours and rivers have speed limits, usually through the water, set by local byelaws. Common examples are 6 or 8 knots in harbours and rivers, and lower in moorings. Some beaches have speed-restricted swimming zones marked by yellow buoys, often 5 knots or less within a set distance of the shore. Penalties apply, and harbour masters can and do prosecute.

Check the harbour authority's website or the almanac for limits before you go.
Speed limits are usually through the water. With a 3-knot stream against you, your speed over the ground will be much lower than the limit.
Speed limits are a maximum, not a target. Rule 6 still applies.

Wash

Your wash can do real damage: capsizing small boats, throwing people around on moored boats, damaging pontoons and eroding banks. You are responsible for damage caused by your wash.

The worst wash is at hump speed, as the boat climbs onto the plane. A boat at 10 to 12 knots, bow up and stern down, makes a much bigger wash than one fully planing or at displacement speed. If you must slow down near other boats, come right off the plane to displacement speed.
Look behind you at your wash, especially in narrow rivers.
Pass moored boats, dinghies, kayaks and divers slowly and as wide as possible.

Lights for Powerboats

The Night Pilotage lesson covers recognising lights and the arcs of each. This section concerns the lights your own boat must show.

Lights for a power-driven vessel under 50 m (Rule 23)

A masthead light forward, white, showing over 225 degrees ahead (from right ahead to 22.5 degrees abaft the beam on each side).
Sidelights: red to port and green to starboard, each over 112.5 degrees.
A stern light: white, over 135 degrees aft.
On vessels under 20 m, the sidelights may be combined in a single lantern on the centreline.

Concessions for small powerboats

A power-driven vessel under 12 m may show an all-round white light and sidelights instead of the separate masthead light and stern light. This is the arrangement on most RIBs and sports boats.
A power-driven vessel under 7 m whose maximum speed does not exceed 7 knots may show just an all-round white light, and should show sidelights if practicable.
Many fast powerboats under 7 m cannot use the 7 m concession because they are faster than 7 knots, so they must show sidelights.

Practical points

The all-round white light must be high enough to be visible above the console, people and the outboard cowl. A light hidden behind the helm's head is not all-round.
At planing trim, the bow rises; low sidelights can be blocked by the tubes of a RIB.
Back-lighting from the shore can hide your lights against the shore lights. Consider how others see you.
Don't run with deck lights or a searchlight on: they ruin your night vision and others' ability to read your lights.
Do carry a waterproof torch to show to other vessels, and to light up your hull if you think you have not been seen.

What others see

Remember that at 30 knots your lights are those of a small powerboat, which other vessels expect to be travelling at perhaps 10 knots. A watchkeeper may badly misjudge your speed and the time available. This is another reason to keep well clear at night, and to slow down near other traffic.

Worked Example: A Crossing at 28 Knots

You are on a 9 m RIB at 28 knots, heading 180 degrees across a busy estuary approach. Visibility is good. Your lookout reports a large ship fine on the starboard bow, about 3 miles. The AIS shows a container ship of 200 m, course 270, speed 14 knots, with a CPA of 0.1 miles in 6 minutes.

Assess. The ship is on your starboard side and crossing. Under Rule 15, you are the give-way vessel. Under Rule 9 (if you are in or near the channel) and local regulations, you must not impede her. The CPA of 0.1 miles confirms risk of collision; the bearing is steady.

Options.

Alter boldly to starboard, about 90 degrees, to head 270 and run parallel to her course until she is past, then resume.
Slow down to displacement speed, let her pass ahead, then continue.
Speed up to cross ahead. This breaks Rule 15 (avoid crossing ahead), and if you have an engine problem halfway, you are under the bow of a ship that cannot stop for a mile.

Decision. You choose option 1, early. At 3 miles there are about 6 minutes; at 2 miles you make a 90-degree turn to starboard. The ship's officer sees your bow swing and your wake change: your intention is clear. After two minutes the ship passes ahead of you at well over half a mile; you resume your course, passing well astern of her and keeping clear of her wake, which can be steep at the stern of a large ship.

Note. If you had been in a channel with a moving prohibited zone, you would have had to keep 1000 m ahead and 100 m to each side, so the same action would have been needed earlier.

Common Mistakes

Not looking behind. Fast boats overtake, but faster ones may overtake you.
Small alterations. A 10-degree turn at speed is not obvious to anyone; make it 60 degrees or more.
Crossing ahead of a ship to save time.
Treating the rules as if everyone else gives way to a fast boat. When overtaking, you always keep clear, even of a ship.
Running in the deep-water channel in front of large vessels, or loitering in a TSS lane.
Slowing to hump speed near moored boats, which creates maximum wash.
Forgetting speed limits are through the water.
Showing only an all-round white light on a fast boat under 7 m. The 7 m concession only applies if maximum speed does not exceed 7 knots.
Assuming you have been seen at night, when your lights are hidden by back-lighting or by your own crew.

Summary

At planing speed, closing speeds are high: 2 miles can close in 2 to 3 minutes. Look further ahead, decide by about 1 mile and act early.
Rule 5: keep a 360-degree lookout and use all means. Rule 6: safe speed depends on visibility, traffic, sea state and stopping distance. Rule 7: steady bearing and decreasing range means risk; if in doubt, assume risk. Rule 8: act early, positively and boldly.
Rule 13: an overtaking vessel keeps clear of everything it overtakes. Rule 14: head-on, both alter to starboard. Rule 15: the vessel with the other on her starboard side gives way and avoids crossing ahead. Rules 16 and 17: give-way vessels act early and substantially; stand-on vessels hold course but must act if collision cannot otherwise be avoided.
Rule 9: small vessels keep to the starboard side and must not impede vessels restricted to a channel. Rule 10: cross a TSS on a heading at right angles, and use inshore traffic zones.
Obey local speed limits (through the water) and keep your wash down by coming off the plane completely.
Powerboats under 12 m may show an all-round white light and sidelights; only those under 7 m with a top speed of 7 knots or less can show only the all-round white.

Check Your Understanding

You are at 32 knots, heading towards a fast ferry at 20 knots on a reciprocal course, 3 miles away. How long until you meet?

Answer: Closing speed is 52 knots. 3 × 60 ÷ 52 = about 3.5 minutes.

Why must a planing powerboat make large alterations of course?

Answer: Rule 8 requires action large enough to be readily apparent to the other vessel. A small alteration at speed is hard to detect by eye or radar; 60 degrees or more makes your intention clear.

You are overtaking a sailing yacht on a fast RIB. Who gives way and until when?

Answer: You do, under Rule 13, until you are finally past and clear. This overrides the normal rule that power gives way to sail, because overtaking applies whatever the type of vessel.

A ship is crossing from your port side with a steady bearing. What is your role, and what may you do if she does not give way?

Answer: You are the stand-on vessel and should keep your course and speed. If it becomes apparent she is not taking action, you may act, avoiding a turn to port for a vessel on your port side. If collision cannot be avoided by her action alone, you must act. Sound five short blasts and call on VHF if possible.

How should you cross a traffic separation scheme?

Answer: On a heading as nearly as practicable at right angles to the general direction of traffic, briskly, without impeding power-driven vessels in the lanes. Avoid crossing if possible and use inshore traffic zones where available.

In which part of a narrow channel should you navigate, and what must you avoid?

Answer: As near the starboard edge as is safe and practicable. As a vessel under 20 m, you must not impede a vessel that can safely navigate only within the channel, and must not cross if this impedes such a vessel.

Why does slowing to 10 knots near moored boats often make your wash worse?

Answer: At 10 to 12 knots most planing boats are at hump speed, with the bow up and stern dug in, which creates the largest wash. Come right off the plane to displacement speed instead.

Your 6 m RIB has a top speed of 40 knots. Can you show only an all-round white light at night?

Answer: No. The concession for an all-round white light only applies to power-driven vessels under 7 m with a maximum speed not exceeding 7 knots. You must show sidelights and an all-round white light (the under 12 m option).