Marine Environment

MARPOL is the international framework for preventing pollution from ships. Its annexes cover subjects including oil, sewage, garbage and harmful anti-fouling systems, and the relevant requirements are implemented in UK law. MCA guidance states that pollution-prevention legislation generally applies to pleasure vessels of all sizes, although equipment, certification and discharge provisions can depend on tonnage, voyage and number of people carried.

For a Day Skipper yacht, the robust operating rule is to stop pollution at source and return waste to shore reception facilities wherever practicable. That means knowing what can enter the bilge, how the toilet and holding tank are valved, where rubbish will be secured, which spill materials are aboard and whether the intended anchorage or maintenance area has special controls.

National guidance is not a permission that overrides the harbour, inland waterway, protected area or foreign jurisdiction being visited. Notices to mariners, harbour directions, signs, charts and current local guidance can add tighter limits. The skipper should brief the crew before the first refuelling, toilet use, rubbish disposal or anchoring decision makes the plan consequential.

MCA guidance says oil should be retained aboard for disposal to shore reception facilities. A small pleasure vessel is not normally required to install approved oily-water separating equipment, so its practical default is not to pump oily bilge water overboard. Find and stop the leak, recover free oil with suitable absorbent material or equipment and follow the marina or waste facility's disposal route.

Prevention includes a clean bilge that makes new leaks visible, a drip tray under the engine, sound hoses and joints, an accessible spill kit and a crew member who knows how to stop the transfer. Before refuelling, confirm the correct filler and expected quantity, extinguish ignition sources, close openings against petrol vapour where relevant and keep the nozzle attended. Slow the delivery before the tank is full; do not rely on fuel appearing at a vent as the stopping signal.

If fuel escapes, stop the transfer and close the source if that can be done safely. Raise the alarm, protect drains and water, deploy the facility's absorbent pads or booms, and contact the fuel berth or harbour authority immediately. Detergent, hosing, propeller wash or dilution spreads or disguises the pollutant rather than recovering it and may make the response more harmful.

MCA MGN 599 Amendment 1 explains that the UK sewage certification and equipment provisions it describes apply to ships on international voyages over 400 gross tonnage, or smaller ships certified to carry more than 15 people. It also states that those regulations make no specific sewage provisions for vessels below both thresholds. That distinction matters: the large-ship MARPOL discharge table must not be presented as though every small yacht has the same legal equipment regime.

The same MCA guidance gives clear best practice for smaller pleasure vessels. Return waste to shore where possible; use a holding tank if fitted and empty it at a pump-out station. If shore disposal is impractical, its UK advice is to empty a holding tank only more than 3 nautical miles offshore in open sea where dispersion is effective. A boat without a holding tank should avoid toilet use in poorly flushed estuaries, inland waterways, inlets and crowded anchorages by using shore facilities wherever possible.

That is a UK small-vessel baseline, not a worldwide permission. Harbours, inland waterways, protected waters and other countries can prohibit or more tightly control overboard discharge. Before departure, trace the valves, label the holding-tank positions, check capacity and pump-out availability, and make sure the crew cannot accidentally select an overboard route in restricted water.

The IMO summary of revised MARPOL Annex V says all garbage discharge is prohibited unless the annex expressly permits it. Plastics, synthetic rope, fishing gear, cooking oil, paper, rags, glass, metal, bottles and similar refuse are prohibited both outside and within special areas. Mixing garbage with another harmful substance applies the more stringent requirement.

Outside special areas and Arctic waters, comminuted or ground food waste that passes through a screen no larger than 25 millimetres may be discharged only when the vessel is en route, as far as practicable from land and more than 3 nautical miles from nearest land. Food waste that is not ground needs more than 12 nautical miles. In special areas and Arctic waters, qualifying ground food waste needs more than 12 nautical miles and the unground-food exception is not available. Additional requirements can apply.

A small yacht rarely gains enough operational value from those exceptions to justify sorting distance, area and processing at the moment of disposal. The reliable routine is to secure all rubbish aboard, separate recyclables and food where useful, prevent loose items escaping in wind and use the next suitable shore reception facility.

England's Marine and Coastal Wildlife Code tells motorised craft to stay under 6 knots at no-wake speed around marine wildlife and remain 100 metres away. Move farther away if an animal shows disturbance, and keep clear if more than two boats are already nearby. Do not chase, follow, crowd, circle, separate, touch or feed wildlife for a photograph or encounter.

If dolphins, whales or porpoises choose to approach and bow-ride, maintain a steady speed and direction and let them leave. A sudden turn towards the group, speed increase or attempt to prolong the encounter removes the animal's choice and can create propeller or collision risk. Other species, seasons, devolved administrations and local wildlife-watching codes may call for more separation than the England baseline.

MCZ and SAC are conservation designations, not identical blanket rulebooks. Each site protects specified features and can have different voluntary measures, byelaws, speed limits, anchoring controls or seasonal restrictions. The skipper must identify the site and read its current management information; the letters alone do not prove that every activity is prohibited or permitted.

Seagrass provides habitat, nursery areas, coastal protection and carbon storage. Current MMO guidance explains that an anchor and chain can uproot plants, expose roots, leave scars and fragment a bed. The risk is not only the point where the anchor lands: a swinging yacht can sweep chain across a wider area and a dragging anchor can extend the damage.

Before arriving, check current charts, notices, harbour information and available habitat mapping. Respect formal or voluntary no-anchor zones and use an appropriate visitor or advanced mooring system where provided. A mooring is not automatically suitable merely because it is empty; confirm its permission, capacity and condition in the normal way.

If anchoring is allowed and necessary, select a mapped or visibly clear bare substrate with enough depth, shelter, holding and swinging room. Lower the anchor under control, avoid searching for a clear patch by dragging, monitor the set and recover vertically as far as conditions and the boat allow. Safety remains decisive: habitat protection does not require accepting an unsafe berth, but it does require planning another safe location rather than knowingly damaging the bed for convenience.

The Merchant Shipping (Anti-Fouling Systems) Regulations 2024 apply to UK ships and to other ships in UK waters. Current MCA guidance lists organotin compounds acting as biocides and cybutryne as prohibited substances: organotin compounds must not be applied or reapplied, and a ship must not apply or reapply an anti-fouling system containing cybutryne. Older non-compliant systems can also create removal, barrier-coating or documentary questions that should be resolved with the yard, product record or MCA guidance rather than guessed.

For routine yacht work, use a product permitted for the boat and waters, follow its label and safety information, and keep purchase or application records. More biocide is not automatically better protection. Hull material, existing coating, intended water, launching schedule and local yard controls all affect the correct preparation and product choice.

The RYA's practical maintenance rule is Protect, Collect, Dispose. Use the yard's designated area, ground protection and extraction or wet methods specified for the job; collect scrapings, sanding dust and contaminated consumables; then use the yard or local waste route. Do not let rain, sweeping or wash-down carry residues into surface drains or the water, and do not assume a marina bin accepts hazardous paint waste.