Module 17 of 17
Marine Environment
Responsibility for avoiding pollution and protecting the marine environment.
Your Responsibility
As a skipper you have a legal and moral responsibility to protect the marine environment. The sea is not a dustbin — everything that goes overboard has consequences for marine life, water quality, and coastal communities.
The MARPOL Convention (International Convention for the Prevention of Pollution from Ships) sets global standards. As a recreational skipper, you must be aware of your obligations regarding oil, sewage, garbage, and harmful substances.
Key Points
- Skippers have legal responsibility for pollution prevention
- MARPOL is the international convention governing marine pollution
- Both intentional and accidental discharge can result in prosecution
Oil and Fuel Pollution
Even small quantities of oil or diesel can cause significant environmental damage. A single litre of oil can contaminate a million litres of water. Never pump oily bilge water overboard — use absorbent pads in the bilge and dispose of them ashore.
When refuelling, take care to avoid spills. Use an absorbent collar around the fuel filler. Do not overfill tanks. If a spill occurs, contain it immediately and report it to the harbour authority.
Key Points
- Never discharge oil or oily water overboard
- Use absorbent pads in the bilge
- Take care when refuelling — use a collar, don't overfill
- Report any spill to the harbour authority
Sewage and Waste Water
Discharge of untreated sewage is increasingly restricted. Many harbours and estuaries are 'no discharge' zones. Use holding tanks where fitted and pump out at designated facilities ashore.
If the vessel has a marine toilet (heads) that discharges directly, only use it well offshore and away from bathing waters, shellfish beds, and environmentally sensitive areas.
Key Points
- Use holding tanks in harbours and coastal waters
- Pump out at designated shore facilities
- No discharge in harbours, estuaries, or sensitive areas
- Direct discharge only well offshore if no holding tank
Garbage Disposal
Under MARPOL Annex V, the discharge of ALL garbage into the sea is prohibited, with very limited exceptions. Plastics must NEVER be discharged at sea. Food waste may only be discharged more than 12 nautical miles offshore, and only if ground to pieces smaller than 25mm.
In practice, the simplest approach for recreational sailors is to bring all waste back to shore. Separate recyclables and dispose of everything properly at marina waste facilities.
Key Points
- Plastics — NEVER discharge at sea
- Food waste — only >12nm offshore, ground to <25mm
- Best practice — bring ALL waste back to shore
- Use marina recycling and waste facilities
Tip: Carry spare bin bags and a dedicated waste container. It takes almost no effort to bring rubbish ashore, and it makes an enormous difference.
Protecting Marine Wildlife
Be aware of marine mammals (dolphins, seals, whales) and avoid disturbing them. Maintain a safe distance — at least 100m from whales and 50m from seals hauled out on rocks. If dolphins approach your boat, maintain a steady course and speed; do not chase them.
Seabird colonies are especially vulnerable during breeding season (typically April–August). Avoid anchoring close to nesting sites and keep noise to a minimum. Be aware of Marine Conservation Zones (MCZs) and Special Areas of Conservation (SACs).
Key Points
- Keep 100m+ from whales, 50m from hauled-out seals
- Do not chase or encircle marine mammals
- Avoid seabird nesting sites during breeding season
- Be aware of MCZs and SACs
Responsible Anchoring
Seagrass beds (Zostera) are critically important marine habitats that provide nursery grounds for fish and food for wildlife. Anchoring on seagrass can rip it out and cause damage that takes years to recover.
Where possible, use moorings rather than anchoring. If you must anchor, choose sandy or muddy bottoms and avoid areas marked as seagrass beds on charts. Weigh anchor carefully to minimise dragging across the seabed.
Key Points
- Avoid anchoring on seagrass beds (Zostera)
- Use moorings where available
- Choose sandy or muddy bottoms for anchoring
- Weigh anchor carefully to minimise seabed damage
Anti-fouling and Boat Maintenance
Anti-fouling paint prevents growth on hulls but many older formulations contain toxic substances (particularly tributyltin, TBT, which is now banned). Use only approved anti-fouling products and follow manufacturer guidelines.
When cleaning or maintaining your boat, prevent paint scrapings, solvents, and cleaning products from entering the water. Use designated boat maintenance areas with proper drainage and collection systems.
Key Points
- Use only approved anti-fouling products (TBT is banned)
- Prevent paint and solvent from entering the water
- Use designated maintenance areas with proper drainage