Hitting an Object: Collision & Grounding
Immediate actions, damage assessment, and the consumables needed to keep your vessel afloat after an impact.
STOP · CHECK · ASSESS · ACT
The first seconds decide the outcome. Account for crew, kill a fouled engine, check for water ingress, and do not rip the boat off the object until you know whether it is plugging a hole.
Immediate Actions — First Minutes
Stay Calm & Head Count
Check immediately that all crew are safe and accounted for. Look for anyone thrown forward or overboard. Treat injuries first — a casualty takes priority over hull damage.
Kill the Engine if Fouled
If you suspect a line, net, or debris around the propeller, shift to neutral and shut down the engine immediately. Running a fouled prop bends the shaft and destroys the gearbox.
Do Not Power Off Blindly
If the hull is breached and resting on the object, do not reverse off immediately — the object may be plugging the hole. Removing it could open the breach and flood the boat. Assess first.
Check for Water Ingress
Open the bilge and floorboards. Look and listen for water. Note the rate — a slow trickle is manageable; a surge is an emergency. Check all through-hulls and seacocks for damage.
Check the Rudder & Steering
Try the helm. If the rudder is jammed, bent, or detached, steering is compromised. On a catamaran, check both rudders and the crossbeam connection. On a monohull, check the rudder stock for play.
Check the Rig
A collision shock can strain chainplates, shrouds, and the mast step. Scan aloft for anything loose. If rigging is compromised, consider dropping the sail to reduce mast load.
Sound the Depth
Check your depth sounder. If you ran aground rather than hit a floating object, note whether the tide is rising or falling — this decides whether to wait it out or act now.
Call for Help if Needed
If taking on water or crew are injured, call Mayday on VHF Ch 16. If the situation is serious but controlled, call Pan-Pan. Give position, vessel name, number of crew, and nature of distress.
Action by Severity
Minor — No Ingress
- 1Inspect hull above and below the waterline visually
- 2Check keel bolts, rudder stock, and through-hulls for play or cracks
- 3Run bilge pump to confirm no slow leak
- 4Proceed to nearest port at reduced speed, monitoring bilge every 15 minutes
- 5Haul out for professional survey at the next opportunity
Moderate — Slow Leak
- 1Drive soft wood bungs into damaged through-hulls from inside
- 2Apply underwater epoxy putty or repair tape over the crack
- 3Run all bilge pumps continuously and bail by hand if needed
- 4Reduce speed and head for the nearest safe harbour
- 5Keep crew on bilge watch for the entire passage in
Severe — Rapid Flooding
- 1Broadcast Mayday on VHF Ch 16 with position and crew count
- 2Deploy a collision mat — a sail or tarp forced over the breach from outside, held by lines, uses water pressure to seal
- 3Stuff cushions, blankets, or clothing into the breach from inside
- 4Run all pumps and buckets; all crew on bailing duty
- 5Prepare life raft and grab bag; abandon only if flooding exceeds pumping capacity
Grounding — Hard Aground
- 1Check tide direction — if rising, wait; the boat may float off
- 2Check hull integrity before applying power to free the boat
- 3Heel the boat to reduce draft (shift crew or swing boom out)
- 4Deploy a kedge anchor astern and winch off when tide rises
- 5Use engine in reverse gently — never force a grounded boat off rock
- 6If wedged on rock, wait for tide and professional salvage
Consumables & Spares to Carry
Soft Wood Bungs
Assorted sizes to plug damaged through-hull fittings from inside.
Underwater Epoxy Putty
Sticks to wet hulls, cures underwater. Fills cracks and small holes.
Dacron Repair Tape
Self-adhesive patches for hull and sail tears above the waterline.
Fibreglass Repair Kit
Resin, catalyst, and mat for structural patching. Mix only in a ventilated space.
Collision Mat / Drogue Sail
A tarp or sail forced over an external breach, held by lines, sealed by water pressure.
Bailing Buckets
At least two sturdy buckets — pumps fail, buckets do not.
Spare Bilge Pump Impellers
Pumps burn out running dry or on debris. Carry spares and the tools to fit them.
Kedge Anchor & Polyprop Line
Lightweight anchor and floating line to winch off a grounding.
Duct Tape & Hose Clamps
Temporary fixes for split hoses, loose fittings, and above-water leaks.
Inspection Mirror & Torch
To see into the bilge, behind engines, and under hull sections.
Tips & Best Practices
Collision Mat Diagram
A collision mat is forced over the breach from outside the hull and held by lines to the deck. Water pressure pushes it against the hull, slowing or stopping the inflow.