Crossing the Port Alfred Bar at Dusk
You intend to enter the Kowie River at Port Alfred in a 9 m twin-outboard ski-boat. It is 17:50 in mid-winter. The tide tables show high water at Port Alfred at 18:30, spring range. The river mouth has a shallow bar with breaking swell reported by the harbour office, and the ebb begins about 30 minutes after high water. Your boat draws 0.7 m. The sea outside is a 2.5 m SE swell with a 15 kn onshore wind. You have two crew, one of whom is nervous and has never crossed a bar. The harbour is 3 nm away and you are low on fuel - enough for about 45 minutes at planing speed.
1. Assess the tide and sea state and decide whether to cross now, wait, or stand off. Justify your decision with reference to the tide and swell.
Read the worked answer
Tide assessment: HW is 18:30, spring range. The safest water over the bar is around HW, when depth is greatest. The ebb starts about 30 minutes after HW, so from about 19:00 onward the ebb will oppose the onshore swell and steepen the bar sea - the classic dangerous bar condition. Crossing 'just after' HW is therefore the worst choice.
Sea state: A 2.5 m SE swell with a 15 kn onshore wind onto a shallow bar produces breaking waves in the entrance. A 9 m ski-boat can handle this only with good timing and speed; a nervous crew member increases risk.
Decision: Do not attempt an immediate crossing in the last of the ebb. Either:
- Stand off in safe water and wait until the flood has built enough depth and the bar has settled (typically 1–2 hours before the next HW), then cross on the flood with the swell and wind behind you; or
- If fuel does not permit standing off for hours, head for the nearest safe alternative harbour rather than commit to a bar crossing in deteriorating conditions at dusk.
Bottom line: The combination of ebb, spring range, onshore swell and a nervous crew argues strongly against crossing now. Waiting for the next flood, or diverting, is the seamanlike choice.
2. Assuming you decide to wait and cross on the next flood, list the concrete preparations and briefings you would carry out before committing, and how you would handle the nervous crew member.
Read the worked answer
Preparations:
- Confirm from the harbour office or local knowledge the current state of the bar and any recent soundings.
- Check fuel: if the wait is long, conserve fuel by slow steaming; identify the nearest fuel or alternative port.
- Rig: life jackets on all crew, kill-cord attached, engine checks, bilges dry, loose gear secured, radio on and monitored (VHF 16 and the local port channel).
- Brief the crew on what will happen: the approach, the speed, the possibility of taking water over the bow, and what to do if the engine fails (anchor ready, life raft/floatation, mayday procedure).
- Identify a transit or leading marks for the entrance and note the swell direction so you can time the run between sets.
Handling the nervous crew member:
- Acknowledge the fear openly and explain the plan in plain language - uncertainty feeds anxiety.
- Give them a simple, concrete job (e.g. calling the set, watching for breaking waves, holding the radio) so they have a role rather than feeling like a passenger.
- Position them where they can see what is happening and where you can reassure them.
- If they remain unable to cope, do not force the crossing; the skipper's responsibility is to the safety of all on board, and a diversion is a legitimate decision.