Can AI help us sail through the Needles?

Almost back in the Solent, my old playground, and I couldn’t resist dusting off the chatbots to see how their sailing advice has improved since we first set off. AI is moving fast: large language models now double in capability every seven months, outpacing even computer chips. Copilot, now running on ChatGPT-4, has been my go-to lately. But how would it cope with tides at the Needles?

The Prompt

“Plan a trip from Weymouth to Lymington tomorrow. The yacht is 10m, averages 6 knots. Leave with the current, go safely round the Needles, and give waypoints.”

Copilot’s response looked solid at first glance: waypoints plotted, a 7–8 hour sail, and sound advice about slack or rising tide through the Needles. But there was a problem: the tide times were completely wrong.

When I checked against Reeds Almanac, high water Lymington was 10:50 BST, not 05:30 as Copilot suggested. To its credit, Copilot corrected itself when challenged.

Round Two – Enter Grok

Next I asked Grok. Cue an argument. Grok insisted high water was 04:33, told me Reeds was wrong, and even suggested I email them to complain! The cheek. After much back-and-forth, Grok tried to justify itself with tidal anomalies, double highs, and possible mis-sourced data. Only when I uploaded an official tide PDF did it finally yield – still no apology.

Different sources then threw up a mix of times:

• Tideschart.com: 08:21 and 11:16 BST

• WillyWeather: 10:54 and 22:08 BST

• Reeds: 10:50 BST

No wonder the bots were confused.

Lessons Learned – AI vs Tides

• Don’t get angry at chatbots – they’re just computers.

• Cross-check with official data (almanacs, charts, weather apps) or even feed it the data to work with.

• Ask it to explain reasoning: “Show me step-by-step how you worked that out.”

• Use it for options, not absolutes: e.g. “What are three safe alternatives if I can’t get through the Swellies at 10am?”

• Lean on it for planning (meal prep, kit lists, tide strategies), but verify execution.

Meanwhile, in the Real World…

While I was arguing with machines, Pete simply did what experienced sailors do: left at midnight, caught the ebb at Portland, and rode the flood into the Solent. Exactly as Copilot had recommended all along.

The human won this round. Svea slept through the whole thing.