17/02/2026
Hi again… we’re back!
And that can only mean one thing — it’s time to give West Wind another go.
This time, though, things are different.
I’ve decided that failure simply isn’t an option. However many attempts it takes, my goal remains the same: to autonomously sail a boat from the UK to Norway.
But instead of patching and tweaking the old design, we’re starting over — a complete redesign from the keel up. Every weak point from the last attempt is being analysed, improved, or eliminated entirely.
And the most likely culprit from the first voyage?
Water ingress through the prop shaft.
So it seemed only natural to begin with a total rethink of the propulsion system.
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The New Propulsion Concept
This time, I’ve opted for a fully enclosed thrust pod mounted beneath the hull rather than a traditional prop shaft passing through it.
That decision brings some major advantages:
1. Cleaner water flow – The propulsion unit sits lower in the water, away from surface turbulence and hull wash, improving efficiency.
2. Lower centre of gravity – By placing weight below the waterline, the boat gains additional stability in rough seas.
3. Engineering challenge – Because apparently sailing across the North Sea autonomously wasn’t difficult enough.
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The Thruster Pod
This is, without question, the most complex component I’ve ever designed and built.
It took months of work in Fusion 360 — literally hundreds of design iterations — followed by hundreds of hours on the lathe machining the final parts. Every tolerance mattered. Every measurement had consequences.
The pod is based on magnetic torque transfer.
Here’s how it works:
• The motor drives a gear train with a 4:1 reduction ratio.
• That turns an outer rotor, lined with high-strength neodymium magnets.
• Between the outer rotor and the inner assembly sits a precision-machined aluminium bulkhead — just 0.25 mm thick — forming a complete physical barrier between the wet and dry sides.
• On the inside of that barrier sits the inner rotor, also lined with neodymium magnets, connected to the output shaft and propeller.
The key idea is simple in theory, but extremely demanding in practice:
Torque is transferred magnetically through the aluminium wall.
No shaft passes through the hull.
No rotating seals.
No direct water path into the boat.
The thin bulkhead acts as a permanent waterproof barrier, while the magnets transmit rotational force across it.
Before committing to machining, I ran shear strength calculations to ensure the 0.25 mm wall could withstand the pressure and mechanical stresses involved. It’s thin — almost unbelievably thin — but strong enough for the job.
In essence, we’re spinning a propeller on one side of a sealed wall, driven purely by magnetic coupling from the other side.
It’s difficult to explain fully in a post, but the cross-section diagram should help make sense of it.
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This redesign isn’t just about fixing what failed.
It’s about building something stronger, smarter, and more seaworthy — something capable of finishing what West Wind started.
Round two begins now.
