As a former associate of the National Sea Rescue Institute in South Africa, I’ve long taken an interest in shore-based life-saving boats and small craft. The wild waters off South Africa (home of some of the world’s largest and most dangerous ‘rogue waves‘ on and around the Agulhas Bank) were – and still are – possibly the greatest test of seaworthiness outside a full-blown hurricane (which they frequently resemble). One’s life-saving boats had to be able to stand up to them, otherwise one would soon need rescuing oneself!
I was therefore interested to read of a new and revolutionary lifeboat design about to be deployed by Britain’s Royal National Lifeboat Institution. The RNLI’s Shannon class lifeboat is currently undergoing final pre-production testing, and will begin its lifesaving duties next year. The Telegraph reports:
Cocking opens the throttles on the twin 650bhp Scania turbodiesels and spins the impellers up to full power. The Shannon, the newest, lightest and fastest all-weather lifeboat in the Royal National Lifeboat Institution (RNLI) fleet roars in approval, but goes absolutely nowhere. Around the hull you can see water being thrown in every direction, yet the twin Hamilton water jets are merely fastening the Shannon’s hull deeper in the water. With a flick of helm and the “bucket” controls, Cocking drives the boat almost imperceptibly sideways and backwards through the water, while the engines howl. This would be impossible with a conventional, propeller-driven craft.
It’s that incredible manoeuvrability that makes the Shannon so special and allows the RNLI to predict with confidence that the 50 examples it plans to build in the next decade (replacing its old Mersey-class vessels) will in their time rescue more than 56,000 people and save more than 1,500 lives.
The Shannon came from a hull design by a young RNLI naval architect, Peter Eyre. Very much a lunchtime project, his radical hull shape was accepted and tested in tanks at Gosport and in open water. Eyre had done his homework, putting the lessons of the previous Severn, Trent and Tamar-class lifeboats into his high-bow design. He even went out with the crews.
“You can’t start to design a lifeboat without knowing what it’s going to go through,” he said. He has the dubious distinction of being the first man to be seasick on the Shannon. His design was a good one, though, showing 70 per cent fewer slams in rough seas than the experimental hull design, 53 per cent less traverse movement and a third less vertical movement. As a fast and manoeuvrable, but stable, working platform, Eyre’s design was the best.
“You probably wouldn’t be starting with water-jet propulsion if all you wanted was straight-line speed up to 25 knots,” says Brook. They are less efficient than more conventional ducted propellers at lower speeds, but they do several clever things. They separate power from steering, so you can have the engines giving everything while the clever buckets on the water-jet outlets divert thrust equally fore and aft. They also offer the chance to drive at full speed at a lee shore in a gale and simply fly up the sand or shingle out of harm’s way.
Cocking tells a tale of an early trial of the flying lifeboat. “We’d got the all-clear and steamed in,” he says. “The beach had been cleared but they’d missed this fella walking his dog. It was perfectly safe, but you should have seen his face when 18 tons of lifeboat flew up the beach.”
There’s more at the link. Here’s a video clip showing the new design’s high-speed beaching abilities. Its waterjets are tucked well out of the way, allowing it to ‘surf the sand’ in remarkable fashion.
Here’s another showing the new design undergoing capsize testing. Note how the waterjets are carefully placed out of the way of obstacles, and the keel extends well beneath the hull and waterjets to protect them from beach sand during landing.
Congratulations to all concerned in bringing the Shannon class to its present state of development. I wish I’d been able to use something similar in my younger, more active days!
If any of my UK readers are feeling generous in this post-Christmas season, the RNLI is still about £1.2 million short of its fund-raising goal to begin production of the Shannons. It’s a cause I strongly support, from my own experience; and I hope you will too.