World’s Coolest Boats: MarySlim – sharp, slender, and piercingly cool

Each month we pick out an iconic boat that can lay claim to the title of world’s coolest boat. This month, we take a closer look at the MarySlim

The biggest obstacle to high-speed offshore boating is the topography. Conventional wisdom suggests that the route to high speed is to use hydrodynamic lift to skim the boat across the surface; the planing hull. And it works well – a flat-bottomed boat on flat water skates effortlessly across the top like a skimming stone.

Unfortunately, it also delivers a back-breaking ride if there is anything more than a ripple on that surface – and there usually is!

To combat this, naval architects bend that flat surface into a vee, helping it cut into the bumpy stuff, and broadly speaking, the deeper the vee, the better it cuts, although inevitably the deeper it gets, the less lift there is and therefore the more drag.

The sharp, slender hull was designed to slice straight through waves. Photo: Lloyd Images

But what if you ignored the need to compromise and made the hull so sharp and pointy that instead of cutting into the waves as it goes over them, it simply slices straight through them?

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Well, this was the thinking of experienced mariners Richard and Mary Reddyhoff when they commissioned MarySlim.

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Adrian Thompson came up with the hull design, Nic Bailey the styling, and she was built by Multimarine Composites in Millbrook, Plymouth, and launched in 2007.

Although 73ft long, she is just 13ft 9in wide, and an astonishing 8ft 9in at the waterline. A 72ft Princess at 18ft wide rather puts those numbers into perspective. Of course the accommodation isn’t quite at Princess levels, but that’s not the point – the point is demonstrated best by the wheelhouse glazing.

The windscreens are 17.5mm thick and designed to withstand a pressure of 284kg per square foot! Because if you plan to travel straight through a wave rather than over it, you need to know that you’re not going to end up wearing it!

Nic Bailey and Adrian Thompson were responsible for MarySlim’s design and styling. Photo: Lloyd Images

Fed from a nearly 3,000-gallon diesel tank, a single huge 32-litre Caterpillar diesel puts 1,650hp into the Kamewa waterjet drive for a top speed of 34 knots and a cruising speed of 25 knots.

Out at sea, the ride is spectacular. When we tested the boat, we described hitting waves at 30 knots with knees braced for impacts that simply never came.

The Reddyhoffs have owned her ever since, reporting “regular trips to France and the West Country, and longer cruises to the Baltic, Scotland and Ireland including a 320-mile, 30-knot run, catching one tide all the way, from Ijmuiden to Portland. Other daylight mileages of 200 to 250 miles are more normal.”

The boat also set a world record from Portland to Rockall and back, taking just over 53 hours.

MarySlim specifications

Year: 2007
LOA: 22.5m
Beam: 4.2m
Power: Caterpillar C32 1,650hp diesel engine
Speed: 34 knots
Price when new: £1.5 million

To submit your suggestion for the world’s coolest boat, head over to the MBY forum.


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