£100k refit: How I turned an old pilot boat into the world’s fastest Nelson

Former airline pilot and serial boat owner Jonathan Napier set about turning his Nelson 40 into the fastest of its kind, but could he break the 30-knot barrier?

I’ve always had a thing about Nelson 40s. The first one I bought back in the mid-1980s was an ex-Abu Dhabi police launch that could only be described as a wreck. I found it lurking at the back of an industrial boat yard on Hayling Island. In fact there were two of them but one had a Nelson-shaped hole in the side from a previous encounter with its stablemate.

Even the undamaged one was in a right old state; the hull was delaminated, the superstructure was rotten, it was full of water and none of its systems or fittings were salvageable – not even the machine gun mounting points on the flybridge and foredeck. More’s the pity – there were times when they could have come in handy on a summer’s day in the Solent!

Still, something must have convinced me to buy it and spend several years of my life restoring it to its former glory. I was a newly qualified airline pilot at the time and must have bored my colleagues witless with my plans. Even now when I bump into them they often ask me whether I ever finished “that MTB you were working on years ago?” Shows how much they were really listening!

Flying on fumes

How I didn’t get tetanus from rebuilding that rotten old wreck, I still don’t know but a combination of youthful zeal and a bloody-minded refusal to admit defeat eventually paid off. The rebuild took five years and more money than I care to admit but it was done to a very high standard and the end result was a lovely boat that gave us ten years of safe, enjoyable cruising.

In that time we got through two sets of engines; initially a pair of secondhand 210hp Sabres and then, when the budget allowed, a pair of brand new Perkins Sabre M225Tis. Both gave us 21 knots flat out with a comfortable cruising speed of 18 knots.

Although these figures are quite respectable in the Nelson world, I personally found it frustrating being overtaken not just by all manner of planing boats (planing boats are considered very inferior in the Nelson world) but also by the Portsmouth pilot Nelsons, which had been re-engined with more powerful lumps and ploughed past us at embarrassingly faster speeds.

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At one point I actually considered fitting a pair of gas turbine engines to show them who was boss. An engineering contact had access to old helicopter engines; Allison 250s with 420hp on tap in a remarkably compact package. Imagine what they would have sounded like on start up in the marina!

The only downside was the fuel burn at sea level – 37 gallons per hour per engine, roughly double the amount of a similarly powerful diesel engine. Fortunately, I had a very sensible co-owner, who vetoed the idea – hence the reason we ended up with the Perkins Sabre 225s.

Sowing the seed

This wasn’t my first boating experience, however, my story started 20 years earlier in the wet fore cabin of a 24ft Yachting Monthly Eventide in the Bosham Channel in the late 1960s. My Dad proudly showed us his new purchase after a car-sick inducing 4-hour drive down from Cambridge (yes, it really took that long in the 1960s!)

We settled down for the night, and being five years old I slept like a log only to wake up drenched and newly aware of the flaws in buying old boats with leaky decks. Quite why this didn’t put me off boating in favour of sensible hobbies like golf or foreign holidays, I do not know, much to my wife’s regret!

In fact, I think this experience sowed the seed for my urge to rebuild old classics throughout the rest of my boating career. After I sold that first Nelson in 1999, I bought a Fairey 28. She was a true classic with racing pedigree but a rather fragile hull (in un-rebuilt state) as my re-engining and high-speed plans revealed!


Team 747 competing in Jonathan’s Fairey Spearfish during the Round Britain race

Her near sinking and sale allowed the purchase of another Fairey, this time a Spearfish called Miss Daisy, which a few of us campaigned as Team 747 in the 2008 Round Britain Race and a couple of subsequent Cowes-Torquay-Cowes races.

Once I’d got the racing bug out of my system, I bought a Nicholson 55 sailing yacht. Quailo III was a stunning craft, built in 1971 to compete in the Admiral’s Cup race. I found her languishing in Ireland in a poor state and proved powerless to resist her charms.

After eight years of gentle refurbishing and pleasurable sailing in the UK, France, and Ireland, I sold her in 2018 and had to decide what to tackle next. I’d done powerboat racing and cruising under sail, perhaps it was time for another Nelson but this time with bigger engines so we could cruise faster and further?


Vigilant spent her early years as a pilot boat before being converted for leisure use

Perhaps I could finally scratch that itch and not just match those Portsmouth pilot boats but beat them. In fact, why not aim higher still and try to create the fastest Nelson 40 ever built? According to my research no other Nelson 40 had yet topped 30 knots and that didn’t sound like a particularly big number.

The trouble is that getting a semi-planing Nelson to reach that speed is no easy task because of the sheer quantity of water it shoves aside as it ploughs through the waves. The upshot is a magnificent ride through choppy seas; they just keep on going through anything.

I recall one particular occasion off Portland Bill a few years back when we burst through a big wave and fell into such a deep trough that the entire boat was airborne. When we landed, all the drawers in the galley came out making enough noise to waken the dead but the boat itself simply carried on untroubled!


Work begins outside

Vigilance pays off

The hunt for a suitable project boat began in earnest. I inspected two boats and dismissed them both; one was too far gone, the other had serious osmosis. Then the Nelson Boat Owner’s Club Secretary Steve Brenner told me about another possible option called Vigilant.

She was for sale on the Isle of Wight with a modest asking price that would allow for a greater rebuild budget. I already knew of the boat having sold the previous owners the old Ford Sabre engines from my Fairey Spearfish, Miss Daisy, in 2002.

The important thing was that she had received an osmosis treatment in the past and the hull was epoxied right down to the laminate. After a bit of to and fro we agreed on a price and arranged for her to be brought to Foulkes Yard on the Hamble to remove the engines and start stripping out any unnecessary junk.


Once inside the deck could be removed

Initially she was placed outside on the hard with a small polythene shed over the cockpit to create a sheltered work space. It soon became clear that this wasn’t a practical solution so when the next shed became available we moved her indoors. Trying to repair rot in the deck in a light drizzle was never going to end well.

The initial plan for repowering her was to find a pair of secondhand Cummins QSB series engines with good old-fashioned mechanical injection pumps and injectors we could tune up. The benefits were that core industrial engines were cheap and plentiful and we just needed to find marinising parts for QSBs.

I found several of the major ancillaries in the USA, had them shipped to my hotel in New York and then carried them back from my layovers there.

The wheelhouse stripped bare

It was a fascinating project and just the sort of thing I really like getting stuck into but the amount of work in just getting the boat back up to scratch meant I didn’t have the time to give the engine project my full attention too. A change of plan was necessary.

I still had a contact for Yanmar engines from my racing days and after a bit of string pulling, two factory refurbished Yanmar 440 6LYs with Twin Disc MG 5601a gearboxes were winging their way to me.

The gearboxes were actually big lumps of rust in need of a complete rebuild but were so far gone that they were donated to the project free of charge. Their availability turned out to be very fortuitous.

The new coachroof takes shape

We were limited to 1.5 inch shafts by the P-brackets so we needed the gearboxes’ 1.75:1 ratio in order to keep the torque within limits. They were also down angle which gave us a
very low profile engine installation. Just as well, as the boat was originally designed with Perkins HT 6.354 horizontal engines so there wasn’t a lot of height available.

Clearing the airways

Another issue was working out how to funnel enough air into the engine room. The clam shell air intakes on the side of Nelson wheelhouses look good but have two disadvantages; they are prone to letting in spray and they need a wide ducting inside the wheelhouse to channel the air down into the engine room (this also makes them difficult to soundproof).

Because of the Nelson’s work boat origins, it has unusually wide side decks and a relatively narrow wheelhouse so we didn’t want to sacrifice any more interior space for that ducting. Instead we moved Vigilant’s air intakes into the aft cockpit. They allow air down into the bilges which then flows forward through a tunnel into the midship’s engine room.


Lifting the new Yanmar 440 6LY’s into Vigilant’s re-designed engine room

The end result is much quieter and keeps the engine bay dry. The other reason she is so quiet is that we spent a small fortune commissioning a bespoke eight-inch-diameter exhaust system from Halyard Marine with massive silencers, custom built bends and the highest spec sound-proofing available. You can now hear the chattering of the fuel pumps coming up the Morse cables to the control head!

Incidentally, I only found out recently why the Nelson pilot boats have such wide side decks. I had always assumed it was to allow plenty of work space and a bigger safety margin for the crew when boarding the ships but it’s actually to stop the top of the wheelhouse hitting the ships’s sides when it rolls around in the swell!

Staying true to its roots we decided not to retrofit guard rails around the deck. They were never used on the pilot boats and the sturdy inner grab rail was functional and more aesthetically pleasing.


It’s a tight squeeze but down-angled gearboxes helps reduce the clearance needed

Besides, you rarely want to be on deck whilst underway due to the spray and provided you take a little extra care when mooring or at anchor it’s perfectly safe and easy to move along the side decks.

As most of our cruising will be done as a couple, we fitted her out to make her as comfortable as possible for the two of us. The fore cabin has two berths and there are two further convertible bunks/seats in the wheelhouse. A decent heads with shower and a good galley ensure we can live aboard quite happily for up to three weeks at a time.

Obviously, she still has around half or possibly even a third of the accommodation that a modern 40-footer would have, but that is not what the Nelson 40 was built for.

All smiles on sea trials

Room for two

At the helm, I applied the tried and trusted KISS principle (Keep It Simple Stupid!). A Sailor RT144 VHF is appropriate to the age of the boat. A basic Raymarine plotter, radar and autopilot give me all the information I need and are definitely NOT integrated.

Aviation has taught me that the fewer buttons something has the harder it is to operate. Touch screens are also a bête-noire for me. Trying to operate a touch screen when rolling and bouncing around with the added complication of wet fingers has always seemed the height of madness.

I’m convinced that their widespread adoption has come about simply because they are cheaper to make and the marketing people love them rather than for any practical reason.

Helm has been kept as clean and simple as possible

Nelsons are known for being wet boats and they certainly throw a lot of spray out sideways as a by-product of the fine entry bow sections needed to cut through the waves in rough weather. Cruising at 15-21 knots, as most Nelsons do, the wind conspires to bring a lot of that spray back across the boat.

To help deal with this I had always fancied a pair of Wynn straight line windscreen wipers but cost was an issue. Luckily, we found a pair in the Chandlery Barge that were about a foot too long.

Judicious use of a hack saw, engineering skills and powder-coating has given us a pair of beautifully refurbished and robust wipers fit for many more years of reliable service.

Fully refurbished and ready for launch

Speed trials

When the time came to relaunch Vigilant and see if we had achieved our goal, it was with a fair degree of apprehension The two competitors for the title of world’s fastest Nelson 40 were Horatia and Debonair. Horatia had 400hp CATs and Debonair had Sabre 370s so our 440hp Yanmars were comfortably ahead of the pack for power.

Horatia was raced in the 1960s by Commander Peter Thorneycroft and rumour has it that she used to be capable of 32-35 knots. However, two Nelson old-timers, who were heavily involved with her early years, suggest that in reality she only ever achieved 30 knots once and then only for a few seconds when the engineer was sent below with a screwdriver to breathe on the fuel pumps. Sadly, she is currently out of commission and unlikely to return any time soon.

Debonair is a beautiful boat commissioned by a well respected Nelson enthusiast in the late 1980s. She was in fact the inspiration for what Vigilant has become, albeit on a much tighter budget.

Debonair is now based in Southern Ireland and has been re-engined with Yanmar 390s. When I had a quick run in her a few years ago she managed just 27 knots – a little short of the claimed 30 knots when launched with her original less powerful engines.

So is it fair to claim Vigilant is the fastest Nelson 40? During sea trials in Southampton Water at slack water, two consecutive runs in opposite directions achieved a GPS measured speed over ground of 30 knots in each direction. I’ll let you draw your own conclusions, suffice to say that I am more than happy with that.

Since then we have cruised as far west as Falmouth, visiting places we have never stopped at before – not an easy remit after so many years in the area. We discovered West Bay, the River Yealm and, hard to believe we’d never been before, the Helford River!

Custom-built exhausts and refurbished woodwork

Ironically, last year we spent the whole summer at 8 knots eking out one tank of fuel as long as possible since diesel had just topped £2 a litre. I can still remember my first tank of Nelson fuel costing a mere 19p a litre back in 1989! This summer we’re planning three weeks in Amsterdam and the Ijsselmeer.

Counting the cost

The most enjoyable part of these projects for me is always the machinery and systems. I claim no expertise and have no formal engineering training, but with guidance from experts when needed and a basic engineering sense, the reward of seeing these things come together is hugely satisfying.

Fortunately, for all other areas of the refit there is my long-term friend and boatbuilder Fred. He is officially retired but seems to enjoy (or at least put up with) my mad ideas and is the secret behind the success of all these flights of fancy. Thank you Fred.

Polished props and shafts

Thanks also to Pete Farmery, with whom I shared Quailo lll. He has done such a beautiful job of all the electrics, that they could be put on display at a boat show!

The total cost of the refit has been just north of £100k, almost half of which was spent on the drive train and ancillaries. Whether I’d see that money back again if I sold her is hard to say. Her survey and insurance valuation is £100k but it was never my intention to make money by refitting her. I never have before so why break the habit of a lifetime?

What I do know is that I’ve already had a lot of fun creating something that not only suits my personal needs to perfection but will hopefully go down in the record books as one of, or perhaps even, the fastest Nelson 40 ever built.

First published in the September 2023 issue of MBY.

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