• The Seaward 39 is a bespoke old-school semi-displacement boat based on a well-proven design that cuts through rough weather with ease.  
  • It is a wet boat, but that does not matter as it is built to deal with that. 
  • While being hugely tough, it offers a degree of luxury and technology that makes long passages more enjoyable.

Seaward 39
Greg Copp heads down Southampton Water for a roller-coaster ride in the new Seaward 39 …
If you have a passion for semi-displacement boats you will understand the ambiguity in the name Seaward Nelson. Seaward are one of several low-volume yards that in the last 50 years have built formidable semi-displacement boats using a Nelson design – in this case the Nelson 42. Probably the most successful all-weather hull in its class, this narrow, round-bilge pilot boat design was the creation of Peter Thornycroft, founder of TT Boat Designs, home of the Nelson. Since the 1960s, this design has remained relatively unchanged, though in 1990 the 42 mk2 gained 15 inches in the beam and a fuller bow with greater flare. These subtle changes improved the boat’s manners and created a template from which many boats bearing the Nelson name would emerge.
Built by the Seaward yard on the Isle of Wight, the Seaward 39 is the latest Nelson incarnation, still with input from TT Boat Designs. Just to add a little more confusion, it is not a 39-footer but a 42-footer. They do build a 42-footer but that is based on a 45ft Nelson hull. It is blatantly a Nelson with its low blue topsides, ribbed in teak and armoured with the traditional thick D-section fendering. Like many Nelson designs, this boat is hugely bespoke. In fact, there are no fewer than five accommodation variations, all with a variety of different options. The Seaward 39 is not built around maximising living space; if it was, it would not have a 3.96m beam. However, the space it does give you for relaxing, cooking, sleeping and eating is realistic inasmuch as most designs recognise the need for a good galley in a boat that is likely to tackle long passages. Seaward go to great lengths to get the internal design spot on, as every boat’s interior is built in a full-scale MDF mock-up to give the customer and themselves a true sense of how the boat will feel internally before construction starts.
Behind the wheel of the Seaward is very much a new take on an old theme. It is laid out with a traditional little ship’s wheel, mounted in a relatively low vertical position, and the surrounding dash area is, of course, wood rather than laminate. However, there is a variety of modern flat screen displays facing you, which you need to sit down and take on board before you start the engines.
The first thing that strikes you is the virtual lack of noise. Mike Burnham of Seaward went to some length to explain to me about the sound-insulating system used on the Seaward 39. Without wanting to go into laborious detail, I will say that the carpet, floor and sound insulation – some 65mm thick – sits on a 13mm sound-absorbing membrane mounted on a 102mm aluminium box section frame, itself filled with sound damping. A high-volume Vetus wet exhaust system further reduces engine noise. Below 8/9 knots it is not impossible to believe the engine is not running, and at 15 knots, a realistic semi-displacement cruising speed, life still feels very relaxed.
Before I got a chance to sample the quieter aspects of the Seaward’s cruising credentials I grasped the opportunity to see what a Nelson hull is all about. The previous night it had been blowing at over 30 knots for 12 hours, and Bramble.net was still recording 30-knot winds an hour before we headed down Southampton Water. Approaching Calshot, Graeme the photographer was snapping the finer points of the lower deck – until the maelstrom of confused water relegated him to the cockpit with a face like a green bean. Like any good Nelson, the Seaward easily penetrates heavy seas – it is the beauty of its design. Its narrow beam and sharp flared bow with a deadrise angle of 45 degrees are the key ingredients behind its bullet-like penetration. With no chines or spray rails, you would think that its round-bilge form would not generate enough dynamic lift to pick up and run into such weather with a healthy turn of speed, but it does.
We were running at 20 knots with a northerly on our stern in what was a very lively roller-coaster ride. If you spend most of your time in planing boats, then in weather like this your ears are tuned for complaint, and your eyes drawn to the next wave. However, driving the Seaward 39 is a very different experience as you simply settle down in the shock-absorbing leather seat to a totally stable and slam-free ride. It has just that perfect amount of forward buoyancy to easily compose itself after coming down off each wave. One aspect of modern technology that has benefited the Seaward 39 is its Humphree Interceptor automatic trim tabs. These work a treat – you can see just how quickly they react by the LED meters on the systems display panel, and there is an inclinometer that tells you how many degrees of trim you have on the bow. They do not just keep the bow down when powering up or running at speed, as they were pretty good at countering the beam sea off Calshot. The faster you go, the more effective they are, and if need be, you can quickly manually override them. They will never match the likes of a Seakeeper gyroscopic stabiliser at low or zero speed (which you could fit in the lazarette), but considering how simple they are, Humphree Interceptors are impressive bits of kit, and a must for any serious sea boat.
Even in a following sea, the Nelson hull lives up to its reputation for a wet ride, but you really do not come to terms with its submarine-like characteristics until you have the sea on the beam or bow. This boat has the most serious set of windscreen wipers I have come across, which go into overtime keeping the three windscreens clear. Being multi-speed, they work well when running into mild weather, as we did later on. And the intermittent settings are perfect for dealing with the sporadic greenies that this hull will inevitably serve up. To a point, the Seaward provides a softer and more stable ride the faster you go, though I imagine a force 8 could take its toll on you. But then pilots frequently go out in all weathers in Nelsons.
This boat is powered by twin 370hp Yanmar 8LV 370s. These are fairly compact and light, and have a healthy power delivery, developing 590ft/lb of torque at just 2200rpm. You can certainly feel it, as the response to the throttles is very good for a semi-displacement boat that is 15 tonnes fully loaded. The Seaward 39 is off in a brace of shakes and past 20 knots before you realise it. However, between 17 and 20 knots, life feels relaxed, and with the boat running in this upper sweet spot, the fuel consumption is slightly less punishing on your bank account. It had no problem topping 24 knots, and you do not get the feeling that you have to squeeze it to get there. Thanks to some serious rudders, she is also pretty sprightly in the turns.
The Nelson design is based on a low freeboard and deck line, so there is limited height in the engine bay, which for the short V8 Yanmar is not an issue. Access is via a hatch in the cockpit, just forward of the lazarette hatch. For major servicing you will need to lift the saloon floor panels. Forward deck movement does not have the luxury of external guard rails until you pass amidships. It does, however, have substantial coachroof grab rails, which, given that the side decks are not that wide, is probably not a bad idea. The forward deck area on this particular boat had internal and external guard rails – a serious big-sea option. Indeed, all the deck hardware was about as serious as you could get.
This boat, based on one of the five accommodation formats, offers two sleeping cabins, a long galley and one large heads. Compared to many modern contemporary designs focused on providing accommodation, this does not seem generous for a 42ft boat. However, this is not the focus of the Seaward, which anyone looking to buy one probably understands. This boat has a long, superbly finished galley that will appeal to anyone looking to stretch their cruising legs. The heads opposite also has no hint of compromise, as it has a full-size separate shower compartment. There are other options offering two heads (one en suite) and a second below-decks dinette, for example, but there is a trade-off in terms of the heads and galley department. The forward master cabin in the boat we tested has a V berth, which can be replaced by an island berth if need be, but the galley is slightly smaller as a result. All versions have an identical mid-cabin layout in the form of two single berths, standing headroom in the doorway and a hanging locker.

The Seaward 39 is a bespoke old-school semi-displacement boat based on a well-proven design that cuts through rough weather with ease. It is a wet boat, but that does not matter as it is built to deal with that. While being hugely tough, it offers a degree of luxury and technology that makes long passages more enjoyable. In particular, it is very quiet as a result of the design input on soundproofing, to the point that at displacement speed you can be forgiven for thinking that the engines are not running. Seaward describe their 39 as ‘the ultimate sea boat in the most refined way’, which is not far off the mark. Mechanically, it benefits from using relatively short V8 engines, which in turn, with the use of V drives, benefits the living accommodation without compromise. Such a beautifully crafted boat, of course, does not have a moderate price tag, but it will always have a hard-core following regardless.

Fuel Figures
Twin Yanmar 8LV 370hp with V shafts (Yanmar fuel flow metering)
RPM          Speed (knots)      NMPG    Trim (degrees)   SOUND (dB)
1000                5.7                     5.55         0.0                     60
1250              6.8                     3.93         0.0                      60
1500              8.0                     2.74         1.5                      62
1750              9.1                     1.95         2.0                      65
2000            10.0                     1.40         2.5                      67
2250            11.2                     1.10         3.0                      67
2500            12.8                     1.05         3.5                      70
2750            15.2                     0.90         3.5                      71
3000            17.5                     0.90         3.5                      74
3250            19.7                     0.85         3.5                      76
3500            22.2                     0.80         4.0                      77
3750            24.2                     0.75         4.0                      78
All performance/consumption readings taken over a two-way average. Sound readings taken at the helm.

What We Thought

  • Granite-like construction
  • Practicality
  • Low sound levels
  • Superb fit and finish
  • Good steering response for a semi-displacement boat
  • Good performance


  • Needs more space to stand at the helm


  • LOA: 12.81m
  • Beam: 3.96m
  • Draught: 1.22m
  • Power options: 5.46L Yanmar 8LV 370hp on V drive shafts
  • Fuel capacity: 2 x 1000 litres
  • Water capacity: 463 litres
  • Displacement: (Full payload of fuel and water) 15 tonnes
  • RCD category: A
  • Test engines: Twin 5.46L Yanmar 8LV 370hp

  • Performance

24.2 knots – sea conditions F4 with 50% fuel

From: £682,000 (inc. VAT)
As tested: £750,000 (inc. VAT) – extensive specification

1 Prospect Road
Isle of Wight
PO31 7AD

Photo credits: Graeme Main

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