BOAT REVIEW Sea Blade 20

I first saw the Sea Blade some three years ago, when it was presented as a concept at an Auckland boat show. I knew instinctively it was something different, something that could change our expectation of how a boat should look and perform.
Conceived by Honolulu-based design group Navatek, the hull is designed with an ultra-fine-entry hull that feeds down to two entrapment tunnels through the midsection. This process creates a 15 percent reduction in wetted surface and greater lift – generating efficiency and speed.
Navatek’s original brief has a military origin to reduce injury and damage to equipment, which for the recreational boatie translates as a seriously comfortable and seaworthy boat.  This is achieved by the advanced hull design for dead rise and planing surface breaking the water in a manner to minimise shock G-force loading.
The company has extensive data to support the entrapment energy recovery in the Sea Blade design, where those tunnels funnel an aerated combination of water and air to act as shock absorbers. The greater the pressure, the greater the energy recovery, which when trapped in the hull is very efficient.

What does this mean for a Sea Blade owner? A hull that’s stable, efficient and sea-kindly but which also delivers ride comfort, speed, safety and performance. All this is a big ask in a single hull, and is almost the ‘holy grail’ of boat design.
When Charles Winstone, CEO of Auckland’s Lancer Industries, saw the Sea Blade design he could see the potential but understood that manufacturing would be limited by the custom-built nature of the original aluminium construction, plus the very high labour costs associated with the complex hull geometry.
But he realised that moulding the hull could reduce the production costs. So he negotiated the rights and set about developing a production 20-foot (6.35m) version of the Sea Blade for the local and export market.
Somewhat of a perfectionist, Winstone was adamant about getting the design and resulting mouldings 100 percent right. This is where the three years (and apparently a combined investment of US$3.5 million with Navatek) has come in.
Finally, he is satisfied and allowed us to have a play with his ‘baby’. The weather gods played ball and it was a fantastic day out on the water.

The boat shows a high level of attention to detail. Absolutely everything about it is perfect, from the quality of the finish (a mirror gloss), the perfectly-fitted Lancer custom decking (with Sea Blade logo in prominent locations), the custom-embroidered squabs, teak capping on the gunwales, beautiful stainless work and the impeccable powder-coated T-top.
But this is no show-pony. A baitboard, rod holders under the gunwales, tackle boxes tucked behind the helm backrest and massive wet lockers show this boat is set up for fun and does not mind getting dirty. The massive boarding platform further adds to the fun factor – and it also houses a livebait tank.

Clear doors slide neatly into their slots on either side of the transom, and they can be fully-removed to provide a true, walk-through flow right from the bow area past the central helm through to the boarding platform.
This is a multi-function boat, which will serve equally well as a hard-core water sports vessel, a family boat or a down-and-dirty fishing machine. The transom seat drops down when not required, opening up access to the bait board and the underfloor wet locker. Similarly, the helm seat can fold away, allowing the skipper the option of standing (with a cushioned back support) or sitting.
Speaking of the helm, this boat is seriously ‘blinged’ out. Front and centre is the Humminbird Onix 10 Si touch-screen chartplotter and fishfinder, with HD side imaging, down imaging and digital sonar processing.  That connects into an on-board NMEA2000 network, from where the CZone digital solution uses one simple display to replace an entire collection of individual switches.
The 225hp four-stroke Yamaha hanging off the back has the Command Link digital electronic control, connected through the Yamaha digital tachometer and speed/fuel displays. A Fusion MS-UD750 stereo sound system provides the beat, and an Icom IC-M304 VHF radio takes care of communication.

Anchoring duties are handled by the Maxwell anchor winch, combined with the AutoAnchor AA150 Rode Counter and remote-control FOB. This allows anchoring off a beach and then running a line back to shore, with the remote control used to bring the boat back in when climbing back on board.  After all this, the livebait tank pump, 60-litre freshwater tank and wash down/shower pump seem almost trivial.
Zipwake
And last but not least is the Zipwake gyro-stabilised dynamic trim control system. Almost worthy of an entire review of its own, this new-generation system provides much more than conventional trim tabs.
On the Sea Blade they are used to close the entrapment tunnels and create a more efficient water wedge, giving better balance and lift. With the gyro-controlled system they do this completely automatically, eliminating the need to continually tweak the trim tab settings.

As it turned out we had little need of this on our review day as conditions were about as perfect as they could be, and at speeds over 22 knots they are not required as the hull completely supports its own weight. The system also allows the skipper to adjust for uneven loads or compensate when towing water toys or similar.
So, enough of the talking – the question is, how does she perform? That is literally the million-dollar questions in this case, given the investment that’s been sunk into this hull design.
It’s impossible to ignore the stability – note that entire width of that boarding platform, sitting only about 100mm above the water, is visible from a following boat.
And there it sat – at 5 knots, 10, 15, 20, 25, even 30 knots, that platform stayed in pretty much the same position. The only thing that changed was the amount of white spray behind it. Under extreme acceleration the bow lifted slightly as the mid section of the hull came up on the plane, and at planing speeds the level was slightly higher out the water but little else changed.

Even when throwing the boat hard-to-port-hard-to-starboard, the platform’s angle changed very little, which is to say the boat hardly heeled over. This is very different to a conventional hull, which leans in towards the centre of a turn.
It is also different from most multihulls, which tend to lean slightly outwards, a motion which many find disconcerting. The Sea Blade however heeled in to the turn by no more than about 10 degrees, and then only at top-end speed.
Shoving the throttle forward, she takes off like a scalded cat. There was no dramatic “ok, we are now planing” moment – we simply rose evenly throughout the power range. This is no doubt due to the energy recovered by the aerated water in the entrapment tunnel, providing a soft rather than a sudden lift.
There were a couple of other boats around, and I found someone pushing a big wake. I hit this at over 30 knots. “Shloosh” is about the best description I can give of the sensation. There was no slam as we hit the wake, almost no lift and definitely no slam as we came down the other side.

Not quite believing it, I repeated the move – several times. The only time I got a noticeable roll was when I went over it at an angle, with one side lifting slightly before than the other. Yes, we did lift the bow slightly – but softly – and landed just as softly.
So, the hull definitely achieves ride comfort. How about efficiency? Although Winstone says he has seen 43 knots with two people on board, we got her up to 38 knots with a four people, a nearly-full tank of fuel, two full sets of dive gear, and a day’s worth of picnic gear, food and several water toys. At that speed, the big Yamaha was turning over at 5,500 rpm and drinking about 90 litres per hour, or around 0.7km per litre.
Mid-range was much more reasonable, and anywhere between 20 and 25 the consumption was a constant 1.0km per litre. The equated to the optimal rev range of around 4,000 – 4,500 rpm. We got the best planning-speed consumption at 18 knots (32km/h), when the consumption improved to 1.2km/l. At that rate the 200 litre underfloor fuel tank would have a range of just over 200km (115 nautical miles), while the optional 300 litre tank would boost that by 50 percent.
Sea Blade has some wetted surface comparisons of its hull versus conventional deep-vee hulls. These clearly show the reduced wetted area (and lower drag) across a range of speeds. Of course, actual usage will depend on load and conditions, and we were also testing this as the upper end of the recommended horsepower. But nothing indicates that the Sea Blade would not also perform adequately with a less grunty power plant.
In the perfect conditions it was hard to judge how much spray the hull would generate, but we certainly had no problem. The bulk of the spray from the central hull is trapped by the tunnels as part of the entrapment energy recovery system, and so only a relatively small amount from the chines is able to escape.
The photos seem to show that what minimal spray is generated is kept low and well away from the boat. The T-top centre console configuration provides limited shelter from showers, but enclosing clears could be added to provide some wet-weather shelter.

Winstone has a winner with the Sea Blade. It delivers everything promised, and then some. He is well aware that people seldom buy a boat based purely on the technology, and that a radically new design like this must also look good and be functional.
He has therefore invested the time and effort into making something that performs well but also looks beautiful, and will serve a multitude of uses. The fact that it rides like nothing else on the market and can go like the clappers certainly helps!/>