TOP OF THE PROPS
Hugo Andreae takes a look at a revolutionary new propeller said to be faster and more efficient than rivals
We report on a radical new tipless propeller that claims to offer more performance and better fuel economy
Aradical new tipless propeller is being touted as the single biggest advance in propeller design since the 1930s. Claimed to deliver significant fuel savings across all different types and sizes of craft as well as faster planing, higher top speeds, superior handling and reduced vibration, it sounds almost too good to be true. However, extensive sea trials carried out by US website boatest.com on the new Sharrow Propeller MX-1 seem to confirm all of the above and show efficiency gains of between 9-15% over comparable 3-blade propeller designs.
The tests were carried out on a 20ft Bayliner VR5 sportsboat fitted with a standard Mercury 150hp outboard engine, comparing Sharrow’s new tipless MX-1 against two market leading competitors. Not only was it the fastest of the three (41.7 knots vs 40.8 knots and 39.0 knots) and the most efficient (4.6mpg @ 32 knots vs 4.2mpg and 4.1mph), it also planed earlier and outperformed them both at every 500rpm increment from idle speed to wide open throttle. This is crucial, as propellers which are designed to give the highest possible top speed often struggle at low to medium revs, and vice versa. So how is Sharrow Engineering claiming to have cracked the conundrum that has stymied so many others?
TIP TROUBLES
As ever it seems to be a combination of inspiration and perspiration. The inspiration came from its inventor and CEO of Sharrow Engineering, Greg Sharrow, a music graduate, who originally set out to solve a very different problem. He wanted to use camera drones to film performers in action but soon found that their microphones would pick up the noise of the drones. He realised that most of this noise was not being created by the drone’s tiny electric motors but by the propeller tip vortices. These swirling pockets of turbulence are caused by high-pressure air on one side of the blade rushing round to meet the low pressure air on the other, creating induced drag, noise and vibration. The same principle applies to boat propellers, where the tip vortices are even more pronounced and can lead to cavitation, when water is momentarily vapourised by the sudden change in pressure creating bubbles.
Greg reasoned that if he could reduce or even eliminate these tip vortices, it should lead to a quieter, more efficient drone. His light bulb moment came on a dog walk when the idea of
a tipless blade, that loops round to rejoin the propeller hub like a strip of twisted ribbon, first popped into his head. It took a further seven years of intensive research and development, substantial investment, 23 worldwide patents and a switch in focus from drones to boats before Sharrow Engineering unveiled its first production propeller at the Miami Boat Show in February. Since then it has already won an award for innovation and the company says it is now in discussion with a number of major propeller and engine manufacturers.
Crucially, although its first offering, the MX-1, is a 15in diameter propeller with pitches from 15in to 21in designed for planing craft powered by outboard or sterndrive engines of 100450hp, it can and already has supplied custom made propellers for much larger craft, including one for a 65ft planing motoryacht. It has also modeled and simulated tests on propellers up to 9.87m in diameter for displacement trawler yachts, container ships and even super tankers, all of which have shown similar theoretical efficiency gains. Much of this modelling and prototype work was carried out by the University of Michigan’s Marine Hydrodynamics Laboratory and involved scale tank testing to prove its findings.
Furthermore, speaking to MBY by phone, Boattest.com’s founder and president Jeff Hammond, confirmed it wasn’t just the performance data that astounded his two test captains but the transformation in the boat’s cruising refinement and handling. Both captains reported less vibration, quieter running and exceptional grip in turns. This appears to be due to a number of different dynamic advantages, including the Sharrow propeller’s ability to draw in more water from the side, the extra traction of what amounts to a six-bladed design and the exacerbated effect of the reduction in induced drag during turns.
PRICE POINT
The only obvious drawback is price. Currently, every MX-1 propeller has to be milled from a solid billet of metal, which helps explain the price of $4,500 for an aluminium MX-1 or $9,000 for a stainless steel one. However, as Greg Sharrow pointed out in an interview with
MBY, “The first Dyson vacuum cleaner cost $10,000, now you can buy one for a couple of hundred.” He also confirmed that in the longer term a move to series-production casting could reduce the price of the MX-1 significantly.
Until we can sea trial one of these new Sharrow Propellers for ourselves we won’t know for sure whether the claims being made for it are as game-changing as they seem. Although we have every confidence in boattest.com’s findings, they were only performed on one boat, and unlike Motor Boat & Yachting’s sea trials, its tests are paid for by the manufacturer. However, the science and the data do point to a significant breakthrough. We look forward to verifying it in the future with our own sea trials. CONTACT: www.sharrowmarine.com
FUZE DECK SHOES
The new Fuze ‘sneaker style’ (trainer style, if you’re British) deck shoe looks like an ordinary trainer, but is actually engineered specifically for life on board. So the strong perforated mesh upper is breathable, quick-draining and dries quickly, while the discreet ‘one-way’ drainage system is created by moulded channels in the mid-sole, which instantly drain water away. Inside the shoe, an antibacterial coating has been added to the fast-drying inner, and the toes are ‘ultra-high grip’ and non-marking so they won’t mess up your decks. They are available in Ash and Grey.
PRICE £99.95
CONTACT www.zhik.com
ZHIK P3 PFD
It is important to know the difference between a PFD (personal floatation device) and a life jacket – the former is an aid to buoyancy, the latter should keep you afloat, turn you the right way up and keep your mouth and nose above the water even when unconscious. But whilst the latter is an extremely important life saving aid, there are plenty of circumstances where the PFD is more suitable (chiefly you remain more mobile in the water and because life jackets often use gas canisters to inflate, which eventually need to be replaced). So for a little extra support when paddle boarding, dinghy-sailing or just messing about in the water, these new PFDS from Zhik are ideal. They have side access, an adjustable side buckle, and there’s even a storage pocket.
PRICE FROM £85 CONTACT www.zhik.com
CHRISTOPHER WARD C60 ELITE 1000
Christopher Ward has updated its C60 Trident Elite, the previous version of which was a sold-out 300-piece limited edition model, with some significant improvements.
For the new watch the movement has been upgraded to the Sellita SW220 COSC – still of chronometer standard, but with a day/date function rather than just a date. A lightweight, quick-release titanium bracelet is available for the first time – weighing just 133g. There is also a hybrid rubber/ Cordura® strap option in black or navy, either with or without a bright underside in red or orange respectively. The quick-release technology makes it easy to buy both and simply swap between them. Matching the bracelet is a Grade 2 titanium case with an exhibition case back that showcases a rotor engraved with Christopher Ward’s ‘twin flags’ – an emblem of the brand’s Anglo-swiss roots. An in-built automatic helium-release valve also assists with equalisation during the ascent from a dive. Swiss-made and an ideal 42mm size, it’s water resistant to 1,000m (if you accidentally find yourself any deeper than that, the integrity of the watch will be the least of your worries!). And unlike the last model, it’s an open series, so you’ll definitely be able to buy one.
PRICE FROM £1,250
CONTACT www.christopherward.co.uk
FISCHER PANDA VS GENERATORS
Fischer Panda UK is introducing a range of variable speed hybrid DC generators designed for electric propulsion.
Hybrid diesel electric propulsion has many advantages: it allows the builder to site the power plant anywhere, since it can be connected by wires to the electric motor that drives the propeller rather than having a direct mechanical link. That allows anything from better internal boat layout packaging to weight distribution and noise benefits. But the chief benefit is efficient running, as the generator can run at its most efficient speed rather than being restricted by a mechanical linkage.
In the case of the new series of Fischer Panda generators, developed specifically with hybrid drive in mind, the speed of the generator can also be varied for even greater efficiency, as it can run at the lowest speed required to meet energy demands, apart from the drive motor (air-conditioning for example). So if the speed of the drive motors is reduced, so can the generator speed to match. Or the generator can simply charge the batteries, again varying supply to match demand.
Available in various output voltages up to a current of 300A and an output power of up to 100 KW, the VS Series enables either silent electric cruising powered from the battery bank alone or hybrid cruising using the batteries and the variable speed DC generator as a range extender.
Interestingly, in emergency mode, the variable speed hybrid DC generator can power the drive system directly. Silent on-board power, with battery only for domestic appliances, can be supplied indirectly using an inverter, or you can opt for hybrid on-board power using the battery and generator during periods of high-power demand.
A new control system, called the FP Control, which allows various set-ups as well as the connection to a CAN BUS system, monitors the VS Series. It provides information on the generator, as well as the connected drive system and batteries, to update data on overall power being drawn, power supplied for battery charging and the electric drive system. When using batteries only, the battery charge status, as well as the remaining drive time, are also displayed. An autostart function prevents the batteries from being drained as the generator will kick in automatically and a digital display shows up-to-date information. Suitable for all electric boats, the range includes the 20-VS, 35-VS, 50-VS, 75-VS and 100-VS models.
Prices are yet to be confirmed, but expect list prices to start at around £50,000.
PRICE TBC CONTACT www.fischerpanda.co.uk
SIMRAD® NSO EVO3S GLASS BRIDGE DISPLAY
As all-glass bridges become ubiquitous, and even humble engine instruments migrate to the virtual world of the MFD (multi function display), the power to run and smoothly display a myriad of different information from disparate sources becomes ever more important. Which is why Simrad’s new MFD, the NSO EVO3S, is driven by the new IMX 8 ‘black box’ integrated six-core processor, which the company claims has “up to twice the CPU performance so instant access to relevant information, no matter the conditions, is a given. It delivers category-leading response times for smooth screen transitions”.
Available in 16in, 19in and 24in touch screen models, each version can be purchased as a system pack or in display-only packs. System packs include a display, GPS, keypad and accessories. And each screen can run up to six different displays simultaneously. So you could have radar, multiple chart plotters (set at different zoom levels), engine instrumentation and more, all running seamlessly on a single display, very handy when helm space is limited.
High definition resolution, ultra-bright display and wide viewing angles keep the screen in view from anywhere in sight, even if you’re wearing polarised sunglasses. Built-in wireless connectivity links NSO EVO3S to mobile devices for remote viewing and control, and delivers online software upgrades via wireless hotspots. Wired Ethernet, NMEA 2000® and J1939 networking provide almost limitless integration options.
PRICE FROM £7,340
CONTACT www.navico.com