Jake Frith takes a test drive of the RS Pulse 63 and ponders whether a 23-knot RIB could change the world…
When RS Sailing, the world’s largest manufacturer of sailing dinghies, announced a few years ago that it would be building a planing electric RIB called the RS Pulse, some ‘expressions of surprise’ were heard from the marine industry.
RS changed the sailing world with its high performance dinghies which took the principle and the fun of the planing skiff concept into a much larger market than it had ever been before, but an electric RIB was surely too far outside their areas of expertise – wasn’t it?
Established motorboat manufacturers were – and still are – struggling with the energy transition, as designing a boat that is quick to charge, has a usable range, but also has enough grunt when needed to get planing with its heavy batteries is a mind-bendingly big ask.
Packaging it in a form customers would want and at a price they could bear is every bit as challenging.
Indeed, several large, and ostensibly technologically advanced brands in motorboating have thrown up their hands, and (usually privately) announced that the technology, particularly battery technology, is not yet mature enough to make the maths work and therefore it’s too early for them to go electric.
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Rather than making excuses and bleating about how much better batteries will be in 10 years’ time, RS got to work on the areas that could be improved to make it work.
They had to get to work fast too. World Sailing set an ambitious target that all countries’ coaching and support boats would need to be zero emission by the Paris Olympics in 2024.
I guess this provided the initial heads-up for RS who have close dealings with the world governing body concerning high performance dinghies, but the market for Olympic support boats alone is not big enough to warrant substantial investment.
Fortunately the requirements of a dinghy racing support boat are broadly similar to those of many other larger markets from superyacht tenders to harbourmasters’ launches, along with a few leisure sales too to the environmentally conscious high net worth individual with a charging pontoon at the end of the garden.
The batteries in the Pulse are off-the-shelf Nissan Leaf car batteries in waterproof boxes, the management software is clever enough to be beyond the scope of this article and the motor boasts an impressive 95% efficiency, but it’s the hull design that makes it work and sets it apart.
What RS worked out very early on is that the standard deep V hull, usually seen on a seagoing RIB would not be much use on a battery-laden boat with only 46kW (63hp) of power to play with.
The first iteration of the RS Pulse was the 58 (5.8m) whose slightly shorter length and the power to weight ratio issues of a smaller boat made the task even harder, and that model was swiftly dropped from the range.
The 58 also used a very futuristic looking hubless rim drive unit from RAD out back for propulsion. This was perhaps a leap too far as we note that the RS Pulse 63 uses a very much more conventional, proven and durable, Mercury sterndrive.
It doesn’t look like an optimised solution to me though, with a general purpose symmetrical-bladed aluminium prop that powerboat enthusiasts would disparagingly refer to as a ‘bunny ears’ or ‘bunny’ prop.
Unfortunately Mercury don’t yet do a sterndrive that’s the right size for this very low power application. While it’s great that the sterndrive is capable of handling 300hp+ and 65 knots, and therefore won’t break, the RS Pulse 63 would go somewhat further and faster with a drive unit with a much smaller diameter gearbox, reducing the parasitic drag as much as possible.
There’s also a whacking great prop hub centre exhaust. I’m no naval architect, but even I know an electric boat propeller for a 23-knot boat needs a cone hub coming to an elegant point some distance behind like the snout of a 1950s rocket, not a system optimised to suck internal combustion exhaust fumes out into the wake.
Back to the hull, it’s got a low, almost flat deadrise, which is needed for early planing, but that usually causes slamming in open water, (hence the development of the deep V hull once engines got big enough to power them).
The stem is steep and the forefoot pronounced, so, cleverly, like a modern sailing yacht, at displacement speeds it keeps a maximised, efficient waterline length.
This deep forefoot design is not an option for very fast petrol RIBS, which, if so designed, would be inclined to change ends (hook) rather suddenly at speed in open water, but at 23 knots it’s not going to be an issue.
RS gets round the slamming problem by incorporating deep air channels, or to put it another way a narrow centre hull with stepped sponsons, and this approach probably also usefully reduces wetted area when planing.
It’s effectively a triple hull, but it’s important to note that this is not a tunnel hull or air lift hull (some triple hull powerboats are and some of RS’s marketing blurb speaks of an ‘aerodynamic hull’).
Getting aerodynamic lift to work on powerboats requires considerably larger lift areas and much higher speeds than the 23-knot top speed that this boat offers. I’d call what RS has done here a ‘modified cathedral hull with stepped sponsons’ and leave it at that.
On the water
I could bang on about the quiet, how all we could hear was the chuckle of the bow wave and the cry of the oystercatcher. But that’s all been said before about electric boats.
The boat was not completely silent – it made a quite pleasing low rumble at most speeds – but it was dramatically quieter than any internal combustion engined boat.
The RS Pulse 63 has a clever RADTag Bluetooth killcord system, which usefully allows performance to be limited for certain users. For our brief test, on Southampton’s river Itchen with its 6-knot speed limit this ceiling was set fairly low, but was high enough to get the boat planing very briefly.
This sort of speed range is where the boat really differs from a V-hull RIB. The transition from displacement to planing on this sort of hull is not like climbing a cliff.
That’s why the hull form is so suitable for electrification; it will spend a lot of its time getting about very efficiently at 10/11/12 knots where a conventional V-hull RIB would be sitting with its bow high in the air, towing a big white rooster tail up the river behind it gobbling a litre of unleaded every four minutes.
This is a really impressive hull. The whole boat lifts fore and aft as one as it gets on the plane, so gently it’s difficult to know whether it’s planing or still in its displacement condition without looking at the speedometer.
This is where the penny suddenly drops. A planing skiff has to do this too and also goes surprisingly fast on very limited power, so for a company with RS’s technological heritage, building this boat begins to make perfect sense.
The handling seems fine, which I was initially concerned about as the boat has a much less aft-orientated weight distribution than a conventional outboard-powered RIB.
The batteries are mounted forward of the console, which is another part of the reason it lifts so evenly under acceleration. The batteries are located in a deck level box which creates a step up to get to the bow, but we got used to this pretty quickly.
The floor level is higher than many outboard-powered RIBs – there’s lots of stuff going on under there, but only extensive open water testing would tell us if this made it feel top heavy or noticeably less secure-feeling than a conventional boat with a lower sole.
Looking out over the stern was a novelty – there’s nothing there! There is a flat floor with EVA deckpad-type foam on it that would prove very useful for getting in and out of the water.
This was a short test drive but the boat behaved perfectly acceptably. It’s always going to struggle as an adrenaline rush over petrol outboard-powered RIBs and I hope sales don’t suffer from this as that’s not the point of the boat.
The real sells for this are the impressive numbers concerning range and charging times and the convenience of in-marina charging that could make electric boating more viable for many more owners.
RS Pulse 63 test drive: Conclusion
Prices for the RS Pulse 63 start at over £80,000 including VAT, but if you look at the much higher price of an electric car versus an internal combustion one, consider the volumes in manufacture (RS hopes to sell 100 this year) and think about the price of a similarly elegant looking 6.3m RIB, it’s actually not completely wide of the mark.
It’s telling, though, that two were recently sold to a Silicon Valley billionaire’s private island. I predict that these will sell like hot cakes to government agencies, port authorities and the like, who only rarely need to get up into double digit speeds, do short trips and can regularly return to a base pontoon for recharging.
With heavy commercial use, the reduced operational cost (lower cost of ‘fuel’) will override the high initial cost of the boat. These bodies all have hopelessly demanding decarbonisation targets and there aren’t many electric boat options for operators who might, occasionally, need to get somewhere in a hurry or operate in open water.
It’s quite a milestone for boating and even a minor one for the planet that a small, quick charging, tolerably quick RIB has been successfully electrified, is being series manufactured and is clearly going to sell.
There will be many boats like this one day, and rest assured ranges and speeds will both increase. There’s no Tesla in my driveway – I’m not a ‘first adopter’ of these sort of technologies and so I wouldn’t buy one, but I’d give it five out of five stars to reflect how important it could prove to be.
OK, I picked on the over-specced sterngear a bit, but RS will know about this and there just aren’t the off-the-shelf products they require yet. This will get sorted, and my overarching sentiments are joy and pride that a relatively small but highly innovative UK company has had the sheer gumption to step outside its comfort zone and may have, just a little bit, changed boats forever.
|5 knots||100 miles|
|10 knots||70 miles|
|15 knots||45 miles|
|20 knots||25 miles|
These ranges are as quoted on the RS Electric Boats website with the standard 46kWh battery pack. An additional 23kWh pack can be added to increase range but with an unspecified ‘reduction in top speed’.
Top speed is otherwise quoted at 23 knots with the standard battery pack. The RS Pulse 63 charges in two hours with its standard 25kW charger that should not trip the power at marinas. A 75kW option is also available which will, impressively, charge the boat in just 30 minutes.
Prices start from £82,800