Vita Power Seal and Sea Dog RIBs
With a reputation for ‘plug and play’ electric propulsion, Vita Power has launched electric RIBs of its own design. Jake Frith drives them
Achieving a day of slow electric cruising per overnight charge is becoming fairly viable in many inland locations, as a trip on any inland waterway will tell you. However, when boats are required to reach higher speeds and plane in open water for a reasonable length of time, and then also be rechargeable to a high percentage in a reasonable length of time, it creates a whole boatload of additional challenges.
Marine safe high voltage
With these very different demands, there is a split developing in electric boat technologies. The de facto safe working voltage for owner-built (read ownertinkerable or DIY-built) electric boats is rapidly reaching a general consensus of 48V. It’s about as high a voltage as the industry dares go with products such as electric outboards with removable batteries, where the lowest common denominator of users could perhaps be expected to plug and unplug battery leads with wet hands while seated in a puddle of seawater. A 48V electric shock in such circumstances would be unpleasant, but unlikely to be life-ending for most.
However, on dry land, 48V would not get you far in the arms race against the likes of Tesla or Porsche; their cars run at up to 800V. Even the more ‘entry level’ electric cars run at 200-400V, and any of these potentially lethal voltages need very careful safety management when in use in or around seawater, taking boats using these technologies out of the scope of DIY boat owners.
There are, however, several very persuasive reasons why electric cars run in the hundreds of volts, not the tens, and these are the same reasons why Vita Power’s RIBs are running at up to 600V. In terms of efficiency, higher voltages enable more efficient energy transfer, reducing the amount of power lost in the conversion process. In terms of performance, higher voltage levels allow for faster acceleration and higher top speeds–a key consideration for electric boats that need to get onto the plane. In terms of range, higher voltages enable longer driving/ boating ranges, as more energy can be
stored in a higher voltage battery pack. Higher voltage battery packs allow higher voltage charging, which can be much faster, assuming the necessary infrastructure exists. When relatively higher voltages are used, current flows become relatively lower, and this means wire sizes can be smaller throughout the boat reducing copper use and weight.
Vita Power, based at
Universal Marina on the River Hamble, creates drop-in propulsion systems and boats in low volumes that boast compatibility with high-speed DC (direct current) charging, supercharging from 10% to 90% in under an hour. This impressive feat is attributed to technological advancements borrowed from the electric motorsport sector, where the company has recruited key talent.
Seal and Sea Dog
Vita Power’s Seal (7.2m/23ft 6in) and Sea Dog (5.8m/19ft) both feature aluminium hulls, built in Serbia, with battery capacities of 126kWh and 63kWh respectively. Despite variations in size and capacity, the boats share mechanical similarities, delivering a continuous power output of 95kW (125hp) and a peak of 140kW (185hp). The starting price on both models is from £135,000.
Designed to navigate typical coastal conditions, these RIBs have impressive power outputs, setting them apart from some other planing electric counterparts. Range-wise, for the Seal, Vita claims an hour at high speed or 25 hours at a harbour speed of 6-8 knots. For the Sea Dog, it claims an hour at high speed and 10 hours at harbour speed. Both the boats are capable of 30 knots for a short sprint but clearly, this is not an efficient speed to use them at. These are significant and useable numbers in the electric boating industry when considered alongside the fast charging capabilities, achieved in part due to their use of the latest electric vehicle-type power management techniques and battery packs that are cooled by circulating oil which is cooled by seawater via a heat exchanger and pump. While these numbers will still not add up for a lot of users, the boats are finding buyers in certain, early adopter scenarios where the usage profile fits them.
These boats make great sense for sailing event support boats, harbourmasters and superyacht tenders, because these scenarios all involve multiple short trips with lots of parked-up charging time in between. It’s perhaps unfortunate that boats for private owners intended for cruising to different locations will be some of the hardest boats to electrify due to purchase cost, vessel range and charging infrastructure.
We drove both boats with three adults aboard in a 15-knot north-westerly in Southampton Water, through a foot or so of chop but plenty of larger wakes from marine traffic. My first impression was that these are both very dry RIBs, and that’s a critical consideration when electrically powering such a relatively small but heavy craft.
The hulls have been designed for electrification. An electric boat, thanks to its battery pack, has its centre of gravity further forward and higher up than outboard-powered designs. It needs a shallower deadrise for earlier planing, and more lift in the central sections.
The battery packs are stored under the floor, as they are in all electrically powered boats of this type. There is simply nowhere else to put these large, heavy, rectangular components. This raises the floor in comparison to RIBs with, say, a petrol outboard and with some electric boats, this can create a somewhat precarious feeling, akin to helming halfway up a stepladder. This does not appear to be the case on the Seal and Sea Dog as they have relatively low profile battery packs, deep, vertical upper chines and high, confidence-inspiring, collars.
The boats we looked at were destined for very different markets. The larger Seal was built to ‘yacht finish’. The Sea Dog was destined for commercial life with a no-nonsense unpainted aluminium checker plate floor that was already achieving its battleship grey patina only weeks out of the factory and chimed in with regular tinny clangs as we danced across the wave tops. Both RIBs employ an inboard motor coupled with a Mercury Alpha 1 Gen 2 sterndrive, a choice that’s likely to prove reliable. Vita Power acknowledges the potential for further optimisation and is actively developing an in-house stern drive solution to enhance efficiency. With an electric motor, any final drive does not need a forward, neutral and reverse gearbox, as this Mercury unit has.
‘These RIBs have impressive power outputs’
Applications
I’m not here to sell Vita Power’s electric RIBs to PBO readers. They aren’t particularly designed for the private leisure market and the financials don’t add up unless you are a large concern with decarbonisation targets to meet.
But they deserve interest from all boat owners as important, milestone boats that could herald the shape and flavour of the craft the rest of us will be using in the decades to come. As with electric cars, ranges are getting better all the time, charge times decreasing, and infrastructure becoming more extensive. As this happens, we’ll see planing electric craft becoming more common, perhaps eventually becoming the de facto choice in the leisure boating market.