Full carbon pilot cutter

Built almost entirely out of prepreg carbon composite with long chord appendages and a towering rig, the Baltic 117 Perseverance looks timeless but she isn’t remotely traditional

What happens when you combine the skills and talents of Baltic Yachts and Dykstra? You don’t end up with a stately but sedate ‘spirit of tradition’ sort of yacht. You’ll more likely get a handsome, high-performance wolf in impeccably tailored sheep’s clothing. Thus it was with their first collaboration, the 67-metre ketch Hetairos and the same can be said for their second, delivered last summer: the 35-metre (117ft) sloop Perseverance.

 ‘The ethos of this project is a pure sailing boat,’ says Henry Hawkins, Baltic Yachts’ EVP. ‘Often on large sailing yachts you don’t get a pure sailing experience because you lose the feel, which is so important and it’s something that Baltic Yachts works hard to maintain. There are distinct parallels with Hetairos in terms of the look of the boat but in most respects she is quite different, more modern but at the same time less extreme.’

Perseverance and Hetairos both stand out from Dykstra’s other pilot cutter style yachts in several ways. They’re built in carbon, not aluminium and significantly lighter and stiffer as a result. They both have notably deep draught, which improves their handling and helm response as well as performance, and they each have an enormous amount of sailpower.

However, Hetairos is extensively optimised for racing, yet at the same time more classic in her proportions with a ketch rig and a tapered stern. Perseverance by contrast is primarily a cruiser but has timeless rather than classic lines and her broader stern, sloop rig and waterline length are more akin to a typical modern yacht.

 Also, as Dykstra is keen to point out, the differences between the two yachts show how these full custom projects are led by the wishes and choices of the clients. The next time the two companies collaborate on a yacht, it could be a completely different type of vessel. Concept & hull design true to her name, Perseverance was a long time coming.

Dykstra and their interior design counterparts, deVosdeVries design, had already spent almost three years developing, refining and revising the concept before Baltic Yachts became involved. The two Dutch design studios had worked together on the client’s previous yacht – an 18-metre (60ft) pilot cutter-style cruiser built in aluminium by Claasen Shipyard – and were tasked with scaling up the style and concept of that boat into a high performance superyacht twice the size.

‘The design brief was classic elegance but performance orientated with good seakeeping capability for long hauls, Atlantic crossings, that sort of thing,’ says Erik Wassen, the lead naval architect for Perseverance and many of Dykstra’s previous pilot cutter-style yachts.

Another key aspect of the brief was to create an efficient charter yacht with broad appeal. Full custom yachts often grow during the design process, but this one went the other way.

’Initially we had a larger boat in aluminium but that changed because aluminium has its drawbacks,’ Wassen says. ‘Corrosion issues, it’s less stiff, it’s heavier. So we squeezed that 40- metre boat into a smaller composite package, 10cm here, 10cm there. You lose weight, you lose volume but you gain interior space by having a sandwich structure rather than frames and a skin. Basically it’s the same layout, though. Also when you lose displacement you lose propulsive power requirement, fuel consumption. It’s a knock-on effect. That was the compromise and it ended up as 117ft.’

The underwater shapes of Dykstra’s designs bear no resemblance to an actual Bristol Channel pilot cutter, of course, nor anything else of that vintage but they do share one functional benefit with the boats that inspired them.

‘The old pilot cutter guys figured out that a longer waterline pays off in seakeeping capabilities,’ Wassen says. ‘Having a sharp bow with a long waterline, it’s a no-brainer. Also, as the forefoot is straight the interior extends further forward so you can have proper stowage in the forepeak. With a spoon bow you might have five metres sticking out beyond the waterline but there’s not much volume that you can use.’

In Perseverance that same thinking is applied at the other end of the hull. ‘Most pilot cutters we design have more overhang at the stern,’ Wassen says. ‘This one is all about maximising waterline length. So the challenge for us was to get the hull out of the water in a proper way and find a good compromise between waterline length, shape and appearance.’

Rig, sailplan & deck plan Dykstra’s Wassen designed the sailplan, working with Doyle Sails and Hall Spars. Light wind performance was a top priority so the rig is huge but it has three sets of spreaders rather than four.

‘If you could reduce weight considerably by having an additional set, I wouldn’t be against it,’ he says. ‘But that was not the case. We did a calculation run with Hall Spars and it all appeared to work out quite nicely and the mast section is not excessively stiff. So then you get a reduction in windage.’

As a result, the mast’s longitudinal sections are stiffened with high-modulus carbon fibre but intermediate-modulus carbon is used in the sides of the mast. A square-top mainsail was put on hold.

‘It is a lot of complication for a small gain,’ Wassen says. ‘You do get a few more square metres, the sail is probably easier to trim, it’s a bit more forgiving in puffs. There are benefits but also the drawback of always needing to use your runners and not having a fixed backstay, making the whole rig more vulnerable. That’s something you need to weigh. The boat is fast as she is, and doesn’t actually need a square top main.’

Even so, the rig is designed to incorporate a square top in years to come as the boat develops, to make sure it’s a simple adaption later on. The deck plan is firmly focused on simplicity.

‘There are a number of fixed points,’ Wassen says. ‘You can have a tweaker on the code sheet and kite sheet if you want. There are all sorts of racing capabilities but in normal operation it’s a very simple and straightforward sailplan.’

The mainsheet and main halyard are on below-deck captive winches, the jib and staysail sheets are led aft via pin-stop cars to primary winches on the coamings.

‘We have the halyards on locks, partly because I like to sail with a clean foredeck,’ Perseverance’s captain Ryan Taylor explains. ‘Also because we only have two mast winches although we do have plenty of jammers.’

Construction

The entire boat is built in Gurit Sprint prepreg carbon with a foam core. Her actual weight is within three per cent of her design weight, which would be remarkable for most builders but is about normal for Baltic Yachts. Despite appearances, there is actually very little solid wood on board.

‘Over a long period of time we have learned how to manage and create a solid wood look for our exterior details,’ says Tommy Johansson, Baltic’s project manager for Perseverance. ‘The basic idea is to have a solid, stiff structure behind the wood. No shortcuts can be taken so we use top quality prepreg carbon sandwich construction. For thick, solid-looking wood like cap rails and bulwarks, several layers of teak are glued and bonded onto a lightweight core. Wood selection starts with the procurement and the final selection is down to the sharp eye of the carpenters.’

Quality control is strict and frequent checks are made. On Perseverance, the deckhouses were finished with 8mm teak veneer. There isn’t enough freeboard for a Pink Gin IV-style through-hull door to be practical on Perseverance – you’d have to crawl, rather than walk through it – so there’s a side boarding platform instead, which folds out from the port topside with a boarding ladder that extends up to the deck. A carbon fibre beam runs along the bottom of the aperture in the hull skin to maintain stiffness and the panel behind the fold-out platform is structural, fixed to the hull skin.

Hybrid propulsion

The main engine is a diesel-electric hybrid with two 129kW diesel generators charging a big bank of lithium ion batteries, powering an electric motor that drives a Hundested controllable pitch propeller on a conventional straight shaft.

 ‘It’s a 128kw/h system,’ Johansson says. ‘Perseverance can run in silent mode for up to nine hours with everything running at maximum capacity.’

The 600V system is stepped up to 750V and distributed via a DC bus. This setup requires a dedicated technical cooling circuit with full dual redundancy built in.

‘Even the hydraulics are high voltage, with two 50kW pumps the size of a small coffee table,’ Taylor says. ‘So we have 100kW on demand.’

‘There has been a huge amount of development since we installed our first hybrid system on Canova in 2019,’ Hawkins says. ‘The biggest difference between then and now is battery technology.’

It’s still far from off-the-shelf technology, though, and a hybrid setup with an extended battery capacity for silent running provides a challenge for the notoriously tight engine room spaces found on sailing yachts.

‘With high-voltage electrical systems it’s crucial to find the right equipment and partners,’ Hawkins says. ‘You can’t just go out and buy a set of class approved batteries for a setup like the one we developed for Perseverance. We had to find a suitable supplier and then help them get class approval. That’s a typical challenge we face.’

Halfway through this process they had to switch battery suppliers, so the engine room had to be reconfigured to fit a different set of equipment. The hybrid drive is designed to regenerate electricity from a boatspeed of 10kts.

‘At lower speeds the advantage of starting to regenerate are lower because you also reduce the boatspeed a lot,’ Wassen says. ‘When the wetted surface is still the largest component of the resistance, then the effect on boatspeed when you start regenerating is really large. The resistance curve is not linear, it goes up by the fourth power or so. When you’re at a higher point of the resistance curve, the effect on boatspeed is a lot less.’

In practice, the regeneration is working well.

‘We’ve been getting about 8-12kW out of it under sail,’ Taylor says. ‘It doesn’t quite meet the full load of all systems but it does extend our silent mode for at least 50 per cent longer. Our power consumption can be anything from 10-20kW and we aim to regenerate 10-15kW.’

Smart systems

‘There is a major focus on energy saving solutions,’ Hawkins says. ‘Not just producing green energy but also where possible not using it at all. An example of this is the smart cabins system. This allows systems such as air conditioning to either be run manually or automatically via the PLC. In the long term it can learn how the cabins are typically used and run the hotel systems accordingly by default. It knows when the cabins are occupied and when they aren’t. Full cooling all day long wastes a lot of energy. There are sensors built into all hatches so it knows whether they are open or closed. To illustrate the efficiency of the AC system I’ve used the example of a week-long charter in the Caribbean,’ he says. ‘The system can identify which cabins are unoccupied, reduce the AC in there during the day and start cooling them down again from around 5pm. During the course of the night, the cabin temperature can be increased from say 18°C to 20 or 21°C and the body will still feel cool. That can make a huge difference to AC compressor run time, the equivalent of 19.2 litres of diesel a day. And we’re also trapping the waste heat and using it to produce hot water. Over the course of a year we can save more than 9,000 litres of diesel just with that. With lots of little bits chipping away at the big picture you can make a massive difference.’

Sailing performance

The real proof of a boat, of course, is in the sailing. Perseverance is still in the shakedown phase but Taylor describes her as ‘super easy, fast and efficient. The rig is exceptionally powerful for this boat and she is very stiff. I’m very happy with the Doyle Structured Luff and Cableless sails. Just like it says in the adverts, the luff does project to windward.’

‘On the delivery down to the Med we had some great sailing,’ he says. ‘We logged 20+kts off Holland quite easily when we weren’t really trying. We started off with the code zero but then changed down to main with one reef and full blade. The wind was about 20-25kts. We’ve been out in winds up to about 35kts; so far I’ve played it safe with the weather. She also goes very well in light airs.’

Interior design and layout

Despite her classic exterior look, the interior is anything but traditional. ‘We came to a certain styling in the previous boat and that was the starting point for the new boat,’ says the lead designer, Michiel de Vos of deVosdeVries design. ‘We elaborated on that and added lots of wooden details. All the exterior deck hardware has a matt finish, there’s no polished chrome and it’s similar inside. It’s a very nice boat to walk through because the styling is consistent throughout. There isn’t a major difference between the guest and crew areas, we have made it a bit simpler and more hard wearing in the crew area but the main details are the same.’

When the decision was made to build a smaller composite boat, fitting everything into the GA was a challenge for de Vos. ‘Her length was reduced by 17ft and her beam was narrowed but we have managed to deliver the same functionality,’ he says.

Baltic Yachts made a virtual 3D model of the interior, with virtual reality headsets to make it easy to visualise and check the size, shape and styling of the various spaces. Significant weight savings were made in the interior,  ‘but that’s not down to us,’ de Vos says. ‘We designed it and Baltic made it work in a lightweight way. They are very good at that. For example In the master cabin the bed frame is carbon with a wood veneer and the top part of the frame is finished with thin, removable leather. The double curved bottom piece is a composite structure.’

For de Vos, the stand-out interior space is the side-by-side saloon and galley. ‘It’s conceived as a communal area and can be opened up with a drop down TV that serves as a partition, or it can be enclosed completely,’ he says. ‘For charter use, you can set up a buffet/ breakfast bar on the central island.’

In a boat designed for long-distance voyaging, it might seem strange to have the master cabin in the bow rather than further aft where the boat’s motion in a seaway will be more comfortable. However, it makes a lot of sense when Perseverance is working as a charter yacht and nearly always anchored or moored overnight. For ocean passages, there are guest cabins next to the keel trunk where the boat’s motion is minimal. The quality of finish throughout the yacht is a showcase of Baltic Yachts’ skills.

‘The combination of light stained brushed oak with all wood grain oriented vertically, including all cornices, marrying with the dark-stained maple floor edges is a stunning look,’ Johansson says. ‘Every single metal piece in the interior has a PVD coating or colour to match. It’s hard to believe all interior parts are fitted with fast mounts when looking in the joints and the lineup of different parts. Every single part can be disassembled to access the systems behind.’

The best thing about it, though, is the absence of noise. ‘It’s a floating interior on rubber-mounted carbon fibre beams,’ Johansson says. ‘Creating a silent boat was one of our main goals.’

Taylor concurs: ‘This boat is super quiet even with the generators running, with noise levels usually less than 42dB. That’s partly due to the quality of the sound insulation but also the science and past development that Baltic has put into noise reduction over the years. Even the hydraulic lines are double insulated. You can’t hear any noise at all in the master cabin.’

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