Hull #1 The Keys - Sprint 20S - photo © Valder Yachts
Dear Recipient Name
Yes. It was one thing that opened the door, as it were. One thing that piqued the curiosity enough to go, "I'll take a look at that!" One thing that when you're trying to crack in excess of 50 knots it reminded me swiftly of an earlier piece entitled, Things do change. And that one thing would be surface drive, AKA the Sashimi Makers.
There were one or two other things that ensured the hook was in the lip, too. These surface drives are not articulated, meaning expensive and finicky bits were not sitting in corrosive salt water all the time. Alas, the key words in surface piercing are just that. Part in the drink, and part not. The stub drives protrude out about a metre and have a water-cooled 316 SS bearing (taking all the load and thrust), with a small jack shaft connecting it all to the gearbox inside, as drop boxes are not required given the running position.
Now if your angle of attack is fixed, then you're going to need some help getting the breeze over the screws, lest you spend an inordinate amount of time as a hole in the water, just waiting for something to happen. So, no one said that breeze had to be fresh, and if you have the aftermath of 16 iron ladies disgorging their leftovers that have been rammed into them by no less than eight exhaust driven hairdryers, then why not use it? Makes sense to me. You'll always have plenty of 'ventilation' going over the screws.
For what it is worth, said craft with its pair of 16.2 litre MAN V8-1300s, does do 38 knots alone as a planing craft. That's impressive in its own right, for a total of 2600hp gets to do that, whereas many a craft would need a PAIR of 2600s to get there, and they are huge, heavy and thirsty by comparison.
And there's yet one more thing. This thing is a foiler, which in reality means skimmer, because it is not totally airborne, per se. Now the cool thing about that is, you guessed it, one thing. Said foil is designed by America's Cup boffins. Does not interest you? OK. Then ponder this. In the America's Cup world they get say 7.5 tonnes fully airborne in 7-8 knots of breeze, and can take the craft off to a tad over 50 knots. Lift is lift, and drag is drag, and the magic that goes into achieving this sort of alchemy is worthy of any propeller hat or pocket protector.
Techy stuff
Additionally, surface drive has one big advantage over water jet. The pump is not trying to suck itself back into the ocean. Surface drive is linear, and projecting forward. The very direction you want to go, as it turns out. On top of that, the placement of the foil is all about CofG and CofB, and not about where the bum is, or wants to go.
Importantly, there is not just one of these things floating about, there are now two in existence. Now might be the time to take a more holistic approach, a helicopter view, if you will, which is kind of ironic, as you can carry a chopper aloft on the pilothouse roof.
If you got all of that, then it means we can only be talking about the Valder Yachts Sprint 20S. Wayne Valder is an Offshore Racing legend, and the two craft of this model to date are 67.5 foot, 35 metric tonne screamers (half ship), with asymmetric hulls penned by the famed Roger Hill.
Want to know why being 'off kilter' is important, then we have a two-part editorial for you to read: part 1 and part 2. Do note that being 'lower' inside means you're closer to the water with the struts for the foil. Always a good look, BTW. Remember that thing called drag? At 50 knots the water is more like concrete, and so you don't have to reinforce the mounts with tonnes of Unobtanium. It is best you be right up and close to share the load...
So, the AC boffins are non-other than designer and hydrodynamicist, Nick Hutchins, from Experienced Hydrodynamics who works closely with ETNZ, and he is responsible for the foil geometry. The all-important CFD is by Matt Hall-Smith from Precursor Development. Say no more in terms of credentials. What we can wax on about is the form they have come up with. Like WOW. No delta planing form here.
It is virtually a straight plane with trailing 'winglets' going out 300mm each side, and these should offer little disturbance to the crucial screws. It is built from pre-preg carbon with steel struts at the inboard edge of the hulls, and will deliver something like 500mm plus of lift, so running a fair bit deeper than your average foil, as well as supporting 20 metric tonnes. As is de rigueur with top end foils these days, the strut area has a proboscis aiming forward and a sweeping tail to the whole nacelle type structure, which is all about removing as much disturbance as possible. Remember the key mission parameters - outright speed and efficiency.
Note too, that the aft sections of the hulls have to be in the drink, and probably cannot set up for much more lift themselves in their current guise. Now the whole thing is adjustable, so fine tune is guaranteed. Also be aware that there is no centre strut, which is usually the thing that 'catches' stuff, and is also difficult to support properly, as it has to go up the bridge deck. Ultimately, the whole PFX 'performance' foil does not sit any deeper than the screws and rudders (around 1.4m BTW). It is also designed to depart from the struts in the case of significant impact.
Without a doubt, key learnings have been taken directly from the 37th edition of the America's Cup. J-foils were in for a while, now it is all T, and in the powercat space the alphabet has been taken out to U, but the cost of manufacture there is just a little bit too high (i.e. off the chart, and we are straight back to Unobtanium. Billet Titanium in this geo-political landscape is Rocking Horse droppings.)
In essence, a 2m seaway with 20 knots SOG is where it all begins and blasts away after that. Increased wave height brings bridge deck height into play, but crucially, the added drag of a foil still allows the Valder Yachts Sprint 20S to do an impressive 2160nm at 10 knots sipping just 46.5 litres an hour a side. Sprint away to over 40 knots and it still amounts to 790nm and only 523lph. Do note that these numbers are with the original CFX 'cruising' foil, and it is hard to comment from here, but 10-20% improvement might be on offer with the new PFX foil, and the craft runs at just around 1.5 degrees, so very flat indeed.
Contemplate this. If you normally run at say 65% load, you will be inside operating temperatures, and not clagging the iron ladies up, meaning you won't need to clear the throats that often. Equally, you still have plenty of punch left upstairs to go from say 35 knots and onto 50 in the right conditions, so you kind of have plenty left in the tank, literally and metaphorically.
Back to Earth
If you're buying one of these powercats you're going places. No sitting in a marina for you. You're going far and wide, but also intend to get there briskly when you can. You also want to take the niceties of life with you. You're an explorer with means, and the wherewithal to crack on and make it happen. Fly First Class and world flies with you applies here, and the R44-66 or Huges 500 chopper is a fundamental extension of that. There is also a 550kg davit for tenders and jet-skis, as the pilothouse roof is rated to 340kg/m2.
Being light is great, but then you have an all-carbon mantra, and the black stuff just loves to carry noise, and is also rather adept at running stray current to places it should never go. Both of the above are less than ideal, and when you add in the whistle from the eight hairdryers the outcomes from the complexities of solutions are integral to the delivery of the best package you want to deliver. You will find a lot of rubber mounts and grommets and PVC tubing to avert the electrical aspect, and significant insulation of the entire engine bays to account for mechanical noise, so you can talk normally whilst under way.
Don't just tell me how good it is - make me FEEL it!
Being built to the ABS Standard for 24m vessels is all well and good, but it is somewhat antiquated, and only survives by virtue of the fact that nothing has really stepped forward to supersede it. It does serve to offer a distinct build quality mantra however, and this is really the masterstroke, for if you are here in this space, you want to put the paperwork down in front of the insurance provider, and just as crucially, have total peace of mind when you're six weeks into a three-month tour. A Valder Yachts Sprint 20S can also go into Survey, if required.
Other nice notes include the craft being engineered to a significant wave height of 1.6 meters at 36 knots, and 2.4g standing or seated. The engineering was carried out by Nina Heatley of Clever Fox Projects, and Peter Lawson of Hauraki Composites. When you have been an offshore racer, as Wayne has, you know shortcuts end in tears, and Maritime New Zealand come and survey the craft in-build. Tick. Tick. Tick.
High-strain (>2%) Toray T700 carbon fibre inner and outer skin (the latter is infused with the foam BTW) is used throughout the hull structure, including some unilateral mat in key situations, combined with Corecell M foam (of various thicknesses depending on where it is going, where the thicker sections are hand glued before being infused down with the inner skin).
The essence of this is being a bit kinder to the boat itself and the human occupants, too. Even at the anticipated cruise speeds of around 36 knots, the water is not enveloping and squishy like falling off a raft, and much more like mild steel plate. So, it's a little bit of give to pick up a whole lot of take.
Short version - If it is structural it is Corecell, if it is cabinetry it is PVC and then taped in.
All those mod-cons add weight. Fridges, AC and so forth, as well as their power drain, so bring on the gensets to assist with the LiFePO4. However, you want the leather, the benchtops, and the wood. Luxury is sumptuous. Poverty pack is just that. Attention is given to allowing that which is 'essential' to meet the mark, and then it's all about application to everything else to make sure it is as light as possible. 35 tonnes half ship is pretty damn spectacular in an über-luxury, high speed, 20.6m LOA 'cruiser'.
Sure is exciting!
If you've got to here, then a normal vessel is just that. Normal. This is exceptional. It has to be. It has to live up to being a Kiwi. The Kiwis showed up to Fremantle with KZ-3, which was ostensibly a direct replica of Australia II, except for one thing. She was not alloy, but glass! KZ-5 enhanced it, and then, in a way, KZ-7 set the tone for nigh on 20 years. Same thing occurring here, just the best part of 40 years later.
Other boats will do other things. This one tells you what it is up to, and demonstrates it anytime you want to turn the keys. You'll pick your battles, and be wining and dining in a gorgeous locale whilst the others are still slipping the lines.
You may never get to work through a lot of the stuff here or the decoupling rubber matting in the hulls to alleviate the sound of the carbon fibre drum. None of that will matter, because you will be immersed in the experience, which will be all about comfort, pace, efficiency, exploration, and the tales to tell. Fantastic memories. They are yours for the taking, should you step up.
You can see what the two vessels look like at youtube.com/@ValderYachts
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Finally. Please look after yourselves.
John Curnow
Global Editor, Powerboat.World
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