Voodoo puts spell on waves

At a recent event in The Cloud, the New Zealand marine industry showcased some of its most innovative products to visiting media and businesspeople. Included were products such as the amphibious Sealegs, Hamilton Jet's new remote control system, the Rayglass Pro-Jet, Core Builders' AC45 racing catamarans and SMI's modular superyacht interiors.

If the Rugby World Cup had been just a few weeks later they could have added another: the quite amazing new Roger Hill-designed Voodoo.

While no two boats are quite the same, the differences are often minor. Those of us who report on the latest offerings sometimes have to work hard to highlight the points of difference. There is no such problem with Voodoo. Indeed, the issue is what to leave out.

Hill is proving to be one of our most versatile and successful designers. Last month we featured his 14m "helicat", the chopper-toting catamaran that attracted so much attention at last month's Auckland International Boat Show.

Although just as innovative, Voodoo is completely different. It is not built to carry choppers, it is designed to cross oceans - and do so at speed.

Mention passagemakers and you tend to think of heavy, trawler-like designs. Even the zippy ones top out in the high teens or, in exceptional cases, the low 20s.

What, then, to make of a vessel designed to cruise up to New Caledonia or across to Australia that can hit more than 40 knots? You don't normally use "passagemaker" and "rocketship" in the same sentence, but both are apt descriptions for this ocean-crossing speedster. While 40 knots doesn't sound like much when you are in a trailer boat, in a 25,000kg, 17.8m powercat it's sensational.

Voodoo has two features that make it exceptional - although one will shortly be exchanged for something more conventional.

The first is an "assist foil" from LOMOcean Design. Such foils are becoming increasingly popular on boats ranging from wave-piercers to catamarans.

LOMOcean's Andre Moltschaniwskyj says that a lifting wing or foil is a far more efficient way to lift the weight of the boat than simply using planing surfaces. However, while hydrofoils (the Boeing Jet Foil for instance) carry almost all the boat's weight on foils, such systems are not easy to reliably control.

But using an "assist" foil between two catamaran hulls to partially carry the weight of the boat offers a good balance - delivering both improved efficiency and high levels of passive control, safety and reliability.

Moltschaniwskyj describes the foil shape used on Voodoo as a simple plano-convex (flat bottom, evenly curved top). Such shapes are commonly used on catamarans overseas and offer a very broad lift "bucket". With the lift force evenly spread, there is a progressive loss of lift as the foil approaches the surface of the water at high speeds.

This reduces the likelihood of "breakout" and sudden loss of lift as the foil moves from dense water to thin air.

Voodoo's foil is made from carbon fibre and weighs less than 30kg. Yet, at 40 knots, this lightweight, high-tech strip of carbon fibre supports about half the weight of the boat.

It also contributes to the remarkably economical fuel-burn figures Voodoo achieves at over 30 knots, predicted to be about 15 to 20 per cent better than the same hull without foil assistance.

Another benefit is the improved quality of ride. The foil helps the boat enter oncoming waves at a better trim angle and dampens both heave and pitch.

Voodoo, which was built in Tauranga by Pachoud Yachts NZ, was designed to satisfy a very particular client. His brief specified that the boat be able to cross seas at a reasonable clip, thus reducing the need for a large weather window. He also wanted to be able to outrun any pending bad weather.

In its present state, therefore, Voodoo has the ability and fuel capacity to travel from Auckland to New Caledonia, a distance of 1000 nautical miles, at 30 knots. This is partly because of its foil and partly attributable to the combination of twin 850hp C15 Caterpillar engines running through Kiwi-made Seafury SF30 fixed-surface drives. With surface-piercing propellers operating half in and half out of the water, surface drives reduce both drag and draft and give good efficiency and performance at the top end. Their drawback is seen at lower speeds.

While Voodoo hit a top speed just shy of 42 knots with the Seafurys, the disadvantages (especially the cost of travelling that fast) have proved too great. This has led to the drives being removed, the engines slid forward on their bearers, the generator moved aft and conventional shaft drives and rudders installed instead.

Hill and Pachoud believe Voodoo will still be able to cruise economically at 25-30 knots, a drop in performance of about 10 to 15 per cent.

The need to switch drives has not fazed the maker, which says the project has been something of an R&D exercise. By having run and tested the design with both surface and conventional drives, it will be able to accurately quote performance and fuel figures to prospective clients.

The design parameters required to accommodate the foil have also created a spacious on-board plan, with a full-beam saloon, huge forward cabin (including a separate en-suite bathroom), three other cabins and an aft dinghy "garage".

Voodoo's interior is contemporary, with squared-off furnishings and nothing intruding above the window line. The cockpit features an eight-seat dining table, bar, icemaker, beer fridge, barbecue and drinks locker. There is also a day head/shower, a rod locker, a custom-made hydraulic rise/fall platform, a bait station, fish stowage, bait freezer and live-bait tank.

Voodoo

LOA: 17.8m

LWL: 14.5m

Beam: 6.1m

Draft: 1.0m

Displacement: 25,000kg

Construction: GRP Epoxy

Composite engines: 2 x 850hp Caterpillar C15 diesels

Maximum speed: 41.5 knots

Cruising speed: 33 knots

Fuel capacity: 5800 litres

Water capacity: 1000 litres

Want to know more?
Check out Barry Thompson's review of Voodoo in the November/December issue of Pacific Powerboat magazine.