Adventure Bay Powercats
Welcome to Adventure Bay Power Catamarans. The new direction for boating where fuel economy, ride, stability and space are all improved exponentially over the conventional monohull alternatives.
Please find below all the information you will want to know about our new range of Power-Catamarans, often called powercats, power catamaran and power multihull.
Click here to view our flyer on "Why a Powercat"
Who are we?
Keen boaters who have spent a lifetime on the water, always thinking how can this be improved!
Building boats to our own styling and layout is Adventure Bay's specialty. Making styling aesthetically pleasing, spaces comfortable, functional and easy to live in is our mantra. The Tooling is also owned by Adventure Bay Motoryachts Ltd so we put our money where our mouth is!
Our Naval Architect who makes the style and layout strong, ride well and efficient is a bright Australian and has worked in Powercats all his life. He has designed for the most experienced Cat yards and Cat design offices in Australasia. Composite Engineering by offices such as SP Gurit ensure qualified composite engineers are making the recommendations for structure to the survey codes required. To date De Norske Veritas (DNV) structural standards has been used.
Our boats are built under our close monthly supervision in the Far East at our yard and shipped to your country of choice. Our Kiwi and composite supervisor has been building light weight America's cup race boats and sailing cats for many years. Our American systems supervisor has skippered, serviced and project managed superyachts and new builds for decades now. To comply to survey rules of the country of your choice is an option we can fulfill.
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We up to our 7th boat with our Far East builder, the yard owner is a Naval Architect and has built 500 boats over 30 years. Their quality and willingness is always superb and building Adventure Bay's own design of Powercats is something they are all excited about. A leap forward for boating is always a motivating force.
Extensive research of Power Catamaran hull and layout alternatives has been on going by our supervisors, Captains and myself over the past 10 years.
Below is a blog of views I have adopted over a decade of time researching and operating Powercats of our own and testing others: |
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Background: The first multihull we owned was a 42 ft Motor-sailor we built in the late 90"s to a Wright Lavranos semi-displacement hull design. This had twin 100hp Yanmars and motored at 15-16 kts on a good day, sailed up to 10 knots. I soon realized the cost of rigging the multihull was a poor investment as the deterioration and investment cost in interest would never equal the extra diesel consumed by a Powercat. We realise we can get our sailing fix with a high performance sailing dinghy aboard the Powercat. When you get there in one third of the time of sailing, many hours of thrilling dinghy sailing can be enjoyed on a boat that's not trying to be a racer and house in the same moment.
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Next project was an 86ft Powercat Superyacht we built for world cruising and Charter and owned for 2 years named Pacific Harmony. See the page on this website.
We designed and built this for the US market and after a successful 4-month Charter campaign watching the America's Cup in New Zealand 2003 we motored her to Florida, some 9000 miles into the trade winds to sell. This gave a valuable lesson in hull shapes and what an offshore cruiser needs. This boat was based on Malcolm Tennant canoe body slim displacement hulls. The experience from owning and operating Pacific Harmony taught us many valuable lessons. |
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Hull shape principles:
Fuel economy vs. ride, comfort and draft issues became determining factors for choice of a new hull shape. The long slim displacement idea was not working offshore as well as wider more sea-going hulls. More beam in the hull for better fuel-load capacity and ride dampening and engine servicing was needed along with less draft, less pitching and less tunnel slamming. Tunnel slam has been researched extensively and the use of wider tunnel chine's and fuller above water bow sections has been included. A slight fuel economy increase will be necessary but in the real scope of the cost of running and buying a boat this size, that will be insignificant. The above improvements will be greatly valued against a small increase in fuel.
2 Power Catamaran markets for the vessel have been enquiring. One that likes the ability to cover great distance in rough water at high speed with quite low fuel burn, the "35 knot market" and the long range most fuel-efficient "10-20 knot market" 2 hull shapes are been developed for these 2 Power Catamaran markets and either can be used with either cabin top style.
Planing:
The 35-knot hull: This hull is a planning hull- foil assisted and top speeds of around 40 knots are expected. The 56 footer requires around twin 800 hp engines and water-jet propulsion, the 46 around 600hp. This is what a semi-planing monohull of the same length would be using to get 25-28 knot top speed but only give 2/3 the volume of boat. Higher horsepower engines are possible and top speed should increase to high 40's. Either engine choice should give an all day cruise speed of 35 knots. Shaft options will increase fuel burn at higher speeds; improve fuel economy at low to mid speeds.
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Foils: Foils are basically a narrow wing (approx 1 ft wide) that bridges the keels close to mid-ships. Precisely sized along with a few strategically placed fins at the stern, this gives great lift which means a higher tunnel clearance and less drag so the economy improves at speed. Also ride is improves as the foil acts like a leaf spring on a car, softening the downward motion and eliminating a lot of the tunnel slam cats suffer at speed. The plus side of the foil assisted hull is fuel economy and ride is very good at speeds over 25 knots. |
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The 10-knot speed should have reasonable economy, especially as running 1 engine means no prop drag when using waterjets. The down side is the 12-20 knot speed range is not very economical with waterjets compared to props. From our experience long range cruising we would do many trips at around 20-25 knots to arrive in unfamiliar anchorages in daylight hours and run 10 knots across oceans. For passages under 1500nm we use to run 10 knots by night and 20-25 knots by day. This is very efficient way to get a high average cruise speed and be safe at night. Imagine a 1500 nm passage in 3 ½ days! Weather windows can be safely predicted for 3-4 days so when the good weather comes, you know it will be there the entire voyage, a great safety and comfort factor.
The lower maintenance and shallow water benefits of waterjets cannot be ignored. No logs to worry the props either and the maneuverability is unbelievable in tight quarters. If an object is sighted in the water, crash stops in 2 boat lengths are no concern for waterjets. The manufacturers claim they can take full thrust in reverse instantaneously. I experienced a crash stop on a 55ft water-jet power- cat at 20 knots and was glad to be holding on, like slamming on the brakes in a bus at 30mph. You do stop very quick, great when an unexpected reef or mammal/swimmer appears in front. |
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Displacement: The 20 knot hull: If the thought of driving a boat at 35 knots is too daunting, the 20 knot hull is a good option. Halve the horsepower and this saves some capital outlay as well. The 20-knot hull is a shaft driven displacement hull without foils that has an efficient hull speed of 20-25 knots. Over 25 knots the foil-assisted 35kt hull becomes more efficient but in the 12-20 knot range, the displacement hull is the way to go. When the weather gets real rough, (12-16ft sea's) we all slow down to 8-12 knots. In mid-rough conditions, 8-12ft sea's the displacement hull will probably feel more comfortable around 14-18 knots. The foil hull will still be happy at 20-22 knots with its higher tunnel clearance due to the foil keeping the boat up higher. Slow the foil hull down to 16 knots and the fuel burn will go way beyond the displacement hull fuel burn. All depends what speed you feel comfortable at, the sea conditions you go out in and how long you like to spend getting from A to B.
My personal preference is a boat that can handle rough water so you can go when it suits you, a faster boat that can get across rough open water swiftly and in comfort. That leaves you more time to enjoy the anchorages and potter around the bays, swimming, snorkeling etc. Long ocean passages to me become boring for most on board and also risky with changeable weather. Hence higher top speeds in open water means less chance of getting caught with bad weather and longer time to sail the bays with the kids and enjoy the sunsets. |
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Shorter passages allowing one to leave and enter unfamiliar islands in bright daylight (9am-3pm) when the overhead sun aids in reef spotting is also very useful and adds to safety.
The displacement 20kt hull can cover 120 miles in that 6 hour time, the foil assisted 35kt boat- 210 miles in the same 6 hour day which opens up the possible safe day passage range a little further." Your preference and boating area may be quite different. With 2 hull types there is the choice.
Both hulls are wide body so interior space is vastly improved over traditional canoe body slim displacement hulls. Personal experience with large fuel loads also tells me the slim hull fuel economy suffers badly for the first half of a long passage. This we hope to avoid with wider body displacement hulls. Also we noticed a very sharp ending when rolling in a slim hull form and believe this comes from the wing deck to hull area immersing and sharply ending the roll. The wider hull form has the extra hull buoyancy to reduce this fast immersion and snappy motion that many find uncomfortable on multi-hulls.
Horsepower needed for the displacement hull to reach 25-knot max, 20- knot cruise should be:
For the 56 footer: around 350-400hp per side,
For the 46 footer: around 250-300hp per side. Lower horsepower is fine to lower the top speed, as displacement hulls are still economic down in the high teens.
For more information, please contact me.
Here is what the press are saying...
NZ Herald Three Adventures story (click to enlarge)
