New technologies in turbo diesel engine design, hull shape and people’s attitudes are changing the way many people use their Rivieras.
Once, long-distance passagemaking was seen as the preserve of slow-moving displacement hull boats. Now, owners are increasingly demonstrating that the planing hull Riviera can offer the best of both worlds: incredible fuel economy and therefore range at slow speeds with the capability of getting somewhere quickly when needed, such as seeking shelter from a storm.
Test results from Riviera’s luxurious new 61 Enclosed Flybridge, launched at the Sanctuary Cove International Boat Show this year, have shown that it is capable of around 1,000 nautical miles with reserve by taking it slow.
When considering range, it is important to know the conditions in which test results are gained. For example, was the boat carrying minimum fuel and water during fuel consumptions test or was it under full load? Are the results calculated on full fuel burn or leaving a sensible reserve for safety? And are the distances stated in nautical or statute miles? Statute miles will make results look better. To compare one boat builder’s results against another, it is clearly important to ensure the conditions are the same.
All Riviera testing is conducted under full load (full fuel and water tanks) and is calculated in nautical miles at 90 percent fuel consumption from standard tanks (leaving 10 per cent for safety).
For example, the Riviera 61 carries 5,700 litres of diesel and 1,000 litres of water. At full load, this puts about 7.6 tonnes of extra weight into the boat. This superb cruising boat, with four cabins, three bathrooms, a penthouse-like saloon and a flybridge that is more like a salon in the sky, is a big boat, yet she is capable of both nimble performance and long-distance voyaging. Clearly, performance will vary depending on whether it is carrying 7.6 tonnes of fluid weigh or just one tonne of diesel.
At 1,000 rpm, the 1,000 horsepower turbo diesels in the Riviera 61 push this big boat along, fully loaded, at 8.7 knots, burning just 50.5 litres of fuel per hour. That’s a range of nearly 900 nautical miles, enough to take the boat from the Australian east coast to New Caledonia – or from Sydney to the Whitsundays without refuelling. And the boat has proven that it is large enough to handle the difficult seas that can sometimes be encountered on a long four-day passage.
At speeds between 16 and 22 knots, an ideal cruise in lumpy sea conditions, she has a range of 450 nautical miles and even at around 26 knots, a comfortable planing speed, the Riviera 61 will cover about 400 nautical miles – Sydney to Brisbane.
In the real world, Riviera owners are already enjoying the experience and the economy of extended range.
Riviera 56 Investigator IV has proven both capabilities, with a cruise 400 nautical mile cruise to Lord Howe Island last year that demonstrated the boat was capable of a range of 1,100 nautical miles with 10 per cent fuel in reserve.
Riviera owners Peter and Narelle Williams returned from a six-month voyage on their Riviera 47 Series II, Kaos, exploring the length of the Great Barrier Reef. They averaged just 8.1 knots throughout that time.
“Our average fuel consumption through the voyage was 29.6 litres per hour,” explained Peter. “That’s less than 15 litres per side. No wonder we didn't have to refuel very often. Kaos has a capacity of 3,700 litres. That gives me a potential range of nearly 1,000 nautical miles, leaving some for safety.”
The longest day's voyage was 170 nautical miles, on the way home, but many days were spent simply at anchor or cruising 10 or 20 miles from one beautiful bay to another.
“We used marinas only to re-supply, pick up and drop off friends or on the couple of occasions we needed to fly home for business.”
Their meticulous records show they spent 160 nights at anchor during the entire voyage.
“Why sit in a marina when you can be at anchor in a secluded bay?” said Peter.
