(Denna sida är skriven på engelska eftersom bidragen och designtävlingen är på engelska)

Proffesional Boatbuilder Magazine announzed in oktober 2008 a Design Challenge with the following criterias:

“Professional BoatBuilder and WoodenBoat magazines are offering a design challenge for new, creatively designed powerboats in any material that are efficient, fun, and could possibly be the only vessel a boating family of modest means might actually afford.”

Design Parameters

• 16’6” to 18’6” overall length, stem to stern (transom)
• 25-hp maximum power
• Must burn less than 2 gallons per hour while maintaining a 15-knot cruising speed and carrying 650 lbs (four adults or equivalent)
• Trailerable weight (with engine) must be less than 2,700 lbs
• Must be able to safely (if not comfortably) get home against a steady 15-knot breeze with higher gusts, and a 2' to 3' chop

Poseidon Konsult in cooperation with Staffan Sjöling joined the challenge with two different concepts, the Evolution 550 and Nordeco 55.

Poseidon Konsult has been in charge of the Evolution 550 concept and Staffan Sjöling of the Nordeco 55. Design parameters about engine, efficiency, hull optimization, sea keeping, hull structure etc. have been discussed back and forth but in the end it is completely different concepts.

The Evolution 550 is a carbon/ Divinycell sandwich optimized hull while Nordeco 55 has a more robust Aluminium hull structure.

Evolution 550

Nordeco 55

Below are an extract from the Evolution 550 report. The full Evolution 550 report without appendices can be downloaded here.

More pictures and the report of Nordeco can be viewed here.

Evolution 550

Main dimensions of Evolution 550

Background

Evolution 550 is a Scandinavian design, a boat that shall attract not only a family of four people out for a day trip but also a couple who wants to be able to take longer trips and stay overnight. The boat is economical and ecological to use with low fuel consumption. The standard model is comfortable equipped and has a 25 Hp Engine which will allow the boat to have low fuel consumption in the cruising speed of 15 knots and a maximum speed of 20 knots.

Layout

The hull and the interior of the boat are carbon sandwich construction to gain high strength in the structure and low weight. Outwards the hull and the deck are painted to have a classic design and the interiors are unpainted to show the exclusive special carbon fibre depth.

The drive console is positioned on the Starboard side to have a clear view. The driver console is well equipped with GPS, Tachometer, lanterns, power trim and tilt maneuvering. On the port side there is a passenger seat. The drive and the passenger are protected from wind drag by a windshield. Aft there is a passenger bench and underneath the bench there is a storage compartment for equipment. Under the fore deck there are two comfortable beds for the overnight stays. The boat is equipped with canvas top which can be folded up in the night or in bad weather.

The canvas top is in its stoved position folded aft of the bench. Aft there are two platforms for bathing and a stern ladder for both safety and bathing.

Hull design

The hull of the Evolution 550 is a mono hull form with developed surfaces. The choice of developed surfaces is due to simple production and low cost construction.

Material

The hull is design according to the standard ISO 12715, Hull construction and scantling for small crafts and mainly ISO 12715:5, Design Pressures for mono hulls, design stresses and scantlings determination.

The hull and interior structure is a sandwich construction based on carbon fibers and Divinycell as core material. In areas where the hull is exposed for wear and tear the hull have been reinforced up to 3 times compared to the standard.

Weight calculation

Evolution 550 is fully equipped from the start with all necessary equipment as well as safety equipment. In the calculation for resistance, speed, stability and sea keeping the driver and three passengers is also included. The total weight including driver, passengers and fuel is calculated to 699 kg.

When all loose equipment is removed the light weight of the boat is 318 kg, with the included 5% margin.

Engine

The chosen Engine to power the boat is a four stroke Yamaha F25AETL with electric start, power trim and tilt. In this version the standard propeller has been chosen in order to be able to evaluate fuel consumption towards similar tested boats with the same propeller. If the boat is set in production the propeller will be further evaluated to optimize it.

The maximum speed for the chosen engine of 25 Hp with full load is 20 knots and the power required at 15 knots is 17.7 Hp.

The maximum speed for the design contest weight is 21 knots with the chosen engine and the power required at 15 knots is 15.4 Hp.

Resistance calculations

The resistance for Evolution 550 has been predicted with Savitsky method for planning boats (1967). The required power including propeller efficiency and design margin is shown in Figure below. A Design Margin of 5% is used within the weight calculation and the propeller efficiency has been calculated to 55%. The propeller efficiency could be predicted a little higher but the 55% might be seen as an ad on design margin. The required power for 15 knots has been marked in the figure.

The maximum speed for the chosen engine of 25 Hp with full load is 20 knots and the power required at 15 knots is 17.7 Hp.

The maximum speed for the design contest weight is 21 knots with the chosen engine and the power required at 15 knots is 15.4 Hp.

Fuel consumption

To calculate engine fuel consumption tests for similar boats with measured fuel consumption in different loads have been but into a diagrams of fuel consumption/rpm and Power/rpm. The boats are all tested with the same engine, Yamaha F25. The calculated required power for Evolution 550 has been compared to the boats and the boat with the power curve that is close to Evolution 550 has been used as a reference object. The required power for Evolution 550 with full load and design contest weight compared to the used reference boat can be seen in below figure.

The fuel consumption for Evolution 550, with full load, at 15 knots has been calculated to 1.476 gallons/hour (5.59 litre/hour) which can be seen in the figure. Evolution 550 is equipped with a 5.3 gallon (20 litre) fuel tank which gives a service range, single way, of 46.7 nautical miles or 3.1 hour with 15 % service margin.

The fuel consumption at 15 knots for the design contest weight is 1.284 gallons/hour (4.86 litre/hour) which also can be seen in the figure as Evolution 550 + 650 Ibs. The service range, single way, with 15% margin is 61.7 nautical miles or 4.1 hours.