The revamping of the Buster S, the uncomplicated leisure boat

The Buster S boat model went through a complete revamp for the 2017 season, whereby three different versions were built on the same hull for varying needs. What were the design goals and the challenges faced, and how was the new boat model created? This is what Buster’s Kalle Kanerva, the product development engineer managing the Buster S project, had to say.

The goal: A good all-purpose boat for versatile uses with more space on board and rainwater drainage

An all-purpose boat such as this one is expected to be versatile, and versatility has indeed guided the boat model’s design and development. The Buster S is designed for use in sheltered waters. Its primary users include leisure-time cabin dwellers basically covering short distances, and it is also aptly suited for fishing and joyriding.

The design brief included incorporating rainwater drainage in line with the times as well as making the craft spacious and even more practical than before. Despite seeing its length reduced by 20 cm, the new Buster S has more flat deck space available than before, achieved by making changes such as reducing engine pit length and making the deck surface flat.

Load capacity and centre of gravity posing challenges in small boat designs

The way the boat is loaded when used has a substantial effect on how the boat runs, particularly in a craft this small. It can be difficult to make the boat plane, if there are several passengers on board and all the gear has been placed in the back. The location of the longitudinal centre of gravity is crucial in a small boat: If it is too far back, it will be difficult to get the boat on plane, and the boat will easily begin to porpoise. 

“Therefore you should always load the boat as evenly as possible to make it run in an optimal position,” Kanerva reminds us.

Engine recommendations present a challenge of their own. Many customers in Finland want to acquire a boat with an engine rating of no more than 20 hp to avoid having to go through with the registration. It is therefore important to ensure that the boat actually works properly with this smallest recommended engine power, too. 

The new Buster S gets on plane better than the previous version. Our requirement was for the boat to get on plane when powered with a 20-hp engine and with two persons each weighing 75 kg sitting on the rear bench – and this was successfully achieved. The boat was tested with all the recommended engines using several different propellers to discover the best possible combinations.

Safety and stability are key

The new Buster S has better handling characteristics than its predecessor. In a boat this small, it would not be purposeful for the hull to have a deeper “V” angle even though it would then perform better in higher waves. A boat’s characteristics are always a balance of compromises, and consideration must be given to those factors that are important specifically for the boat size category and boat model in question.  

“While safety and stability are always the most important things even in small boats, good handling characteristics add a degree of comfort into the mix in addition to safety," Kanerva says.

The right choice of propeller ensures optimal running

It is important to choose the right kind of propeller, since the propeller choice is very significant even in smaller boats. If the pitch of the propeller is too steep, the engine will not be able to reach the desired RPM range when the boat is loaded and will consequently fall short of its optimal performance. If the propeller pitch is too low, the engine will rev too high, and the engine RPM limiter will kick in to delimit the power available.

“When acquiring a boat, it is a good idea to tell the dealer what kind of load the boat will typically be expected to carry. Knowledgeable dealers will then be able to select the most suitable propeller for the boat and engine package," Kanerva explains.

The Buster S’s journey from the drawing board to the production line

The design work for the new Buster S line-up commenced in spring 2015 when Naval Architect and Designer Kai Ilmanen designed the appearance of the new boat model. The work was continued by Mechanical Designer Aleksi Juusti, who designed the technical solutions. The first two new prototypes, each with a different “V” angle of the hull, were launched for trials in summer 2015 to see how the hull shapes respond in action.

They were equipped with the bare minimum, just an engine and a steering console. Even so, already at this stage the aim was to make the weight and weight distribution as realistic as possible.

The first tests were primarily focused on the hydrodynamic and hydrostatic properties of the boats. With the right keel profile, it was possible to achieve a good directional stability at hull speed and a suitable amount of grip for brisker turns.

Once the hull and its characteristics were deemed satisfactory, it was time to commence the designing of more specific technical solutions including component choices and strength calculations. Furthermore, the factory began to design the tools and aids required for the boat’s serial production.

With the hull geometry confirmed, the hull was manufactured for the purpose of acquiring certification for the boat. At this stage, characteristics such as boat weight and floatation material were required to be in line with the production boat specifications. 

Finishing touches provided in the 0 series production process

The custom-made hull jig and the other critical production tools were completed in early 2016, after which the factory was able to start the assembly of the so-called 0 series. The purpose of this test series is to finish off the boat including every detail and make it ready for serial production. 

The 0 series’ production process also serves to verify the functionality of new production tools. The product development and production functions need to interact closely and effectively at all times, particularly during the 0 series' production process.

“Both product development and production are always represented in the project team to ensure that the best solutions can be found in collaboration and avoid any surprises in the production stage,” Kanerva explains.

“In a project like this, undoubtedly the most challenging phase is when the product goes into serial production. Every detail of the boat must allow smooth workflow. With a serial production boat, it is important to determine the right assembly sequence and to have well-designed parts that are simple enough and easy to fit,” Kanerva states.

Based on the first test run estimates, it appears that the goals set by the designers have been met.  Despite its small size, the new Buster S is a practical and spacious all-purpose boat for leisure-time boaters.

“The new hull marks a clear step forward in riding comfort, and the straightforward space solution maximises both the space available and versatility. In this case, simplicity means advancement, and actually rather beautifully as well,” says Jan Sjölund, the seasoned Editor-in-chief of the Venemestari magazine. 

For more information on the Buster S and Buster Scc model versions, go to Buster S, S1 ja Scc