Its all in the Design

What makes one boat different to the next? Of course you can look at the boat and tell the difference between a half cabin and a bow rider, and a center console against a runabout. When we are looking to buy a new boat we look at the configuration that suits our needs, size, power etc, but how many people really pay attention to the shape of the hull?

There are many different hull shapes on the market today ranging from:

  • Planing Hull: designed to glide on water surface as boat gains speed

  • Pontoon Hull: two or more pontoons to create lift and floatation

  • Displacement Hull: designed to power through water, non planing

  • Round Bottom: typical to sailboats and canoes, less stable tend to roll

  • Flat Bottom: river boats, stable at rest

  • Deep V bottom: most common type of powerboat hull

  • Multi Hull: multi hulls such as catamarans are very stable and soft riding

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Each of these hull types have their place and will perform totally differently to each other, so as an individual the aim is to get a design that suits your intended use. Today we are going to have a close look at our hull design and discuss the features and benefits that we offer in the OceanCat range.

Bow

High bow and high tunnel clearance are words that we have used regularly to describe our OceanCat range, but what does it all mean, and will it make any difference? Well, the simple answer is yes. The explanation takes into account a lot of different factors which should help you understand why OceanCat have been labelled the next generation in powercats.

With today’s users travelling further and wanting more from their boats, it is essential to look at areas where things can be improved to offer better handling and fuel efficiency. Hull efficiency is a major part of this equation. Multi hull boats sit very high in the water, due to having the pontoons (hulls) at the full width of the vessel. This spreads the weight over a bigger surface area as compared to a mono hull where all of the weight is more central and resting on the single keel. Due to the depth (freeboard) in the OceanCat range we are able to carry that through to the bow which also helps raise the tunnel (wing deck) clearance between the pontoons. The pictures supplied below best show what we are talking about here. Notice the light at the end of the tunnel. Hull efficiency comes down to how easy the boat travels with minimal power. By having such clearance through our hulls means that water flows through with minimal resistance, using less power to propel forward.

When you watch a multi hull boat in the water you will notice a lot of different forces working with water going in many directions. In the right hull configuration this broken water can be used in benefit to the ride and not loose any of the efficiency

In each of the photos above we can see different forces at work. Photo 1 shows the boat at slow speed. Even here the OceanCats tunnel clearance allows the water to flow through the tunnel. Low bow and low tunnel heights will push that water to the front, creating drag and loosing efficiency. Photos’ 2 and 3 show the boat on the plane. Notice that all parts of the hull are now working. The sharp entry with the two pontoons cuts through the water allowing the spray chines to take over. The spray chines are there to deflect water. In rougher conditions these will assist in keeping the spray low, minimizing water around the windscreen and keeping the crew dryer in rougher conditions. The spray chines on the inside work the same, however the water is pushed to the centre of the tunnel. When the water from both side meets you will notice in the above photo’s that the broken water meets and boils at the start of the tunnel creating a cushion as the bow raises and falls in different conditions. The high tunnel clearance then allows that water to pass through ready for the next wave or impact with minimal change to your power which in turn helps with the efficiency.

Midship

The following picture best shows you the complete underside of the boat. Working again from the bow we get a better appreciation of the sharp entry points that we have created with our design. The entry point follows through, giving the bottom of the hull a deep V section running the full length of the vessel. Assisting the deep V we also have one large reversed chine on each side, an inner and an outer chine. These assist getting to the plane, improve stability at speed and at rest, and also help channel dirty broken water away from each propeller. Channeling the dirty water away from the propeller minimizes cavitation or prop slip which is an extremely important factor to those doing dangerous bar crossings etc.

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Stern

Although the bow is the first part of the boat to see any action, it is the stern that does the heavy lifting. Most current outboards have negative trim. From a standing start with engines trimmed all the way down are normally in a negative position meaning the propeller faces downwards from the boat. As you power on, the negative force pushes the bow down. As the bow lowers you start to trim up which reduces drag with your engines and allows the hull to work more efficiently. The OceanCat range have all been designed with full length transoms which gives maximum surface area for the boat to get to the plane. Boats that use pods or extended transoms cannot claim the same.

In General

Multi hull boats are built to travel but are the most stable platforms at rest. Although they generally have less boat in the water, the spread or beam of the pontoons cover more area allowing a multi hull boat to sit flatter. Due to this, multi hull boats aren’t built to do tight turns. When turning a multi hull vessel, the boat won’t lean like a deep V bottom mono hull. The Deep V hulls allow them to roll into the corner which is great when water skiing or doing activities that require lots of boat maneuverability. It only makes sense that a deep V boat when turned will roll to that side. On a multi hull when you have pontoons at the full width/beam of the boat, when it turns it has nothing to roll on, so it does limit how quickly and at what angle you take a turn. For this reason, multi hulls do not make good skiing or tube pulling boats, but this would be there only limitation.

OceanCat are building their range of boats to HSCV commercial survey standards using Lloyd’s scantlings requirements. The extra attention to detail and build quality ensures we can deliver a package that will handle the rigors of time. Using a combination of products including aluminium and fiberglass composite, helps to keep weight to a minimum and strength where we need it. Using 5mm plate 5083 aluminium through all wetted areas of the boat, makes them extremely tough. When OceanCat was first founded the criteria was to make sure that the boat could handle just about anything that was put in front of it and being able to beach and run into the shallows was a must for a boat that we know will be exploring the outer reefs and islands. Using 2 completely watertight bulkheads, OceanCat split the hull into four watertight chambers. Each of these chambers is fitted with an individual 6000 LPH bilge pump that are fitted with float switches and separate audible alarms. If any water penetrates these compartments the alarm will sound, giving you reason to check out what the issue might be and take action accordingly. This hull design is very safe and easy to use and maintain. All of the pumps have been fitted in areas where they can be checked regularly as part of your normal service routine. OceanCat with their hull configuration makes accessibility much easier with room to be able to check things on a constant basis.

With a purpose built factory and using current tooling OceanCat Marine are able to minimize welding by using large presses to bend and shape the material where possible. Using current procedures available OceanCat have designed and are now constructing one of the best riding multi hulls that are on the water today.

The OceanCat range designed by world renowned Roger Hill, are constructed in Queensland, Australia only by qualified tradespeople and backed by a five year structural hull warranty. Check out the full range on the OceanCat website www.oceancat.com.au or email any inquiries through to Tony on sales@oceancat.com.au for any other details.