Fact and Fiction on Hull Design
Hyde Drift Boats has built its reputation on producing the highest quality product and setting the bar in the industry for its innovation and design. We spend a tremendous amount of time and money researching and developing products like the G4 bottom, 360 degree knee brace , level floors and many other innovations so that our customers can have the ultimate fishing experience. Hull design and its hydrodynamics remains our top priority in the research and development department. The ease with which our boats row is second to none and we have and continue to search far and wide to find new technology that truly improves the row ability of our boats.
The following is a brief overview on Hydrodynamics, turbulence, and drag as it relates to drift boat design, as well as a brief summery of the technology that we are currently using in our Drift boats. We will also review a few ideas that we have researched and found invalid for use in a drift boat situation and even refute some common myths on hull design.
Ask any scientist about fluid dynamics and if they are honest with you they will tell you how complex a subject it really is. That is because figuring turbulence mathematically is very complex. There are two types of flow in fluid dynamics that we must understand to see how it pertains to drift boat hull design. The first is called laminar flow. Turn on a water faucet slowly and watch as the water leaves the tap. As it first leaves the tap it is smooth and undisturbed. The flow at that point is laminar and drag is minimal. Laminar flow is very fragile and can change quickly. Turn the tap on more and watch as the water as it speeds up. The water is disturbed by air and surface texture and becomes less smooth rippled with eddies, swirling, and random motions. At that point the water is in a turbulent flow. To Learn More Click Here.
Laminar flow conditions are what you look for in hull design because drag is considerably less than with turbulent flow. That is not to say that turbulence is all bad and should always be eliminated. Take for example the dimples on a golf ball, while traveling at high speeds and rotating there is a tremendous amount of pressure on the front of the ball much more so than on the rear of the ball. The dimples create a turbulent boundary layer that brings the high speed air stream around the ball closer to the surface. This in turn increases the pressure behind the ball propelling it forward further. To Learn More, Click Here.
So why not put dimples on boat hulls, cars, airplanes and anything else that has performance reduction because of drag? Dimples wouldn’t work on Boat hulls because they are flat, slow, and don’t rotate. Dimples on a boat hull could create more drag. To Learn More, Click Here.
We won’t get into cars, airplanes, and other things as Boat hulls are our main focus but the same principles apply. It is the shape speed and rotation of the ball in addition to the dimples that allows turbulence to work on golf balls. The same principles apply to tennis balls and their fuzz and Baseballs with their stitching. There is however technology developed by NASA Langley Research Center that helped America win an Olympic medal and the America’s cup in yacht racing; it is also saving the airline industry hundreds of millions of dollars annually (To Learn More, Click Here). This technology is called Riblets. To Learn More Click Here
Riblets are tiny v-shaped grooves no deeper than scratches precisely applied and angled in the direction of the flow. Wind tunnel testing done by NASA on flat aluminum sheets shows a drag reduction of about 8%. Riblets are currently being used on airplane wings and can be found on things such as Olympic swimming suits, speed skating suits, down hill ski racing suits and a variety of other things. To Learn More Click Here
This technology appears to be supported by nature on the skin of sharks. Shark skins have tiny, tooth like denticles that appear to serve the same purpose as riblets. To Learn More, Click Here
There are complications with riblets which makes it unsuitable for drift boats. First the groves must be precisely machined or applied to the bottom to have an effect, and it’s not one size fits all. The depth and width of the groves are critical and different sizes are required for different speeds (To Learn More, Click Here). To the naked eye they appear as sand paper scratches, they must also be in the direction of the flow to reduce drag. If they go against the flow drag is increased. While ferrying a river in a drift boat you don’t spend very much time with your hull going straight with the flow. Another big problem with riblets on drift boats is that the boats are made to float in low water conditions and as everybody knows can take quite a pounding on rocks and gravel beds. Once the groves are distorted even a little, the drag reduction effect is ruined. It is a common practice for people to wet sand the bottoms of their Sail boats and speed boats to achieve a similar effect. There is a lot of controversy in these markets as to weather or not there is a benefit to doing this. To Learn More, Click HereSpeed is a key element in the equation, the faster the speed the more the effect and many believe it is unlikely for speed boats to go fast enough to feel the effect let alone a drift boat. Hi Speed is one reason the technology works so well on the wings of airplanes.
The key to having an easy rowing drift boat is by maintaining laminar flow as much as possible through hull design. The following is an overview of the proven technology we use at Hyde Drift boats to do just that. Drift boat hulls are unique to other boat hulls because the stern or transom acts as the bow or keel would on a power boat. The water flow runs from stern to bow on a drift boat. We use a rounded stern on our boats to allow the water to continue its flow as normally as possible while traveling under the boat. Sharp or blunt back ends on drift boats are a bad idea as the water would immediately become turbulent creating more drag. Any added surface area at this point through adding grooves, tunnels, or funnels would disrupt the fragile laminar flow and create drag by quickly making the flow turbulent. A smooth transition is so important here and Hyde boats are the only manufacture that currently uses this technology. Tunnels are used on some power boats but are located at the rear of the boat or the waters exit point. One must remember that the exit point on a drift boat is actually the front or bow.
We use flat, rigid bottoms on our boats. As the water flows under the boat it creates lift by forcing the boat upward. Flexible bottoms will quickly turn laminar flow into turbulent flow by the up and down movement of the hull. Wave tanks intentionally create waves and turbulence by moving a panel back and forth. Remember we want to disturb the flow as little as possible to keep drag at a minimal. Rounded rocker style bottoms create more drag by having increased surface area in the water. Take a flat sheet of plywood along with a warped sheet and throw them into the water. The flat sheet floats much better and is pulled around easily compared to the warped one.
An important element that is commonly over looked in hull design is the chines. We use sharp angled chines on our boats which allow you to control the boat much like sharp edges on a ski would. Sharp chines on your drift boat are like having low profile Z rated tires on your car. They are a must to control of you craft well.
We continue at Hyde boats to research and find solid technology that improves the way our boats row. We are committed to our customers to use the best material along with proven design so that your experience on the rivers will be one of enjoyment and of making memories to last a life time. We invite you to inquire and find out more about what makes Hyde Drift boats the best drift boats in the world. As new developments are brought to light in the hydrodynamic world you can rest assured that we will find them and where possible apply it to our boats. We will also continue our mission of educating the consumers and the drift boat industry on solid technology. Knowledge is power and we can dispel the myths and sales gimmicks that surround us all. “Superstition is a belief with out foundation and intelligence is the application of that knowledge.” (unknown)