D-Style vs. Gawn Burrill-Style Propellers

There are two broad product categories in this market: open propellers and ducted propellers. The differences in these two applications are vast, so, we’ll focus on open propellers. Within this category, two time-tested propeller designs prevail—D-Style and Gawn Burrill-Style. Although they are both superior designs, deciding between D-Style versus Gawn Burrill-Style propellers depends largely on what they are being applied to.

Gawn Burrill-Style

Today’s push boats and tow boats are built with greater horsepower than they were two decades ago. However, the aperture for tow boat propellers is not increasing proportionally. This means that more horsepower must go through a propeller of a relatively small diameter, thus, the blade area must increase to absorb the greater horsepower.

Compound the additional horsepower with draft limitations and boat builders are faced with a challenge. The water flow into the propeller can be less-than-perfect. In these scenarios, where high horsepower, limited draft, and aperture all come together, vibration can, in certain cases, be a problem with the Gawn Burrill-Style propeller. An answer to this problem can be the use of the D-Style propeller.

D-Style

Computational Fluid Dynamic studies have shown that in cases where the boundary layer of water flow around a hull form is less than perfect, the D-Style can resist vibration better than the Gawn-Burrill Style props of a similar dimension. However, the Gawn-Burrill design is slightly more efficient on paper. The term ‘on paper’ is important to note because the theoretical gains are so slight that it’s hard to prove them in a practical environment with ever-changing variables such as loading and weather conditions.

In an era where crew comfort is paramount, many fleet owners opt for the D-Style propeller in the D-Style versus Gawn Burrill-style propeller debate to minimize noise levels and vibration. This also helps in the longevity of the other systems in the vessel by allowing them to run smoother and avoid being rattled around by vibrations.