EXPERTISE IN DEPTH

Propeller polishing

"...thousands of dollars are lost annually due to propeller inefficiency caused by surface roughness."

Cause
• Marine growth
• Mechanical damage
• Cavitation erosion

Effect
• Increased drag resulting in increased torque
• Decreased thrust
• Increased load on propulsion plant at a given speed
• Increased fuel consumption

A smooth and properly polished propeller costs less to maintain, reduces fuel consumption by up to 10 percent, and does not foul as easily.

Testing for propeller roughness

The Rubert Gauge Roughness Comparator :
• Six roughness samples are taken from new propeller finish (A) to very rough surface (F).
• Diver feels blade surface and compares to Rubert Gauge.
• This provides a reliable measure of propeller surface roughness.

Generally several readings of the propeller roughness are taken at 4 radii, approximately 0.3, 0.5, 0.7 and 0.9R and at three positions on the face and back at each radius providing an indication of the average overall surface condition.

Roughness measurements & efficiency

Recommendations:
To deal with propeller roughness the following steps should be taken:
The maximum allowable roughness should be set at (D) at which point or before it should be polished to (B).

Treated at an early stage the roughness can be removed by light and fine polishing. If remedial work is delayed however, the increase in the depth of the roughening will be accelerated, resulting in a loss of efficiency and an increase in fuel consumption. Propeller surface polishing should be carried out as part of a planned maintenance programme.
Wherever conditions permit, it is desirable and cost effective to polish the entire surface of the propeller blades. If this is not possible it is worth remembering that approximately 75% of the benefit is obtained by polishing the outer half and leading edges of the blades. For the best possible results polishing should be carried out on a regular 4-6 months cycle.

Benefits

Through the Worldwide Network, Scamp will programme your on-going underwater propeller polishing maintenance, enabling you to make significant savings on fuel costs.

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	*Propeller polishing*
	"...thousands of dollars are lost annually due to propeller inefficiency caused by surface roughness."
	Cause • Marine growth • Mechanical damage • Cavitation erosion Effect • Increased drag resulting in increased torque • Decreased thrust • Increased load on propulsion plant at a given speed • Increased fuel consumption A smooth and properly polished propeller costs less to maintain, reduces fuel consumption by up to 10 percent, and does not foul as easily.
	Testing for propeller roughness The Rubert Gauge Roughness Comparator : • Six roughness samples are taken from new propeller finish (A) to very rough surface (F). • Diver feels blade surface and compares to Rubert Gauge. • This provides a reliable measure of propeller surface roughness. Generally several readings of the propeller roughness are taken at 4 radii, approximately 0.3, 0.5, 0.7 and 0.9R and at three positions on the face and back at each radius providing an indication of the average overall surface condition.
	Roughness measurements & efficiency Recommendations: To deal with propeller roughness the following steps should be taken: The maximum allowable roughness should be set at (D) at which point or before it should be polished to (B). Treated at an early stage the roughness can be removed by light and fine polishing. If remedial work is delayed however, the increase in the depth of the roughening will be accelerated, resulting in a loss of efficiency and an increase in fuel consumption. Propeller surface polishing should be carried out as part of a planned maintenance programme. Wherever conditions permit, it is desirable and cost effective to polish the entire surface of the propeller blades. If this is not possible it is worth remembering that approximately 75% of the benefit is obtained by polishing the outer half and leading edges of the blades. For the best possible results polishing should be carried out on a regular 4-6 months cycle.
	Benefits Through the Worldwide Network, Scamp will programme your on-going underwater propeller polishing maintenance, enabling you to make significant savings on fuel costs.
Back to Services