Introduction to R & P
Resistance and Propulsion of Ships Preliminary propeller design using charts
Introduction to R & P
! Example 3
Resistance and Propulsion of Ships
Fishing vessel Use the K-J chart to select the appropriate P/D ratio for a B4-70 screw to be used for this vessel. Estimate open water efficiency.
Introduction to R & P
! Example 3
Resistance and Propulsion of Ships
J = 0.36 KT = 0.131 Find this on the chart… …it lies on the KT curve for a prop with a P/D of 0.6. Find the corresponding KQ for P/D = 0.6. KQ = 0.0155
KT=0.131
10KQ=0.155
Introduction to R & P
! Example 3
Resistance and Propulsion of Ships
This chart may be easier to use…
KT=0.131
P/D (KT) = 0.60 P/D (KQ) = 0.60
10KQ=0.155
Introduction to R & P
! Example 4
Resistance and Propulsion of Ships
Harbor tug Use the µ-σ chart to select the appropriate P/D ratio for a B4-70 screw to be used for this vessel. Estimate open water efficiency.
Introduction to R & P
! Example 4
Resistance and Propulsion of Ships
µ = 5.19
φ = 2.10
Go to chart and find µ = 5.19.
µ = 5.19
Introduction to R & P
! Example 4
Resistance and Propulsion of Ships
µ = 5.19
φ = 2.10
Go to chart and find µ = 5.19.
Track along φ =2 and then estimate (interpolate) the point on the line for µ = 5.19 and φ =2.1.
µ = 5.19
φ = 2.10
Introduction to R & P
! Example 4
Resistance and Propulsion of Ships
µ = 5.19
φ = 2.10
µ = 5.19
φ = 2.10
Go to chart and find µ = 5.19.
Track along φ =2 and then estimate (interpolate) the point on the line for µ = 5.19 and φ =2.1. Read the P/D ratio as approximately 0.92. (Interpolation is required).
P/D = 0.92
Introduction to R & P
! Example 4
Resistance and Propulsion of Ships
µ = 5.19
φ = 2.10
µ = 5.19
φ = 2.10
Go to chart and find µ = 5.19.
Track along φ =2 and then estimate (interpolate) the point on the line for µ = 5.19 and φ =2.1. Read the P/D ratio as approximately 0.92. (Interpolation is required). Note also that ηo = 0.44 and σ = 1.1
P/D = 0.92
σ = 1.1
ηο = 0.44