HOME
Introduction
Quick
Start
Quick Series
Facts
PSModel
Program
Data
Input
Data
Output
Importing a
Data file into
MS Excel
Main Menu
Main
Screen
Printing
Graphs
and Data
Screen Colors
and Fonts
Screen
Graphs
Shortcuts
Working
with Data
Testing:
Test
Sheet
Examples
19' Ski Boat
34' Sailboat
41' Utility Boat
Technical
Blade Area
Ratio
Calculating
the Cavitation
Number
Horsepower
Losses
Hull
Speed
Kt
Breakdown
Propeller
Geometry
Propeller Law
Wake
Factors
Glossary
References

Quick Series Facts:
The following is a description of the various
Propeller Series used in PSModel.
Notes:
1) Blade Area Ratio
(BAR) as used in PSModel is a generic term referring to either
Expanded Area Ratio (EAR) or Developed Area Ratio (DAR). Normally, the
EAR and DAR of a propeller are very close in value. The tables below
show which ratio, EAR or DAR, was used in the published data or reference
for each Series.
2) Efficiency curves for all Series in PSModel are
calculated from Kt and Kq values as follows:
Efficiency = (J × Kt) / (6.28319 × Kq)
3) PSModel uses linear data interpolation for
Series that utilize tabular data
such as 'GBD', 'GBA', 'NR', 'NV3' and 'NV4'. In most cases, linear
interpolation works fine. However, in some cases  such as
interpolating Kt or Kq at very low Cavitation Numbers  linear
interpolation may not be accurate. This is due to the highly nonlinear
nature of the data associated with these cases. Series that are
represented by
polynomials  such as 'GBL', 'GRJ',
and 'GBR'  eliminate this problem and also produce smoother propeller
curves. Keep this in mind while evaluating propellers.
4) Use PSModel as a guide only. Keep in mind
that the following items can affect predicted propeller performance:
 angle of propeller shaft with respect to inflow
 wake, or flow velocity into the propeller, is
usually an approximation
 pitch and diameter values may differ slightly from
values marked on the propeller or advertised
 the published BAR for a propeller is usually not
exact: e.g., 0.70 published, but actual may be 0.69 or 0.71
 boat speed and RPM need to be as accurate as
possible
(B)  B Series
Description  A
noncavitating Series that
uses a polynomial to represent a large body of experimental data. This
Series can be used to evaluate propeller performance on low speed vessels
including yachts, recreational boats, and ships. This Series has a
unique geometry but can be used to approximate performance of many
commercially available propellers including 2 and 3 blade propellers
commonly used on sailboats.
Calculation method used by PSModel  Polynomial
evaluation, see reference 1
Blades 
EAR 
P/D Ratios 
Cavitation Number Range 
2 
0.20 to 0.40 
0.50 to 1.40 
Noncavitating Series 
3 
0.35 to 0.80 
0.50 to 1.40 
Noncavitating Series 
4 
0.40 TO 1.00 
0.50 to 1.40 
Noncavitating Series 
5 
0.45 to 1.050 
0.50 to 1.40 
Noncavitating Series 
6 
0.50 to 0.80 
0.50 to 1.40 
Noncavitating Series 
7 
0.55 to 0.85 
0.50 to 1.40 
Noncavitating Series 
Notes:
1) The EAR range for the 2 bladed propellers tested
is actually 0.30 to 0.38 but PSModel allows 0.20 to 0.40 by
extrapolating the polynomial calculations. This was done because
commercial, two bladed, sailboat propellers are available with EAR values
less than 0.30. The value 0.38 was rounded to 0.40 for uniformity
purposes.
2) P/D ranges used by PSModel (as shown in
the Table above) are slightly larger, in some cases, than presented in the
available literature concerning the BSeries. This was done to make
the Series more uniform.
3) PSModel output is for a
Reynolds Number based on chord
length of 2x10^{6}
4) Propellers being evaluated can have some cavitation
present as long as Kt Breakdown has not
occurred.
5) Click here
for propeller Series geometry details.
6) The most resent version of the B Series can be obtained
from the Marine Research Institute Netherland (MARIN) at
http://www.marin.nl.
(GBA)  Gawn Burrill Atmospheric, Digitized
Description  A 3 blade
subcavitating
Series used by many to approximate performance of flat faced
commercial propellers typically found on small high speed vessels
including recreational boats.
Calculation method used by PSModel 
linear interpolation of digitized Kt\Kq curves from reference 2
Blades 
DAR 
P/D Ratios 
Tested Cavitation Numbers 
3 
0.50 
0.6, 0.8, 1.0, 1.2,
2.0 
6.3 
3 
0.65 
0.6, 0.8, 1.0, 1.2,
1.4, 1.6, 2.0 
6.3 
3 
0.80 
0.6, 0.8, 1.0, 1.2,
1.4, 1.6, 2.0 
6.3 
3 
0.95 
0.8, 1.0, 1.2, 1.4,
1.6, 2.0 
6.3 
3 
1.10 
0.8, 1.0, 1.2, 1.4,
1.6 
6.3 
Notes:
1) Series 'GRJ' below calculates Gawn Burrill Kt\Kq
curves from a polynomial obtained by regression analysis. A
polynomial produces smoother curves and reduces nonlinear errors.
However, the P/D range of 'GRJ' is less than that of 'GBA'.
2) Efficiency curves calculated by PSModel
for 'GBA' in some cases do not appear smooth. This occurs
because PSModel calculates Efficiency directly from Kt and Kq
values as presented in reference 2, and does not fair or
smooth the resulting curve. For smoother Gawn Burrill Kt, Kq,
and Efficiency curves, see Series 'GRJ' below.
3) Blade section shapes, except near the hub, are
segmental (flat face and circular back).
4) Click here for propeller Series geometry details.
5) Experimental work for this Series was funded by
the U.K. Ministry of Defence.
(GBD)  Gawn Burrill Cavitating, Digitized
Description  A 3 blade
cavitating Series used by many
to approximate performance of flat faced commercial propellers typically
found on small high speed vessels including recreational boats.
Calculation method used by PSModel  linear
interpolation of digitized Kt\Kq curves from reference 2. To reduce
nonlinear errors, linear interpolation is performed both vertically and
diagonally.
Blades 
DAR 
P/D Ratios 
Tested Cavitation
Numbers 
3 
0.50 
0.6, 0.8, 1.0, 1.2, 2.0 
0.5, 0.75, 1.0, 1.5, 2.0 
3 
0.65 
0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 2.0 
0.5, 0.75, 1.0, 1.5, 2.0 
3 
0.80 
0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 2.0 
0.5, 0.75, 1.0, 1.5, 2.0 
3 
0.95 
0.8, 1.0, 1.2, 1.4, 1.6, 2.0 
0.5, 0.75, 1.0, 1.5, 2.0 
3 
1.10 
0.8, 1.0, 1.2, 1.4, 1.6 
0.5, 0.75, 1.0, 1.5, 2.0 
Notes:
1) Series 'GBR' below calculates Gawn
Burrill Kt\Kq curves from a polynomial obtained by regression analysis.
A polynomial produces smoother curves and reduces nonlinear errors.
However, the P/D range of 'GBR' is less than that of 'GBD'
2) Efficiency curves calculated by PSModel
for 'GBD' in some cases do not appear smooth. This occurs because
PSModel calculates Efficiency directly from Kt and Kq values as
presented in reference 2, and does not fair or smooth the resulting
curve. For smoother Gawn Burrill Kt, Kq, and Efficiency curves, see
Series 'GBR' below.
3) Blade section shapes, except near the hub, are
segmental (flat face and circular back).
4) Click here
for propeller Series geometry details.
5) Experimental work for this Series was funded by the
U.K. Ministry of Defence.
(NV3)  Navy 3 Blade
Description  Cavitating Series that consist of
commercial, flat faced, 3 bladed propellers typically found on small
commercial vessels, yachts, and recreational boats. Blade Area Ratio (BAR)
is limited to 0.54. This Series was tested by the Navy, using 2 ft.
diameter propellers on an instrumented boat under actual sea conditions.
Calculation method used by PSModel  linear
interpolation of tabular data, see reference 3
Blades 
EAR 
P/D Ratios 
Tested Cavitation
Numbers 
Cup 
3 
0.54 
1.004 
2.334, 3.963, 5.136, 11.692, 16.914 
None 
3 
0.54 
1.239 
2.396, 3.630, 5.544, 12.939, 18.581 
None 
3 
0.54 
1.503 
2.729, 4.013, 5.445, 12.359, 18.198 
None 
3 
0.54 
0.996 
2.741, 3.630, 5.334, 12.050, 17.618, 19.760 
Light 
3 
0.54 
1.244 
2.729, 3.581, 4.791, 11.173, 17.038, 19.760 
Light 
3 
0.54 
1.497 
2.717, 4.001, 5.544, 12.828, 19.760 
Light 
3 
0.54 
0.996 
2.704, 3.605, 5.198, 11.754, 17.865, 19.760

Medium 
3 
0.54 
1.504 
2.754, 3.926, 5.433, 12.470, 19.760 
Medium 
3 
0.54 
1.00 
2.766, 3.642, 4.988, 10.865, 16.593, 19.760 
Heavy 
3 
0.54 
1.492 
2.717, 3.568, 5.334, 11.840, 17.420, 19.760 
Heavy 
Notes:
1) Cavitation Numbers used in PSModel are
based on inflow velocity to the propeller but Cavitation Numbers reported in
reference 3 are based on boat speed. Cavitation Numbers reported in
reference 3 were divided by (1w)^{2} [or 0.9^{2} = 0.81]
to obtain the values above.
2) The Michigan Wheel Dyna Jet propellers tested
were commercially available and had flat faced, circular back, blade
sections.
3) The nominal EAR value reported in reference 3 was 0.50, but reference
4 reported additional details about this Series including measured EAR
values which ranged from 0.53 to 0.55 with 0.54 appearing as the average.
Therefore, PSModel uses a nominal EAR = 0.54 for 'NV3'.
4) Click here
for propeller Series geometry and cupping details.
(NV4)  Navy 4 Blade
Description  Cavitating Series that consist of
flat faced, 4 bladed propellers similar to those found on small commercial
vessels, yachts, and recreational boats. Blade Area Ratio (BAR) is
limited to 0.70. This Series was tested by the Navy, using 2 ft.
diameter propellers on an instrumented boat under actual sea conditions.
Calculation method used by PSModel  linear
interpolation of digitized data, see reference 4
Blades 
EAR 
P/D Ratios 
Tested Cavitation
Numbers 
Cup 
4 
0.70 
1.058 
1.20, 1.80, 2.20, 3.40, 5.50, 11.70 
None 
4 
0.70 
1.224 
1.30, 1.70, 2.30, 3.40, 5.60, 11.80 
None 
4 
0.70 
1.472 
1.20, 1.70, 2.30, 3.30, 5.80, 12.20 
None 
Note:
1) EAR = 0.70 is nominal. EAR values for test
propellers varied between 0.70 and 0.72.
2) The propellers tested were specially manufactured to
have an approximate EAR = 4/3 of the 3 bladed propellers used for the 'NV3' Series, but
otherwise were similar to the 3 bladed Michigan Wheel Dyna Jet propellers.
3) Click here
for propeller Series geometry details.
(NR)  Newton Rader
Description  High speed, 3 bladed, cavitating Series
based on a unique propeller geometry. Predictions from this Series
should be limited to use with propellers with the Newton Rader geometry.
Calculation method used by PSModel  linear
interpolation of tabular data, see reference 5
Blades 
DAR 
P/D Ratios 
Tested Cavitation
Numbers 
3 
0.48 
1.05, 1.26, 1.67, 2.08 
0.25, 0.30, 0.40, 0.50, 0.60, 0.75, 1.00, 2.50,
5.50 
3 
0.71 
1.05, 1.25, 1.66, 2.06 
0.25, 0.30, 0.40, 0.50, 0.60, 0.75, 1.00, 2.50,
5.50 
3 
0.95 
1.04, 1.24, 1.65, 2.04 
0.25, 0.30, 0.40, 0.50, 0.60, 0.75, 1.00, 2.50,
5.50 
Notes:
1) The blade section shapes were designed with
cavitation in mind; hence, the shapes are unique to this Series.
2) Click here
for propeller Series geometry details.
3) Experimental work for this Series was funded by the
U.K. Ministry of Defence.
(GBL)  Segmental Sections, Blount Polynomial
Description  Noncavitating Series uses a polynomial to
represent performance of 3 and 4 bladed, flat faced propellers typically
found on slower recreational boats, yachts, and commercial vessels.
The polynomial for this Series was synthesized from published data for other
experimental Series. The polynomial was validated by comparing
performance predictions with existing data for commercial, flat faced,
segmental section propellers.
Calculation method used by PSModel  Polynomial
evaluation, see reference 6
Blades 
EAR 
P/D Ratios 
Cavitation Number Range 
3 
0.50 thru 1.10 
0.80 thru 1.40 
Noncavitating Series 
4 
0.50 thru 1.10 
0.80 thru 1.40 
Noncavitating Series 
Notes:
1) Segmental sections are composed of flat faces with
circular backs. This is typical of many commercially available
propellers.
2) Propellers being evaluated can have some cavitation
present as long as Kt Breakdown has not
occurred.
3) Geometry that is representative of this Series is shown
by 'GBD',
'NV3', and
'NV4' .
(GRJ)  Gawn Burrill Atmospheric, Radojcic Polynomials
Description  Series uses a polynomial to represent the
performance of the subcavitating portion
of the 3 bladed Gawn Burrill Series: i.e., the portion of the Series that
does not show signs of Kt Breakdown.
This Series can be used for higher speed boats with flat faced, commercial
propellers with minimal cavitation, i.e., higher speed lightly loaded
propellers. Also see the 'GBA' Series above.
Calculation method used by PSModel  Polynomial
evaluation, see reference 7
Blades 
DAR 
P/D Ratios 
Cavitation Number Range 
3 
0.50 thru 1.10 
0.80 thru 1.80 
6.3 
Notes:
1) Propellers being evaluated can have some cavitation
present as long as Kt Breakdown has not
occurred.
2) Click here
for propeller Series geometry details.
3) Polynomial was developed by Professor Dejan Radojcic,
Department of Naval Architecture, Faculty of Mechanical Engineering,
Belgrade University.
(GBR)  Gawn Burrill Cavitating, Radojcic Polynomials
Description  Series uses a polynomial to represent
performance of the cavitating portion of the 3 bladed Gawn Burrill Series.
The maximum cavitation number is 2.0. Representation
with polynomials minimizes nonlinear problems that can arise when linear interpolation
is used as in
'GBD' above. The P/D range for this Series is slightly less than that
of 'GBD'. This Series can be used to approximate performance of flat
faced, heavily loaded, commercial propellers typically found on small high
speed vessels, including recreational boats.
Calculation method used by PSModel  Polynomial
evaluation, see reference 7
Blades 
DAR 
P/D Ratios 
Cavitation Number Range 
3 
0.50 thru 1.10 
Minimum P/D =
1.25 − 0.3×DAR − 0.2×(Cavitation Number)
but not less than 0.80,Maximum P/D =
1.60 
0.50 thru 2.00 
Notes:
1) Click here
for propeller Series geometry details.
2) Polynomial was developed by Professor Dejan Radojcic,
Department of Naval Architecture, Faculty of Mechanical Engineering,
Belgrade University.
