Wood Mast Bending Calculator
Created 11/20/2002
This Java application calculates the Mast Bending Deflection, Forces and Moments for an Aft Mast Cutter/Ketch Configurated Trimaran when given the structural dimensions and rig stay and shroud tensions. It is used to predict the mast's performance in a simplified manner.

In the Aft Mast Configuration, the mast is tilted forward approximately 10 degrees from vertical, stepped above the rear main beam, and hinged for ease of mast laydown for clearance under bridges and other low overhead.

Sail Plan
Recalculation of output data is automatic when an input value is changed.
TAB or click out of a field, to see the effects of the changes on the sail forces.
All input measurements and outputs are US Standard.

This Calculator is for tapered wooden masts of this section construction only.

Mast Section
Dimensions and Properties
Bot Radius in Top Radius in Mast Length in
Bot Width in Top Width in Mast Weight lb
Bot Depth in Top Depth in CG Height in
Wall Thickness in Mast Raise Crutch Load lbf Mast Raise Winch Ten lbf
Bot Area si Top Area si Material
Crutch Hght in Jack Hght in Wood Allow Max Stress psi
Crutch Lnth in Jack Lnth in Stress at Jack psi
Moments and Loading
Bstay Load (adjust) lbf B'kstay 5/16 Allow Load lbf Stay SWL Factor
Upper Bstay Load lbf Lower Bstay Load lbf Miz'n Stay Load lbf
Section Mom
of Inertia
in4 At Jack Hght in Deflection
at Jack
Section Mom
of Inertia
in4 At Any Hght (adjust) in Deflection
Any Hght
Jack Load lbf Sect Width in Sect Depth in
Up B'Stay
Angle C
o Low B'Stay
Angle A
o Mz'n Stay
Angle M

Note: The Mast will be somewhat stiffer than calculated due to the effect of the taper on the Moment of Inertia.

Barefoot Bob Hardison