Dark Harbor
(Original Gaff Sail-plan)

Go to Dark Harbor Links

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The 'Sailplan Ratios' below were calculated using a Computer software iprogram.

About Sailplan Ratios


The initial inputs required were the location of the corner points in, 'Decimal Foot', dimension format.  The dimensions were taken from Dark Harbors Sail-Plan drawing shown below. 

sail-gaff-4.jpg

The below Charts shows the Hull Characteristics that were also required and can be found in the previously posted Static Hydrostatics.

However the 'Righting Moment  at 20 degrees' is estimated, since I have yet to make that calculation.  Four Thousands Pounds (4,000) will suffice for now.  I will update later. 

The following drawing is a screen plot of the above Sail points and Hull Characteristics in graphic form.  Shown are the Center of Effort of the Sail-plan and the Location of the Center of Laterial resistance. 

Go to Dark Harbor Links

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New - Ongoing

The redesign of the classic sailboat Dark Harbor for Aluminum construction

Updated - June 22 2025

dark-harbor-model-file.jpg

Go to Dark Harbor Redesign

New to Steel and Aluminum True Round Boatbuilding

The Catspaw Dinghy

Click Here

Steel and Aluminum True Round Plans

Click Here

"Lighting Strike'

Why weight does not the sole factor in determining the speed of a Displacement hull.

Go to Lighting Strike's Velocity Predictions

How to layout and fabricate Hull Intergrals

Fabricating Hull Intergrals such as a Hatch Coaming is the next stage of boat construction.

The below pics is an initial dimensioned hand sketch - The first step in the layout process.


Click here to continue the process.

Complimentary

English Wheel Test Pattern

Includes the flattened layout for the second section from the bow of the 'Bezier 28', in PDF file format, to be formed in your English Wheel along with the plywood 'Forming Templates' used to guide the 'English Wheeling' process.

(Practice your English Wheeling Skills)

While, this may not be your 'Forte'. It sure will give you the feel for English Wheeling!)

To receive a Full-size test pattern simply send a request text to:

617-653-1063

Go to English Wheeling page:

Which type of hull is faster - A True Round design or Hard Chine design? See which via the results of 'Velocity Prediction' software.

Click Here

conversion1.jpg

The top pic is the orginal design - The bottom pic is the converted True Round version.

conversion2.jpg