The Race
between
Lighting Strike - Steel
and
Lighting Strike - Aluminum


To illustration the relationship between the 'Speed to Length' and 'Displacement to Length' ratios I designed 'Lighting Strike’  a classic style  sleek styled thirty-five (35) foot , Length on Deck, Day-Sailor that can be constructed in both steel and aluminum.

She is not quite the design that one might expect for steel construction, because in the ‘Minds Eye’ of a vast majority of Sailors, steel is a heavy construction material and simply does not fit their vision as a classic, sleek, racing day-sailor.  

However, if ‘Lighting Strike’ was constructed of aluminum, the ‘Minds Eye’ of most Sailors would find this construction material acceptable for this classic sleek racing day-sailor, since aluminum construction is about equal in weight to a fiberglass constructed hull.

‘Lighting Strike’ has a shoal keel, just my preference, as I wanted a boat that tracked well over a deep fin keel that would demand a bit more attention to the helm. 

Both the steel and aluminum versions, of ‘Lighting Strike’ will have the same hull form, interior layout, Engine, tankage, Rig, ballast and so forth.  The only difference is that the steel version, being heavier than the aluminum version, would have a deeper draft and longer Design waterline  than the aluminum version. 

While this design was on the drawing board the design was evaluated for  performance using 'Aero-Hydro's velocity prediction software.  to predict the ‘Seconds per Nautical mile’ for both the steel and aluminum versions of ‘Lighting Strike’. These results will give a good indication of how Displacement affects the performance of a steel hull.

Click the below link about 'Hull Speed'.

What is Hull Speed

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The following two links will take you the engineering calculations for each construction material, if you are so inclined. 

Aluminum Version- Engineering Details

Steel Version- Engineering Details


Click the below link to see the results of the race.

Velocity Predictions




New - Ongoing

The redesign of the classic sailboat Dark Harbor for Aluminum construction

Updated - June 22 2025

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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.


English Wheeling

This is not your Father's 'English Wheeling' method.

See how the 'True Round' shell plating is reduced to a flat patternsthat take the mystic out of the English Wheeling process.


Click Here for Details



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

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

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