Three-quarter Lug Rig: Historical Two-mast Arrangement

Posted by Robbie Dickson on

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Hiscox movement 770 shows a two-masted three-quarter lug rig with two long or lug sails and a jib stayed to a bowsprit. The labeled sails are 2, jib; 4, foresail; and 5, mainsail.

Three-quarter Lug Rig Interactive Calculator

Set an illustrative hull length and mast separation. The calculator positions the two masts symmetrically about midships for the diagram only; it does not infer historical dimensions, sail area, balance, loads or performance.

0°

Foremast from bow
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Mainmast from bow
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Illustrative mast separation
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Labeled sail count
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Equation Used

separation = L*s/100; x_fore = (L-separation)/2; x_main = (L+separation)/2; sail_count = 3.
Hiscox supplies the rig topology and sail labels but no dimensions. Symmetric mast placement is an explicit display convention, not a design rule.
  • The illustrated rig has two masts, two long lug sails and one bowsprit-stayed jib.
  • The entered separation is a percentage of illustrative hull length.
  • For display only, the foremast and mainmast are placed symmetrically about midships.
  • Yard geometry, sail area, centers of effort, wind, stability, forces, spar strength, reefing, handling and vessel suitability are omitted.
FIRGELLI Automations - Interactive Mechanism Calculators
Same mechanism and inputs as the interactive calculator.

Hiscox Movement 770

Gardner D. Hiscox describes the three-quarter lug rig as a two-masted boat carrying two long or lug sails, with a jib stayed to the bowsprit.

His labels are 2 for the jib, 4 for the foresail and 5 for the mainsail. The source does not define the name as a 75% sling point on one yard.

What This Explanatory Calculator Does

The tool scales an illustrative hull and places two displayed masts at the entered separation, symmetrically about midships. The diagram shows a jib stayed to the bowsprit, with a foresail and mainsail on the two masts.

The dimensions are not historical specifications or naval-architecture recommendations.

Illustrative Layout Convention

separation = L s/100
foremast from bow = (L - separation)/2
mainmast from bow = (L + separation)/2
labeled sail count = 3

Symmetric placement is used only to make the diagram adjustable. Hiscox provides no scale or placement dimensions for movement 770.

Worked Display Example

For an illustrative 8 m hull and mast separation of 40% of hull length, the diagram uses a 3.2 m mast separation. The foremast is shown 2.4 m from the bow and the mainmast 5.6 m from the bow.

The rig still contains the three source-labeled sails: jib, foresail and mainsail.

Model Boundary

  • Historical arrangement: two masts, two long lug sails and a jib stayed to a bowsprit.
  • Calculated: simple illustrative mast coordinates from hull length and separation percentage.
  • Not calculated: yard sling points, historical dimensions, sail area, centers of effort, balance, wind force, heel, stability, loads, spar or rigging strength, pointing ability, speed, handling, reefing or vessel suitability.

Frequently Asked Questions

Does three-quarter mean the yard is slung at 75%?

Not in Hiscox movement 770; the source does not state that relationship.

How many masts are shown?

Two.

Which sails are identified?

Jib 2, foresail 4 and mainsail 5.

Where is the jib stayed?

Hiscox says it is stayed to the bowsprit.

Are the mast positions design guidance?

No. They are an explicit display convention.

Does the calculator predict sailing performance?

No.

References

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