For the selected collinear fully-hoisted reference, effective stacked length is mast length plus yard length minus their overlap. Signed target error is effective length minus selected target.
Sliding Gunter · Spar Hoist and Stack Dimensions
Explore a sliding upper spar and compare its fully raised height with a selected target.
Equation Used
- Mast and yard are treated as collinear projected lengths at full hoist.
- Selected overlap is the duplicated length in the stack and a physical stack requires overlap no greater than either spar.
- Target is a selected comparison value, not an approved sail or rig dimension.
- Attachment offsets, rake, stretch, loads, strength and safety are excluded.
The visual maps spar lengths and overlap exactly on one reference line; sail shape is illustrative. Overlap greater than the shorter spar cannot form the shown stack.
Short mast with a nearly vertical sliding yard
The visual stacks selected mast and yard lengths on one reference line and maps their selected overlap exactly. A sail outline makes the sliding-gunter arrangement recognizable but is illustrative.
What the calculator determines
Select mast length, yard length, overlap and target height. The calculator reports effective stacked length, overlap share of total spar length, signed target error and absolute target error.
Selected collinear stack
Leffective = Lmast + Lyard − Loverlap; overlap share = 100Loverlap/(Lmast + Lyard); error = Leffective − Ltarget.
Selected-input arithmetic
For a 2.30 m mast, 2.20 m yard and 0.30 m overlap, effective stacked length is 4.20 m.
Projected dimensions
The relation assumes collinear projected spars and treats selected overlap as the duplicated length. Actual sail luff depends on tack, throat and head attachment positions, yard rake, stretch and hardware. The model does not determine minimum safe overlap, spar strength, rig loads, stability, sail shape, performance or safety.
Questions
Is effective stacked length always the sail luff?
No. It is a selected collinear reference; attachment offsets and yard rake can change actual luff.
Does the calculator approve an overlap?
No.
References & Further Reading
- Wikipedia contributors. Gunter. Wikipedia
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