FULL ROACH MAIN
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Geoff Cruze · Sloop
WELBOURN 12M
Start with a sail plan for how you sail, or choose from profiles already matched to this boat.
Known boat geometry
Rig data,
ready to verify.
Matched sails 24
WELBOURN 12M Sloop rig
Model reference · final dimensions require onboard verification
P 16.39 m Mainsail luff
E 5.60 m Mainsail foot
I 16.39 m Forestay
J 4.71 m Fore triangle
ISP 18.30 m Spinnaker hoist
SPL 6.77 m Spinnaker pole
LOA 12.200 m Length overall
Visual sail selection
See the sail.
Then inspect the data.
Browse sail profiles matched to this boat, then open measured dimensions and observed ranges in the detail panel. Want a complete setup? Plan an inventory around how you sail.
Main sail
STANDARD MAIN
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Headsail · Jib
J3
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Gennaker
A2
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Historical sail data
How these numbers are calculated.
Every profile summarizes measurements observed on matching boats. It is useful comparison context, not a production specification.
Example: A2 areaPositions use actual measurement values
Min170.2m²
P10170.2m²
Median170.2m²
P90188.2m²
Max192.8m²
Collect matching measurements
Each dimension uses valid records from the same boat model and sail profile.
Keep the typical range
P10–P90 contains the middle 80% of observations. The lowest and highest 10% remain outside the displayed range.
Use the median as centre
The median is the middle observation, so an unusual measurement affects it less than an average.
Final dimensions are confirmed onboard before design review and production.
Model data is context, not a build specification. Rig version, hardware and final onboard measurements are confirmed before production.