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Cirrus LT - Stitch & Glue
(plywood, hard chine)

Technical specs...


 Classic, hard chine 'Greenland style' touring kayak for smaller to medium height and weight paddlers.






Plywood          Hybrid

Cirrus LT description | MATERIALS | S&G Kits

Cirrus LT Hybrid Wood strip deck version of this kayak model
CirrusLarger (original) displacement version of this kayak model
Cirrus SLT Smallest displacement version of this kayak model


Here are a few images off the shop floor as the Cirrus LT prototype is being "buttoned up". Note the size comparison with the Cirrus. The perspective forshortened view distorts the relative size a little. The CirrusLT is full 18" shorter.

Building Materials

PropertyEnglishUnitsMetricUnitsComments
Length Overall 16 ft 4,87mlength from bow to stern as designed
Beam Overall 21.5 in 54,6cmwidest part of kayak
Draft 3.864 in 9,81cmbaseline to Designed Water Line (DWL)
Volumetric Properties
Displacement 198.8 lb 90,36kgat DWL
Volume 3.1 ft^3 87,9litersdisplacement in cubic feet and liters of sea water
Wetted Surface 18.06 ft^2 1,67m^2underwater surface area to DWL
LCB 7.75 ft 2,36mlongitudinal center of buoyancy from x=0
LCB % LWL53.23%53,23%LCB as a percetage of waterline length from x=0
VCB2.426 in 6,16cmvertical center of buoyancy from baseline
Waterplane Properties
Waterplane area 14.617 ft^2 1,358m^2at DWL
LCF 7.55 ft 2,3mlongitudinal center of flotation from x=0
LCF % LWL51.9%51,9%LCF as a percetage of waterline length from x=0
LWL 14.558 ft 4,437mlength of waterline; same as DWL
BWL 19.18 in 48,73cmbeam of waterline
Sinkage 77.96 lb/in 13,95kg/cmpounds displaced per one inch of sinkage
Form Coefficients (no units, same for metric)
Cb 0.414    block
Cm 0.783   midship
Cp 0.529   prismatic
Cwp 0.628    waterplane
Area/Displacement8.483   Area / Displacement ratio [ft^2/(ft^3)^2/3]
Length / Beam9.104   Length / Beam ratio [LWL / BWL]
Miscellaneous
Area of cockpit 2.9 ft^2 0,269m^2for cockpit template in plans (red)
Circumference 6.5 ft 1,98mcockpit
Depth in front 11.5 in 29,21cminside cockpit
Depth in rear 9 in 22,86cminside cockpit
Deck area 19.23 ft^2 1,786m^2includes cockpit area
Hull area 27,61 ft^2 2,56m^2 
Kayaker Fit & LoadingSmaller to madium size paddlers
130 lb min. -> 162 lb ideal -> 187lb max. (59 -> 74 -> 85,4kg)
Recommended max. load: 221lb (100,6 kg)
Paddler height: 6' and under (183 cm and under)
x=0 the start of waterline (DWL) at bow

All English units (ft / in) in the plans have a Metric (m / cm) eqivalent !

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Material

  Plywood
Unit converter
Metric / Standard unit converter

The minimum required plywood amount for the CirrusLT hull is 3 half sheets - 2' x 8' x 4mm marine plywood (60.96cm x 243.84cm x 4mm) or similar. The minimum plywood for the deck is the same but only 3mm thickness is required. If building the whole kayak from 4mm thickness you need three full 4' x 8' sheets.
NOTE: Occasionally, marine plywood sheets are couple inches longer that the exact 8 feet. If your plywood is 98.5" (vs. 96") long, only three scarf joints are required for the whole project. The kayak hull plates will all fit on 3 joined half sheets and the deck plates on 2 joined sheets plus a single unscarfed sheet.
Both deck and hull can be built with up to 6mm plywood thickness.
Minimum plywood thickness for hull: 4mm
Minimum plywood thickness for deck: 3mm (1/8")

Notes & Tips:
  • What is Marine Plywood?
  • If you desire to make the kayak from different plywoods (more than one wood type/color), more sheets will be required. For example the dark deck plates of the Cirrus are made from Sapele veneer plywood which required one additional half sheet of plywood.
  Fiberglass coverage
assumes complete coverage of inside and outside of hull and deck to make full sandwich core
 
Coverage of fiberglass
(plain weave e-glass)
yards
(yd)
feet
(ft)
meters
(m)
How to estimate
Deck - 4 oz. e-glass11.3 10,4two times the kayak length + 1 yard (1m)
Hull - 6 oz. e-glass 11.3 10,4two times the kayak length + 1 yard (1m)
2" wide glass tape 7121,6four times the kayak length + 9 ft (3m)

Notes & Tips:
  • Minimum width of fabric is 38" - will no allow for full hull abrasion patch
  • Order 50" width of the 4oz. glass to get the extra hull abrasion patch material
  • If 50" fabric is not available, order one 'waterline length - LWL' of additional cloth (any weight)
  • Round figures to the nearest higher number when ordering fabric
  • The 6oz. glass can always replace the 4oz.
  • See different types of reinforcement fabrics
  • Glass tape is sold in 'feet' and cloth in yards (in the US)
  • Glass tape is used to bond the kayak shells and for additional stem reinforcement
 Epoxy
 Minimum total volume of epoxy mix (resin + hardener): 2 to 2.5gallons

Notes & Tips:
  • Usage may vary (+-) 0.5 gallon as a result of the thickness of lay-up, fillet size, unused batches, spills, bad (unmixed) batches, care in application (overapplication), additional composite components such as coamings, hatch seals, rudders etc...
  • If epoxy is sold by weight, the density of epoxy is very close to water (1dm3 = 1 liter = 1kg)
  • 1 gallon = 3.8 liters
  • Learn about epoxy

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Last page update: 29 October 2013