Strip planking cedar for catamaran construction
Cedar stip planking catamaran hulls and wingdeck

strip planking in durakore

Durakore is Manufactured by ATL Composites and consists of a balsa or foam core with timber veneers, usually Hoop Pine about 1.5mm thick.

The timber veneers are easily sanded to fair the surface and this system provides the advantage of cedar strip without the weight penalty.



We specify PVC foam/timber Durakore for strip planking hull bottoms and other moulded surfaces as an integral component in our DuFlex kits. .

Detailed information on Durakore material and build process  is available on ATL's web site.

http://duflex.com.au/duflex2/products/durakore

 



STRIP PLANKING WITH CEDAR

Strip planking in western red cedar became a popular construction method in the 1980's and largely replaced cold moulding or double and triple diagonal planking in timber veneers which was the most common way of building light weight timber boats at that time.

 

The method is fast, economical and many builders find timber a more pleasant material to work with than foam. Cedar construction is heavier than foam but many successful lightweight boats have been built using this method. 

 The strips are typically 25mm to 50mm wide depending on local curvature. This type of construction does not require longitudinal battens on the mould.

 

Cedar strip planking is strongly recommended for ease and simplicity where the ultimate in light weight is not an imperative.

 

Catamaran build in cedar strip planking

Cut Loose is 55' LOA and the hulls, deck and cabin structure were all built in Western Red Cedar strip.



STRIP PLANKING IN FOAM WITH GLASS SKINS

Barefoot 40 catamaran built from DuFlex kit

A Barefoot 40 built with a Duflex kit and foam/glass strips for the hull bottoms

Not long after cedar stripping became popular some builders started using foam strips to reduce the weight. This process requires more work because the foam has to be glassed both sides before it is cut into strips. 

PVC foam strips are not as stiff as a cedar batten and you may have to use closer frame spacings than you would with a cedar planked hull. As with cedar the strips still need to be glassed inside and out so you have an additional glass laminate to apply. 

Glass can't be sanded so more filler is required to achieve a fair surface compared to a cedar hull.

 

The strips are similar in width to those used for cedar strip. Cutting the foam glass panels into strips blunts saw blades rather quickly and creates unpleasant dust which may not be that good for your health.

It's not the designer's preferred planking system and the preferred solution we have found is to use the Durakore strips manufactured and sold By ATL Composites.



SHEET PLANKING IN FOAM

This method is conventional foam sheet planking over a batten mould. It is sometimes referred to as foam strip planking but is not to be confused with the strip methods described above. The difference is that the mould has longitudinal battens and the strips are considerably wider. To avoid confusion I prefer to describe them as sheets rather than strips. The width of each sheet depends on the core thickness and amount of curvature in the mould.


The strips may be laid on the diagonal or at 90˚ to the x axis. Sometimes the strips are laid in two laminates double diagonal style  depending on the thickness and curvature required. The sheets are tied or screwed to the mould from the inside, the external laminate is applied, cradles are fitted to the hull to stabilise the shape, and then the hull is turned over and glassed on the inside.

Sheet foam construction for catamaran hull bottom

Sheets of foam on a batten mould. The hull is a Barefoot 40. Thanks to Julian Griffiths of Noosa Marine for the photo.