We offer two variables on stringers, traditional centre ply stringers and parabolic balsa stringers.
Traditionally, all surboards required a stringer (stiffener) to strengthen the core of surfboards. Without a stringer, (always centrally placed down the middle of a blank), the core became too flexible and too prone to breakage. Stringers have usually been wood. The best stringers are made from knot-free milled timber chosen for strength, not brittle, usually a blond wood such as American basswood. Australian blank manufacturers have mostly used ply stringers, which have served them well. US Blanks best selling stringer is unidirectionally milled basswood in a range of sizes.Stringers can also come in varous other woods such as Birch, Redwood, Laminated Ply, Cedar and Balsa.
The most common stringer of choice is 1/8″ Basswood. This is unidirectionally milled, giving strength over the next most popular stringer, 4mm ply. (US Blanks Ply stringers are also unidirectionally milled, making them far stronger than peel ply stringers). Stringer sizes can increase in 1/32″ (1mm) increments, but we usually increase in 1/16″ (2mm) increments. 4mm uni-ply and 1/8″ (4mm) basswood are usually more than adequate for surfboards up to 6’02”. Then its a clear trade off between strength and weight. You have to chose. We can make light boards with less thick stringers to save weight, but the chances of breakage increase. We suggest 3/16″ (6mm) Bass(wood) on boards above 6’08”, 1/4″ (8mm) on 7’06” and above, and usually always 3/8″ (12mm) Bass on longboards. (A good test of quality is the width of stringer in a longboard – the thicker ones cost considerably more as the length increases). Watch out for cheaper milled ply, which is peeled and does not always offer strength savings. Common in imported surfboards or in surfboards that are machine shaped.
The traditional centre stringer has been the staple of board design for decades. It’s simple and it works offering both strength and durability.
At Seabase we also offer our own stringer technology called ‘Seaflex’. This uses a Parabolic balsa stinger that runs through the rails. This gives a more useable flex in twist and torsion than single stringer boards ever make possible. Every team rider of ours who has surfed a parabolic strung surfboard does not want to change back.
When describing turning on a ‘Seaflex’ board, team rider Egor says “it’s like the board is fling you from the bottom to the top of the wave, it has so much energy”
For more of Egor’s views on the tech, check out the video below.