> am going to build a kayak, can mahogany doorskins be used or is the core
> too thick and outer layers too thin? the 4mm okume has apretty hefty price
> tag in canada. the thinking is that you are going to cover all with cloth
> and epoxy anyway so the strength of the doorskins may be enough?

Roddy,

I used 1/8" (actually less than that) mahogany plywood (like doorskins) for my last kayak. On plywood this thin, the three plys were almost of equal thickness. The main concern would be voids in the inner ply. The doorskins should be plenty strong, as most stitch and glue plans call for glassing. Try to avoid the 1/4" stuff as it will be difficult to bend, 1/8" bends nicely. To keep weight down and strength up I used multiple (1 to 3) layers of 3.25 oz satin weave glass inside and out. The satin weave glass is more difficult to wet out but the weave fills with less epoxy, it is also much stronger for its weight. The resulting kayak weighed in at 33 pounds before putting the hatches in.

It is my understanding that this layup should be at least as strong as a standard strip layup but have more flexibility, before failure.

The grain of doorskins may not be as even as that of marine plywood, but that may make the kayak more visually interesting.

Marine plywood makes a stronger lighter kayak, but doorskins should be sufficient. If I used 3mm marine plywood for my last kayak, I may have been able to save a pound or two.

Mike