My gunnels are made of a special laminate of strong and lightweight spruce with an exterior edge of hardwood for abrasion resistance. This design is pounds lighter than conventional all hardwood designs. My gunnels are scuppered, which means that spacer blocks set the inwales away from the hull. This makes the gunnels more rigid than solid gunnel designs. Only one thwart in the center of the canoe is necessary.
Scuppered gunnels allow easy drainage of water when the canoe is inverted.
They also give you many places to tie in gear, an anchor or a fishing stringer. I glue my gunnels on instead of screwing them on. It takes more time to glue them ,but it's worth it to eliminate the weight of 60 to 80 screws. While repairing other canoes with screwed gunnels ,I've found that because there is no seal between the gunnel and the hull, dirt and moisture get trapped there and cause rot. That can't happen with a gunnel that's glued to the hull.