In case anyone has ever thought of making a drop in rowing rig for their canoe, here are some pictures of one I made this winter. It is based on the plans in the 1956 American Red Cross book on Canoeing. I added laminated out-rigger arms so it would be a complete drop in unit. It is made mostly out of ash and I used contact cement to glue on gripping rubber on the bottom of the unit, so there is no need to clamp it, or modify the canoe. It helps to have a long canoe with no center thwart, in this case my 18 foot "Thompson" Hiawatha. I am no expert at rowing, but it seems to work just fine.