Cliff Jacobson's book on Expedition Canoeing writes about tumplines but his contracption involves sewing a canvas strip and securing it to the canoe with rubber straps and steel S-hooks...not appealing. Call me a nostalgia freak, but I wanted something a bit less "modern".
This Abnaki or Penobscot tump from the American Museum of Natural History is a woven from basswood cordage shows a typical native design although its construction is way beyond my current skill set.
AMNH Catalog No: 50.1/ 7611 - Tumpline
The forums at FrontierFolk.net have some replica designs of traditional tumps, although nothing I could spot that was meant for canoe portaging. Another design I came across was that on Bob Abrames' voyageur gear page pictured below. A combination of rivetted leather with woven cordage.
Bob Abrames' Voyageur Tump
In the end, I got the inspiration from one of my favourite sites about wildnerness canoeing, The Northwest Woodsman, which has some fantastic videos showing some wonderful backcountry. The emphasis on this site is on basic, traditional bushcraft rather than modern, ultralite techno. This page describing his tumpline has some fantastic pics and details of the general construction. I also came across Don Merchant's Pole & Paddle Company site which also has a page on leather tumps.
NW Woodsman Leather Canoe Tump
Strapped to the centre yoke
Ends can be used to lash in paddles too
The construction looks straight forward enough. I've already got a piece of latigo suitable for the headpiece will have to obtain some 3/4" latigo strips for the ties as well as getting some rivets. Update on this ongoing project soon.