Dave Halsey, the 20-year-old McLean house painter whose heart is set on adventure, has confirmed his plans for a trans-Canada canoe-snowshoe-backpack-cross-country ski voyage and will leave Washington about April 20 for Vancouver, B.C.

Halsey concocted his plan over the winter and drew up an extensive 75-page proposal, but he had no money.

In the last two months he's secured support from a number of people and organizations, including National Geographic, and filled out the party of three that will accompany him on the 4,700-mile odyssey.

The journey begins May 1 with a long hike from Vancouver to Hinton, Alberta, in the Rocky Mountains.

"We plan to take enough money to get to Hinton," where the wayage is to shift to canoes, Halsey said. The travelers hope that by then promised grants and other monetary support will have come through so the expendition can continue.

"We'll just leave with whar we've got May 1 and our faith in the promises we've received."Halsey's companions are Mark Jusko, 27, a student at Illinois Benedictine College; Neil Cogen of Bowie, 24, a University of Pittsburgh grad who joined when 44-year-old geography professor Lyman Echola dropped out with a bad back; and Charles Bratz, 24, a photographer from Stevens Point, Wis.

The men will take canoes to Flin, Flon, Manitoba, then cross Lake Winnipeg in winter on cross-country skis, snowshoes and pack toboggans. They are slated to arrive in Ear Falls, Ontario, in spring. The remainder of the trip to Tadoussac, Quebec, will be by canoe.

Halsey considers his plans at this point "absolutely definite." He's leaving. And in 1 1/2 years he'll be back, if all goes well.