in his imagination , martin had pictured himself , livingstonesque , attired in a white safari suit and pith helmet - not that he possessed the latter - kneeling upright and alert in the hull of a small , single occupant wooden canoe , every now and then idly caressing the surface of the gently flowing waters with the tip of his rounded paddle , purely in order to maintain the optimum navigational course , while the river carried him effortlessly , relentlessly onwards , ever closer to his final destination .