getting back up river to the launch …
...... that's about what you have to do for the scenario you posted .
That means you have to paddle against the current all the way going up river , no surprise of course . Like going up a hill , you'll get to top when you get there . Some stretches in the climb will have steeper slopes , same in the river , some stretches will have faster currents to go against . Some faster currents you can escape to slower ones . Sometimes you can't get back up through what you've gone down through , it's too fast a current ... you may have to get out and line your canoe up current for awhile .
A little lighter and sleeker hull design will cover the required distance a bit quicker , but it seems to me you still will be paddling against the current with the same amount of effort applied to each paddle stroke regardless of which canoe (that's what I think) . With the sleeker faster canoe , you just won't have to exert this "same required amount of effort on each paddle stroke" , for as long a period of time .
We have two canoes of almost equal length . I paddle each with the same amount of effort per stroke , in the same waters up river against current , or down river , or on flat water lakes . One is not any easier to paddle than the other , but one will cover a bit more distance in the same amount of time .
The heavier you load the canoe , as in people , children , gear , etc. ... the more weight you have to move with the paddle . The heavier the load , the slower it goes , especially up river .
You want to make this loaded up river task as easy as possible . The only way I know to do that is only apply the amount paddle pressure in each stroke that you're comfortable with , and at a pace that's comfortable for you . Of course there is the minimum pressure and pace that's manditory to meet the current speed (that will hold you still in the current) ... beyond that it's what you are comfortable with to make forward progress .
You know , you can paddle up river against the current all day long ... go as far as you have time to go , as far as you can get in that time , or simply as far you feel like going . In order to do this you need to paddle at the pressure and pace that's comfortable to you , and not constantly be exhuasting yourself (as if you were trying to race up the river) .
Paddle harder and paddle faster , and it's more work ... paddle slower and lighter and it's less work . Going up a hill you can walk slow in short steps , you can walk in large steps , you can walk faster , or you can run . At some point of energy exertion you become uncomfortable and tire quickly not being able to maintain your pace and end up slowing down again or stopping to recover .
I just don't subscibe to the theory that one canoe is "easier" to paddle effort/energy wise than another canoe . A heavier loaded canoe will go slower for the same amount of energy applied than a lighter loaded canoe . A sleeker hull design will go faster than a less aquadynamic design for the same amount of energy applied ... and that's what I see it boiling down to .
You are the engine , you only have X amount of power to exert (or a range of power to exert at your will) . This is the amount of energy "you will" exert on each stroke , regardless of canoe or load . If you are a smaller 4 cylinder , you are not as powerful as a large V8 . Both engines will move the load , be it up hill or level ground .
In summary , there are two things you can do as I see it ... (1) get a sleeker canoe and (2) lighten the load . Both will make the trip up river faster . Both will make the trip across any distance on any waters , in any direction faster ... niether will make the amount of energy per stroke easier , only that you will be paddling for less time to cover the same amount of distance . I suppose that "paddling" for less time could be considered easier , than paddling for a longer period of time , if that's the kind of easier you are wanting .
If "paddling" for less time is what you want , if greater distance for energy appied is what you want , then those are the two choices as I see it .
I really never concern with how long it takes to get from A to B ... I just arrive or return when I get there . If I want to go further , I stay longer (which is a good thing) .
I guess I am very unconventional in my feelings about canoeing , because in my mind one canoe is as good and as pleasurable as the next . One is not in any way better or worse than the other when it comes to the amount of effort and energy required to make it move forward , they all are the same . Some go faster but I paddle with the same applied energy regardless which canoe .
A particular type of canoe is better for a particular type of water condition and load than another (better in the sense of manuverabilty and safety) , that I will agree with .
ps., ... a less flexy hull like Royalex or composite layup will give you more efficiency (speed) per stroke also I beleive , as compared to a flexier hull that may oil can on bottom .