I am wondering how to estimate the needed motor power for boating upstream on big rivers like, for example, Danube. (mean the bottom to middle part, i.e. where the Danube is wide and "slow"?).
To be more exact, let say having an 12' (3.6m) long jon boat, fully loaded with lets say 800lb - how much thrust is needed for going upstream (even with slow speed - but upstream) i.e. having enough power to "beat" the river's current).
The practical merit of the question is: will it be enough to use some electric (12V) trolling motor e.g. with 30lb or 55lb thrust?
Do not need some rocket-science based calculations, enough some rule-of-thumb based estimates.
Because of the comments trying be more precise:
- I haven't any motor
- and I haven't any boat (yet)
So, I can't try it. (What, of course, would be the obvious solution if I had any boat.) :)
Moreover, I haven't defined any exact river. This question is in the idea-gathering phase - when trying to do first and rough estimates of the needed gears and or possible solutions.
Everything what I currently know (more or less precise) is:
- I need to move against the current of some rivers (more different rivers, not only specific one). Mostly only for straight river-crossing, but not limited.
- I will never use the boat on high-velocity rivers - only on slow & calm waters. e.g. let say, the max. velocity of the current where I will use the boat is 4 km/hour (aka approx: 1.11m/s or 2.16 knots)
- also, if the wind against will be too strong - will not use the boat. (I'm not sure about this, how to define it more precisely as calm wind).
- My (custom made, riveted) boat dimensions will be: max. 3.0 up to 3.6m long and the beam will be approx. max. 0.8 to 1m wide (it is not defined exactly yet).
- It will be (sure) flat bottom & straight nose boat - aka like an common jon boat
- The total weight of the boat+motor+batteries+persons+other will be approx. 250 (max.300) kg only. The above 800lb was only for safety. :)
- For some reasons (smallest as possible, lightweight motor) I must to use electric motor. (trolling motor)
- I will have enough batteries (and also 2Kw electric generator) already onboard...
So, is possible to have a jon boat with electric motor under the above conditions? How to estimate the needed motor size (type, power, thrust, etc..) :D.