If I added a spare 12V battery weighing about 50lbs to the back, how much speed would I lose?

Zx190. Thank you

I think your best bet would be to get some ballast (sandbag) weighing 50 lbs. put it back there and do a test run.

Do you go to the lake to race or fish?

The correct answer is C.
Both.
Nothing wrong with finding your rigs potential.

To answer the original question is yes adding weight slows you down. Usually figure 1 mph for ever 100 lbs on a average bass hull.

Good idea. It depends if the current setup is barely suitable or not. If it is borderline without the weight it might need a change with it. If it is solid now it will probably be ok. Also the cool weather now will cause it to run better than in the summer....

I have a TZX190. Before the Ultrex, PowerPole, extra battery, bigger “trolling and motor” batteries, etc, I could run 61or so GPS. Afterwards, around 58-59...depending on solo or team, both livewells full of water, light fuel or filled up.

Not a significant impact on top speed.

Holeshot was far more impacted. Used to jump up quick, now it’s a few seconds longer.

https://www.go-fast.com/boat_speed_predictions.htm

Try this. Enter current weight, max speed and horsepower, calculate the constant. Then, use your constant, additional weight and HP to calculate the new max speed.

To be any closer, I think T Birds point of running with an extra 50 lbs is your best bet. Just measure your speed on the way to the fishing hole, catch 50 lbs of fish and measure speed on the way back...

six gallons of water weigh about 50 lbs ,
Make a run with back livewell empty and full,

Mo