Somewhere i read that a boat can only go like 5 mph without getting on plane. If thats the case then I can do that with my two trolling motors and not run my 9.9. Anyone know anything about this?

that is called hull speed. That is how fast a boat can go before it gets on plane. what that speed is is determined by is hull length at the water line. Once a boat reaches hull the speed the amount of power required to plane increases exponentially.

so does that mean that my two tm will power the boat the same speed the 9.9 will or am I interpreting this wrong. I really dont see how this would be possible, but i'm not sure. Thanks for the reply

I cannot imagine a trolling motor could get ANY boat on plane. Not even two of them.

after rereading your post. A boat will not plane at 5MPH. My 47lb. minnkota will push my 12' v bottom close to 5mph. it will depend on how big you boat and motor as to whether you can get close to 5MPH. At some point you will be putting more power out and not going any faster. The extra weight from extra batteries, motors and drag will work against you.

I know the trolling motors will not get the boat on plane but neither will the 9.9 johnson that i have. My boat is a 14ft semi v. What I'm asking is will the boat go faster with the 9.9 than with the two trolling motors? They way I intepreted what I read was that top hull speed is the same regardless of the engine size. I know this may be a dumb question but  it seems hard to believe that 2 trolling motors would be as fast as the 9.9 even though neither will get the boat on plane.

I used to run a 16' semi V with a 9.9.  I'm thinking no trolling motor I have ever seen would push as fast as the 9.9 did.

If your cannot get on plane with the 9.9, and put the electric motors in the water, it will go slower due to the drag of the electric motors.

Each electric motor would have to have the capability of the same prop speed and thrust of the 9.9 to give any benefit.

My 9.9 Merc. 4-stroke pushes my Tracker 170 at a blazing speed of 7.4 mph. I could only get that by changing the prop from the stock 8.5 pitch to 6.5 pitch. The rpm with the stock prop would only go to 3,800 and I get 5,900 with the 6.5.

When I had a 2-stroke Merc 9.9 on a 12' jon boat, it would run 25 mph with the stock 9.5 pitch prop.

edited: when I put the 2-stroke on my friend's 1448 Grizzly jon boat, it would not get on plane with both of us. It pushed a lot of water but I do not know how fast it would go since he didn't have a GPS.

I know the trolling motors will not get the boat on plane but neither will the 9.9 johnson that i have. My boat is a 14ft semi v. What I'm asking is will the boat go faster with the 9.9 than with the two trolling motors? They way I intepreted what I read was that top hull speed is the same regardless of the engine size. I know this may be a dumb question but it seems hard to believe that 2 trolling motors would be as fast as the 9.9 even though neither will get the boat on plane.

Ah! much clearer now. You will need to find out what RPM your 9.9HP is turning. If it is under 5500RPMs or so you will need to changes to a smaller prop. I would also check to make sure you are firing on all cylinders. I had a 14' tri-bull that would go over 5mph with a 9.9 merc.

i think what youre saying is that you are under the impression that any boat going under 5mph will not plane out.. and therefore you think that your 9.9 is not going any faster than 5mph... so its not much bnetter than your two trolling motors which are also not planing out (<5mph)

i get what youre saying now. and no i think that is wrong. its takes different speeds for different boats. youre 9.9l is probably making you go faster than 5.5... but your boat needs more than that to plane out.

thanks guys. im pretty sure im not getting 5500 rpms out of the 9.9 and i think it sits too low in the water.