# trolling motor speed



## fshnace (Jan 13, 2013)

I fish electric boat only tournaments, and I am wondering if some one can help me figure this out. I currently have an 80lb thrust motor on the back of my boat an a 101lb thrust on the front. My question is, would i be faster adding another 80lb thrust motor to the back of the boat, or should I just go with 1 motor at 101lb thrust for the back? Thanks for the help


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## shawnfish (Jan 13, 2013)

good question....im guessing the 101 is faster than 2 80's


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## Charger25 (Jan 13, 2013)

shawnfish said:


> good question....im guessing the 101 is faster than 2 80's



That IS a good question.......hhmmm........ with two 80's you'd be pushing more water. But with the 101 you'd have 21 more lbs thrust. Might depend on how much weight you'll be pushing. :-k


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## RAMROD (Jan 13, 2013)

I know it’s a long shot but is there anyone you could borrow from to try or test it out? Maybe a local media add offering a few bucks to an individual to use their motor to test your theory out.


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## JMichael (Jan 13, 2013)

Charger25 said:


> shawnfish said:
> 
> 
> > But with the 101 you'd have 21 more lbs thrust. :-k


Actually, you'd have 59 lbs less thrust since 2 x 80 = 160. I agree that it doesn't necessarily mean more speed and it does make one wonder what the comparison would show. I would certainly expect the dual 80's + 101 setup to achieve it's 0 to max speed quicker than the dual 101's. It's just a guess on my part but I think the determining factor on which setup would be best is going to be overall weight. The more total weight of boat + load, the more the dual 80's setup would become the better setup.


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## Bailey Boat (Jan 14, 2013)

Back into the speed by using the prop diameter and pitch against the rpm's of each engine factoring the approximate weight to be moved.


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## russ010 (Jan 14, 2013)

we fish electric only tourney's too... you will be faster with 1 - 101 than you will be with 2 - 80s. With only one trolling motor in the water, you have less drag (it's amazing what an additional TM shaft in the water pulls you down in speed) - and you'll have one less battery in the boat with the 101 (3 batts compared to 4 for the 80), so you'll shave off about 50-100lbs depending on what type of battery you use

But remember... you'll only achieve your boats hull speed, unless you can get your boat on plane with trolling motors!

The fastest I've ever been in an electric boat was around 6.2mph. Most of my boats have run right around 5.5-5.7 with just me in it and that was with a 70# Motorguide on the front with a 80# Minn Kota on the back.

I haven't tried out my new setup on my 18' boat, but I've got a 101 on the front and a 101 on the back... I'll be happy if I can still hit 5mph


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## Bugpac (Jan 14, 2013)

I get 4.7 with a single 101 on the bow. Russ, elaborate on the hull speed. The more thrust the faster you will go. There is gonna be a hull speed that you reach before you plane.


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## russ010 (Jan 15, 2013)

I may be totally off, or using the wrong verbiage... but to me, hull speed is the fastest you will get your boat to go before you plane; however, it is possible to go faster than your hull speed- but I've never seen it done with trolling motors.

Hull speed (I think, I'm going back to college now..) is more of a drag on the hull than it is an actual speed. It has something to do with displacement of the water creating wave drag (I think it's how fast your boat can displace water, and how the wave action of the water creates drag as it goes under and down the sides of your boat). Hence why bass boats only have a few inches of water under the transom and motor at WOT. 

I think if I remember correctly, to figure out the hull speed of your boat, take the square root of the waterline length (length of boat that is at the meeting point of water and boat while floating) and multiply it by 1.3 or 1.4 (I honestly can't remember).. I think I determined my 18' hull speed is around 5.3-5.4. It will go faster without planing I'm sure, but there are too many variables to account for such as: 1 - adding more batteries for more trolling motors and 2 - drag created by each additional trolling motor. That's why the bigger 48-72v motors are better... you have more batteries, but you also have a lot more thrust/prop spin with a constant 60v as opposed to a 105# trolling motor running on 36v. I have ran my Xpress (71# bow TM, 2 - 80# transom TM) against guys who had 48v motors, and I thought they would leave me sitting... but I stayed right with them for about 10 minutes, then they started to walk a way a little bit, but only by a boat length or so. Now if you get one of those Ray electric motors - you'll plane and won't need to worry about hull speed!

Kayaks are really the only things I've ever seen that can go faster than their hull speed without planing - but that's what they are designed to do.

If I missed your question on hull speed, let me know. I should have probably researched this a little more before I wrote all that, so I could be totally off.


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## Bugpac (Jan 15, 2013)

That is what i figured you meant was up to plane.


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