Trolling motor for cabin cruiser

[Neilmac42]

I have a 29' Thundercraft Magnum 290. I have just installed some downriggers on it and am gonna start trolling for trout. I would like to buy an outboard strictly for trolling. Will a 6hp push this boat (boat weighs about 8000lbs) at least 2mph. I do not need this motor to steer the boat so the smaller the better.
Any suggestions?

 

[sutor623]

Re: Trolling motor for cabin cruiser

Man I would probably go with at least a 9.9-15hp for that. On second thought, probably even bigger. I think a 29' boat would laugh at a 6hp. That way you have a decent back-up motor too if need be. Plus I wouldnt want to have to run a motor at WOT the whole time while trolling, it would get a little obnoxious!! Have you considered a trolling plate? How slowly will the boat move at idle speeds, or is gas consumption more of a concern?

 

[haulnazz15]

Re: Trolling motor for cabin cruiser

If the 290 is a twin screw, why not just use one screw to troll with? Also, 6HP probably isn't going to get an 8Klbs boat anywhere. Use the regular engine and employ a trolling plate or drift sock or two if you need to in order to slow the trolling speed.

 

[Home Cookin']

Re: Trolling motor for cabin cruiser

around here, people with boats that big just use the primary motor(s) for trolling

 

[Neilmac42]

Re: Trolling motor for cabin cruiser

Ya gas consumption is my problem. Even trolling on one engine at idle speed uses lots of gas!! Would also like to keep the hrs down.

 

[sutor623]

Re: Trolling motor for cabin cruiser

Ya gas consumption is my problem. Even trolling on one engine at idle speed uses lots of gas!! Would also like to keep the hrs down.

Yeah thats a tough one. You would need a large motor to move that boat 2MPH, especially when you factor in wind, current and tide. Truth of reality is if you want to save on gas don't buy a 29' boat. Just kidding. But for real

 

[Neilmac42]

Re: Trolling motor for cabin cruiser

Yeah thats a tough one. You would need a large motor to move that boat 2MPH, especially when you factor in wind, current and tide. Truth of reality is if you want to save on gas don't buy a 29' boat. Just kidding. But for real [/QUOTE

Lol ya thats a good point!! Its not so bad going back and forth to my anchor spot but not exactly a fishing boat......was hoping to get double the use without spending thousands on gas.

I was just told a 9.9hp with a high thrust prop would do the job.....
any thoughts on that?

 

[haulnazz15]

Re: Trolling motor for cabin cruiser

Yeah thats a tough one. You would need a large motor to move that boat 2MPH, especially when you factor in wind, current and tide. Truth of reality is if you want to save on gas don't buy a 29' boat. Just kidding. But for real [/QUOTE

Lol ya thats a good point!! Its not so bad going back and forth to my anchor spot but not exactly a fishing boat......was hoping to get double the use without spending thousands on gas.

I was just told a 9.9hp with a high thrust prop would do the job.....
any thoughts on that?

So you're going to spend several grand on a trolling motor + bracket for the swim platform/transom, then try to steer with the normal outdrives/rudders (depending on which you have)?! Seems like you could just suck up the couple hundred per year you might spend on trolling at idle with the main engine, and that's if you troll for many miles.

 

[sutor623]

Re: Trolling motor for cabin cruiser

So you're going to spend several grand on a trolling motor + bracket for the swim platform/transom, then try to steer with the normal outdrives/rudders (depending on which you have)?! Seems like you could just suck up the couple hundred per year you might spend on trolling at idle with the main engine, and that's if you troll for many miles.

Haulin, that is exactly where I was going to go from there. Kinda like the "I have a gas guzzler 2 stroke and want a more efficient 4 stroke to SAVE $ on gas." How long will it take to offset the price of the new motor to save any money at all?

 

[Neilmac42]

Re: Trolling motor for cabin cruiser

Thanks for the advice. I have the motor and mount already from another boat. Was just wondering if I could use it.

 

[sutor623]

Re: Trolling motor for cabin cruiser

Thanks for the advice. I have the motor and mount already from another boat. Was just wondering if I could use it.

Gotcha. Yeah I doubt it will do you any good. Here is a video of my 4hp pushing my 16' aluminum boat. It is 1/10 the weight of yours and on a calm day. This will show you how worthless a 6hp will be on a 29'er. http://www.youtube.com/watch?v=rIEuD0-LAMc

 

[ondarvr]

Re: Trolling motor for cabin cruiser

Your 6 won't do it, a high thrust 9.9 or 15 would get it done though.

 

[JoLin]

Re: Trolling motor for cabin cruiser

Ya gas consumption is my problem. Even trolling on one engine at idle speed uses lots of gas!! Would also like to keep the hrs down.

Honestly, how much can it use? Each of my 4.3's sucks 1 gph at idle (confirmed with a scan tool). I assume you have big blocks- so we're talking maybe 2 gph? The cost and effort of mounting a trolling motor big enough to move that boat in a headwind just doesn't make economic sense. The trolling motor is still going to use fuel (you'll be running it at a higher rpm than idle speed), and now you have a third motor to maintain and repair.

My .02

 

[Home Cookin']

Re: Trolling motor for cabin cruiser

penny wise and pound foolish

 

[Neilmac42]

Re: Trolling motor for cabin cruiser

To those of you who gave me good advice....thanks!
To those who poke fun.....you know where to go! I didn't realize that trying to save a buck using equipment I already had makes me pound foolish. Infact I know it doesnt

 

[haulnazz15]

Re: Trolling motor for cabin cruiser

We aren't poking fun, and you didn't state that already owned the equipment beforehand. Regardless, you need to understand the cost vs. benefit. If you run one 454 @ idle (I don't know what size your main engine(s) is(are)), you would get somewhere between 2-3gph fuel usage. So you'd be spending $10/hr trolling. That seems like a pretty miniscule cost to do what you want to do for an hour. Sure, if you troll for 3 hours a day, 5 days a week, you might look at other solutions (diesel), but the kicker wouldn't be one of them. You will have to leave that 6HP motor running at full throttle the whole time, and I bet you end up burning close to 2 gph on that in addition to burning up the engine pushing a 30' boat with it.

 

[greenbush future]

Re: Trolling motor for cabin cruiser

The cleanest way to accomplish your task is to just run one of your mains, you can alternate if you like to keep the hours straight. But the extra cost, and a third power plant will never be as good as using one of your existing ones. Even having the equipment already, still wont help, steering, fuel, manuvering will all be compromised using a kicker, which would really need to be at 15 hp or bigger to give you any control. Downrigger fishing is all about control. 1/2 mile per hour can make the difference between a limit and nothing. Wait till you tangle the downrigger wires once, because the wind pushed you back or over. It can be done, but you wont enjoy the day or the powerplant for this kind of use. Hope this helps you out.

 

[UncleWillie]

Re: Trolling motor for cabin cruiser

Gotcha. Yeah I doubt it will do you any good. Here is a video of my 4hp pushing my 16' aluminum boat. It is 1/10 the weight of yours and on a calm day. This will show you how worthless a 6hp will be on a 29'er. http://www.youtube.com/watch?v=rIEuD0-LAMc

I was actually impressed at how fast you were going with the 4hp. (3-5 mph?)

Power needed is proportional to the square of the waterline and cube of the speed.
Assuming the 29 has twice the waterline of the 16 and your 6 is 1.5 time the hp of the 4....

(2^.5 / 1.5) ^ 3 = .84

Your 6 should push the 29 footer at ~85% the speed we saw in the video. (2.5-4 mph?)

My physics is old and rusty and someone will correct it, but it does not take much power to move large objects slowly through water.
It DOES take huge power to move even small objects Fast through water. It is that cube factor that kills you.

Those Hugh container ship are some of the most efficient mass movers ever produced.
They can achieve in the neighborhood of 50-100 ton-miles per gallon of fuel.
That is on par with rail transport efficiency.

 

[Fireman431]

Re: Trolling motor for cabin cruiser

I would look into a 15 or 25 HP. Less work, easier on fuel, and possibly a way home in the event of fuel delivery problem or electrical failure of the main engine systems.

 

[laserbrn]

Re: Trolling motor for cabin cruiser

My buddy who has a 24' skipjack like mine uses a 25hp kicker for trolling. It's really not that uncommon as this big block motors wolf down gas. I plan on putting one on my boat too. That boat is probably closer to 5500 lbs, and it can move pretty good with that 25hp. I'd be glad we had it if the main screw fails.