trolling motor used as bow thruster?

[Kamahele]

Has anyone used a trolling motor to work as a bow thruster? We have a 38 ft LOA/12 ft beam fiberglass live-aboard in France designed to cruise canals. The problem is that the boat has no bow thruster, which makes it difficult to negotiate locks and docks. The way she?s designed it would be difficult and expensive to install a typical bow thruster in a through-hull configuration. It could be possible to mount a trolling motor by clamping to the railing on the bow (as long as the shaft is at least 4 ft long). Having it aimed perpendicular to the boat, with a port (forward) / starboard (reverse) momentary rocker switch (with relays), and use it to swing the bow back & forth. Would only be deployed at slow speeds (like when entering/exiting locks) and pulled up when cruising.
Any thoughts/comments/suggestions?

 

[crabby captain john]

Re: trolling motor used as bow thruster?

Doubtful a 100# thrust would have any immediate effect like a bow thruster. Moving the amount of weight and volume you have with wind and/or current...... I think you will be disappointed.

 

[H20Rat]

Re: trolling motor used as bow thruster?

gut feeling is that any reasonable size trolling motor is going to do next to nothing... Unless you are talking something along the lines of one of the electric outboards at least.

 

[alldodge]

Re: trolling motor used as bow thruster?

Has anyone used a trolling motor to work as a bow thruster? We have a 38 ft LOA/12 ft beam fiberglass live-aboard in France designed to cruise canals. The problem is that the boat has no bow thruster, which makes it difficult to negotiate locks and docks. The way she’s designed it would be difficult and expensive to install a typical bow thruster in a through-hull configuration. It could be possible to mount a trolling motor by clamping to the railing on the bow (as long as the shaft is at least 4 ft long). Having it aimed perpendicular to the boat, with a port (forward) / starboard (reverse) momentary rocker switch (with relays), and use it to swing the bow back & forth. Would only be deployed at slow speeds (like when entering/exiting locks) and pulled up when cruising.
Any thoughts/comments/suggestions?

Agree with previous posters with a trolling motor, but what about using an outboard? If your thinking of hanging a trolling motor of the bow how about a 10 to 20HP outboard? Either work it by hand or fix it in position and use forward and reverse.

 

[crabby captain john]

Re: trolling motor used as bow thruster?

Agree with previous posters with a trolling motor, but what about using an outboard? If your thinking of hanging a trolling motor of the bow how about a 10 to 20HP outboard? Either work it by hand or fix it in position and use forward and reverse.

A lot of weight/volume to be moved in a short time especially with wind/current. Certainly will not be in the most efficient location. Not sure 20 hp would be enough and don't know where he would find one with a 4' shaft.

 

[Scott Danforth]

Re: trolling motor used as bow thruster?

They make 24 volt electric bow thrusters that are a big brother versions of trolling motors. Although they have twin props

 

[frantically relaxing]

Re: trolling motor used as bow thruster?

Shortly after we bought our Party Cruiser the stator went out in the outboard. Being slipped, and not wanting to drop wrenches and various engine parts in the water I tried using a trolling motor to move the boat from the dock to the trailer.

I might as well have been trying to push a freight train uphill. It wasn't a large trolling motor, wasn't all that small either but it had absolutely no effect on the boat. None. I checked several times to make sure the prop was turning...

 

[smokeonthewater]

Re: trolling motor used as bow thruster?

hmmm I once used a 2 man plastic bass boat with a 35? lb trolling motor tug boat style to push a disabled 38' cruiser around a marina. it worked fine but was SLOW .... I can't imagine 100 lbs of trolling motor doing you much good in the conditions where you NEED a thruster... IE cross wind and current... in calm conditions it might work but in calm conditions you don't need it.

 

[Kamahele]

Re: trolling motor used as bow thruster?

Thanks, guys, for useful comments. I looked online at bow thrusters, and for our size boat in medium wind conditions a thruster of 92-128 lbs thrust would be recommended. I don't know whether there are other factors to consider (eg prop diameter), but some trolling motors are speced at 105 lbs thrust. My understanding is that the further forward the thruster is installed, the more efficiently it can swing the boat side to side.
The obvious reason I'm thinking about this is that a trolling motor costs a few hundred bucks, a bow thruster a few thousand, if a thruster could even be installed in our boat.
Our boat handling skills could undoubtedly use improvement, but often the desire for a bow thruster has little to do with wind or current, but rather the need to make small adjustments when in close quarters in a lock with other boats, or backing into a slip in a marina when your boat has a noticeable prop walk side thrust in reverse.
Anyway, I'll keep pondering the possibilities.

 

[JoLin]

Re: trolling motor used as bow thruster?

Have to agree with the others that a trolling motor probably won't work, but this might.

https://www.sideshift.com/shop/category.php?id_category=2

It isn't exactly cheap, but you wouldn't have the potential issues (and cost) of installing a tunnel through your bow. And since your boat doesn't plane, it wouldn't show.

 

[fishrdan]

Re: trolling motor used as bow thruster?

The obvious reason I'm thinking about this is that a trolling motor costs a few hundred bucks, a bow thruster a few thousand...

A trolling motor in the 100# range (36V) will cost somewhere between $1000-$2000, depending on the TM options.

 

[Kamahele]

Re: trolling motor used as bow thruster?

Thanks JoL.in, I had seen the sideshift thruster online, but am concerned that (in addition to being not cheap) since it always lives under the waterline it would create drag and also would be susceptible to damage from underwater obstructions. Looks like a nifty device however.

 

[Kamahele]

Re: trolling motor used as bow thruster?

Thanks fishrdan, Cabela's sells the MotorGuide Xi5 105 Bow-Mount Trolling Motor with 60" shaft for $1400. Yes more than a few hundred $ but still way cheaper than traditional through the hull rig or even the Sideshift thruster. Mounting it would be DIY plus a few more bucks to adapt the electronics.

 

[64osby]

Re: trolling motor used as bow thruster?

Mount an outboard on a modified trolling bracket at the bow. Maybe some really long control cables. Raise and lower as needed?

 

[NYBo]

Re: trolling motor used as bow thruster?

I'd LOVE to see a picture of a trolling motor mounted on the bow of a 38-footer. Just imagine the ribbing you'll get!

 

[crabby captain john]

Re: trolling motor used as bow thruster?

If mounting a trolling motor or outboard on the bow of a large boat was viable there would be no bow thrusters.

 

[alldodge]

Re: trolling motor used as bow thruster?

I'd LOVE to see a picture of a trolling motor mounted on the bow of a 38-footer. Just imagine the ribbing you'll get!

If mounting a trolling motor or outboard on the bow of a large boat was viable there would be no bow thrusters.

I'm thinking it would work but not look very good. Could put it on a modified outboard motor lift which could be lowered when docking.

 

[pisherofmen]

Re: trolling motor used as bow thruster?

MinnKota has a 101 lb. thrust trolling motor that clamps on to anything and Amazon.com sells it for $710.00 plus shipping. It has a 52" shaft and has a 2 yr. warranty.

 

[Kamahele]

Re: trolling motor used as bow thruster?

MinnKota has a 101 lb. thrust trolling motor that clamps on to anything and Amazon.com sells it for $710.00 plus shipping. It has a 52" shaft and has a 2 yr. warranty.

Thanks pisherofmen, pretty much what i had in mind, but I'm starting to doubt whether it's a workable idea.

 

[Kamahele]

Re: trolling motor used as bow thruster?

+ = bad idea? :blue: