Bow or Stern Thruster?

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Boilermaker75

Veteran Member
Joined
Dec 23, 2018
Messages
85
Location
USA
Vessel Name
Kimberly Dawn
Vessel Make
1984 Marine Trader 40 Sundeck Trawlet
To all owners of 40-foot+/- single-screw trawlers, who have experience using either bow or stern thrusers:

If you had your choice between two nearly identical boats, one with a bow thruster (only) and the other with a stern thruster (only), which would you choose?

What are the advantages of having a bow thruster over having a stern thruster?

What are the advantages of having a stern thruster over having a bow thruster?

Thank you in advance for your consideration and feedback responses, experience, opinions, and advice.
 
We have a 41’ trawler with twin engines. I put a stern thruster in our boat 2 years ago. If I would want to put a bow thruster in it would probably have to be a pod type thruster since there isn’t room for a tunnel due to our water tank. I wanted a stern thruster because my wife handles the bow lines and I do the stern line but I have to come down from the bridge and sometimes the stern has blown off the dock so I can use the thruster with the remote to bring the stern back to the dock. Having said that I would choose the boat in the best condition rather than which thruster it has. You can always add the other thruster but bringing a boat in poor condition back is going to cost way more than a thruster.
 
A twist on the same question. Which is easier to add (to the better condition boat) - Bow Or Stern thruster?

My guess would be a stern thruster would be easier, less hassle and less money.

However I don't know the answer.
 
Comodave, the underlying assumption of my question was that both boats were, for all practical purposes, identical and in the same condition -- the only difference between them being that one had a bow thruster and the other had a stern thruster: which would be preferable, all less being equal?
 
Boiler, I would choose bow in the scenario you have presented.

BTW, our previous two boats had twins, so I would be lying if I said I wasn’t a bit nervous to transition to a single. I definitely have room for improvement, but After a year, it has not been a big deal.

BTW, are you a boiler maker by trade?
 
I’ve had both and the most important thing is to be sure it has enough horses to be effective. I can tell you conclusively a 5hp bow thruster and a 5hp stern thruster on a 42 Nordic Tug is 10hp short of being enough. Being underpowered is the best training there is to get better at handling a single screw boat. Anything over 40ft should have an 8-10hp thruster. If I could only have one, I liked the stern because it was more useful when docking to port.

Tom

Tom
 
If the boats are in the same condition then I would go with a bow thruster since on most boats adding a stern thruster is simple. It took 2 of us about a day and a half to do the stern thruster. Pretty simple DIY job.
 
Fletcher500,
I'm a 1975 Purdue University graduate/alumnus; Purdue is known as the Boilermakers, and their mascot is "Boilermaker Pete." Hence my "Boilermaker75" user ID.
 
Comodave,
Does your response imply that you would add a stern thruster to the boat that had a bow truster, and vice versa, you would add a bow thruster to the boat that had a stern thruster, so you had both? But since adding a stern thruster is simpler/easier than adding a bow thruster, you'd buy the boat that had the bow thruster and add the stern thruster to it?
What if you could have only one -- either a bow thruster or a stern thruster? Which would you choose?
 
Bow thruster, and kick the arse over with bursts to the rudder...with an intention to modify rudder into a Thistle/Fishtail so it moves stern even better.
 
MurrayM,
I've never hear of a "Thistle/Fishtail" rudder; could you explain or clarify further? Thanks.
 
Boilermaker,
Our boat is a single engine with bow thruster (Nordic Tug 37). We can kick the stern fairly well with either a burst in forward (rudder placed first appropriately) or using the starboard prop walk in reverse. Using the bow thruster and the above mentioned "bursts", we can basically "walk the boat" sideways to the starboard side. Using the bow thruster we can even "back to port" but it is way more difficult and takes lots of practise. If I had a spare $10-15 grand, I would add a stern thruster, but we are doing fine without it.
So, in my humble opinion, a bow thruster is very useful on a single engine, and a stern thruster is a "nice to have".
Hope that helps,
Tom
 
My vote is a bow thruster
We have a 44 Swift Trawler with both bow and stern thrusters.
Bow thruster helps get the bow in control
 
We put the stern thruster in for a specific reason, in a generic boat I would go for the installed bow thruster. It is more work to install and therefore much more expensive than a stern thruster.
 
For me in that scenario I'd want a bow thruster. You already have a degree of control in the stern with a) prop walk and b) rudder maneuvering. In the bow, you have nothing, nadda, zippo, so more control in the front would be a good thing. I installed an Exturn bow thruster in front, an external pod type thruster - still not cheap.
 
rsn48 said:
For me in that scenario I'd want a bow thruster. You already have a degree of control in the stern with a) prop walk and b) rudder maneuvering. In the bow, you have nothing, nadda, zippo, so more control in the front would be a good thing. I installed an Exturn bow thruster in front, an external pod type thruster - still not cheap.
Click to expand...

Did you do the install yourself or did you pay to have it installed? I have been looking at the Exturn pod thruster if I can figure a way out to access the interior without ripping out all of the forward cabin.
 
I have a 40 Eagle w/single engine. It came with a bow thruster and 4 years ago I installed a Lewmar stern thruster. If I could choose only one it would be the bow for all the reasons rsn48 cited. I have installed both and the stern is much easier but with a reasonable amount of fiberglassing and wiring skill you can do either.
 
I run a 38' single screw with a bow thruster but no stern thruster. Never really felt the need for a stern thruster as I can control that end with rudder and prop. I do REALLY like the bow thruster!

My vote is the bow thruster is at least a few times more handy than stern.
 
J
steelydon said:
I have a 40 Eagle w/single engine. It came with a bow thruster and 4 years ago I installed a Lewmar stern thruster. If I could choose only one it would be the bow for all the reasons rsn48 cited. I have installed both and the stern is much easier but with a reasonable amount of fiberglassing and wiring skill you can do either.
Click to expand...

Sigh...when Badger grows up, it wants to be a Transpac Eagle 40 :thumb:
 
For my two cents I totally agree with Firehoser75, Ski and MurrayM.
The schilling rudder uses the Bernoulli effect and their fine but a much cheaper option and just as effective is to 'fence' the rudder to make the thrust more effective.
As Firehoser75 says you can easily 'walk' your boat sideways with a little practice.
If fitting a new bow thruster I fully endorse tpbrady's extremely valid point that its advisable fit the next size up than recommended, the difference is very noticeable and you won't regret it.
 
Ski in NC said:
I run a 38' single screw with a bow thruster but no stern thruster. Never really felt the need for a stern thruster as I can control that end with rudder and prop. I do REALLY like the bow thruster!

I agree with the above as I ran a 32' single with a bow thruster for 8 years and had absolutely no trouble with getting the boat to do what I wanted.
Click to expand...
 

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I have been looking at the Exturn pod thruster if I can figure a way out to access the interior without ripping out all of the forward cabin.

The boat is in for a very extensive refit, she is 50 years old in 2019. I had the Exturn installed. My V birth isn't that extensive, but the water tank had to be removed and will placed elsewhere. I have wooden beams, and the main long beam that is the keel had to be re-inforced as the large main hole went right through it leaving very little wood on either side, so that area has been built back up. Amazingly, after removing just about everything equipment wise, engine and stern wise and fuel tanks, no rot anywhere has been found. The plug that came out of the keel looked like it had been installed yesterday. The re-fitter was so impressed, he kept the plug!

This short install video shows the model I bought. It is a solid heavy unit. It will be painted with the same bottom paint for my hull. The install doesn't look that difficult. Just make sure you use a separate battery or two for the unit as per the instructions. Don't hook it up to your main battery bank.

This unit draws a massive amount of power so the advertising that says it can last 5 minutes is true but misleading. You would need a very large battery bank just to run the unit for 5 minutes. But bow thrusters are only meant to be run for seconds, not minutes.

 
Bow thruster. You already have a stern thruster.
I singlehand a 54ft single engine trawler. Bow thruster has made it easy (I adapted a radio remote control that has been an absolute game changer). I get midship line on, step off the boat and power the bow in if it has drifted off.
 
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Screaming04 said:
Bow thruster. You already have a stern thruster.
I singlehand a 54ft single engine trawler. Bow thruster has made it easy (I adapted a radio remote control that has been an absolute game changer). I get midship line on, step off the boat and power the bow in if it has drifted off.
Click to expand...

You have a beautiful boat :thumb:

From this designer? https://www.parker-marine.com/trawler54page.html
 
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A Bow thruster is more costly and complex to install than a stern thruster. I suspect those boats with a stern thruster only opted for this route for that reason. I would prefer a bow thruster or both. I wouldn't be interested in a stern thruster only. The stern is the easiest part to move.

If given the OP's scenario, I would opt for the bow thruster, knowing I could always add a stern thruster later.
 
To the OP's question, which is better, bow or stern thruster, then the answer "bow" is quite obvious.

However I would add that if the newly acquired boat did not have either then I would not rush in to installing one yet. Spend money for a day's training with a good captain/line handler team to teach you and your wife the art of boat handling with springlines, bow warps and a capstan. Depending on where you dock regularly, you may not need the assistance of a $6-10k device.
 
My single engine 42 Nordic Tug had a bow thruster only when I bought it. The first thing I did was to add a stern thruster and a wireless thruster remote. It’s the best combo there is for the single-hander skipper who almost never sees a dock hand! Bring the boat in to the dock, step off, and use the remote to keep the boat in place while getting the lines secured...
 
2 Comments.

1. Start with a left turning prop. To back it straight, put your rudder ABOUT 25-30 degrees to port at a very slow maneuvering speed aft. Practice because "results may vary with your boat." Center the rudder if you are maneuvering at slow speed and you will back to starboard.
2. I have a Cummins QSB 5.9 380hp. The bow thruster was hooked to the start battery. While bringing into the dock, I kicked the bow thruster and the engine stopped. (scratching my head) Restarted the engine, same thing, same results. Well it was an easy docking situation and the bow thruster was just used to nudge the bow over. BUT, the main engine quitting was different story. Turned out, the start battery was on it last legs and when I goosed the bow over with the thruster, voltage dropped to somewhere about 10vts which shut down the electronic to the engine, hence the engine.

I had added a 3rd 4D house battery and replaced the start battery (4D)
I moved the bow thruster to the house battery bank which also has the stern thruster.
My reasoning was/is, keep the main engine running in all cases. The docking can be accomplished with spring line or bow line to the midship cleat on the dock and the rudder. (I always go in bow first. The RIB, in the davits makes the boat close to, by today's standards, 40 ft. Plus, the neighbors do not need to see me walking around inside the boat, in my skivvies.)

IF I am wrong in my reasoning, please give me your reasoning.
 
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be sure it has enough horses to be effective.
Click to expand...


Read this again.
Very frustrating when wind & current against you and the thrusters you depend on are ineffective.
 
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