Bow thruster

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Iggy

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Mar 1, 2020
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Vessel Make
Pacific Trawler 40
Wonder if this is worth doing? I have a 40' trawler with the 21 year old thruster that produces, as the spec's say 147lbs. of thrust. Now the next model up does 161 or 14lbs more. Cost $1,100 just change the motor out. Bolts right in!

The next model does 212lbs of thrust, but everything needs to be replace but the tunnel. Cost around $3500 if I do it myself. But I will need to add one more battery due to the increased amperage. More$$

This being my first boat with a bow thruster I don't have any experience with one. So my questions, is 14lbs more worth the it?? The spinoff to this, the new motor uses 25A less. From 355 down to 325, a very small plus.

Another way to put it! How many lbs to HP with thrusters?
 
I'd use it as-is for a bit first and see if you find the current thrust level adequate. If it is, the small upgrade might be worth it at some point, but that's debatable. If you find it's not effective against enough wind, then you might want a bigger upgrade (which, as you pointed out, will cost some money).
 
This is going on my 3rd year. I think its underpowered but I have nothing to gauge it on. Maybe a expect it more than I should?

At $1,100 the hit I can take! At $3,500 plus will hurt. But will I gain anything?
 
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Iggy said:
This is going on my 3rd year. I think its underpowered but I have nothing to gauge it on. Maybe a expect it more than I should?
Click to expand...


Expectations are personal. Plenty of thrusters are undersized in my opinion and won't move the bow upwind in more than 10 - 15 kts of wind. I'd personally want to be able to push the bow upwind in at least 20 kts, preferably more. What you really need depends on how you use the boat.

If you're feeling it's underpowered, the small upgrade likely won't make much difference. You'd be better off spending a bit more and upgrading to a larger size thruster with significantly more thrust.
 
Iggy said:
This being my first boat with a bow thruster I don't have any experience with one.
Click to expand...

Go use it for a year. If you're not satisfied check all the electrical carefully. Lots of support here as needed.

Then consider options.

Edit to add: I see you've satisfied the waiting period. Let's go to the next step :)
 
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Iggy, you’ve been using the boat with existing thruster for three years now.

How have your boat handling skills grown, can you get by without it, have you become so reliant that your skills have possibly NOT developed? Some people do become over reliant after all. Or perhaps your home port slip is so challenging that a thruster is make-or-break.
 
Iggy said:
Wonder if this is worth doing? I have a 40' trawler with the 21 year old thruster that produces, as the spec's say 147lbs. of thrust. Now the next model up does 161 or 14lbs more. Cost $1,100 just change the motor out. Bolts right in!

The next model does 212lbs of thrust, but everything needs to be replace but the tunnel. Cost around $3500 if I do it myself. But I will need to add one more battery due to the increased amperage. More$$

This being my first boat with a bow thruster I don't have any experience with one. So my questions, is 14lbs more worth the it?? The spinoff to this, the new motor uses 25A less. From 355 down to 325, a very small plus.

Another way to put it! How many lbs to HP with thrusters?
Click to expand...


A: Can you dock without the thruster?

B: $1100 and not much work sounds like a maybe, depending on your answer to A. $3500 and lots o' work sounds like too much trouble, no matter what your answer to A is.

-Chris
 
I went from a 30' foot boat to this 40 footer. Big jump for me. In most cases the thruster is ok. But, when the lower my boat onto the water once a year I must make a 180 degree turn in a tight place. They drop me in towards the left side of a U I drop it in reverse and the boats stern goes to port about 8' from the main. Pointing me towards the main. Not good.

So yes my skills are rough for a boat this size with 2 years under my belt. It's backing up is the hard part for me.
 
Most thruster installs seem to be undersized. I don’t understand putting one in and skimping on size. If you are going to do anything then I would go for the gusto. Spending $1,100 for a minor increase isn’t worth it IMO.
 
I.M.H.O. it is not the power of the bow thruster that makes the biggest difference. Of course that does figure into the equation, but the time length of the power bursts is often more important. A three second burst may be helpful but sometimes you really need 30 seconds or more. Try to find one that has longer duration of run time.

Whoever installed your bow thruster, you can be sure they did a lot of research before selecting the one they did. If it was the original manufacturer or a marina mechanic or just the boat owner, there was a considerable expense involved. I would bet they weighed all the options.

Personally, I would go with the one just a little bigger. BIGGER isn't always better. You need to consider the battery power available, the fuses, wires and switches might need to be replaced for a truely large unit.

pete
 
The Sidepower thruster we put in our last boat was rated for 3 minutes before it would overheat. We never came close to that, usually 10 to 15 seconds was all we needed.
 
Thrust doesn't convert directly to HP... see below... but that is beside the point.
The point is the current thruster adequate?
What difficulties are you experiencing?
Do you stern in or bow in?
Do you have to run the thruster continuously for extended time to accomplish what you are trying to do?
Do you overheat or activate over current/ thermal protection often?
Can you use rudder more and fine tune w thruster?
Have you asked for any help from someone experienced w your or your type vessel?

I dont think it's practical for others to advise re the decision remote... only you can decide.
I'll also throw a few other points you may need to consider...
You mentioned possibility of adding a batty... does that also imply possible need to replace fuses and/ or cables to handle higher A w/o V drop?
Have you considered adding a stern thruster vs changes to bow? It may be even higher $ but could help even more depending on answers to the initial questions. Generally no fiberglass work ( other than cutting) needed for stern as it usually bolts on.

See. https://newportvessels.com/blogs/bl...unds of thrust is,a measurement per unit time.

"First, pounds of thrust is a static force measurement while horsepower is 550 ft-pounds of work per second, a measurement per unit time.**So you cannot make a direct comparison between thrust and horsepower unless you also know the speed of the vessel when it is absorbing that thrust. So although there is no direct translation, you can estimate the horsepower rating of a given electric motor by multiplying the amp draw times the voltage to find the wattage of the motor. Then wattage divided by 746 will give you an estimate horsepower of the motor. So every 746 watts is roughly equivalent to 1 horsepower.

The HP equivalent of our motors:

36lb Thrust (All Series) = 0.48HP

40lb Thrust (All Series) = 0.55HP

46lb Thrust (All Series) = 0.64HP

55lb Thrust (All Series) = 0.84HP

62lb Thrust (All Series) = 0.93HP

86lb Thrust (All Series) = 1.50HP"
 
Iggy said:
I went from a 30' foot boat to this 40 footer. Big jump for me. In most cases the thruster is ok. But, when the lower my boat onto the water once a year I must make a 180 degree turn in a tight place. They drop me in towards the left side of a U I drop it in reverse and the boats stern goes to port about 8' from the main. Pointing me towards the main. Not good.

So yes my skills are rough for a boat this size with 2 years under my belt. It's backing up is the hard part for me.
Click to expand...


Main? Main what?

Is this a single-screw boat?

-Chris
 
Pete Meisinger said:
I.M.H.O. it is not the power of the bow thruster that makes the biggest difference. Of course that does figure into the equation, but the time length of the power bursts is often more important. A three second burst may be helpful but sometimes you really need 30 seconds or more. Try to find one that has longer duration of run time.

Whoever installed your bow thruster, you can be sure they did a lot of research before selecting the one they did. If it was the original manufacturer or a marina mechanic or just the boat owner, there was a considerable expense involved. I would bet they weighed all the options.

Personally, I would go with the one just a little bigger. BIGGER isn't always better. You need to consider the battery power available, the fuses, wires and switches might need to be replaced for a truely large unit.

Good point on D.C. power.

pete
Click to expand...

Good point on D.C. power. After pulling 350 Amp for 30 sec will bring the batteries down!
 
ranger58sb said:
Main? Main what?

Is this a single-screw boat?

-Chris
Click to expand...

Is this a single-screw boat?

Meaning the "main" docks and than you have the fingers that the boats are in-between. Very close as I back out.

And yes a single screw. If it was a twin I would not have this problem!
 
Check the cabling to make sure it's not undersized. Voltage lag can really take a bite out of available power. Should likely be 2/0 cable.

Assuming the existing setup is in good working order, I don't think you'll see an appreciable improvement unless you go with a physically larger thruster and corresponding tunnel. $3500 won't do it for you.

Peter
 
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Bacchus said:
Thrust doesn't convert directly to HP... see below... but that is beside the point.
The point is the current thruster adequate?
What difficulties are you experiencing?
Do you stern in or bow in?
Do you have to run the thruster continuously for extended time to accomplish what you are trying to do?
Do you overheat or activate over current/ thermal protection often?
Can you use rudder more and fine tune w thruster?
Have you asked for any help from someone experienced w your or your type vessel?

I dont think it's practical for others to advise re the decision remote... only you can decide.
I'll also throw a few other points you may need to consider...
You mentioned possibility of adding a batty... does that also imply possible need to replace fuses and/ or cables to handle higher A w/o V drop?
Have you considered adding a stern thruster vs changes to bow? It may be even higher $ but could help even more depending on answers to the initial questions. Generally no fiberglass work ( other than cutting) needed for stern as it usually bolts on.

See. https://newportvessels.com/blogs/bl...unds of thrust is,a measurement per unit time.

"First, pounds of thrust is a static force measurement while horsepower is 550 ft-pounds of work per second, a measurement per unit time.**So you cannot make a direct comparison between thrust and horsepower unless you also know the speed of the vessel when it is absorbing that thrust. So although there is no direct translation, you can estimate the horsepower rating of a given electric motor by multiplying the amp draw times the voltage to find the wattage of the motor. Then wattage divided by 746 will give you an estimate horsepower of the motor. So every 746 watts is roughly equivalent to 1 horsepower.

The HP equivalent of our motors:

36lb Thrust (All Series) = 0.48HP

40lb Thrust (All Series) = 0.55HP

46lb Thrust (All Series) = 0.64HP

55lb Thrust (All Series) = 0.84HP

62lb Thrust (All Series) = 0.93HP

86lb Thrust (All Series) = 1.50HP"
Click to expand...


I looked into a aft thruster. But I have a fuel tank there. Is was suggested to put 2 thrusters, one on ether side of the tank. That would lower its self into the water. BIG BUCKS on that one.

Yes I do need to use the thruster a lot to make the 180 deg turn. Another battery may be needed. Upgrading to the next thruster motor would save 30amps.

It never goes into a over current/ thermal protection.

Looking that the chart/specs. that 14lbs more would equal about 1/4 of a HP. Not much at all.

Its sounds like, adding one more battery and the next size up on the thruster. This would do two things.

1. Keep the thruster running longer at full power. How much longer is in question.

2. The new motor pulls about 8% less power with 10% more thrust.

If I did upgrade 2 models up 212lbs thrust. I would have to add another battery anyways.

Thank you all for your input!
 
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I dont understand the layout and manuever from the description, but for once / year (if I understand correctly) is there another way to skin the cat?
Would use of (spring) line enable you to use rudder & fwd to make a turn and avoid backing that puts you in a compromising position?
Or is there a way to tie off from stbd stern that backing would pull the stern to stbd and allow room the use fwd & rudder to turn CCW?
 
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Our Formula has very low bow rails. My wife didn’t want to buy it because she felt unsafe on the bow. I told her that if we bought it I would put bow and stern thrusters in it so she didn’t have to go up on the bow. I had a company that was going to come to Michigan install both for about $25K. But after we bought the boat and I started looking and digging around I figured out that traditional thrusters wouldn’t fit due to the configuration of the boat. I decided on SideShift thrusters. They install externally and are simple to install. My wife and I installed the bow thruster in a day and a half. My neighbor helped with the stern thruster and we got it put in in one day. They work well and the total cost was about $11K. If you have access issues for a stern thruster you might check out SideShift. It takes 4 bolts and 2 holes for the cables all above the waterline. The access at my stern it really tough but we got it done pretty easily.
 
For a once a year event there are other options to consider. Especially if your thruster is adequate for your other needs. An outboard dingy or skiff can be used. A RIB is it's own fender. Have the RIB driver work under your command. Position the rib to push which ever end you know needs to be pushed. I once turned an 85' single with no thurster in a space with less than 10' to spare. Not something I care to do very often but you are talking about once a year.
 
Bacchus said:
I dont understand the layout and manuever from the description, but for once / year (if I understand correctly) is there another way to skin the cat?
Would use of (spring) line enable you to use rudder & fwd to make a turn and avoid backing that puts you in a compromising position?
Or is there a way to tie off from stbd stern that backing would pull the stern to stbd and allow room the use fwd & rudder to turn CCW?
Click to expand...

Good point! thanks!!

To understand the maneuverer:

They lower the boat into the water with the bow facing the shore. So I must back out. Where they put me in is between two main dock with boats on both sides. Its a U. Now I am lowered in the far left of that U about 8 feet or less from the boats on my port side. On the starboard side about 60ft away from other boats.

Now in backing out, as soon as I go into reverse the stern goes to port heading me into the boats. At this point I use the bow thruster to keep me starlight but I am still in the pit with pilings midship. I almost don't make it out without hitting anything. Now out, I must turn 180 deg to get out of the U.

At that time I shift 3 or 4 time in forward that kicks the boat to port. Than 3 to 4 seconds in reverse to keep me away from the other boats. Meanwell, hitting the bow thruster to port. So I am shifting, turning the wheel and running the thruster all at the same time. Three things with 2 hands! Never mind watching forward and aft that I don't hit anything! For the twin engine boats it easy.
 
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Yeah, I'd look at the sideshift. It's easy to mount, reasonably priced and effective. It would make easy work of the maneuver you're describing.

I wouldn't be rushing to upgrade the bow thruster until doing the checks suggested at least. Cabling and batteries really need to be up to snuff. If you can, measure the voltage at the motor while operating for 30 seconds.

I would expect that with hands-on coaching and experimentation in a non-threatening environment you could get pretty comfortable backing up in control with the tools you have. If you want the comfort and control that thrusters offer a stern thruster would help a lot more than a bigger bow thruster IMO.
 
Iggy said:
At that time I shift 3 or 4 time in forward that kicks the boat to port. Than 3 to 4 seconds in reverse to keep me away from the other boats. Meanwell, hitting the bow thruster to port. So I am shifting, turning the wheel and running the thruster all at the same time. Three things with 2 hands! Never mind watching forward and aft that I don't hit anything!
Click to expand...

The most effective approach in this case is to turn the rudder hard to port before you start moving and leave it there.

You have to get a sense for how much throttle to apply. Don't be afraid to do a brief aggressive burst in forward any time you want to make the stern move to starboard. Use the bow thruster to keep the bow clear as you exit, which may in fact require a brief push of the bow to starboard. After that use sparingly.

Shift into reverse and slowly get underway backwards, and at any time you can do a really brief but assertive shot in forward to kick your stern to starboard.
 
Another thing to think about is that as you get older you will not be a strong and able to horse the boat around as easily. Thrusters make it easy to move the boat around without pushing or pulling the boat by hand. If having thrusters enables us to keep boating for more years they are worth it.
 
Jeff F said:
The most effective approach in this case is to turn the rudder hard to port before you start moving and leave it there.

You have to get a sense for how much throttle to apply. Don't be afraid to do a brief aggressive burst in forward any time you want to make the stern move to starboard. Use the bow thruster to keep the bow clear as you exit, which may in fact require a brief push of the bow to starboard. After that use sparingly.

Shift into reverse and slowly get underway backwards, and at any time you can do a really brief but assertive shot in forward to kick your stern to starboard.
Click to expand...

So you are saying by leaving the rudder hard to port the boats stern will go starboard/right due to the drag? Yes? Than if I go forward or reverse the boat will be turning towards the left/port. Keep the rudder to port until I make the 180 degree turn. Yes?
 
Iggy said:
So you are saying by leaving the rudder hard to port the boats stern will go starboard/right due to the drag? Yes? Than if I go forward or reverse the boat will be turning towards the left/port. Keep the rudder to port until I make the 180 degree turn. Yes?
Click to expand...
Here's an image of what happens in relation to rudder position when moving ahead or astern. The arrows are different because the rate of turn is different. And you'll have to learn how much stern way your boat needs to respond to the rudder going astern. This image does not take prop walk into account.
 

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Portage_Bay said:
Here's an image of what happens in relation to rudder position when moving ahead or astern. The arrows are different because the rate of turn is different. And you'll have to learn how much stern way your boat needs to respond to the rudder going astern. This image does not take prop walk into account.
Click to expand...

So I DONT want the rudder hard to port! I had the rudder hard to starboard but the prop walk sends me to port backing out.
 
Only if you are trying to steer in reverse. For slow speed maneuvering turn hard towards the prop torque - in the OP's case port - and use the shift and throttle only.

Steering in reverse may work once you're up to speed and free of obstructions, but for getting out this'll do it on just about any boat.
 
Iggy said:
So you are saying by leaving the rudder hard to port the boats stern will go starboard/right due to the drag? Yes? Than if I go forward or reverse the boat will be turning towards the left/port. Keep the rudder to port until I make the 180 degree turn. Yes?
Click to expand...

Not quite. In reverse gear your stern will be pulled to port. The more speed and/or throttle, the greater the tendency of the stern to move to port.

Offsetting that are intermittent busts of forward throttle that push the stern to starboard. The higher the throttle the more the push to starboard. What you want to do is get the stern swinging as fast as it can go to starboard before the boat stops.

The delicate part is balancing the two. At first it's strange, then you can kind of do it, and with practice and experience you can point whichever way you want while slowly moving backwards.
 
Iggy said:
Good point! thanks!!

To understand the maneuverer:

They lower the boat into the water with the bow facing the shore. So I must back out. Where they put me in is between two main dock with boats on both sides. Its a U. Now I am lowered in the far left of that U about 8 feet or less from the boats on my port side. On the starboard side about 60ft away from other boats.

Now in backing out, as soon as I go into reverse the stern goes to port heading me into the boats. At this point I use the bow thruster to keep me starlight but I am still in the pit with pilings midship. I almost don't make it out without hitting anything. Now out, I must turn 180 deg to get out of the U.

At that time I shift 3 or 4 time in forward that kicks the boat to port. Than 3 to 4 seconds in reverse to keep me away from the other boats. Meanwell, hitting the bow thruster to port. So I am shifting, turning the wheel and running the thruster all at the same time. Three things with 2 hands! Never mind watching forward and aft that I don't hit anything! For the twin engine boats it easy.
Click to expand...
That helps my understanding, but I think I might try the opposite maneuver trying to turn to stbd to make thev180° turn. I'm thinking...
Rudder hard to stbd
Reverse short burst only to get you moving in Rev with min prop walk to port.
While drifting back thruster bow to stbd
Once you have enough room ahead to allow a short burst fwd possibly w thruster assist to swing bow to stbd
Burst in Rev only as necessary to stay away from shore
Continue to alternate fwd burst + thruster to turn bow to stbd
Reverse to provide room and if anything continue /thruster help the CW rotation until you are at 90+° to use more fwd to get away from boats astern and continue the CW rotation. Usebshort bursts followed by drift combined w thruster.

I know EZ for me to say but my thinking is to try to use the natural tendency of the reverse and make the rotation CW instead of fighting it and trying to make the boat do what it doesn't do naturally.

From your description your boat will turn CW much easier than CCW when using (back & fill) bursts of Rev & fwd with the rudder positioned to aid the fwd turn & left there. No steering reqd just shift, throttle burst, shift / drift and combine with thruster to compliment the above.
Does the above make any sense in your case?
 
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