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Old 12-01-2012, 12:58 PM   #21
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Electric would also be my choice over hydraulic. They are much quieter to operate and you don't have to change filters.
Hmmm.... the electric thrusters I hear being used sound like rocks in a giant cuisinart. Absolutely horrible sounding things and you can hear them all over the marina. In fact I think their noise is part of the stigma that seems to be attached to using a bow thruster. It's like shouting to the world, "Look at me, I don't know how to maneuver a boat properly!"

I think a thruster is geat tool if you have one. The single-engine GB36 we chartered had one and it came in very handy on a number of occasions, particularly as we were new to this kind of boat and boating. So other than the people who use them to steer their boats as a matter of course (like a car) even in open water, I don't belittle having or using a thruster.

But I would have thought that the manufacturers of electric bow thrusters would have by now figured out a way to make them quiet other than the sound of the water being moved. I have no idea why they are so irritatingly noisy--- it's just an electric motor so I assume the grinding sound is the gearbox. The few hydraulic ones I've heard don't seem to make any mechanical sound at all.
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Old 12-01-2012, 01:41 PM   #22
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I would give my left nut for a bow thruster.

Stern thruster....not so much.
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Old 12-01-2012, 02:51 PM   #23
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I would give my left nut for a bow thruster.
Stern thruster....not so much.
Even with a twin there have been many times I wished I could move the bow sideways one way or the other and leave the stern where it was. However I don't know that I've ever wished I could move the stern straight sideways and left the bow where it was. But I can certainly envision situations where one would want to do this.

I have watched boats with stern thrusters only come into the docks in the marine parks on occasion. Unless the wind or current is setting them onto the dock, it seems that while they have no problem in getting the stern up against the dock, there is still a mad scramble to get someone on the dock to catch the bow line because the bow still drifts away, sometimes quite rapidly depending on how hard the stern hit the dock.

The boats with bow thrusters always do quite well in this respect, assuming the helmsman knows what he's doing. They angle the boat in by the bow, then use the prop(s) and rudder(s) to move the stern in, and the bow thruster to hold the bow in since a boat will pivot to a degree with the application of rudder and thrust so the bow will want to swing out as the rudder moves the stern in.

This is the situation we encounter the most in which it would be nice to have a bow thruster. We've always been able to deal with it by getting a spring line to the dock right away but there is certainly an appeal to eliminating the fast line handling by the use of a toggle switch.

So my conclusion is that if money is not a limiting factor a bow thruster is a much more useful and versatile tool. Not that a stern thruster isn't a help. But if you can only have one or the other, outside of its lower cost I do not see nearly as much overall value in a stern thruster as a bow thruster.

And while the notion of getting the cost of improvements to a boat back when the boat is sold is a pipe dream, I think a bow thruster adds more appeal to a boat when it's for sale than a stern thruster, unless the boat has both.
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Old 12-01-2012, 03:22 PM   #24
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Just had the boat hauled and bottom cleaned. While out of the water I discussed installation of bow thruster. Cost est about $10k. My boat has a single Lehman 120 and all the poor maunverability that comes with it. There are a couple of trawlers in our marina that have stern thrusters rather than bow thrusters. Does anyone have experience with thrusters and advice as to which is best. As further info boat backs to starboard.
While not familiar with your vessel i do have extensive small boat experiance on a small budget. I learned with a single one plans his approach very carefully then uses sudent bursts of power to keep on course. With a neavy underpowered boat like most trawlers are a short burst of fuel throttle won't move your boat much but it will move it. Beginning boaters are afraid to hit the throttle at dockside and tend to just do things ta close to idle speed. Just be sure to take into consideration not only the wind direction but the current. With practice my money is on you not needed a thruster. Experiment when at the dock on a calm day to learn.
10k is too much. How much does the bow thruster itself cost without the labor?

Not having experiance with trawlers only planning hulls my experiance may not be entirely valad
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Old 12-01-2012, 03:35 PM   #25
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Thanks for the link Sceptic, I have been thinking of doing an instalation myself. I just don't think it will be that hard and your experience seems to bears that out.
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Old 12-01-2012, 03:56 PM   #26
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My boat had a bow thruster on it when we bought it, and I added a stern thruster. The stern thruster allows us to do things like move sideways into a tight spot, do a 180 quickly or easily back down a fairway with inches between us and the boats on each side. I love the stern thruster, but if I was choosing one over the other I would pick a bow thruster.

Both thrusters are made by Vetus. Our old bow thruster matched Marin's description. It sounded like we were crushing rocks. The stern thruster is very quiet. The blades have been redesigned by Vetus to be quieter and more efficient at moving water.

I changed the motor and blades in the bow thruster to the new design. It is still noisier than the stern thruster, but is significantly quieter than it was.
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Old 12-01-2012, 05:39 PM   #27
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My boat has a bow thruster and it's a big help in tight situations.. "Back and fill" is fine when you have the room and the time, but it's a big help to have other tools (thruster) as well.

The sound of the thruster doesn't bother me at all.
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Old 12-01-2012, 09:00 PM   #28
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Quote:
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Not sure why it should be any harder to move the stern to port with the prop and rudder than to starboard. Prop walk has an influence but unless your boat has a very small rudder with very limited travel it should be able to easily overcome the prop walk influence. If you're talking about moving the stern when the boat is stationary in the water, try using more power to get the stern moving.

A lot of boaters, including me until a year or two ago, tend to leave their power at idle when maneuvering into and out of slips, up to a dock etc. But I finally watched enough tugs, lobsterboats, and fishboats maneuver to realize that power is every bit as helpful a tool as the wheel and the shifter(s). So now I use power, or bursts of power, all the time-- sometimes a lot of power momentarily--- and it has greatly improved both the speed and accuracy of putting the boat where I want it.
Thanks for your responses. I have always been concerned that the helm won't respond to rear port. I will try more power. I wonder now if the rudder and prop are correctly proportionate. Attached is a pic took last week when the boat was hauled.
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Old 12-01-2012, 09:18 PM   #29
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Great Laker has both a bow (factory installed) and stern (previous owner installed) thruster. I use both together in turning the boat in a narrow fairway, lets say for entering a slip. I use the bow thruster mostly for keeping the bow near a dock after an approach and during tie up. I use the stern thruster mostly for steering the stern while backing into a slip.

I agree that the bow thruster makes the most sense if you have to choose between one or the other, as you can control the stern with the rudder/prop. However, backing down a channel or into a slip is really easy with the stern thruster. Since the stern thruster is much less expensive to add to a boat, there is a good argument to pick that one if you can only afford one.
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Old 12-01-2012, 09:24 PM   #30
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Thanks for the link Sceptic, I have been thinking of doing an instalation myself. I just don't think it will be that hard and your experience seems to bears that out.
I did my own bow thruster install as well. I stumbled upon a great deal ($750)for a new in box Sidepower SP55 and 7" ID tube that I bought from a guy whose boat building dream had died. I upgraded it with all of the kits I could purchase so that is essentially a SE60 model now.

I estimate (I'm not at home now) that I spent ~ $1,200 on supplies to install. I used top quality, and bought wisely, but it adds up.

The boat was conveniently located at my house which made it easier.

I read all the manufacturers literature out there and many websites (like sceptics) before proceeding. Regardless of the brand you purchase, or even if you have someone else install, I would recommend downloading the manuals of of the Sidepower/Imtra site as they have very detailed installation instructions. Tube location and fairing are very important for the increase in efficiency and decreasing the noise that Marin alludes to.

I used West System epoxy and lots of biaxial cloth. Spent a lot of time doing the proper step tapers so as not to create any sharp or lumpy transitions which cause stress risers.

The electrical was straight forward. All Blue Seas and oversized cable.

I used lasers and rare earth magnets to help with my location layout. Measure a bazillion times and cut once.

I made my own cut out tool. ( No 70's Defever hull thickness here, only 9/16"). Leave tabs to saw out later. Remember you have to cut the other side!

Ensure you radius the tube for smooth flow.

I put an eyebrow on the front of mine so there is no flow noise underway.
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Old 12-01-2012, 09:32 PM   #31
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I guess I should add that I didn't really need a bow thruster as I can turn in my own hull length by judicious use of throttle and rudder, but I wanted a bow thruster (as a toy), and at that price I couldn't refuse, even if it was oversized.

But as my boat has a fair amount of windage, and it can get breezy in my harbour, I am sure glad I have it. It is a great tool and I use it all the time. Came in one time after the breeze picked up this summer and it can easily counter a 25 knot breeze on the beam.

Maybe the novelty will wear off, but I doubt it.
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Old 12-01-2012, 09:45 PM   #32
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Hmmm.... the electric thrusters I hear being used sound like rocks in a giant cuisinart. Absolutely horrible sounding things and you can hear them all over the marina. In fact I think their noise is part of the stigma that seems to be attached to using a bow thruster. It's like shouting to the world, "Look at me, I don't know how to maneuver a boat properly!"

I think a thruster is geat tool if you have one. The single-engine GB36 we chartered had one and it came in very handy on a number of occasions, particularly as we were new to this kind of boat and boating. So other than the people who use them to steer their boats as a matter of course (like a car) even in open water, I don't belittle having or using a thruster.

But I would have thought that the manufacturers of electric bow thrusters would have by now figured out a way to make them quiet other than the sound of the water being moved. I have no idea why they are so irritatingly noisy--- it's just an electric motor so I assume the grinding sound is the gearbox. The few hydraulic ones I've heard don't seem to make any mechanical sound at all.
I know exactly what you mean. But mine are extremely quiet. Both bow and stern. Most of the louder units in our marina are hydraulic not electric.
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Old 12-01-2012, 10:02 PM   #33
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Hmmm.... the electric thrusters I hear being used sound like rocks in a giant cuisinart. Absolutely horrible sounding things and you can hear them all over the marina. ...
Good. Mine sounds the same. So it must be working OK even if it sounds broken.
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Old 12-02-2012, 12:08 AM   #34
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Thanks for your responses. I have always been concerned that the helm won't respond to rear port. I will try more power. I wonder now if the rudder and prop are correctly proportionate. Attached is a pic took last week when the boat was hauled.
What I know about hull design and the proper sizing of props and rudders wouldn't cover the head of a pin, but from your photo that looks like an awfully small rudder to me.
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Old 12-02-2012, 08:01 AM   #35
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Rudder position makes little or no difference on my boat when backing because the prop wash doesn't hit the rudder, only the minimal flow of water from backing.

My marina has a very narrow fairway and there's often current and wind so docking stern to would be verry difficult without a bow thruster.
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Old 12-02-2012, 11:40 AM   #36
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There is a choice of a bow thruster and stern produced in the Netherlands as a combi system. HMP.nl
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Old 12-02-2012, 11:57 AM   #37
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Thanks for your responses. I have always been concerned that the helm won't respond to rear port. I will try more power. I wonder now if the rudder and prop are correctly proportionate. Attached is a pic took last week when the boat was hauled.
I just re-read your post and I screwed up. I had missed the rear port. Going backwards your rudder may be ineffective at best. Propwalk will be a dominant force that the rudder may not be able to overcome, particularly at low speeds. So more power is not necessarily the correct solution.

For that, in a single engine boat, the more effective technique is to " back and fill". You get the boat going backwards and then correct the sideways yaw of the stern by putting the rudder over, giving a shot of forward thrust against the rudder to straighten the stern out, then immediately back into reverse (or sometimes just neutral if the boat is still moving backwards) to continue backing, another correction, and so on. It's all about inertia and if done correctly your boat will track backwards in a straight line as you correct for prop walk along the way.

Much easier to do than explain.. I learned to do this with 60' narrowboats in England which back horribly but have big rudders and fairly powerful engines. Once you get the hang of the timing and using inertia to your advantage it's an easy thing to do and is actually kind of fun.
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Old 12-02-2012, 12:32 PM   #38
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On thrusters for my boat I'd opt for a stern thruster.

One other big reason is that they are so easy to install.

Almost the only time I feel the need for a thruster is when backing down on an anchor, especially in a breeze. One could compensate for prop walk w a bow thruster but the boat would be going sideways. I'd rather be going straight back.

And I can position the bow practically anywhere the stern thruster would only increase that capability.

But of course thrusters at both ends is no doubt ideal but any thruster will funnel significant funds away that could otherwise be used for much more useful things than thrusters.

I noticed Mark didn't say "don't need no stink'in thruster".
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Old 12-02-2012, 12:51 PM   #39
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First, bow thrusters, tunnel or is it produced by Holland Marine Parts are used primarily to assist in maneuvers such as the mooring in ports, their power is individually tailored to the size of the unit and is calculated to overcome the force of the crosswind 5-6 bft. Tests of these systems in the company so I can accurately determine if their power is correct or not. Tunnel are efficient but noisy and not very flexible in installation, Dutch very quiet, small holes on the sides of the nozzles can be mounted on the bow or stern, but limited power to 90kgf. Best to see how they work and compare the two you can always find a compromise. Ryszard
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Old 12-02-2012, 04:33 PM   #40
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Thanks for your responses. I have always been concerned that the helm won't respond to rear port. I will try more power. I wonder now if the rudder and prop are correctly proportionate. Attached is a pic took last week when the boat was hauled.
That looks like the image of an mmc with dual engines not a single. The ones i have seen with a single have much bigger rudders.
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