STERN vs BOW THRUSTERS

Any openions on which is better for a 36' to 40' trawler. Is the bow thruster more effecient or is the stern thruster? Thanks in advance - Capt Ray

My opinion is that with a single screw the bow thruster really helps if you park stern in or in windy conditions. With twins the bow thruster is not too important to me, but in high winds I do use it occassionally. Stern thruster? I have no use for one as I try hard not to add systems that need regular maintenance but are seldom used. As with most issues on this forum there will be many divergent opinions.

The bow thruster will be more expensive to install but will be more effective. Having run hundreds of different boats I can move the stern of the boat easily with prop wash if needed, but it is always harder to move the bow.

captain ray said:

Any openions on which is better for a 36' to 40' trawler. Is the bow thruster more effecient or is the stern thruster? Thanks in advance - Capt Ray

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Depends if Single or twin?

A bow thruster is almost a must for the single screw because of the reverse prop walk. Also a sink engine can be push/thrust to the side in forward. I can mostly turn the Eagle 360 degree put it in forward thrusting the stern to port as the port prop walk will pull the stern to port. So turning to starboard, the bow thrust is seldom need/used. However turning to port is where the bow thrust is need/used. I try to maneuver/turn to starboard.

I would think on a twin, a stern would be better as the props move the bow. The stern stays relatively stationary. However, most twin have a bow thruster also.

captain ray said:

Any openions on which is better for a 36' to 40' trawler. Is the bow thruster more effecient or is the stern thruster? Thanks in advance - Capt Ray

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You left out pertinent info for anyone really to help you.

1. budget?
2. twins or single?
3. year of vessel
4. what happened that made you think thruster?

When you answer those questions, people can help you. With all due respect to Phil, a bow thruster would most likely give the best performance for a vessel with twin engines. Again, we need more info to help you Ray.

bow or sturn thruster?

Thanks for the thought! I am looking at two trawlers which have (one Bow, one stern). Have lots of exp. with 5 issues of USCG masters Lic. It would seem that with the long keel and large rudder, a bow thruster would be the best bet. -- Thanks for the thoughts -- Capt Ray

I would like to pick up on Captain Rays question, I too am considering bow/stern thrusters but I take the sales hype with a grain of salt. Does anyone here actually have a stern thruster & if so could you share your thoughts.

If you can afford just one, get a bow thruster. Far more useful in most situations, although there are some unique situations where a stern thruster can be very beneficial.

But since every boat already has a stern thruster in the form of the prop thrust and rudder(s), being able to move the bow straight sideways without moving the stern is beneficial in all manner of maneuvering situations.

If you can afford both, then get both.

I have both bow and stern thrusters on a 47ft single screw. The bow thruster helps far more than the stern thruster. Stern thruster helps push the boat into the dock against the wind after tying on. Also enables spinning the boat using both bow and stern thrusters together. On its own the stern thruster is marginal at best.

Marin said:

If you can afford both, then get both.

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Or buy a boat with both already installed. Ours came with both and its been very nice to have both on a single engine boat. On the other hand, if the boat had had only a bow thruster, or none at all, we would probably have bought it anyway. On the other, other hand, I'd rather have twin engines than any thrusters at all.

(No, don't restart the single vs twin topic please).

captain ray said:

Any openions on which is better for a 36' to 40' trawler.

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Which one is in better shape? What suits your mission better? 4' isn't that much of a size difference but it may bump you into a larger berth.

captain ray said:

Is the bow thruster more effecient or is the stern thruster? Thanks in advance - Capt Ray

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You'll get used to handling either. If I had to choose one give me a bow. Having said that, I have neither and still manage to get my boat docked after each use. Thrusters for me fall into the "nice to have" and not the "need to have" category.

As always, your mileage may vary

Bow thruster regardless of single or twins. You'd only add the stern thruster to supplement the bow thruster.

If installing in an existing boat, make sure it is powerful enough! Also check the run time. Many thrusters have a limited run time before they blow the breaker.

Variable speed 120/240 VAC would be the gold standard. May be too pricey for that size boat.

I have used Wesmar in all our non-IPS Island Pilots with no complaints from owners.

We have twin screws on our 47 foot Sea Ranger and although we can maneuver without our bow and stern thrusters, we are quite happy to use them both to make docking easier. We believe in making life as easy and as stress free as possible.

Capt Kangeroo said:

I would like to pick up on Captain Rays question, I too am considering bow/stern thrusters but I take the sales hype with a grain of salt. Does anyone here actually have a stern thruster & if so could you share your thoughts.

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You have heard the rest, now I'll opine. I actually DO have a stern thruster on my 30 foot Tung Hwa Clipper. Thrusters, bow or stern, allow you to have finite movement. when in a marina, this can be a life saver or a marriage saver . I actually will steer with the stern thruster when going around tight corners as does my father who owns a bow thruster on his 34' CHB.

When cost isn't an issue, are bow thrusters better? Sure, go for it. Whether you're moving the bow of your boat side ways or the stern of your boat sideways, it does the same thing when you're looking for finite movement to turn a sharp corner or completely spin your boat around on its axis. It also allows me to run at much slower speeds without constantly putting my 30 year old transmission through a work out.

With all due respect to Marin, prop walk is not a replacement for a stern thruster's ability to turn sharp corners and spin your boat around without propelling the boat through the water. It's not a replacement for the finite movement that all thrusters give the captain.

So, at the end of the day, the $7K that I saved by buying a stern thruster was well worth it. Good luck with whatever you decide is right for you. They are both good choices for an added safety device that will help keep your wife, children and other passengers out of harms way while you navigate to your port.

We bought our boat with a bow thruster, and it certainly helped with our single screw GB. We also have practiced using a spring line for moving the stern. That being said, my wife is a bit nervous about docking. At our age, I didn't want her to worry about jumping off the dock to secure a line. Thus we installed a SideShift stern thruster. Great investment. We boat more, the Admiral is happy, and all is well!

Scout said:

We boat more, the Admiral is happy, and all is well!

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And that everybody is the single most important point about equipment purchased for a pleasure boat IMO.

Adelaide said:

With all due respect to Marin, prop walk is not a replacement for a stern thruster's ability to turn sharp corners and spin your boat around without propelling the boat through the water.

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I wasn't talking about propwalk, although it can be a major help, as much for a twin engine boat as a single (prop walk is the main reason, although not the only one, why a twin pivots so nicely with one in forward and one in reverse).

I was talking about prop thrust against a hard-over rudder (or partially over rudder). That creates the same sideways force as a stern thruster and will move the stern of the boat left or right as needed.

BUT.... this also induces forward movement of the boat as well. Which is where intertia comes in. When the operator really understands and knows how to take advantage of inertia, which is as much the tendency of an object to resist movement as much as it is the tendency of an object to keep moving once it is, then it and the thrust being directed by the rudder can make a boat do whatever the operator wants it to do.

I first learned about all this with 60 foot, 20 ton narrowboats on the canals in England. Flat bottomed, no keel, only about 2-1/2 feet of draft, very susceptible to crosswinds, steered from the stern with a tiller attached to a big rudder and with a good size prop with a pretty powerful diesel attached to it. Tons and tons of propwalk effect. No thrusters. And, once we learned about inertia and how to use it, it didn't take long before we (my wife learned the same things) could make that unwieldy monster sit up and dance in terms of maneuverability.

I don't say all this to discourage someone from getting a stern thruster if they feel it will enhance their boating experience. Just that if you don't have a stern thruster, or can't put one on your boat, or can't afford one at the moment, there are ways to get the same end result with the tools you have now--- prop, rudder, shifter, throttle, thrust and inertia.

My AT 34 came from the factory with a bow thruster, so this seems to be the industry view of which is most important. However, the previous owner added a stern thruster, because his admiral hurt her hand trying to push the stern off a dock from the cockpit. So I have both.

I find that I can usually bring the bow to the dock with forward momentum and rudder steering. It is the stern that is most challenging. Once the bow line or mid-ship spring line is attached, the stern thruster brings the stern over easily.

In addition, I frequently choose to back into a slip, and it is easy to steer the boat when in reverse with the stern thruster. No need for constant gear change for back and fill. I also agree that the stern thruster can spin the boat just as effectively as the bow thruster.

So, if I only were to have to choose one or the other, I would strongly consider just the stern thruster.

rjtrane said:

If installing in an existing boat, make sure it is powerful enough!

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Glad someone said this. On our recent charter we were caught in strong wind being blown sideways and needing to turn 90 degrees to port into the wind. There was very little maneuvering room fore and aft due to docks lining both sides of the channel. With the weight of our single-screw boat and a full keel, the bow thruster was anemic even in normal conditions and all-but-useless in the conditions we were in. We made a couple of desperate maneuvers that got us out before we ran out of channel, but I came close to dropping the anchor. The charter company has previously recommended a 24-volt thruster to the owner. Don't know that it would have helped in our situation, but it's definitely something I'd want to check out if we ever buy a KK-42.

My boat came with a stern thruster already installed. While I would have preferred a bow thrust originally, now I am not so sure which is really better. I certainly got used to the stern thruster and can put the boat anywhere I want to. I think it comes down to learning your boat and using what you have.
I certainly would NOT let the thruster position become a factor in which boat to buy based on my experience.

Our boat came with bow.
We added stern.
BEST investment we could make!
Which is better? Both.
There have been times the bow "saves the day", but just last week we had a strong cross wind comming into the dock and it was the stern that allowed us to "place" the stern exactly where we needed it at the speed my admiral wanted it and then she walked the line up to the bow as I perfectly backed in.
In our case, the stern thruster is newer and stronger.
Love both and now I can focus on having FUN and not on figuring out or worrying about non ideal docking conditions.

We have both bow & stern thrusters on INFINITY. I'm spoilt now, I love it

nemier said:

We have both bow & stern thrusters on INFINITY. I'm spoilt now, I love it

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Doh! Getting used to this new iPhone now is more of a challenge... Anyway, meant to continue my last post by saying; if you you have the opportunity for both bow & stern thrusters, do it!! I promise you. You will not regret any part of the decision.

nemier said:

We have both bow & stern thrusters on INFINITY. I'm spoilt now, I love it

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I'm with Andy on having both if available. Sea Eagle has both a bow and stern thruster and although I find the bow thruster to be more useful, I do sometimes use the stern thruster. The gap in the breakwater at our current marina is very narrow (about 1' clearance on either side of the boat). Tapping the bow or stern thruster to keep the boat aligned when passing through the breakwater works much better than using he rudder (the stern will then swing out and try to kiss the pilings).

YMMV,

Marin said:

I was talking about prop thrust against a hard-over rudder (or partially over rudder). That creates the same sideways force as a stern thruster and will move the stern of the boat left or right as needed.

BUT.... this also induces forward movement of the boat as well. Which is where intertia comes in. When the operator really understands and knows how to take advantage of inertia, which is as much the tendency of an object to resist movement as much as it is the tendency of an object to keep moving once it is, then it and the thrust being directed by the rudder can make a boat do whatever the operator wants it to do.

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There is no question that a very good captain can use inertia to assist him in maneuvering his/her boat. But inertia and prop thrust often offer a single shot at your target (strong winds/currents). not to mention undue strain on often fragile transmissions.

I have seen too many single engine trawlers get pushed off target by winds and strong currents. Some people don't like the headache....others want the capability of single handling their vessel while their passengers are safely inside the cabin. Both types of thrusters offer this extra layer of safety and ease.

Marin, we'll have to agree to disagree on the value of a relatively inexpensive stern thruster on a single engine trawler.

Adelaide said:

Marin, we'll have to agree to disagree on the value of a relatively inexpensive stern thruster on a single engine trawler.

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No disagreement. If a boater has one or can afford to install one he should use it. If we had one on our boat, even with two engines, we'd use it. Same with a bow thruster.

My only point is that if you don't have one it's not the end of the world. There are techniques to accomplish the same result, but they do require more understanding and practice than pushing a button or lever.

99.9 percent of the boats I see when we're out don't have stern thrusters and from my observation they all seem to do just fine when docking, be it calm conditions or adverse winds and/or currents.

So I think it's a great tool if you have one but I don't think it's a necessary tool for precise maneuvering if you don't.