Counteracting prop walk

Hi All. *I thought this may make for fun discussion and hopefully I'll learn a thing or two. *Our Monk is the first single screw boat we've had, excluding ski boats, etc. *Our bigger boats (33' and a 38') had twins with no thrusters and we could put them anywhere we wanted in any weather without issue. *I was extremely, extremely good at maneuvering them and never had a problem docking anywhere/anytime, more or less, including being able to back them in stern first to the slip on only one engine if needed. *I am still getting used to the trawler. *Actually I have, overall, found it very easy to handle...have never had an issue docking, always goes where I want it to, etc. *So thus far, with my limited time at the wheel to date on her, I've never had an issue handling her. *HOWEVER- I've only been docking her bow in first! *Previously we always docked our boats stern to and that is pretty much the custom around here. *Access to our boat on the dock is great as we are on a covered floating dock with wide fingers so I can get on or off easily whether bow or stern to. *What bothers me though is I am not sure I could park her stern to if I wanted to or had to and well, that bothers me. *I like knowing I can get my boat to go anywhere/do anything so I want to be able to back her in if only as a matter of principal. *The prop walk in my Monk in reverse, in my opinion, is pretty severely to starboard (i.e. stern kicks hard to starboard in reverse). *I have toyed with just popping it in reverse and then quickly out of reverse, short burst of forward, etc. but doing that is hard to make headway in either direction and tends to keep me in one place.
So I guess the question is, for those of you with single screws and no thrusters...what trick do you use to get your boat to back up straight? *Let's say I go into a new marina as a transient and the slip they assign is at the end of a narrow fairway and I get down there and the slip is full and I have to back out in reverse? *I need to know how to make the boat effectively go in reverse in a straight line in case something like that happens or any other scenario that may require me to get the boat to back straight out for a certain distance. *Right now, within about one boat length distance of backing up, the boat wants to do a 360 spin. *It's causing me to seriously ponder getting a thruster but I know I need to figure out how to do this without a thruster for my own ability and just to be as competent as possible.
I thought I'd try backing into my slip earlier this week when I took her out with the family but I decided not to as it was late, we were tired, and the approach is a little odd since my 40' slip is next to an 80' slip so I can't come in parallel to the slip, go past it a bit, then just put it in reverse and let the prop walk swing me in b/c to clear the 80' slip I am a good distance out from the dock.
I love having a single screw when going forward, but in reverse I wish I had twins! *

My approach to the slip isn't nearly as bad as yours, I can get pretty close before I cut hard to starboard and then start backing in.*

I turn past a straight back approach and leave the wheel hard over to starboard to move the bow to the right & the stern to the left as required.* Then goose her in reverse to bring the stern to starboard and move backwards.* It takes a bit of backing & filling, but it does work. It usually ain't pretty, but it works.* And, when I get lucky she backs straight in at a nice pace like she's on autopilot.* (1 in 10 tries!) Get the spring line on first and you'll be mostly OK.

Many times I bail out, circle around and try again.

If you have a Chapman's manual, it describes a single screw's handling attributes. To a T.
I have always had single screw boats, and have learned to back in.
The first step is understanding that the boat will behave the same way every time. Learn that characteristic and use it to your advantage.
I could never get my previous boat, an old 34 Mainship, to back straight. Never happened. But I never had any trouble getting it into a hole (after some practise). Use the "back and fill" technique, let the wind/current help you. Use some engine RPM to help you spin the butt end, or use idle depending on how much turn you need.
And forget trying to use the rudder in reverse unless backing a long distance.
One additional approach that has helped me is I always stop the foreward motion of the boat before I start to back in. This helps make the first turn sharp.

It's hopeless... Buy a stern thruster.

GonzoF1 wrote:

It's hopeless... Buy a stern thruster.

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It's easy, man up!*

Commercial water-men have been doing it for decades.

Personally, I am determined to master the skill.* How hard can it be?

*

It's not hard, all it requires is an understanding of how to use the boat's*inertia and the rudder's control of the thrust direction, and then get a feel for the timing required.

I learned this on 60' narrowboats in the UK where the boat's bottom is flat as a board and the propwalk pivots the boat fast around a point more or less in the middle of the boat. Basically you get the boat moving backwards, then use the rudder and prop thrust to correct the stern's yaw to the side, take out the forward thrust just before it overcomes the boat's inertia to the rear, then put in some more reverse, then another shot of rudder and forward to counter the yaw, and so on. I've backed a 60' narrowboat up 100 yards or more straight down a narrow slot between other boats using this technique and it works perfectly.

It's all a matter of timing, of knowing when to correct the yaw with forward thrust and the rudder, when to put reverse back in, and so on. The tendency is to wait until you see something happening and then put in the correction. Doing this will guarantee that you are always behind the curve, and the boat either won't go where you want it or will make no reverse progress at all.

The application of reverse and the forward thrust/rudder corrections have to be made before the boat starts to move the wrong way. Thus the need to really understand how the boat reacts to inertia. Don't forget, inertia has two "ends." Inertia is the resistance to the force needed to start the boat moving, and it's the resistance to changing the direction of movement once the boat is moving.

I think it is virtually impossible to explain the process in writing. You can get the theory from a written description, but the only way you'll truly understand it is to get on a boat and start trying it. Feel, judgement, and timing are only developed by doing. And those three things are the key to making it work.

-- Edited by Marin on Wednesday 3rd of November 2010 11:51:34 AM

We're not dumb. Sure we can learn boat handling***** .....but it would take as much time for us to learn it as the commercial boys*** ... and we only have a small fraction of the time at the helm as they do. An equalizer would be to practice. Big time. Load the boat up w tons of fenders and go at it time and time again. We don't do that. We go play. We do what we bought the boat to do*** ...go cruising. But if we take the time to do lots of practice we CAN learn to handle our boats. But for those that don't practice**** ... they will remain ham fist-ed and unpredictable. What we're doing as small boat operators is a very challenging, demanding and deep subject. There is soooo much to learn**** ...and for those of us NOT retired it's a big challenge. And for those that just don't have the time** ..or interest*** ..don't despair. If the harbormaster says "back your boat into stall 16 on D float" and you know you can't do it dependably you need to buck up and tell the man it's beyond your skill level. It's stupid to put yours and other boats, and/or infrastructure at risk to feed your ego. I remember doing that and it went real well. I did something most responsible skippers would not attempt. Someone said "nice landing" and and it was but it also was mostly very good luck and to a significant degree ** ..an accident. I have'nt (I'm proud to say) done anything so stupid since but it's always tempting**** ...the reward potential is high and to admit your skills are lacking is hard to do. But for those without the skills the only responsible thing to do is buck up, admit to one's lack of skills and do the only responsible thing.
BUT** ..."yes we can"*** ..we CAN learn boat handling.

nomadwilly wrote:

you need to buck up and tell the man it's beyond your skill level.

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Which is why my slip is on the outside of the marina, not between parallel docks!* After my first couple attempts I walked up to the marina office and asked to move to the outside.* The owner (90 some years old!) chuckled and said, "Yeah, I was watching you bump around out there. Try slip B-4."

FWIW - the PO brought the boat over to my marina with me on day 1.* He was very, very good at manuvering the boat in and out of his tight slip.* But he couldn't back it into the spot I had originally at my marina.* He finally gave up and we muscled and dragged it in.

When reversing, try having your steering set fairly well to starboard (the rudder's not going to do much in reverse) and when the stern moves out to starboard too far, give a quick burst ahead to kick the stern back towards port. It's sorta like a series of hops but works just fine.

After a bit of practice, you'll be able to anticipate the starboard movement and correct it before it really happens. Then anyone watching will think you're a genius.

nomadwilly wrote:

We're not dumb. Sure we can learn boat handling***** .....but it would take as much time for us to learn it as the commercial boys*** ... and we only have a small fraction of the time at the helm as they do.

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Eric you nailed. it It is all about Practice, something you just don't get as recreational boaters.* I have even tried anchoring a couple of finders in a small cove just to practice.
Totally different when you get to the harbor and the wind is up or the tide is running.

Good to have mates or other boaters ashore. Don't feel embarrassed ask for help when you need it. Better than playing bumper boats.

I really hate it when at the end of the season you have just about got it. Then 6 month lay up and it's brand new in the spring.

I must be getting old. How are you supposed to remember this stuff all winter long?


SD

-- Edited by skipperdude on Wednesday 3rd of November 2010 01:45:12 PM

I've posted this link before. But it speaks to Eric's comment about the "practice" commercial skippers get as opposed to recreational boaters. But it serves to illustrate how well an experienced boater can back a single-engine boat. The skipper (who is driving from a helm station near the back of the boat on the starboard side) only makes one correction during his back in (you can hear the brief burst of forward power on his way in). This is a docking contest held by watermen on (I think) the Chesapeake.

I agree with what Bendit wrote
"
When reversing, try having your steering set fairly well to starboard (the rudder's not going to do much in reverse) and when the stern moves out to starboard too far, give a quick burst ahead to kick the stern back towards port. It's sorta like a series of hops but works just fine.

After a bit of practice, you'll be able to anticipate the starboard movement and correct it before it really happens. Then anyone watching will think you're a genius."

I have a bow thruster but whenever possible I try not to use it. the above works well although no one has ever mistaken me for a genius while doing it!
Good Luck
Steve W

Marin,
that video is INSANE! Seriously- totally impressive. It reminds me of the capt that runs the big tourist fishing barge/boat/thingy at Hubbards Landing @ John's Pass near Clearwater/Treasure Island. That guy comes GUNNING in and each time I watch him I am SURE he is gonna wreck but darned if that guy doesn't set her gentle as a newborn baby in a crib each time!

Thanks all for the comments and tips- definitely appreciate it and clearly I need more practice.

Woodsong wrote:

Thanks all for the comments and tips- definitely appreciate it and clearly I need more practice.

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If my wife and I could learn to back one of these things-- 20 tons, 60' long, 6'-6" wide, 2.5' draft with an absolutely flat, slippery*bottom, large three-bladed prop right at the back*end, and*a tiller---- and put it wherever we wanted to, you will have no problems learning to*do the same with*your boat


*


-- Edited by Marin on Wednesday 3rd of November 2010 06:23:14 PM

An old salt commercial captain bought a sister boat of our 58 ft which was moored two slips from us.* He used the bow thruster to off set the prop walk that brought the bow around.* He back straight up for about 100 yards.* I think on a single a bow thruster is better than a stern thruster as the stern can be moved/pushed by the side thrusts, so its the bow that need to be move about.*


*
Our prop walk is to port so the bow goes to starboard so when maneuvering in tight areas I try to maneuver/turn to starboard.* If it was not for the bow thruster is would be very difficult to maneuver to port.* Most days I watch the commercial's dock their boat using just the prop thrust and walk.* They unload at the peir in front of us.* Its a little un nerving when a 100 ft commercial comes and starts maneuvering.* They usually move us with the prop wash, and blind us with there bright lights.* However, they do push/brush/come up against*the dock quite often, where us pleasure boater would have a heart attack.* Oh, My I hit the dock!* My poor boat! *I hope nobody saw that.* My poor boat!* That is one nice thing about having an ugly trawler!* There is nothing wrong with hitting the dock.* In fact it might be good if some of*us did hit the dock to see its not so bad and the boat will*survive.**


*
My problem is I do not take the Eagle out enough, so by the time I get the hang of it again, we put it away for the winter.*Also if you don't make it the first time, then bail and try it again.* Its not like its due or die*on the first try.**I tend to rush, be in a hurry when I don't have to be.* So I have to remind myself to slow down, take the time/take a deep breath.* Last week*I help a neighbor dock his 75 ft, 100 ton*steel trawler which took over 5 minutes manuvering.*******

Oh, by the way its for sale, "SteelLady".* There is also a 60 ft steel motor sailor on a dock for sale.* Both will take you anywhere in the world.

" I think on a single a bow thruster is better than a stern thruster as the stern can be moved/pushed by the side thrusts, so its the bow that need to be move about. "

That's what I though but I found a boat I thought I wanted to buy that had a stern thruster and had to think about it. You could go down a narrow fairway and turn around in almost your own length. When you turn into your (a typical slip) you can make almost a square turn with 2 big pluses. 1. You can make the turn in either direction no matter which way your propeller turns and 2. When you complete the turn a short squirt w the thruster in the other direction will stop your stern going wide from inertia. This cannot be accomplished w a bow thruster.But the most important stern thruster deed for me would be backing down while anchoring in a breeze. The bow will get blown downwind and it seems if I don't figure it out quickly which way to allow this to happen the stern will walk upwind and I will be broadside*** ...or even worse. In the future I plan to work hard at keeping the bow from going downwind on the wrong side. With the stern thruster that should be no problem. The wind could switch numerous times while backing down and one could back straight down in complete control. You could even reduce the tendency of broaching in heavy going with a stern thruster. Most of this could be accomplished w a bow thruster but the stern thruster may be more effective much of the time and some things will not be possible w a bow thruster. Another advantage (for most trawlers) is that the unit can be mounted in the lee (so to speak) of the slipstream and be installed much more simply.
The stern thruster may be may be the better tool but even if not it's far more capable than I had previously thought.

" I think on a single a bow thruster is better than a stern thruster as the stern can be moved/pushed by the side thrusts, so its the bow that need to be move about. "

I agree 100% with this. I have a hydraulic stern thruster and while it does help a bunch, no doubt in my mind I would be better off controlling the bow.

Woodsong...I'm with you on this. *I also bought my first single screw recently. *I can't add to the wisdom above, but I found the articles on single screw handling very helpful from the Krogen owners site. *Here's the link:

http://www.his.com/~vann/KrgStuff/Krognidx.htm


Scroll down to FAQ section 9.1, and there's some interesting character articles on handling single screws. *Of course, it's all the same info, but sometimes I need to read numerous descriptions before I can envision it. *Of course, there is no substitute for just doing it. *Thanks for your "bucking up" and asking the question.

healhustler wrote:


*Thanks for your "bucking up" and asking the question.

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*Thanks for the article- I am going to check it out.* As far as me "bucking up" and asking...the great thing about internet forums...I can post stuff here, get answers, and then swagger*with the best of them on the dock as a knowledgeable old salt!* hahaha- doubt I'll be fooling anyone on that matter but hey- you gotta ask sometime or another!*

*
Gee, now I have to added a stern thruster to my want list?* I can turn the Eagle on her axis with the bow thruster but its hydraulic so we can run it for hours, which might make a difference instead of short bursts.* I have looked at adding a hydraulic stern thruster using the same pump and tank with a remote controlled valve for stern or bow.* I still think a fish tail or articulating rudder would be a cheaper/simpler improvement which could also counter the prop walk and thrust the stern more to the side? **


*
I would think a stern thruster would be better on a twin as its the bow that move not so much the stern?* However, there are some of US that need all the help we can get!*


*
I have tagged the dock several times.* Hard enough the scratch the paint/varnish but not gouge it.* I am more concerned about the teak varnish than the hull as the teak has to be taken down to bare wood and multi coats added back which take days.* *Where as the hull is painted with Interlux Brightside which is cheap and easy to repair and match in about 30 minutes.* *********


*
Now if I had an extra 50 grand or so, I could do most of the improvements and wants!*


*

I just got a different slip yesterday and I think I'll go down and move the boat today.
Buck up? * Yea** ... I think I'll try backing in this time. I like to to get the bow into the wind (from the SE). The fwd cabin takes the weather better than the stern** ..mostly because of the teak door that dosn't fit quite right.
Phil Fill,
Yup** ..if I had your boat I'd get another thruster too.

Marin:
What was the name or job description of the guys who walked barges thru tunnels in the UK? I seem to remember you mentioning it or posting a picture. Thanks.
Mike

-- Edited by Gulf Comanche on Friday 5th of November 2010 11:24:44 AM

I don't know what the men themselves were called but the practice was called "legging." The men would lie on boards on the the boat or placed on top of the loads and walk along the tunnel sides and ceiling. While the boat was being legged through the tunnel the horse would be led across the hill to the tunnel mouth at the other end.

Given the tunneling technology of the late 1700s and early 1800s when the canal system was built, the tunnels were made just barely wide and high enough to accommodate the boats. A few of the last tunnels built incorporated a towpath for the horse but these are rare. Once boats became self-powered they either ran through the tunnels under their own power or were pulled through in "trains" by a tug. This last practice was sometimes used in the really long tunnels where exhaust fumes were a problem.* Today you take your boat through under it's own power.* With the exception of a few steam powered narrowboats in the late 1800s (which were not efficient) and a few early motorboats that were gas powered, self-propelled narrowboats have always been diesel or semi-diesel powered.

Here is a photo I pulled off of Getty Images of a boat being legged, and a shot I took on one of our canal trips showing the entrance to a typical tunnel.* Tunnel entrances, bridge arches, and the ends of the lock gate beams were always painted white to make them visible at night.* Today while I don't believe night running is illegal none of the hire boat companies permit their clients to move a boat after dark.* But in the working days of the canals boats often ran at night to stay on schedule.




-- Edited by Marin on Friday 5th of November 2010 12:01:54 PM

Thanks. I found a website that has some re-enactments of legging.
http://www.blisworth.org.uk/images/Walks-Legging.htm

Well, if we're doing tunnel pictures...
Top of the Canal du Nivernais (2008)

Pardon me for saying so, but those of you that write of a stern thruster OBVIOUSLY have never had one because it is BY FAR a better tool for backing a single-screw. Especially with the problems that are well documented here about an under-ruddered boat.

The benefits are almost as good when going forward, but there are a few things a bow thruster can do slightly better. But think about it, the boat already steers from the stern. All the thruster does is enhance that maneuverability. To me... A bow thruster is just for correcting mistakes you made at the stern.

Now, making sternway, when the ONLY "control surfaces" you have are now in front of you (assuming you face the stern like I do when backing), would you not want greater control over those? It's like a rudder which a switch. A bowthruster when backing up is like putting steering control on a trailer you are towing... better yet... any of you that have ever driven a forklift know what I am talking about. A stern thruster is like giving it front-wheel drive. It doesn't matter what direction the stern wants to go, a few little bumps of the old sterny thrust and you are right back straight again. The bow just follows right along without a care in the world.

Would I like a bow thruster? Yes, but I'll never be without a stern thruster on a boat again. Having both would just give me the ability to show-off a little, but only having a stern thruster is a VERY useful and powerful tool.

GonzoF1 wrote:

But think about it, the boat already steers from the stern. All the thruster does is enhance that maneuverability. To me... A bow thruster is just for correcting mistakes you made at the stern.

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I'm not going to buy into that one.* A boat steers from the stern as you say.* So what you can't do is move the bow sideways without moving the stern.* You can point the bow another direction but what you're actually doing is*moving is the stern the opposite direction as you know. The bow stays more or less where it is--- you're just swinging the boat around it.

There are plenty of situations where what you want to do is move the bow sideways and NOT move the stern when you do so.* The rudder, prop, or stern thruster's not gonna do that for you.* And based on my boating experience, the times I would like to move the bow*sideways*and keep the stern where it is far outweigh the times when I've wanted to move the stern more or faster than I could with the rudder and prop.

Single or twin, you*can always move the stern sideways with the rudder(s) and thrust.* If you get a sense of the timing and the boat's inertia, you can do this without actually moving the boat forward (or backwards).* One term for it is back-and-fill.

But there is no way, no-how, that you can move the bow sidways without moving the stern anywhere unless you have a bow thruster.

The bow thruster doesn't "correct for mistakes you make at the stern," it allows you to do things that are impossible to do without one.

I'm not saying a stern thruster is useless.* For people who have to deal with situations where they can't use back and fill, or simply cant get the hang of it, then a stern thruster can save a lot of gelcoat.* But in terms of usefulness in the widest number of situations,*the bow thruster* is where it's at in my opinion.

And judging by the huge number of boats with bow thrusters and the relatively tiny number of boats with stern thrusters, particularly a stern thruster and no bow thruster, I'm thinking that most boat drivers put far*more value on a bow thruster than a stern thruster.* And it's not like stern thrusters were just invented.* They've been around as long as I've been involved in this kind of boating.

Our GB doesn't have a bow thruster--- it's a twin--- but there have been--- and will be again---*times it would have been very handy to have one even with two engines.* The single-engine GB we chartered before buying our own boat had a bow thruster and there were a few times when it was the only thing that prevented us from damaging something.*

But*I cannot recall any*maneuvering situation where a stern thruster would have been any help to me*at all.



-- Edited by Marin on Friday 5th of November 2010 11:17:52 PM

Point taken... And I kinda retract that statement... to a degree. However, until you have tried a stern thruster, single screw, you'll not be completely sold on it, because it IS a tool I would rather have. I suppose something can be said to the idea of it being a good training tool that doesn't have you relying on moving a boat around in "un-natural" ways (can't think of a better word to describe it). And to be honest, I try NOT to use it all that often. I have leaned what the boat can and cannot do and try to not use it as a crutch and I feel like a better operator because of it and I believe I have the stern thruster to thank for that. IMHO

Marin wrote:"Single or twin, you*can always move the stern sideways with the rudder(s) and thrust.....* I'm thinking that most boat drivers put far*more value on a bow thruster than a stern thruster....** there have been--- and will be again---*times it would have been very handy to have one even with two engines....* The single-engine GB we chartered before buying our own boat had a bow thruster and there were a few times when it was the only thing that prevented us from damaging something..... I cannot recall any*maneuvering situation where a stern thruster would have been any help to me*at all."

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Having owned 8 boats from 30-54' since 1995, with some of the twins having a bow thruster and all the singles having one, the above quotes sum up my experience with bow thrusters.


*

GonzoF1 wrote:"However, until you have tried a stern thruster, single screw, you'll not be completely sold on it, because it IS a tool I would rather have."

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Fair enough! The point I'm trying to make is "I've never been in a situation where I
considered adding a stern thruster. I've really never needed one!"

*