In this chapter I'm going to focus on the final few boat lengths of the approach to a wharf or floating dock. This is perhaps the most important part of the whole operation and where we see the most SNAFUS, usually because the boat does something the helmsperson did not expect in the final few seconds of the approach, often when he or she applies reverse to stop.
The key point being that if we are going to be happy boat handlers we must understand and anticipate how the boat will react.
And this vital understanding lies in the things we learnt in the last chapter. Once moving slowly or stopped:
- In reverse the stern will react to prop walk.
- In forward the stern will react to prop wash over the rudder.
To make our approaches easy and trouble free, all we need to do is set up and execute the approach so that these fundamentals work for, not against, us.
Let's get our boat alongside so that the deckhand can step (never jump) ashore and get the required lines on without fuss or shouting.
My comment is “no comment, because this puts literally everything I’ve experienced handling a heavy full-keeler in a docking situatio in one place”. Great work, you two.
Thanks John, my wife finally understands what we been talking about for years.
Jim, your lucky!
John, I am finding these chapters on docking very very useful. We have a 36ft steel Roberts Spray with a full length keel…… she loves going in a straight line no matter what the conditions, but absolutely hates getting into tight berths. These docking hints may well save a lot of embarrassment and save others from ” Feeling The Steel”
Hi Marc, Jim, and Lee,
Thanks very much for the kind comments, I really appreciate the encouragement, particularly since I’m wrestling with the next chapter.
Just perfectly described, adds a lot to my own (sometimes painful) experiences 😉
One thought on reverse propwalk when needing to go a couple of boat lengths backwards: I position the boat in some angle to the intended direction so the propwalk “puts me straight” before the boat starts to move. I usually give a good lengthy burst backwards so I gain some speed, them idle out completely to remove the then unwanted propwalk. This way I am completely able to steer straight backward.
Of course this works best with more heavy boats as they tend to run some lengths after they finally started to move…
Absolutely a good technique. We have an entire chapter coming, on backing into tight places.
Thanks for packaging this up so neatly. We have learned a good deal of this stuff by trial and error since getting our first “big boat” nine years ago, but under pressure it is hard to get it right when one thinks “How does that work in this situation?”, but we are getting better. I am going to print out this book so that Pat and I can thoroughly digest it and gain a better understanding of the forces at work and how to use them to our advantage. You make it look so simple, but that obviously comes with great experience.
Thanks for the kind words and I’m very glad that we have been able to simplify things. The interesting thing is that while struggling (and it was that) to come up with simple explanations we too have learned a lot. As they say, sometimes the best way to improve our understanding of something is to try and explain it!
Thanks for your informative well written posts on docking and manoeuvring! I look forward to the next chapters, especially backing into tight quarters(with a long keel)! Keep up the good work!!
Best regards -> Christian
We will be publishing an entire chapter on backing in. We even have a video all done to illustrate it. I think it will be the chapter after next.
Great article and well thought out. My 29′ Paceship has a very nasty prop walk that I use to great effect. My slip is sort of med style in that its up against a wall, is very tight (11′ and me with a 9’8″ beam) with a pylon at midships on either side (but I don’t have to anchor first). Most of the boats at our yacht club have difficulty and/or “chicken out” and nose straight in (and then have to push themselves out hand over hand on the other boats). In fact, everyone usually stops doing what ever they are doing and watches (and silently rates) any docking effort but I seem to have it down to a science that only has to be modified very slightly depending upon significant winds and currents (we’re in a river entrance). My uncle, who taught me to sail, had the same type of boat for about 30 years and when I took him and his wife sailing he took one look at the slip and gave me back the tiller to put it in which I did effortlessly and singlehandedly – prompting his (ever “helpful”) wife to remark (“he NEVER docks that well!”). Absolutely made my month… 🙂 My “secret”…. I steam perpendicularly past the slip about 3′ away from the bows of the boats on either side… as I (personally in the cockpit) pass the anchor of the nearest boat (to my starboard), I throw the boat into reverse and go hard over on the tiller to point the boat away from the wall. The boat turns about it’s Genoa winches so with a bit of momentum, I let the prop walk the stern of the boat 90 degrees and then right into the slip. As soon as it’s lined up, I put it in neutral, centralize the tiller and use the momentum I’ve built up in reverse to let it continue into the slip. As I’m passing the pylons on either side, I grab and cleat my spring lines from the pylons (which stop me from hitting the wall if my engine fails) then wait until I’m almost at the wall before giving it a bit of forward to come to a gentle stop. I didn’t have people to go with me much when I first learned so do everything single handed. It’s VERY important to have the spring lines set up at the exact point of balance of the boat (so that the boat doesn’t turn one way or the other when you pull on them). I find that if I’m single handing it to a dock like you’ve shown above, I come in exactly as you suggest and then can reach out and throw on a long springline to a dock cleat while I’m still in the boat and then I use the prop to stop the boat just as the springline is becoming tight (and to hold the boat on to the dock while I get the… Read more »
I will be publishing a post on backing in soon and will look forward to getting your wisdom then.
Hi Again Brent,
Another member just pointed out to me that my above comment sounded harsh, and he is right. Sorry. That said, it was not my intention to be rude, but the problem is that if I engage with comments that are on subjects of future chapters, that tends to take on a life of it’s own and use up much of my time, so said future chapter gets delayed.
That’s why I ask at the bottom of nearly every post that members stay on the topic of that particular post.
No worries John… it wasn’t taken that way. Newbie here and I sort of thought I was on topic as the second bit was about docking alongside but I see your point. I look forward to the next chapter.
Thanks for your understanding. I’m probably way more sensitive about this that is warranted because writing this Online Book is taking everything I have…and then some!
Great stuff. I’m no expert on monohulls, but it all rings true, particularly comments on steerage way, planning, and bursts of throttle.
Catamarans, specifically sail power with keels, have another trick, helpful when you need to move sideways. I’ve parked in bulkhead spots shorter than my diagonal measurement.
Although cats generally have minimal prop walk (engines often counter rotate), most have some. They also have the “bulldozer” steering mode, where they pivot in one spot by opposing engines, and the one engine steering mode, where a single engine, accelerates, turns, and can make the boat slide sideways. Thus, if you alternate buldozer steering and one-engine turns, you can slide the boat sideways. Obviously, light winds and currents are required, and an extra set of eye at the bow is really handy, since you may work it very close.
The down side of cats in a marina, of course, is massive windage and shallow keels. You can’t be timid with speed or throttle, and you need to have a bail plan. A well though out bail never looks foolish, not compared to pinballing around!
As John repeats many times, a simple set of rules is not enough. You need to study how the boat actually responds to combinations of inputs. I think it helps that I have to back into a slip in a cross tide and wind; it makes you think and observe.
Yeah, twin engine cats are very cool for manoeuvrability. A friend of mine had a twin power cat with outboards and I had a blast some years ago getting in and out of tight places, even with a far larger disabled monohull lashed alongside. Bottom line you can beat twin engines in tight places and the further they are apart the better it gets.
I’ve been following these articles and tried some techniques.
However, the engine/shaft on my Mirage 33 is offset at an angle to port to eliminate prop walk. It does pretty much eliminate prop walk. Some techniques with prop walk do not work for us offsetters.
Prop wash on the rudder has minimum effect. When reversing, it pulls water in pulls water on the port side of my rudder, and not much so it does not pull much to port when the rudder is to port and practically nothing when the rudder is pointed to starboard.
I noted that Mirage stopped offset propeller in later models.
No questions, but comments and suggestions are welcomed.
I have no experience with an offset but it seems to me to be killing a fly with a sledge hammer as prop walk is only a problem when the boat is not moving relative to the water and the rudder has not yet got any effectiveness. You are right in that the prop “wash” doesn’t have much of an effect on most rudders as it’s a fairly contained stream compared to the normal flow of water over the rudder. The prop “walk” is easily thought of as a paddlewheel effect – at zero relative motion to the water, the blades actually try to “walk” the stern in the direction of rotation as well as pull water backwards over them (there are components of force both ways). To be most pedantic, what’s actually happening is that prop is trying to rotate the boat around the shaft but of course the keel and the water have something to say about that and the water can move. The water at the bottom of the blade is marginally more effective than close to the hull which introduces a lateral force (there is also a vertical component but the weight of boat easily counteracts that). Once the boat is moving through the water, the rudder easily has enough effectiveness to overcome the lateral force. It actually happens in forward as well but the effect is not as noticeable because the prop is much more efficient at pushing than pulling so the magnitude of the force in the desired direction (forward) is much higher than the lateral motion of the prop walk.
With propeller airplanes, we call it the P-Factor. It’s a hell of a lot more powerful and you HAVE to take it into account if you don’t want to ground loop your airplane. The bigger the engine, the more noticeable the effect. Airplanes with nose wheels (like most Cessna’s and Piper small airplanes) have much less of an effect than “tail draggers” as the nose wheel counters much of the lateral force and can be steered into the direction of the force. WW2 fighters with huge engines and tail drag configurations like the famous P-51 Mustang demanded that you put the power on gently until you had enough airflow over the rudder to counteract it. There are planes with offset engines as well but it’s overcomplicated in my humble opinion as prop walk is neither good nor bad… just another factor to be taken into consideration when dragging your pride and joy into tight spaces. Like the wind or. current, you can use it to your advantage – or it can make things a lot worse if you don’t plan for it. Interesting about the Mirage and the offset… I wasn’t aware of any boats that did that.
Interesting theory. P-factor, as applied to ‘planes is actually a result of the prop operating at an angle to the airflow as is the case with most inboard sailboat installations with respect to the flow of the water. This angle to the flow results in the descending blade having a greater angle of attack, or “bite’, than the ascending blade, therefore causing greater thrust on that side and a tendency to turn in that direction. Ask any CFI or google it. There are other forces at work also: Torque, which you mentioned, spiraling slipstream and gyroscopic precession, which may or may not affect sailboats. P-factor disappears when the prop is operating with the thrust parallel to the flow, as with a saildrive and when the ‘plane levels in cruise, for example. The other effects you mention are new to me. A fascinating subject for sure.
I’m sorry, but I just don’t have any good answers for a boat with an offset prop since prop wash and prop walk are the key to easy close quarters boat handling. That said, installing a balance point spring as I detail in earlier chapters will certainly go a long way to helping out and would be my first step.
Exactly… I didn’t want to get into every single detail but the P Factor is very close to what happens with our sailboats albeit in air versus water. I will disagree though that it “disappears” when the plane levels… it’s always there but the magnitude is such that it’s very small relative to the forces imposed by the rudder in forward motion at design speed… you’ll feel it on your rudder if you don’t have the rudder trim set correctly. I have far too many hours instructing ab initio students to fly (and doing ground school) to forget those details! The gyroscopic precession (a force exerted on a spinning prop will act 90 degrees in the direction of the rotation from the axis in which it was applied) is the one area where there isn’t a great similarity… in a taildragger, when you lift the nose on a clockwise rotating prop, the force that you applied to the top of the spinning prop arc will act as if it was applied to the right side of that arc causing the nose to go left. It’s even worse in helicopters. In a sailboat, I guess if you did a very hard turn at full speed, you might be able to measure the stern sinking or raising depending upon the direction but it would be pretty slight. Not nearly as impressive the first time a student shoves the stick forward to lift the tail!
I recall from my WWII airplane model building days that two-engined fighters such as the Lightning P-38 and the de Havilland Mosquito had contra-rotating props (inward, I believe) to counteract this effect and to give them equal facility at rolling either to port or starboard. Of course, you’d only see that on a catamaran in the watery situation, and I don’t know if cats generally have contra-rotating props. It strikes me as a sound idea.
Cool! So what’s the MTOW of your boat? (tongue in cheek – sorry John).
Give or take about 14,000 lbs… but I think Vr would be about 400 knots which is well beyond the range of my little 12 HP one lung Yanmar :-).
Timely article…. As we are very new to docking. and currently we are moored in Sambro, the wind has been very strong. So far is has been pushing directly on our port side pushing us away from the dock.
I knew about prop walk, and have been doing as you said… pulling into a port side dock, turning and then prop walking which tends to swing my bow out. Hadn’t considered the momentum factor and that I should let the prop walk twist my bow away. Or the idea that turning on a starboard side dock will help negate the prop walk. Very useful info.
I’m really glad to know it’s working for you, makes all the work to write these chapters feel worthwhile.
A class like American Sailing Association’s docking endorsement (118) or even a few hours of private instruction is a truly worthwhile investment, and may just be the second-best use of boat dollars right after a Morgan’s Cloud subscription!
Thanks for the kind words. One point: those who are new to docking need to be very careful in who they select to teach them since, as Chad discovered above, many, maybe even most, experienced sailors are actually pretty bad at close quarters boat handling and clearly don’t understand the basics of prop walk and prop wash. And this seems to go double for some of those that have boating-teaching qualifications.
The point being that someone new who uses this Online Book and applies the fundamental theory in a thoughtful way, and practices a bit, will often be way better off than if they listened to an “old salt” who will just transfer his or her own bad habits and lack of understanding to the poor newbie.
Great treatise on the simple yet complex challenge of docking a boat. Which often feels like chewing bubblegum and patting your head at the same time while doing a jig.
Love your simple guidance. NO CREW LEAVES THE BOAT TILL IT IS STOPPED AND THEY CAN WALK OFF SAFELY!
Couple of years ago I found my go to docking method. A “stern spring bridle” . It is a line run from mid ships along the side I plan to dock. Long enough so that I can toss the middle section of the line out over a cleat from the boat, and bring the tail back in to a stern cleat. I have one of those typical sailboat stern cockpits and I often am the solo handler of the boat.
The line once over the dock cleat provides the same spring line connection you describe. The boat control is the same. Yet I have the line tail back on board the boat and have not had to step off the boat. I put the boat at idle in gear and the boat (even if it was a few feet from the dock to start) snuggles up nicely to the dock against teh fenders. Assured that the boat is not going anywhere, I can then leave the helm (and boat – step to the dock) and secure the other lines (bow and stern – which are layed out on the rail in preparation) to dock. Hop back aboard and shut down engine.
Keep your ideas and writings coming. They are great sharing to enjoy when the snow slows down my sailing adventures.
Hi John S,
Sounds like we are on the same page, and thank for the kind words. Reminds me that I need to get back to this online book with a couple more chapters.