The Offshore Voyaging Reference Site

Going Alongside (Docking) in Current—Fundamentals

Let’s get the bad news out of the way upfront: I don’t have any simple answers that will make docking in current easy, and neither does anyone else.

It’s just one of those cruising tasks that’s damned difficult to do well, bundled with a heaping helping of boat damage risk.

What I can do is explain the theory and then provide some examples of how to apply it.

Not only will this understanding help us get docked safely in current, it will enable us to determine when a situation is not going to end well, no matter what we do.

Knowing when to fold ’em is one of the most important, and yet under-rated, seamanship skills, not an admission of failure. Or, to put it another way, anyone who says “I can dock in any situation in any conditions” or anything like that, is a dangerous idiot, not someone to be admired.

Before we go any further, please make sure you have read the rest of this Online Book and maybe reread it if it’s been a while.

If you don’t clearly understand prop walk, prop wash, turn sidle, and what a magic spring is and how to use it, none of what follows is going to make a bit of sense.

With that out of the way, here’s the vital tip that makes docking in current easier:

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Matt Marsh

I like your approach to thinking about this, John.
Treat wind as a force.
Treat current as a moving reference frame.
Yes, the two are mathematically interchangeable if you mess around with enough algebra, but some ways of conceptualizing it are always going to be easier (or harder) than others when you need to do the math on-the-fly in your head.

Dan Manchester

Hi John, one of the trickiest berths I have had was a pen on finger wharf that had me berthing facing upstream in a tidal creek with about 2 knots of current. Getting in wasn’t so bad, with the right lines to arrest the boat, however, reversing out on an incoming tide was an absolute nightmare – veering off in either direction when reversing back and failure to react quick enough resulted in being wedged up against a pile across the tide, with the whole yacht club out watching and offering handy berthing tips. I ended up moving marina to save my sanity.

Richard Ritchie

Factually accurate and well structured as usual!
I hope I have not missed something in making the following point (because it is a while since I read teh previous chapters in detail)
I am intrigued by the flow of your book on docking: starting with prop walk then wind, then complex situations, and only then getting to current. It has been my experience, and drummed into my head by several trainers, that in almost any docking situation, current will dominate the manoevre: find out what it is doing first. (OK, I have been based from the Solent most of my life…) Once you understand the current, look at the wind and work out how you will balance the forces. Yet you get to current last….
I do wonder if even this chapter would have been clearer to the novice and more digestible if you had started with the parallel current situations, where a current is your best friend (because it enables complete control of speed and zero speed docking) and only then moved to sideways currents.
None of that is to criticise the material! But for me current wins every time.

Richard Ritchie

Thanks. Agreed. Choices. It is good that you do not sheer away from the hard bits. And crucially,you emphasise that there are times NOT to try! Knowing your limits and not being pressurised are keys to safety.
Yes, the Solent is a good teaching aide!

Stein Varjord

Hi John,
My take on docking in strong side current towards the dock is to abort, as you suggest. I think it makes the location unsuitable. Thus, I need to find a better location, or wait until the conditions change.

Waiting for conditions to change is a tool that was much used in the days before engines and electronics. It was standard procedure for almost everything. In our time we’re too spoiled by predictability of plans to accept waiting hours or days until we can safely do anything. As ocean sailors we’re used to waiting for a weather window before an offshore crossing, and we might wait for the right tide at a headland or to get trailing current. The same tool is useful in other contexts too, like docking. Since I do my own boat repairs, I know for certain that any repair would take much more time than any wait. Easy choice. Impatient passengers can swim. 🙂

If the current goes off the pier, not too much, I prefer to go bow in, let off a person with a bow line, stern line and a long spring from the bow. When they’re attached well, I let the boat a bit out, and then gradually winch in the ropes. The spring doesn’t need a winch, but the others often do. Without the spring, the bow will probably hit the boat ahead of the slot you aim for, or the pier. You can avoid that by letting out the bow line enough and carefully winch the boat sideways in, but I find it cumbersome and less predictable.

Some years ago I took a sailing boat from Greece to Norway through central Europe via The Black Sea, the Danube and Rhein rivers. That meant 2500 kilometers against the often very fast current on the Danube, which is why I’d strongly recommend going the opposite direction… 🙂 This trip gave me a lot of experience with anchoring and docking in strong current.

Piers there are always aligned with the current, which made it really easy to dock, no matter what the wind was doing. The current means you have full control over the boat position by means of the rudder and throttle. The wind has close to zero influence. You can just position the boat next to the spot you want and then easily go straight sideways to dock softly. We did this with current up to about 5 knots, but mostly around 2-3 knots. It was intimidating only the first time, before I had grasped how easy it really is. The only important crux is that you absolutely need to have your ropes ready and get the bow line and stern spring on and adjusted quickly.

We also hitched rides with big barges, via the VHF. That meant docking on their side at speed, which is the exact same procedure as above. The main issue is that, just as above, you absolutely need to get the bow line and stern spring attached and adjusted fast, to keep the boat in the right parallel orientation. With just one of those attached and really strong current, (or tied to a barge at cruising speed) you can quickly get into grave danger.

If the spring is off, the boat will turn hard onto the pier/(barge), heel away from it and the bow might be pulled under water. If only the spring is on, the boat will rapidly swing around and then something similar to the above will happen. In really strong current, the boat will probably not survive this.

Luckily, we’re rarely docking in anywhere near this heavy current, and we can always choose to go somewhere else or wait for better conditions. The latter two actions are, in my opinion, usually signs of superior seamanship.

Ben Garvey

Good additional info Stein. I’ve done the ‘drop a person and long docklines off the bow first’ thing many times in a current-off-the-dock situation, and it can tame things nicely – as long as the lines are handled well and there is enough pulling power available on the boat. Frequently it comes down to managing just 2 lines- a spring and bow or stern line, since you can bias the direction of travel and hopefully the swing/rotation of the boat using your own power on the spring. It is absolutely correct to say though, that the loads on lines and gear in these situations can be huge and quite dangerous. Smart and experienced line handling is critical.

Interesting to hear about hitching rides on moving barges… that sounds exciting… of course bowsprits, boomkins, stern davits holding dinghies that are wider than the stern of the mothership and other dastardly protrusions also add to the drama if present…

Dick Stevenson

Hi John,
One consideration I have in choosing a place to moor where current is a factor is to attempt to anticipate how difficult it will be to extricate the boat when I leave. This question alone has saved me some grief as it concentrates my mind to factors I might have paid little attention to otherwise: such as the state of the tide or the strength of the current or whether there is a current at all. This is particularly important when the current is onto the dock. (One port in England looked enclosed but had a river flowing into the end in a way that was not apparent but allowed considerable current where none was expected.) These factors play a part especially when I know I want to leave at a specific time: like at dawn.
My best, Dick Stevenson, s/v Alchemy  

Marc Dacey

Since we came out to Nova Scotia, the very first thing I check before releasing the bridles or raising the anchor is the state of the tide and the likely effects of tidal current on that day’s plans. Waiting for slack is better than getting into no-win situations with physics.

Eric Klem

Hi John,

I agree that current is best viewed as a moving frame of reference.

For someone who knows how to read it, it is amazing how much you can learn from looking at the surface of the water. You can see current lines so that you can steer an almost straight course through them when most would turn >90 degrees and you can also tell an amazing amount about what is going on underneath the surface, I have avoided more than a few rocks several feet underwater thanks to this. Unfortunately I don’t know a great way to read it other than getting into whitewater canoeing or kayaking or keeping a sailboat in a really tricky spot for several years. But if you are going through places like L’Etete Passage or the reversing falls at St. John, it can be incredibly useful.

When establishing a ferry angle, I personally find it easiest to keep glancing between my start point and where I intend to go and making sure I am still on the line. This takes some practice as you can’t see both at once but I found that once I learned it (while whitewater kayaking), it is what is easiest for me. I find that techniques like trying to maintain constant bearing using the compass are much harder and I really don’t like using the chartplotter due to the lag in that.


Dick Stevenson

Hi Eric,
I have some experience, but I sure wish reading the water as you describe could be taught. My SOP when I see some surface disturbance is to stay away and, when that is not possible, to be prepared for something happening which I will need to respond to. Being ready with a variety of responses is what works (usually) for me as I am continually ready to be surprised by Alchemy’s antics as she approaches the hard stuff.
My best, Dick Stevenson, s/v Alchemy

Eric Klem

Hi Dick and John,

Thinking a bit more about this, I think that there are 4 types of features that you will commonly run into and are good to know about. Being able to actually identify these and deal with them would definitely be considered advanced techniques that are pretty low on the priority list for most people.

Current lines including eddy lines are something you can run into in enclosed spaces and even out in the open ocean. Offshore, these are often filled with weeds and trash even when weak. In enclosed areas, they will often have foam or whirlpools and are in predictable places like behind points of land. As John mentioned in the article, they will try to turn you, the bow will end up in water moving one way and the stern will be in water that is effectively stationary in the boat’s frame of reference so the bow will get pulled around by the new current. When crossing one of these, the boat will get spun least at shallower angles to the line such as 20-30 degrees and will get spun most when close to perpendicular. If you try to go too shallow, you can actually get bounced off the current line and end up not crossing it so I wouldn’t recommend shallower than 20 degrees. It is also generally good to keep your bow pointed into the new current (based on your current frame of reference). Once you get used to crossing a current line, you can actually steer a straight course across it correcting with the rudder at the right time, just don’t correct too early or you might get bounced back. If the current line is strong enough, it can flip your boat upcurrent relative to the new current direction so crossing one with a really strong speed differential is not recommended except in a whitewater kayak. I can’t actually imagine going somewhere that the differential would be strong enough to flip an offshore cruising boat but it could well get you in the dinghy. Watching how paddlers get in and out of eddies is quite instructive on this.

Waves are the next thing to be aware of as they indicate a change in depth with flow over it. The wave will be in the deep water just downcurrent of a shallower area. The wave shape will tell you what the shape of the depth contour change looks like, if it is breaking, it will be a more abrupt change and potentially closer to the surface. These can transmit up from quite deep depths. Anyone who frequents the Cape Cod Canal near max current will know the standing waves that can develop near the power lines with a westbound current. If you watch your depth sounder here, the depth goes from ~35′ to ~50′ quite abruptly and that is what you are seeing on the surface.

One really important trick is to draw an imaginary plane perpendicular to the current and look at the height contour. The safest place is almost always where the water is lowest. Where the water is high, especially if it is higher than it is immediately upcurrent, that means that it is getting pushed up and over something like a rock or ledge. This is more subtle to see than standing waves and if you can see it humping up, you probably shouldn’t go there with a boat having a keel. So when you see standing waves as mentioned above, always look just above them to see if the water is going up first as the depth change could be from very shallow to something deeper as opposed to the prevailing depth to deep.

Boils are another thing to watch out for, they look like periodic upwellings of water in a specific spot and are often circular and can be 10’+ or much smaller. They most commonly come from some isolated disturbance on the bottom like a rock. If you see a boil, try to go to the side of it and definitely don’t go upcurrent of it as that is where the rock will be.

I hope this is interesting even if not particularly helpful, it is just what I can think of off the top of my head. The bay by my parents house has up to 4 knots of current with several unmarked hazards and every time we go there whether it be in our boat or a skiff I am thankful for the 15 years I spent paddling whitewater multiple times a week.


Dick Stevenson

Hi Eric,
A really nice tutorial: thanks for the effort. I will be watching out for those tell-tales.
My best, Dick

Peter Herrman

For the first case, with the current heading under the dock (and no wind), why not head straight at the dock (slowly), aiming to the forward end of the “hole” you’re trying to park in, put it in reverse as the bow is nearing the dock (thus nearly stopping your motion and momentum and kicking the stern to port), have the crew or preferably someone on the dock put a fender (or hold the boat at a piling) and let the current gently swing the stern into position? No drama. If you start to miss the hole, back up and try again. Works with wind toward the dock too, but may be a little more difficult depending on the handling of your boat.

Drew Frye

Two experience in docking with a current that shaped my thinking:

  • Strong current under a floating dock. The harbor master directed me to a bulkhead at the end of the fairway. Twin screws on my cat no problem. Because the bulkhead was visibly within 15 feet of the clubhouse, I wrongly assumed the bulkhead was on land and did NOT have the tide running under it. By the time I realized my mistake the current had me beam-on and there was no room to pivot in the narrow fairway. I wumped the dock sideways at considerably more than 1 knot, saved only fat fenders and a boat that had a VERY strong rub rail on a very strong hull chine. As John said, at that point there is nothing you can do.
  • Strong current through marina. The municipal marina in Chincoteague VA has a solid 2-knot current at the peak and I was assigned a slip no more than 2 feet wider than my boat. I looked at it, consider my family crew, and decided against it. I docked at a near by bulkhead that was parallel to the current, so I could easily ferry over, stopping and holding inches away while my daughter took a stern and spring line ashore. Easy and safe even in a strong current.The down side was the commercial dock pilings made for a longish step to shore, but not too far. The bulkhead exposed us to some workboat wakes, but we had solid fender boards rigged. But I felt a little whimpy when I saw another boat swing int o the slip 20 minutes later. There was some yelling. An hour after that we went to dinner, and saw the 2″ x 8″ patch of severe dock rash on the other side of the boat. I felt vindicated in my decision to whimp out.

Nope, I can’t dock in all conditions. Or rather I won’t try. I can ask for a different slip and I have an anchor.

Wind is usually more workable, but not always. My other rule is never to approach a dock without an escape plan. I’ve made multiple approaches many times, and it was always worth the time.

Drew Frye

The dock rash was 2 feet by 8 feet, not inches. It was ugly.

Robert Krinner

It’s worth to mention, that if you move with the current, the rudder could render useless as there is no relative waterflow. No speed through water.

On the other hand, having the current against you, you can manoever on the spot.