Question
Here in the [M]ed, I’m very anxious when parked bow-first to the pier […] with my boat, which has a prominent prop-walk. The problem is that more or less in line with the boat is a block underwater tethering the mooring for the boats to the left and right. Often enough, those blocks are set in a way that I have about a boat-width of free space for the bottom of my keel.
Answer
First off, your fears are totally justified. That set-up, so common in parts of Europe, is a real pain in the neck and fraught with potential for disaster.
As an aside, I once, while in northern Spain, saw a catamaran foul not one but both props on the offshore lines while attempting to go stern-to in this kind of set-up—not a fun day.
Several other members have commented with suggestions that have merit, but I’m going to concentrate on the boat handling aspects of the problem.
The solution is the same as it is for all close-quarters manoeuvring:
using prop walk and wash to move the stern without putting any forward way on.
The Proccess
Since your boat has a right-hand prop, and therefore the stern kicks to port, you would:
Hi John,
Thanks for the concise explanation that helps demystify the med mooring for those of us used to slips.
Would the technique be much the same for backing into a stern-to med mooring?
Scott A.
Atlanta, GA, USA
PS. I really like this format of short Q & A with links out to “further reading” on the site.
Hi Scott,
Yup, as I say in the post, once we master the fundamentals backing in is the same. Check out the linked post. The example I use is backing in between two finger piers, but the technique is exactly the same for med-moor. In fact med-moor can be easier because we can check the anchor and reverse against it to get the boat straightened out if she starts to wander.
Glad you like the format. Maybe I will do some more like that.
Hi John,
I have no additional info, but would just like to “amplify” one issue I notice most people don’t really receive properly, even though you already made it very clear: The course correcting forward burst must be applied with plenty of throttle. A careful attitude in this will certainly sabotage the results.
I work as a skipper on tourist boats on the Amsterdam canals. Manoeuvring space is always very tight, the turns are 90 degrees, the edges are brick walls and there is a lot of other boats. On top of that, some of the boats steer really poorly. Still, we manage it with no problems, by constantly using the principles described in this article.
I frequently teach skippers new to the canals how to handle the boats. One issue seems hard for them all to absorb: How much throttle they need to use. It seems counterintuitive to use brute force when you feel insecure about the whole situation. Still, that’s what’s needed. We need to make the blast SHORT and at close to FULL throttle.
The reason is that we want to just rotate the boat, not move it. This is done far better by 1 second of exaggerated power than by 4 seconds of 1/3 of that power. We also want to exploit the inefficiencies of the propeller, which is most prominent at high power and when it has not had time to make much water flow anywhere or the boat move. At that time, the prop wash spins more outwards off the ends of the blades, creating more prop walk and less drive. This also explains why you should be careful with the throttle when you want to actually make the boat move straight.
So, as i normally have to say 10 times to new skippers: When applying course correction blasts, use much MORE POWER than you think, perhaps full blast, and use it very shortly.
And in case I didn’t mention it; use MORE power! 🙂
Hi Stein,
Great comment that I totally agree with. Well over half the time when I see someone get in trouble not using enough power in a burst was the reason, and most of my own screw ups have had the same root cause.
Great explanation of the reason and that we are actually exploiting a weakness of propellers. I had not thought of it that way. Thanks.
Certainly, now that we are aboard and heading down the St. Lawrence, I am getting daily affirmation that shyness on the throttle doesn’t help much. Thanks for the explainer, John.
Hi John and all,
I found the learning of under-power handling of awkward sailboats hard until I pushed myself to practice and the practice, for me, had to include a fixed object. Eyeballing this fixed object while tweaking and goosing the boat in the ways described enabled me, eventually, to develop some sense of outcome and prediction.
For fixed objects I started (on a calm day) with a hammerhead pontoon/dock and did the maneuvers about 10 feet off the dock. In this way I got immediate feedback on the boat’s reactions while remaining far enough away not to entertain anyone watching.
I then graduated to a pick-up buoy (again start with calm conditions and unobstructed water): first attempting to keep the bow hovered over the buoy and then backing up to the buoy from a distance.
It may be possible to find an empty slip where coming in port and starboard, bow in and stern in, can be practiced.
Then do all the above with a little breeze from different directions and then, for PhD level handling, try current.
It was best for me to push myself, in the beginning, to do this regularly each time I went out or came in rather than one afternoon’s crash course.
I find at the beginning of each season, after a winter of forgetting, a little practice jump starts the memory and gets the season off to a good start.
My best, Dick Stevenson, s/v Alchemy
Hi Dick,
Good practice scenarios, thanks.
Same here, Dick. Hover around the softer sort of buoy in different scenarios until improvement is seen. We also have been known for our post-launch springtime COB drills under sail. It’s how I get new hats.
Last week, I was waiting at a nearly-empty transient pier, and the Coast Guard Auxiliary training boat came in to do exactly that. Aircraft pilots call it “touch and go” on some rarely-used runway, the Coasties do basically the same thing – run through the approach & docking, right up to the point where someone would step ashore with a line, then they’d back out and do it again. Switching between port-side-to and starboard-side-to the wall, bow-in at a slip, stern-in at a slip, and bump-the-buoy out in the open, for variety. Over and over for about four hours until the new skipper really got the feel for that boat.
I took a few hours after them to do the same exercises. It was definitely worth the time.
Enjoyed your read and I agree thoroughly with your techniques and comments. We are sitting out our 11th year unfortunately in California due to the travel ban. I have noticed some major improvement since we first sailed there in ’98-99. We always prefer bow first when possible and it’s much easier now since lay lines seem to be the standard. Assuming we live long enough, it would be nice to not have to to deal with boats crossing bow anchors. Last year in Ischia it took two days for a big tour boat to undo its rap. Hopefully you won’t have to write a chapter on that little trick. It’s just another thing they didn’t tell us at the boat show. Good luck with you next boat project.
Hi Jim,
Good point on the fun and games that get going when everyone lays an anchor, just a recipe for disaster.
This past week I pulled into a city marina with 2 finger slips with two large motor yachts on one side, so no space for me, and one large motor yacht on the other side and an open space, about a boat and a half long. Using the techniques I learned here I pulled right in, stepped off with center springer in hand, and tied up like a pro. Even got claps and cheers.
Leaving was a bit trickier, strong current on the bow, twenty knot wind on the stern. It took a couple of tries, as not much room forward, and wind and current turning me to whichever side presented itself, but again using what I learned here, backed out like I knew what I was doing. Maybe I did know. Again everyone watching and clapped when I was out. Thanks.
Hi Ralph,
Great to hear that the techniques worked for you. Reports like yours really make the effort that goes into the online books feel worth it, thank you.
John,
In years past I was one that thought a full keel equaled stress, embarrassment, fear and possible crunching of fiberglass… and that was on my Bristol 40. When I purchased a 75′ Pilot Schooner (which I recently sold) I had a friend teach me (in less than an hour) how to use prop walk and prop wash exactly as you describe. I practiced a little and regularly received nods of approval and compliments when I confidently backed into a slip or spun it in a boat length in a tight harbor – and let’s face it, in a 75 foot schooner they all seem kind of tight.
My only difficulty was when the wind is at my back and the bow tends to be difficult to bring around – lots of windage with a bowsprit, roller furler, staysail and foremast all forward of the center of effort. This schooner is rather unique in the fact that it has a center board. So my question to you is, do you think that if I put the board down would it be easier to pivot the boat around it similar to a fin keel boat? I never tried this technique when I had the boat, but now I wonder. Also would the same be true of other modern centerboard boats?
Lee
Hi Lee,
Interesting question. I think that the centreboard should help bring the boat up into the wind since lovering it will bring the centre of lateral resistance of the hull forward closer to the centre of lateral resistance of the rig and other windage.
Does propwash/propwalk work with a saildrive as well?
Hi Eric,
Yes, the drive system has no direct influence on prop wash, which seems to have several different explanations. As far as I can see, the primary mechanism is asymmetry in the surroundings of the propeller. A propeller surrounded by open water, no hull or rudder nearby, will not only push water in the intended direction, but it will spin the water in the same direction as it rotates. That spin doesn’t only influence the water within the radius of the propeller. A quite large area around it also spins. The further away, the slower the water spins, of course.
If we introduce something into that spinning water on one side, like a hull just above the propeller, the spin becomes asymmetric. At the top much less water can rotate to starboard, (right hand turning propeller), while at the bottom water does get rotated/moved to port. This unbalance means that the stern will receive a push to starboard. Reversing the same installation will of course have the opposite prop walk.
Since propellers are made for efficiency in forward, not reverse, they tend to rotate the water more in reverse. Also, the angles are often not optimal, so they throw the water more outwards, like a centrifugal fan, rotating a larger water cylinder, giving significantly more prop walk. As mentioned previously, the same occurs at the initiation of a rotation, especially at exaggerated power.
If the installation has the same distance to a blocking item below as on the top, like some long keel boats with the prop in a cutout between keel and rudder, they might not have significant prop walk. Also, a saildrive with an extra long leg, putting the propeller blade ends further below the hull, might have little prop walk. The shape of that part of the hull etc will also influence the amount of prop walk.
I would add that “rotating the water in reverse” is even more significant when one has differing pitches, as I have, set up on a feathering prop. I flattening the pitch in forward last year to get higher RPMs, and that worked well. I left the pitch coarser in reverse, however, to get the most stopping power AND backing down power (with the helm over as John describes) because my boat is pretty heavy and I’d rather clip a dock than another vessel if there’s trouble ahead. Which posts like this help us to avoid.
JH: “Make sure your throttle and gear linkages are properly maintained. A broken cable at the wrong moment will ruin your whole day.”
Yeah, I’ve definitely had that happen once, and had to kill the engine and bring her alongside the pier with just inertia and a springline. Thankfully it was a calm day.
There’s no way to properly inspect / verify a teleflex cable, short of disconnecting both end fittings and pulling the entire core out, then putting the whole thing back together. Surveyors never do that. Mechanics rarely do that. I feel like it needs to be part of routine maintenance every few years.
Hi Matt,
True, we just replace ours on a regular schedule and so recommend in the coming alongside book.
Thank you all for sharing your experience. The principles of wash and walk are simple but all boats are a little different. I just want to share my experience of my long keel boat, a Swedish Vindö 50 displacing 6,5 tonnes, LOA 10,65 m. Her propeller is rotating in a cut-out in the rudder. I have the feeling that prop walk works well but the prop wash effect is not so strong. I believe this is due to the cut-out in the rudder or perhaps small engine with low effect. With the rudder hard over to starboard or port, there is actually not a rudder aft of the propeller, only a hole, i.e. the cut-out. I believe that the prop wash is pushed through the cut-out without hitting the rudder much. Of course the rudder works well when the boat makes way forward through the water but before that, I do not get much lateral movement of the stern, not even with the propeller working full ahead. And with my old two-cylinder diesel of modest effect it takes several seconds for the engine to reach full revs and by that time the boat has started to move forward. So, she is a challenge to manoeuvre in tight waters. However, practice and experience help.
Hi Carl,
Good point. In fact Dave Gerr writes about exactly that issue in his Propeller Hand Book.
We tend to do stern-to mooring most of the time. While this is still tricky at times, we are getting more comfortable with the concept and execution. My question relates to leaving a stern-to mooring with boats and their associated lazy-lines on either side in a cross-wind. This always seems fraught with the danger of catching the leeward boat’s lazy-line. Any insight on a good technique here?
When there’s crosswind, just put some power ahead so the stern lines are taught, drop the moorings and wait until they’ve sunk to the bottom. If the crosswind is quite stong you may support with a bit of rudder to weather.
When the moorings are away you can easily move out by feeding the stern lines – weather side last.
Hi Colin,
Ernest’s solution sounds good to me. The only thing I would add is to be very careful when handling the lines as the loads when motoring ahead against them can be surprisingly high. So I would practice his idea a few times with little or no wind to make sure the crew have it all figured out before trying it in a big breeze.
Good god, yes, of course. One time I assumed that the HM rope that was used as the stern line was taught, and as HM is quite slippery it simply unwound from the cleat in the worst possible moment… having enough crew on the right places saved me from a hard crash.