Q&A, Coming Alongside (Docking) With Twin Rudders

Question:

I have a boat with twin rudders and a single propeller on centre line. Will your docking techniques in this Online Book work for me and, if not, what should I do?

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DUPUIS

Hi John
I have an Ovni 445 with twin rudders. I agree with you for the usefulness of a bow thruster , but also of the Maxprop propeller. I can turn the boat in one side “in her lenght” with the propeller only , when the wind is light (big windage…)
KR

Dartanyon Race

I’m hoping that you’ll cogitate, perhaps even ruminate, on coming along side with a heavy current, perhaps even one that’s in opposition to the wind.
If you’re interested in more specificity – we back our 45 foot Norseman along about 275 feet of before getting to our section of dock. The marina is in the mouth of a river that when the tide is going out gives us a 3 knot current pushing off the dock. The fairway is about 65 feet wide.

douwe

When we had our 55 foot Aluminium lift keel boat designed the designers informed us that due to our request to have a minimum draft of 1,5 meters we had to have twin rudders…For the reasons obvious I was mordicus against it given the crowed entrances to locks and harbours in the Netherlands. They than came up with the solution to fit a, much smaller, third rudder behind the propellor. Jefa had done this a few times before and they designed the rudder geometry. We now sailed 15000 Nm in four seasons and are very happy with this configuration although it’s more complicated and costly… And yes we also have a bow thruster but only have to use it in unfavourable windy conditions.

Svein Lamark

Hi Douwe, is it the wonderful ship Stayer you are writing about?

douwe

Hi Svein, Yes it is… hopefully you and your wife are well and we can meet again in the near future!

Svein Lamark

Hi Douwe, we are fine sailing in Denmark in our small double- ender hoping to get home in the North before the sea ice close our harbour. I believe Stayer represent a new positive development in yacht construction with her tree rudders and many other solutions. I have observed Stayer enter rather difficult harbors in Loften and docking elegantly without using trusthers. However the rigg of Stayer is very tall. How is Stayer to handle when docking in much wind? When I saw her there was no wind.
I have observed that Stayer is extremely fast when sailing off-shore. Is she also comfortable off-shore? To mee Stayer seems like a unique modern construction: Good in shallow coastal waters, but also a fine long distance sailor. We would like to meet you again and discuss you experiences with Stayer.

Karl

For those considering a bow thruster, check out a Yacht Thruster. It’s an external unit, easy to install and able to be run for long durations because the motor is underwater-no overheating issues. It’s not speed robbing like a tunnel and requires one hole the size of a typical thru-hull. I was skeptical at first about having this torpedo shaped device hanging from the hull. But after three years, no complaints. One benefit, if the next owner doesn’t want it, it can easily removed and hole faired in a jiffy.

richard s

your observing that dual rudders are becoming more commonplace makes me wonder why ad this defeats the k i s s principle so important with sail craft especially…is also just that much more to incur damage…i think more than the std single rudder is jst asking for trouble

Eric Klem

Hi John,

My limited experience with twin rudder boats has highlighted a few things for me.

Like most boats, you can usually get the stern into the wind even if it is against the direction of prop walk. Once you are in this orientation, it is relatively stable even without prop walk to help. I use this trick a lot on full keel boats and it works reasonably well here as well.

Backing down fairways can be a better bet as it makes changing direction easier and these boats usually back just fine. By getting steerage up in reverse out in the open, you deal with the harder to control direction change (assuming it is not a tailwind) out there.

Twin rudders is really unforgiving for people who drive as if they are using an outboard. It is crucial that you steer for the direction of water flow across the rudder and not whatever the engine is doing (this seems to be an issue for a lot of people based on my informal observation).

I learned something new in our single screw single rudder boat that should have been obvious a few weeks ago. I was trying to turn around our 36′ boat in an ~50′ wide creek that was turning hard to the left with the current behind us. I started my usual back and fill turn to starboard for our prop walk and the boat didn’t seem to want to turn. I then realized that the current on the outside of the turn was going faster so I switched to a port turn and the boat went around really easy despite being against the prop walk.

Eric

Peter Tobiasen

Hi John
As I do most of my sailing single handed, I am still crossing my fingers that you will make another video of you coming alongside singlehanded using the balanced-point aft running spring and tying everything off singlehanded.
Please 🙂
Kind regards, Peter

Peter Tobiasen

Looking very much forward to reading that chapter. Happy cogitating ?

Ernest E Vogelsinger

Hi John, did you already come around to that “single handed chapter”? I’ve just searched AAC and couldn’t find one except preparing for a singlehanded atlantic crossing?

Hans

Hi all,
on two delivery trips with french raceboats (Archambault 35) I found that these boats -twin rudders, very wide stern- really ask for being backed into their slots. As Eric mentions, they are backing very well pretty much regardless of wind direction. Position one crewmember at the docking side of the pushpit, get a line ashore and power forward to pull the boat alongside. Works really well because of the wide transom and the resulting good leverage. The challenge comes when singlehanded, you have to be quick as the distance from tiller to the boat’s corner is rather long on this type of boat.

rene

Hi John and Douwe,
On my brothers sail boat Flyer, where the prop is maybe 20ft forward from the rudder, I guess he would love to have a small 2nd rudder just behind the prop.
When we recently hauled out my motorboat, was surprised to see the (large)rudders could only swing 60 degrees from side to side, while the rudder indicators show about 100 degrees and yet it handles very well in tight spaces.
During my hi-school summer hollidays I worked on river Rhine barges, single prop and two rudders about 3 ft apart, but could turn the rudders close to 180 degrees. No bow thrusters in those days, but did have a bow (balanced) rudder that could be lowered and handled with a long tiller. As you know, now the maneuvring is (greatly?) enhanced with articulated rudders. Has that system found its way on pleasure boats?
Rene

Drew Frye

Your focus is on larger boats with inboards. As multihull sailor, even the larger cats I’ve sailed or owned have always been outboard powered. With twin screws that far apart you have a whole world of tricks that I’m not going to get into. Some have had single engines. And what all of these have in common is trivial prop walk and no flow over the rudder.

But many small boats with outboards have something else they forget about all the time. The thrust can be directed by turning the motor. Unlike power boats, they have a rudder that works without prop wash.

One handy trick, say coming alongside on port, is to turn the rudder to starboard (tiller to port) while turning the engine to port and bumping reverse. The result is that the boat goes mostly sideways, slowly coming to a stop just touching the dock. Quite handy on a bulkhead with boats fore and aft.

There are other variations.

Ronnie Ricca

John,

I have concern that the balance point spring aft method may not work like it would with a single screw/single rudder vessel. In a normal setup the prop wash over the rudder and the rudder angle dictates where the bow and stern go when you are pivoting on that spring. A twin rudder will only be able to push ahead on that spring and not control any direction of bow/stern. In my opinion, I think a further aft spring would help with keeping the boat pinned to a dock as there wouldn’t be as easy of a pivot. Once pressed to the dock other lines could be made off the the thrust left off.

Am I making sense with this? Just to be clear, I’m still suggesting a quarter point for a spring, but only a little more aft for a single screw/twin rudder yacht.

Thanks for the very detailed posts on this too, by the way! Hope your cruising has gone well this season!

Ronnie

Ronnie Ricca

John,
Good points, I didn’t think about a offshore howling you off. I do agree that a bow thruster is probably your only option.. Well, next to adding a third rudder or removing the two in lieu of one big one. I don’t think any of them is cheaper than the other once said and done.

Ronnie

Eric Klem

Hi Ronnie and John,

I think that the magic spring line will still work well even without the help of prop wash. The thing that pulls the boat against the dock is the spring line itself (with a single rudder you can cheat and use prop thrust instead if the spring line has no angle to it) so the keys are getting an appropriate load on the line and having it pull in the correct direction. To get a load on it, you simply need to power against it, the more throttle you give it, the higher the load will be.

Getting the direction of the load correct is dependent on where each end of the line is attached to. Lines can only react tensile forces in line with them so the line needs to have an angle to the dock so that it can react your engine thrust and also pull the boat towards the dock. Too steep an angle and the stern will end up too far in, too shallow an angle and it will end up too far out (where the line is fore and aft also has a similar effect). For boats with shape like Morgan’s Cloud, you get a decent angle with a short spring that leads to a cleat right there on the edge of the dock. If the boat carries her beam aft, you might need to lead it to the far side of the dock finger to get some angle. Unless the boat is quite large, getting the exact right angle is not that big of a deal, you should be able to deal with a 10 or even 20 degree misalignment using fenders and by pulling on the bow and stern lines. The point is that you can hold yourself stationary indefinitely in approximately the position you want to be in while you sort out the other lines.

Even in the case where you have wind blowing hard off the dock and you start perpendicular to the dock stern-to, you should be able to get into place with this method, it will just take a minute. Because the line will be coming from the rail rather than centerline, there will be a torque when you motor ahead that will turn the boat so that the thrust will start to push the boat along the dock causing the spring line to pull you against it. In this extreme case, it is likely you won’t come in parallel so wide fender placement is critical.

Eric

Brian Russell

Hi John, Perhaps I missed it, but was hoping to find some hints in this book on docking related to a wind + current situation. We experienced this the other day and I made rather a mess of it…That’s no anchor roller, it’s a battering ram.! Wind was from ahead, current from astern , dock on port side. On retrospect i probably should have faced into the 2 kt. current rather than the 13 kt wind… thanks!