Backing up a 31 ft sail boat

[TrentePieds]

Solomons:

Quote: "should we be facing forward or backwards?"

Short answer: BOTH!

Longer answer: Boats DON'T steer like cars, and what you know from steering a car can largely be disregarded. As to where you look: You look all around - continuously, i.e. you "rubberneck". You touched yourself on the reason for that, viz that wind and current will have an effect on the boat, and that effect must be continuously comprehended and corrected for. A second reason that backing a boat is NOT like backing a car, is that in contradistinction to a car, a boat doesn't have a set of back wheels that becomes the pivot point for "changes of heading". In a boat such as yours, the pivot point is located approximately at the after edge of the fin keel. That means that when you are going forward, and induce a turn to port, the STERN will swing wide to STARBOARD, often, at low speeds, quite significantly. When you are going astern, and induce a turn to port, the BOWS will swing wide to STARBOARD, often, at low speeds, quite significantly.

Quote: "tell me the difference between prop walk and prop wash"

Prop WASH is a stream of water generated by the prop. You can conceive of this stream as a "tube" of water that moves faster than the surrounding, undisturbed water. wherefore it contains more energy (imparted by the spinning prop) than that surrounding water. Imagine now that you are moving ahead, without the prop spinning, and that you lay your helm to port. Then the bows will move to port and the stern to starboard. Now, maintain the helm in the same position and set the prop spinning at, say, 3/4 throttle. The resulting prop wash impacting the rudder will now force the bows to port and the stern to starboard MORE POWERFULLY than before, due to the energy contained in the propwash.

Now imagine that you are going astern. Lay the helm to port (turn the wheel to the left in landlubber terminology). The stern (which is now leading) will go to port and the bows to starboard. Go to 3/4 throttle IN REVERSE. The effect on the "twisting" around the pivot point will be negligible, because the prop wash will NOT hit the rudder, but the keel at just about the pivot point, so there will be no "moment arm" to induce the "twisting". Steering behaviour when going astern is therefore significantly different from steering behaviour when going ahead.

And that takes us to Prop WALK :-)!

"Prop walk" is the term we use for a prop turning in reverse causing the stern to "walk" sideways without imparting any significant sternway. Imagine you are standing BEHIND (astern of) the boat and looking at the prop. If, when in forward gear, the prop turns CLOCKWISE, you have what we call a "right handed prop". If, as some props do, it turns COUNTERCLOCKWISE, you have a "left handed prop". A right handed prop, when the engine is in reverse gear, will turn COUNTERCLOCKWISE, i.e. the bottom blade will move from left to right. Imagine that that bottom blade is a paddlewheel. It will shove the stern of the boat to PORT (because it is aft of the pivot point).

In ALL boats the stern walk kicks in before the prop can pull the boat astern. You therefore have to allow for the resultant twist in determining your desired track as the boat gathers sternway. The ability to do that accurately comes with experience. In each particular boat you handle. No two boats, even of the same type, react the same.

One of skills I recommend you practice is that of making the boat "pirouette" taking advantage of the stern walk. With a little practice you can make your boat twist through 360º around its pivot point while not going anywhere. I use that technique all the time coming into a very tight slip. Once you know how, it's dead easy to do, and absolutely infallible. IOW the prop walk works FOR YOU, rather than against you.

I hope that screed is of some help :-)

All the best,

TrentePieds




"

[Larry T.]

I second that Scotty. Years ago I was backing up way to fast for my own good (and the boats) and when I went to turn, the tiller ripped out of my hand throwing me down in the foot well. The rudder slammed over so hard I still cannot believe it didn't shear the rudder post.

[deblen]

Don't overthink it,or get hung up on prop wash & other terms.
Practice "back & fill" in a quiet area.
Boats do not steer like a road vehicle,because they steer from the stern like a fork lift.
You can't move the pointy end sideways,but you can move the stern sideways.
This guy has the right ideas.
Practice for a couple hours-AWAY from distractions.


Hope this helps/Len

https://www.youtube.com/watch?v=oGE85oU8bUU

[Paul Howard]

Prop walk: the tendency of a boat's stern to move in one direction or the other dependent on the rotation of the prop. Most Yanmars are left hand rotation so when reverse is engaged the stern of the boat will move to starboard. When forward gear is engaged the stern moves to port. The amount of prop walk is dependent on the diameter of the prop and the angle of the prop shaft from horizontal. Saildrives give less prop walk - horizontal shaft - highly angled shafts give more prop walk. There will be a favoured direction to turn the boat resulting from prop walk.
Prop wash is the flow of water pushed by the prop past the rudder when in forward gear. Prop wash does not reach the rudder when in reverse.

Always try to reverse with the stern pointed into the wind. The wind will keep the boat straight, as the bow is more likely to be blown by the wind than the stern with any keel and rudder configuration.
If you turn around and face astern, the wheel is turned just as when going forward. Turn the wheel to starboard and the stern moves to starboard. The boat needs to be moving at some speed before the rudder can steer the boat and overcome prop walk. Hold on to the wheel (or tiller) as when powering in reverse there will be pressure on the helm trying to slam it hard over.

[wingssail]

On many boats the key is to start backing up well before you get to your dock, probably out in an open area or fairway. Once you get is going backward keep the application of power low and go slowly. Be careful of the rudder whiplash. It can be severe if you are going too fast. The boat will back up the way the wheel is turned, and coasting there will be no prop walk, so get it moving and coast it the last bit to the dock.

Some fin keel/spade rudder boats exhibit very little propwalk. With these you can just overshoot your slip, going slowly, then shift into reverse and back in. But you should practice and learn how it will react when you first put it in reverse.

For med moor situations we recommend you back all the way in and drop the bow anchor well out, while you are already backing. Trying to spin the boat around on the anchor, in a narrow berth that is open, is going to be risky. Our approach requires some communication between the helm and the windlass operator. Hand signals are best, and talk it over first.

The main thing is anticipate the effects of the wind and current and take things slowly. Using bursts of power can quickly get out of hand; if your first burst does not do it and you follow it up with a stronger burst, soon you will be making a scene.

[conchaway]

Consider taking ASA101, 103, and 104.

[belizesailor]

Much of this has been mentioned, but below is another article which covers "back & fill" and "prop walk". Two key concepts to handle your boat under power, esp in reverse.

https://www.sail-world.com/-106819/

Get familiar w these concepts then get an experienced friend/captain/instructor and go practice...a lot!

When I teach boat handling under power, I first have students practice in open water. I drop a mark and have them practice using that mark as a reference. After they are comfortable with that, we move to a relatively open dock area and do touch and goes, maneuvering close to docks, but not actually docking. This gets them comfortable maneuvering near obstacles. Then we move to tighter quarters for more touch and goes and actual docking.

[gonesail]

the prop walk will always turn your boat when backing. so you pretty much come in parallel to the slip (depending on how much prop walk you have) and when you shift into reverse the boat turns and backs into the slip. other factors are wind and current. always approach the dock at the speed with which you wish to hit it.

[waterman46]

Another thing to observe is that as you steer along in reverse, the bow may swing to port or starboard with some momentum, once it starts swinging. You must observe the direction of the swing and turn wheel in other direction or at least back to center well before bow has swung to the desired orientation. Anticipate the movement and apply rudder in direction to counter the movement.

Hopefully you have a rudder position indicator on a wheel steered boat, otherwise it is hard to keep track of where your
rudder is pointing.

[badadim]

https://youtu.be/PoGMAEjiHmU

https://youtu.be/8qOPM_SMJCc

[Sofa King Fishy]

Install a bow thruster & you can back up like you’re driving a car- makes my C42 very nimble!

[wingssail]

Originally Posted by Sofa King Fishy

Install a bow thruster & you can back up like you’re driving a car- makes my C42 very nimble!

Plus you get a nice draggy 10" hole in the bow, a lot of extra wiring and weight, (not to mention the cost) and you get to make a bunch of obnoxious noise in the marina advertising how little skill you have a driving your boat. Go for it.

[Sofa King Fishy]

Originally Posted by wingssail

Plus you get a nice draggy 10" hole in the bow, a lot of extra wiring and weight, (not to mention the cost) and you get to make a bunch of obnoxious noise in the marina advertising how little skill you have a driving your boat. Go for it.

Man! You must be real fun at parties!

[s/v Jedi]

Stern into the wind, “back and fill” motor control etc. all work but all are fighting prop walk, instead of positioning to compensate before reversing or even using it to your advantage. If reverse throttle puts your boat 60 degrees off intended course before the rudder bites, why not turn 60 degrees the opposite direction before reversing?

Find a different approach where prop walk helps turn the right direction or, if there is no such way, go back out then from far away start coming in backwards all the way. Once you have some speed, you can leave transmission in reverse with idle throttle because the rudder can overcome prop walk. Don’t slow down too much

[TrentePieds]

ModCons like bow thrusters are nice to have, but sound seamanship beats technology any day. Get the seamanship - THEN get the ModCons :-)

Remember also that a 10-tonner like a C42 is a different beast from a 5-tonner like our new friend's Hunter31.

There is merit also in answering the SPECIFIC question asked by our new friend :-)!


TrentePieds