Docking prop walk

[LindaFlorida]

Good morning,

We own a 34 Mainship Flybridge. I would like to master backing into our new slip. With a single engine, backing in can be a little tricky.

For those of you with a Mainship/single screw, when backing in does your boat have a tendency to move towards the portside?

Trying to understand prop walk, I understand that if you turn the steering hard starboard, and give a short burst in forward gear and then a short burst in reverse consistently. You can actually move the boat in a 360 degree turn.

Before we start practicing, was hoping for some advice from those who are familiar and experienced with the 34’ Mainship.

I believe that our prop moves clockwise while moving forward.

Thank you in advance.
Linda

 

[rslifkin]

A prop that turns clockwise in forward when viewed from the stern is a "right hand" prop. That should walk to port in reverse.

 

[mvweebles]

Interesting article on propwalk with graphics that may help. Warning - some of the authors explanations are not universally agreed, but the basics are usable. The general technique of approaching a side tie illustrated towards the end is a good practice routine and shows how effective prop walk can be to assist landing the boat.

https://www.passagemaker.com/technical/how-to-use-prop-walk

Good luck. Nice boat.

Peter

 

[Cold Duck]

Unfortunately, the MS 350/390s have a lot of windage and no real keel underneath. If there is any crosswind component at all, it will be very difficult to back down with much control. By the way, my MS350 walks to stbd as does my buddies MS390. With no wind, you can learn to use the bowthruster to compensate for the stern walk. Add a little wind and it becomes very difficult to back down. You definitely need to plan knowing which way your vessel will walk and add that into the procedure. I generally adhere to the addage, "slow is better" when docking, but with the 350 there are times that significant headway is needed for control. I love my 350 but I find it to be one of the worst handling vessels I have ever owned. Small poorly placed rudder, lots of windage with no keel makes it a challenge in windy and current situations.

 

[DDW]

No experience with Mainship, but be aware that some trawlers cannot back straight. Period. My AT34 cannot be made to go in a straight line in reverse no matter what you do - the prop walk overcomes the rudder. I spent a couple of hours one day in calm open water, there was no combination of throttle, rudder, and gear shift that would do it. With the bow thruster, I could make it do whatever I wanted of course.

 

[HeadedToTexas]

The amount of prop walk depends on enough variables that generalizing is as confusing as helpful. Our boat has very little prop walk thanks to a relatively level shaft and prop angle, and significant keel. What you might learn from me may not have much bearing on a Mainship.

 

[High Wire]

Good morning,

We own a 34 Mainship Flybridge. I would like to master backing into our new slip. With a single engine, backing in can be a little tricky.

For those of you with a Mainship/single screw, when backing in does your boat have a tendency to move towards the portside?

Trying to understand prop walk, I understand that if you turn the steering hard starboard, and give a short burst in forward gear and then a short burst in reverse consistently. You can actually move the boat in a 360 degree turn.

Before we start practicing, was hoping for some advice from those who are familiar and experienced with the 34’ Mainship.

I believe that our prop moves clockwise while moving forward.

Thank you in advance.
Linda

What year 34?
Generally a right hand prop will back stern to port; left hand prop will back stern to starboard. Its pretty easy to verify somewhere out in the open in calm winds. Idle forward in gear a few knots with the rudder centered. Pull the transmission to neutral for 2 or 3 seconds then into reverse. Bring the throttle up to stop the boat (1500-2000 rpm) without touching the steering wheel. Throttle quickly back to idle and gear to neutral. The stern will walk to one side or the other. Make a note of it in your log.

 

[Max1]

I read up on propwalk here before ever splashing my "new" project trawler but was confused as heck. I found the best way to learn about my boat's handling of propwalk was to just do it. You will find this is probably true for you.

My prop is left handed. What does that mean? How do I know? But from experience I now know when backing out of my slip, the ass of my boat will go right(Starboard) when backing out. Now that I learned the feel of how it handles, I take advantage of this feature to help me maneuver the boat (Single engine, fixed shaft, no thrusters).

 

[LindaFlorida]

She is a 2009. Thanks for that information. We will give it a try. You mentioned that the rudder should be straight. I was under the impression that the rudder needed to be hard starboard in order to turn port when in reverse. Looking forward to practicing in calm winds.

 

[LindaFlorida]

Interesting that your MS350 walks to stbd. Maybe she has a counter clockwise prop? Are you turning the rudder hard to port?

When the wind is blowing, we open the isinglass up on the Flybridge to cut down on being pushed when docking. We need to start practicing. Thanks for the advice.

 

[LindaFlorida]

Interesting. Looking forward to practicing. We have a thruster too, hopefully we can nail this.

 

[Bmarler]

In close quarters with a single screw, all your steering happens with forward thrust. If my boat backs to port, I leave the helm to port as I back out. Use short bursts of forward to kick the stern out, shift to reverse to get the boat going backwards, pop it into neutral and let it drift back.
The idea would be to maintain reverse motion, but use little bursts of forward to kick the stern over as needed. Use neutral as much as possible as there’s no prop walk in neutral.
In open water you can try just backing up and trying to steer with the rudders. I bet you have to have good speed and quite a distance before that’s possible.

 

[mvweebles]

..... You mentioned that the rudder should be straight. I was under the impression that the rudder needed to be hard starboard in order to turn port when in reverse.....

You are correct. Rudder needs to be used. In your case, when pivoting when pivoting to make a turn without adding forward momentum, hard over to starboard - in forward, prop wash pushes stern to port. In reverse. Prop walk pulls stern to port.

A boat has two prop induced turning tools: prop walk; and rudder wash - the effect of prop flow across the rudder. A tip: to maximize turning momentum while minimizing forward momentum, rudder should be hard-over BEFORE putting the gear in forward.

BTW - prop walk isn't just a tool for singles, it's very useful on twins too, though many twin screw helmsmen can get by without knowing a thing about it.

Peter

 

[rslifkin]

BTW - prop walk isn't just a tool for singles, it's very useful on twins too, though many twin screw helmsmen can get by without knowing a thing about it.

Peter

Agreed. The best thing I ever read (and it's possible you wrote it) about handling a twin is that it's just 2 singles with really bad prop walk tied together.

 

[Bmarler]

In close quarters with a single screw, all your steering happens with forward thrust. If my boat backs to port, I leave the helm to port as I back out. Use short bursts of forward to kick the stern out, shift to reverse to get the boat going backwards, pop it into neutral and let it drift back.
The idea would be to maintain reverse motion, but use little bursts of forward to kick the stern over as needed. Use neutral as much as possible as there’s no prop walk in neutral.
In open water you can try just backing up and trying to steer with the rudders. I bet you have to have good speed and quite a distance before that’s possible.

I should have mentioned, this is to back up in a straight line.

 

[mvweebles]

Agreed. The best thing I ever read (and it's possible you wrote it) about handling a twin is that it's just 2 singles with really bad prop walk tied together.

Nope. I got that analogy from you some time back. I knew it, but that was a perfect visual for me. I love docking twins - dropping the outboard engine into reverse as the bow closes on the dock. Thing of beauty. Something to be said for ambidextrous boats (twins).

You found it elsewhere.

Peter.

 

[PhilPB]

Good morning,

We own a 34 Mainship Flybridge. I would like to master backing into our new slip. With a single engine, backing in can be a little tricky.

For those of you with a Mainship/single screw, when backing in does your boat have a tendency to move towards the portside?

Trying to understand prop walk, I understand that if you turn the steering hard starboard, and give a short burst in forward gear and then a short burst in reverse consistently. You can actually move the boat in a 360 degree turn.

Before we start practicing, was hoping for some advice from those who are familiar and experienced with the 34’ Mainship.

I believe that our prop moves clockwise while moving forward.

Thank you in advance.
Linda

Mine backs to port also and would take a lot of F/R shifts to get into our slip. The boat is rather light and the wind likes to blow it around. I decided to have a bow thruster installed and that was the best thing I could have done. I single hand the boat often and no longer have to decide if it's too windy to not take it out. I can handle it without the thruster if necessary but it can become frustrating to say the least so I use that Thruster and can back in the slip on the worst days without any doubt or stress at all.

 

[rslifkin]

Nope. I got that analogy from you some time back. I knew it, but that was a perfect visual for me. I love docking twins - dropping the outboard engine into reverse as the bow closes on the dock. Thing of beauty. Something to be said for ambidextrous boats (twins).

You found it elsewhere.

Peter.

Huh. I think I picked it up from someone on here. I just have no idea who it might have been.

 

[SteveK]

Would a stern thruster negate the prop walk and allow straight backups?

 

[Bmarler]

Would a stern thruster negate the prop walk and allow straight backups?

Absolutely. I have one, and it does.

 

[SteveK]

Absolutely. I have one, and it does.

Thanks for confirming.

Do you also have a bow thruster. I ask because that was also mentioned but I could not visulise how that would keep boat on a course line, parrallel yes but imagine a slight side drift with bow thrust as well as prop walk.

 

[koliver]

Backing in reverse with a single:
1 set rudder to centre
2 engage engine in reverse
3 note direction of prop walk
4 speed up until the rudder can exert some control. Remember that in fwd gear the rudder is washed by the prop, but in reverse all of that wash is going in the opposite direction, so unless your rudder is gigantic (think sailboat rudder) you won't get any steering from the rudder. In reverse at low speeds, you need more speed or more rudder to be able to steer, but speed is a better solution than more rudder, as too much will only act as a brake.
Do this a few times to get used to speeding backwards, before attempting it in a crowded marina, especially one with a cheering section.
Make your next boat come with twins, then you will have one rudder that you can direct prop wash over, just for steering purposes, the other, with its engine in reverse, will happily remain set for forward prop wash, and do nothing contrary while that engine is in reverse.
Have a great time practicing reversing at enough speed to actually steer.
At low speeds, leave the rudder set to correct with bursts of forward gear. The rudder, set that way, will not turn your boat while in reverse as there is no prop wash going over it.

 

[DDW]

Would a stern thruster negate the prop walk and allow straight backups?

To some extent - but in my boat (with both bow and stern thrusters) it is more effective to use the bow thruster. It is further from the axis of rotation and has more, and more immediate effect. Since the rudder (again on my boat) is completely ineffective backing down, I set it over the direction that I may want to go if I need a burst of forward, but otherwise ignore it and use the bow thruster.

 

[PhilPB]

Would a stern thruster negate the prop walk and allow straight backups?

I negate the prop walk totally with the bow thruster.

 

[psneeld]

Thanks for confirming.

Do you also have a bow thruster. I ask because that was also mentioned but I could not visulise how that would keep boat on a course line, parrallel yes but imagine a slight side drift with bow thrust as well as prop walk.

I tend to agree that offsetting prop walk with a bow thruster will create some drift in that direction, but it probably seems minimal compared to back and fill.

Then many times it may be difficult to assess fully and drift from wind/current is there too.

 

[Bmarler]

Thanks for confirming.

Do you also have a bow thruster. I ask because that was also mentioned but I could not visulise how that would keep boat on a course line, parrallel yes but imagine a slight side drift with bow thrust as well as prop walk.

Yes, I do have a bow thruster as well. When backing, I will leave the helm centered, and use bumps of reverse to maintain speed, then mostly stern thruster for direction. Add a bit of bow thruster when needed.
This is a full displacement vessel btw. Semi displacement may act differently.

 

[rgano]

I am not familiar with the hull shape aft of your 34. Do you happen to have a photo of the stern out of the water, or do you perhaps know if there is a prop tunnel?

 

[HeadedToTexas]

Prop walk and the whole left hand vs right hand prop seem like a difficult concept to grasp. While there are a lot of variables that determine how much impact prop walk will have when backing any given boat, the direction depends entirely on prop rotation, at least in the absence of factors like wind or current that may overcome prop walk.

Don't the drive shafts of virtually all Lehmans rotate in the same direction? And Cummins and John Deere and Volvo? Can prop rotation be changed by rearranging the gears in the transmission? There seems like a lot of confusion about the left-right thing.

My prop rotates counterclockwise when in forward and viewed from aft. That makes it a left hand prop. Prop walk moves our boat to starboard when in reverse, though not dramatically.

 

[rslifkin]

Prop walk and the whole left hand vs right hand prop seem like a difficult concept to grasp. While there are a lot of variables that determine how much impact prop walk will have when backing any given boat, the direction depends entirely on prop rotation, at least in the absence of factors like wind or current that may overcome prop walk.

Don't the drive shafts of virtually all Lehmans rotate in the same direction? And Cummins and John Deere and Volvo? Can prop rotation be changed by rearranging the gears in the transmission? There seems like a lot of confusion about the left-right thing.

My prop rotates counterclockwise when in forward and viewed from aft. That makes it a left hand prop. Prop walk moves our boat to starboard when in reverse, though not dramatically.

Yes, standard engine rotation is left hand (counterclockwise) when viewed from the flywheel end. But depending on the transmission setup used, the prop may rotate the same as the engine or it may rotate opposite.

 

[HeadedToTexas]

So some transmissions rotate the shaft and prop in the direction as the engine crankshaft and some transmissions reverse that direction of rotation? That would explain some of the confusion about which is which.