Prop Walk

[carter1272]

I have a new to me 2005 Mainship 34 Trawler and would like to practice prop walk maneuvers without relying on the bow thruster. Q: Is my prop left-handed or right-handed? Also, is there much noticeable prop walk with these vessels? Thanks.

 

[jleonard]

Put it in reverse and you'll know which way the stern will walk in reverse.
You can do this tied in your slip/berth or out in more open water.
Try at idle first.
Then give it a little power and you'll be amazed at how you can control the walk and use it to your advantage.
It's easier than you think.
Have fun.

 

[High Wire]

Just look at the shaft inside the boat and have someone bump it into FORWARD then back to neutral. If the shaft turns clockwise when viewed from the stern, it’s right handed rotation. Opposite equals left handed.

 

[dhays]

As was mentioned, if your boat has noticeable prop walk, you should be able to tell as soon as you put the boat in gear. My boat’s stern definitely moves to port in reverse. Center your helm and put it in reverse and see if your boat starts to back to port or starboard. If it does neither, then you don’t have enough prop walk to worry about or use.

 

[rgano]

The single engine 34 will be right handed but the tunnel will negate just about any prop walk.

 

[carter1272]

The single engine 34 will be right handed but the tunnel will negate just about any prop walk.

Thank you. What does the "tunnel" refer to?

 

[Comodave]

The prop tunnel. The prop is partially recessed into the hull. Just give it a try and see what it does. Give it a burst in reverse with the rudder straight and see if it goes to port or starboard or neither. Just don’t do it near the dock until you get a feel for it.

 

[mvweebles]

Prop walk will be most noticible when the boat is moving forward slowly and gear in reverse. As the vessel comes to a stop, the prop will bite and move the stern. A light 2-3 second "burp" of RPM (200 added rpm or so) as the boat slows will often exacerbate rhe prop walk.

Two exercises to practice are back and fill - used to make a u-turn in a fairway. Series of forward and reverse thrusts with helm hard over. Maintaining rotation momentum is what you're looking for.

Second is coming into a side tie such as a fuel dock. Find an open side tie and a calm day to practice. Pick a point on the dock where you want your bow to end up (usually a cleat) and aim behind that point 1/4 boat length. Approach that point at a 30-45 degree angle at slow speed - idle forward, maybe in/out of forward/neutral to keep speed down. When you're 1 boat length away from dock, put helm hard over and put gear in reverse, and use reverse thrust to modulate speed. Goal is for boat to glide sideways and gently press on its fenders as it comes to a stop.

Not everything is possible with a single and no thruster. Discretion is the better part of Valor.

Good luck

Peter

 

[LongJohn]

My 34T single (with the prop in a half-tunnel) has no noticeable prop walk in reverse. In forward at idle, it will turn to port slightly more sharply than to starboard, but I don't know if that has any relevance to prop rotation.

 

[backinblue]

Sorry, but I have tried and think prop walk is overated. (Granted I also have a prop tunnel so maybe it's differnt for others) Yes it exists and yes you can make a u turn if the conditions are right. But fighting a strong current and/or wind, better to rely on trusters. It's helpful to know and learn about prop walk, but it's not the best solution in all situations. If it's you only solution, you better not navigate in challenging conditions.

Cargo ships rely on thrusters called tug boats.

 

[markpierce]

while making use of propwalk, much prefer using bow thruster rather than forwarding/reversing drive train to turn around to avoid overworking transmission and shaft.

 

[markpierce]

....
Cargo ships rely on thrusters called tug boats.

Cruise ships rely on thrusters.

 

[Hippocampus]

Practicing slow speed maneuvering with our new to us Nordic Tug 42. Totally different than a sailboat with a high aspect fin keel. Doesn’t pivot on the keel.Have found with a SD hull and nearly no shaft angle back and fill is just about the same to port or starboard. Found you really need a very brief burst of rpms and water flow across the rudder to get it to turn. Very unlike a high aspect balanced large spade rudder on a sailboat. So learning to give a very brief burst of throttle and right back to neutral. Prop walk is negligible. Other than sportfish with exposed running gear or non saildrive sailboats have come to think there isn’t enough prop walk on most recreational power craft to be very helpful or a major concern.

 

[Hippocampus]

Prop systems on many large vessels alias. Tug use is disappearing.

 

[Portage_Bay]

Practicing slow speed maneuvering with our new to us Nordic Tug 42. Totally different than a sailboat with a high aspect fin keel. Doesn’t pivot on the keel.Have found with a SD hull and nearly no shaft angle back and fill is just about the same to port or starboard. Found you really need a very brief burst of rpms and water flow across the rudder to get it to turn. Very unlike a high aspect balanced large spade rudder on a sailboat. So learning to give a very brief burst of throttle and right back to neutral. Prop walk is negligible. Other than sportfish with exposed running gear or non saildrive sailboats have come to think there isn’t enough prop walk on most recreational power craft to be very helpful or a major concern.

The effect of prop walk is very boat dependent. With some boats it is pronounced enough that you can use it to advantage or if you aren't aware of it it can bite you in close quarters. I think it better to simply keep prop walk in mind. Most boats will turn in a tigherer radius one way than the other when backing and filling.

Do learn you boat's pivot point. Often but not always 1/3 the water line from the bow. Do learn your boat's turning radius at various engine speeds.

Regarding the need for water flow over the rudder. Yes, that is very important. One way to take advantage of that is to have a bit of stern way on then swing the rudder over and give the short burst of ahead. You can leave it in ahead longer while the boat stops the stern way while turning at the same time.

I have found with a lot of boats windage is a key factor to learn to handle and even use to your advantage. Many boats when backing the bow will fall down wind. With enough room or clever backing and filling you can end up stern into the wind. This can be very useful in the right situations.

Don't fight the boat or wind. If backing out into the fair way or turning the "wrong" way favors the boat and conditions then use it.

 

[rslifkin]

The effect of prop walk is very boat dependent. With some boats it is pronounced enough that you can use it to advantage or if you aren't aware of it it can bite you in close quarters. I think it better to simply keep prop walk in mind. Most boats will turn in a tigherer radius one way than the other when backing and filling.

Do learn you boat's pivot point. Often but not always 1/3 the water line from the bow. Do learn your boat's turning radius at various engine speeds.

Regarding the need for water flow over the rudder. Yes, that is very important. One way to take advantage of that is to have a bit of stern way on then swing the rudder over and give the short burst of ahead. You can leave it in ahead longer while the boat stops the stern way while turning at the same time.

I have found with a lot of boats windage is a key factor to learn to handle and even use to your advantage. Many boats when backing the bow will fall down wind. With enough room or clever backing and filling you can end up stern into the wind. This can be very useful in the right situations.

Don't fight the boat or wind. If backing out into the fair way or turning the "wrong" way favors the boat and conditions then use it.

Agreed. The pivot point is often further forward on inboard powerboats compared to sail. To some extent, you almost place the bow and maneuver the stern around it.

Amount of prop walk varies widely depending on the boat and prop in question. And you'll usually feel it more when you engage the gear that's opposite of the direction you're moving. Put the boat in reverse while moving forward and you may have enough prop walk to start a turn as you stop. But backing from a stop may not give much.

 

[Hippocampus]

Thanks guys. Have a lot of relearning to do. Finding my brain is used to 35 years of sail and it just gets in the way. Unlearning is harder than learning so frustrating right now. I’m a total newbie. Find the remoteness of electric helm and hydraulics hard as well. No feel. Totally dependent on your eyes and instruments to know what’s going on.

 

[rslifkin]

Thanks guys. Have a lot of relearning to do. Finding my brain is used to 35 years of sail and it just gets in the way. Unlearning is harder than learning so frustrating right now. I’m a total newbie. Find the remoteness of electric helm and hydraulics hard as well. No feel. Totally dependent on your eyes and instruments to know what’s going on.

After a while you start to get a gut feel for now much steering input to give with the hydraulics. Even with no rudder position indicator. The upside is that if you need your hands for other stuff, you can take your hand off the wheel and know that the rudder will stay right where you left it.

 

[koliver]

Totally dependent on your eyes and instruments to know what’s going on.

Watching the effect of any change in gear, throttle or direction is the critical piece. Seems you have already figured this out.

Once you know what to expect, in your own circumstances, of any addition or subtraction of thrust, change in direction of thrust, will lead to immediate predictability and reliability.

Much more eyes than instruments, though without rudder feedback, you need a rudder indicator. Hearing can replace tachometers, gear lever position is sometimes needed, always available by feel rather than eyes. You can maintain a constant watch (eyes only use) for the movement of your boat relative to the docks, boats, shorelines, while knowing what the engines and rudders are doing from other cues that are available to hands and ears.

 

[OldDan1943]

The single engine 34 will be right handed but the tunnel will negate just about any prop walk.

On my AT, I park bow in. When I wish to depart, I swing the rudder about 30 degrees to port, at idle, it will back straight.
Of course, that degrees to port may have to 'modified' depending on wind and current.
Practice a bit and you will not only surprise yourself but also impress the "observers".
One further point, you should center the hyd stabilizers before backing up.

 

[Marco Flamingo]

For a rudder indicator, I finally noticed that my autopilot provided that info while in standby mode. Only took a few months before I noticed that. Duh.

Knowing when the rudder is amidship is usually the important info. My stern walks to starboard in reverse so I much prefer a starboard tie. As I approach the dock I can bump reverse and then wait as the stern swings in towards the dock. The boat pivots around a spot just about where I'm standing at the helm. Because I'm going slow, the rudder doesn't have nearly as much effect as does the prop walk. Even when I have a little way on (in nuetral) and the rudder set such that I would normally turn to starboard, the effect of a little reverse prop walk overcomes that and pulls the stern to starboard. And because I'm going so slow, the effect of the prop walk in twisting the boat "lasts longer" than the rudder trying to twist the boat the other way after I go back to nuetral. It is possible to do a weird feeling crab walk, but only to starboard for my boat. Port ties aren't generally as graceful. I constantly warn my line-handler/wife that no heroics are allowed.

The part that feels the most awkward for me is remembering that I'm really up front seeing less than half the picture. The stern is swinging around on a different arc. It's like parking a bus.

 

[SteveK]

Thanks guys. Have a lot of relearning to do. Finding my brain is used to 35 years of sail and it just gets in the way. Unlearning is harder than learning so frustrating right now. I’m a total newbie. Find the remoteness of electric helm and hydraulics hard as well. No feel. Totally dependent on your eyes and instruments to know what’s going on.

Keep track of previous moves that require change for docking or leaving with power compared to sail. For instance I could approach a dock at 90* and lay a sailboat alongside. Now 30*-45* to land a power boat.
That ability to turn on a dime is gone. What else?

 

[markpierce]

Having starboard propwalk, when backing out of the berth, I swing the stern slightly to port using the bow thruster (preferred), or push off, or use starboard rudder with small burst of forward throttle.

 

[dhays]

Practicing slow speed maneuvering with our new to us Nordic Tug 42. Totally different than a sailboat with a high aspect fin keel. Doesn’t pivot on the keel.Have found with a SD hull and nearly no shaft angle back and fill is just about the same to port or starboard. Found you really need a very brief burst of rpms and water flow across the rudder to get it to turn. Very unlike a high aspect balanced large spade rudder on a sailboat. So learning to give a very brief burst of throttle and right back to neutral. Prop walk is negligible. Other than sportfish with exposed running gear or non saildrive sailboats have come to think there isn’t enough prop walk on most recreational power craft to be very helpful or a major concern.

With my NP 43, there is definitely prop walk. The prop isn't in a tunnel, but is well protected behind the keel and over the shoe. There are times when the prop walk is annoying, and other times it is very useful.


The absence of an effective rudder and the change in the rotational point of the boat, was one of the hardest things to get used to coming from a lifetime of sailboats.

 

[backinblue]

With many of us coming over from sailing, I have to ask why the very small ineffectual rudder? Is it to reduce drag? I never had any concerns movinng my sailboats wherever I wanted and now have to rely on bow and stern thrusters. Not saying I want a 6' by 4' rudder on my curent boat, but it seems minimal to me. In a following sea, my autopilot is doing a lot of work to stay on course.

 

[SteveK]

I don't remember a following sea and AP not struggling on the sailboat.

 

[Hippocampus]

There has to be flow over the rudder for it to steer. Either from the prop or from the boat moving relative to the water when you’re surfing without the engine running. In really big seas will fall off waves at a sufficient angle to maintain that flow. Usually that regains steerage.

 

[rslifkin]

With many of us coming over from sailing, I have to ask why the very small ineffectual rudder? Is it to reduce drag? I never had any concerns movinng my sailboats wherever I wanted and now have to rely on bow and stern thrusters. Not saying I want a 6' by 4' rudder on my curent boat, but it seems minimal to me. In a following sea, my autopilot is doing a lot of work to stay on course.

Smaller rudders are for less drag, but some powerboats go too far with it, particularly if they're meant to go fast.

The Mainship pilots I've seen on the hard appear to have a reasonable amount of rudder, but some others like the 350/390 and 400 seem under-ruddered, at least in single engine configuration (rudder only slightly bigger than mine, but they have 1 vs my 2).

Many of the Sea Ray types have downright tiny rudders (dock neighbor has a Sea Ray basically the same size as my boat, his rudders are less than half the size). And yes, he complains of sluggish steering at low speeds.

 

[backinblue]

Here is what mine looks like on my pilot, seems a little small to me

 

[rslifkin]

Here is what mine looks like on my pilot, seems a little small to me

That definitely looks smaller than the setups on earlier year Mainship Pilots that I've seen. More in line with the size on the other Mainship trawlers. The ones I've seen had the prop right behind the keel with a shoe extending all the way to the rudder, more like a typical downeast.