Moving boat sideways

[markpierce]

Those with both bow and stern thrusters must find this discourse amusing.

 

[ancora]

Those with bow and stern thrusters are not "boat handlers."

 

[Capt.Bill11]

Marin
The reason it is not working for you is you have your engines backwards. Stbd tside moor should be helm away (port, you have that correct) and stb eng reverse, port ahead, WITH SOME FWD MOMENTUM.

That's how I do it with boats up to say 100' to 110' or so. Not that you can't do it with larger vessels.

But I rarely have to put the inside engine in fwd at the last second to help pull the stern in with the out side engine in rev. In most cases I just come in with way on and turn the wheel hard, or close to it, over away from the dock and use momentum, the water flow over the rudders and the out side engine in reverse to pull the stern in. If you get it right the boat just settles slowly against the dock with no fwd or aft movement.

As to walking boats side ways straight away or to a dock with just the engines and rudders, some boats will and so won't. But it's very rarely necessary. And even in cases where it might be, I'd rather use a spring line.

 

[Marin]

But I rarely have to put the inside engine in fwd at the last second to help pull the stern in with the out side engine in rev. In most cases I just come in with way on and turn the wheel hard, or close to it, over away from the dock and use momentum, the water flow over the rudders and the out side engine in reverse to pull the stern in..

That is generally the way we do it, too. Sometimes, however, depending on wind, current, etc., a shot of forward on the inside prop against the rudder is needed to get the stern up close enough to the dock so the person handing the deck can jump/step to the dock with the spring line.

 

[markpierce]

... But I rarely have to put the inside engine in fwd at the last second to help pull the stern in with the out side engine in rev. In most cases I just come in with way on and turn the wheel hard, or close to it, over away from the dock and use momentum, the water flow over the rudders and the out side engine in reverse to pull the stern in. If you get it right the boat just settles slowly against the dock with no fwd or aft movement '..

So true, but some of us sometimes miscalculate our landings.

 

[Hawgwash]

But our boat has counter-rotating props with the port prop being a right-hand prop (turns counter-clockwise going forward) and the starboard prop being a left-hand prop (turns clockwise going forward). (photo)

Marin.
Do you not have the LH/RH rotation backwards?
Looking from the stern and your picture shows it, starboard turns clockwise and is a RH prop. Port, LH, counter clockwise.

Or, said another way, starboard leading edge moves clockwise, to the right, going forward.

 

[Baker]

Strangely, I do not even really think about it. I just do what works. ANd what works for me is what S O F and rardoin have explained. With that said, for the OP, you have to think of it as a "falling leaf". You are going to have a little bit of forward and reaward movement. Just a little. Because once it goes forward then you change direction and wiggle into the dock. There are people on here(Ksanders I believe) that claim they can walk their boat straight sideways. I would have to see it to believe it. There will always be some wiggling.

Current pretty much helps you in 3 directions. ANd hurts you in one(toward the dock if you are trying to get away...and away from the dock if you are trying to toward it). If the current is coming from the dock and you want to go toward it, THAT will be your biggest test on getting your boat to the dock. ANd it will also force you to be the most aggressive.

 

[Marin]

Marin.
Do you not have the LH/RH rotation backwards?
Looking from the stern and your picture shows it, starboard turns clockwise and is a RH prop. Port, LH, counter clockwise.

That's what I said. Starboard turns clockwise in forward when viewed from astern, port turns counter-clockwise in forward when viewed from astern.

Or put another way, when both props are turning in forward gear, the upper blades of each prop are moving toward the prop's side of the boat.

The way I was taught to determine if a prop is right or left handed is to squat down behind the the prop (looking forward at it) and if I reach out with my left hand and it lays flat on a blade on the left side of the wheel with my hand angled up and away from me, it's a left-hand prop. If I reach out with my right hand and it lays flat on a blade on the right side of the wheel with my hand angled up and away from me, it is a right-hand prop.

Which is how the props on our boat are oriented.

But even if I was taught the right-hand/left-hand determination incorrectly, this doesn't change the fact that I have the actual rotation and thrust generation of both props correct.

 

[Sailor of Fortune]

Good idea!!

But don't expect the boat to just "jump sideways" to the dock, like a bow thruster. The effect on the bow is much less dramatic than the effect of moving the stern by counter shifting the port and starboard engines. In a perfect world, where there is no wind or tidal effect, the boat would glide to a stop parallel to the dock and allow you to take your time and walk it slowly in, but it's rare that you have those conditions.

Real world you're probably going to approach the dock at minimal speed, with a bow "in" angle and then reverse the outside engine, maybe a little forward thrust with the other, to move the stern to the dock as you come to a stop.

If you haven't already done so, before you practice docking you need to find the pivot point of your boat. It's probably a few feet somewhere behind your bow. (Mine is just ahead of the salon door.) Take your boat out on a calm day and find a buoy or a dolphin to use as a fixed reference point. Point your bow at it and put one engine in reverse and the other in forward. (The reverse engine will probably need a little more throttle to stop forward movement.) Note how your boat rotates around it's pivot point in relation to the reference point. That's your pivot point and knowing that will help you visualize how your boat will "probably" move when you approach a dock and apply different thrust techniques.

Now add wind and tide to that and all bets are off!!

The docking maneuver Eidleweiss and I just described works perfectly for us and has for the 17 years we've owned the boat. It's how we do every single docking we've ever done, in fact. Maybe you're thinking of a boat with the opposite prop arrangement. But our boat has counter-rotating props with the port prop being a right-hand prop (turns counter-clockwise going forward) and the starboard prop being a left-hand prop (turns clockwise going forward). (photo)

So to move the stern to starboard you put the starboard engine in forward and the port engine in reverse. This causes both props to turn clockwise which means the propwalk from both props is in the same direction and moves the stern to starboard. At the same time, the port engine in reverse is exerting some leverage on the boat to "pull" the port side of the boat back while the starboard prop in forward is exerting leverage to "push" the starboard side of the boat forward, which creates a pivoting moment which, when added to the propwalk effect moving the stern to starboard, makes the whole boat pivot counterlockwise (viewed from above) even more smartly and moves the stern even more smartly into the dock on the starboard side.

Then if you add rudder away from the dock, the forward thrust of the starboard propeller against the hard-over rudder directly behind it moves the stern even more smartly to starboard.

If we did with our boat what you describe, we would defeat the maneuver because the thrust against the rudder would be countering the effect of the propwalk.

If you're talking moving the boat straight sideways for anything more than a couple of feet, that doesn't work no matter what you try to do. And having forward momentum sort of defeats the whole notion of moving the boat straight sideways into a tight spot anyway, right?

No they don't. Because when the thrust is opposed, both props will be turning the same direction assuming counter-rotating props. So one will be turning inboard and one will be turning outboard. Oppose them the other way, and one will still be turning inboard and one will still be turning outboard. So the amount of propwalk will be the same in either direction.

Marin
The last time this subject came up you swore that not boats can walk sideways. Your Coast Guard "expert" boat handler couldn't walk your rig so you pretty much discounted this maneuver as urban legend if I recall. Go to any port and see this as a routine manuever by thousands of boats and operators. Crew boats, supply boats and tugs (with barges) do this daily. I'm not going to argue if it works or not. Cappy and I are in the same business in a busy port that this is a routine operation. I'm not trying to convince you of anything other than your doing it wrong. If you get the results desired, great.
You arguing boat handling with me is like me arguing sentence structure with you.

 

[Hawgwash]

Talking about sideways, I watched a 70(?) Cheoy Lee come in today.
Skipper stood outside the wheelhouse door with a wireless remote smaller than my cell phone and brought that thing forward and sideways about 200 feet. The fenders didn't even squeeze as he settled it to the dock. He stepped off and secured it, Solo all the way.
So nice to watch.

 

[Baker]

Talking about sideways, I watched a 70(?) Cheoy Lee come in today.
Skipper stood outside the wheelhouse door with a wireless remote smaller than my cell phone and brought that thing forward and sideways about 200 feet. The fenders didn't even squeeze as he settled it to the dock. He stepped off and secured it, Solo all the way.
So nice to watch.

There were thrusters involved as well as electronic controls...and maybe even pods.

 

[markpierce]

My most recent (this Spring) difficult landing was at "my" boatyard. While I made a perfect landing, the strong side winds blew the boat away from the dock before my three-step journey to the midship line could be lassoed to the dock's cleat. Had to back away and try again. Alas, success although it took most of my strength to pull the boat to the dock as I was alone.

 

[Hawgwash]

That's what I said. Starboard turns clockwise in forward when viewed from astern, port turns counter-clockwise in forward when viewed from astern.

Or put another way, when both props are turning in forward gear, the upper blades of each prop are moving toward the prop's side of the boat.

The way I was taught to determine if a prop is right or left handed is to squat down behind the the prop (looking forward at it) and if I reach out with my left hand and it lays flat on a blade on the left side of the wheel with my hand angled up and away from me, it's a left-hand prop. If I reach out with my right hand and it lays flat on a blade on the right side of the wheel with my hand angled up and away from me, it is a right-hand prop.

Which is how the props on our boat are oriented.

But even if I was taught the right-hand/left-hand determination incorrectly, this doesn't change the fact that I have the actual rotation and thrust generation of both props correct.

Yes, we agree on the direction. Your starboard prop does turn clockwise and is therefore a RH not LH prop. I was just trying to tactfully and respectfully point that out.

 

[Hawgwash]

There were thrusters involved as well as electronic controls...and maybe even pods.

Agree.
His thruster was amidships.

 

[Marin]

Yes, we agree on the direction. Your starboard prop does turn clockwise and is therefore a RH not LH prop. I was just trying to tactfully and respectfully point that out.

Okay, did a bit of research on the Michigan Wheel website (our props are Michigans) and it turns out that I was in fact taught incorrectly how to determine left and right-hand props. Can't remember who taught me that palm-on-the-blade method, but it was someone who should have known better (surveyor, perhaps?).

Anyway, thanks for pointing out the correct "hand" orientation of a prop. Doesn't alter what we do in our maneuvering but it's good to know the correct terminology. Thanks much.

 

[Hawgwash]

Okay, did a bit of research on the Michigan Wheel website (our props are Michigans) and it turns out that I was in fact taught incorrectly how to determine left and right-hand props. Can't remember who taught me that palm-on-the-blade method, but it was someone who should have known better (surveyor, perhaps?).

Anyway, thanks for pointing out the correct "hand" orientation of a prop. Doesn't alter what we do in our maneuvering but it's good to know the correct terminology. Thanks much.

I just hated the thought of you sitting in Ocean Fall's waiting for a left hand prop to be flown in for your starboard shaft.

 

[Baker]

I do this stuff with only one engine running!!!!!...

 

[Art]

To properly know how to handle a forward or reverse moving twin screw boat without using helm-wheel steering, via alternating engines’ rpm and shift positions only, it simply takes experience/practice.

In difference to single screw (although with a single screw bow and stern thrusters play well at very slow speeds - i.e. docking, near standstill) twin screw can be maneuvered quite well in forward or reverse via engines alone at nearly any speed... without using helm-wheel steering... as long as rudders are maintained in straight position during the forward or reverse travel. Rudders, as well as per engine alternate rpm and shift positions do come into play on twins when moving boat directly sideways from a standstill, while not trying to simultaneously attempt forward or reverse travel – see #3.

1. At higher speeds the rpm allowed per each engine can alter course as needed as well as maintain the course needed... even for long periods of forward travel if necessary.
2. At very low rpm (docking, slow canal travel and the like) carefully actuated per engine shift positions in coordination with their rpm can keep boat placed where desired or maneuvered into positions desired.
3. For making a standstill twin screw boat to move directly sideways to starboard or port (without thrusters)... the following works well:
“Directly-Sideways” Movement/Handling of Twin Screw Boat
Move boat sideways to port (opposite items for starboard)

- Turn rudders 80% +/- to starboard
- Place starboard in forward and port in reverse
- Starboard kept at idle rpm / Port approx 150 rpm higher

Once rudders in position with engines in the correct gear at idle rpm quickly adjust direction desired engine rpm - higher equivalent rpm for both engines with same %age difference = faster sideways motion – to a point – it can get hairy, go slow! Correction can become a bitch if boat gets moving sideways at too quick a speed... especially in close quarters! Also, depending on rudder size and prop size the numbers mentioned may need to be adjusted. However, the general mechanical/physics properties of thrust and water flow remain the same for described sideways travel.

Take it slow: Gently move a boat laterally. Be careful to not get boat moving too quickly as stopping sideways motion takes considerably more rpm, shift, and steerage adjustment time than simply forward or reverse or circular rotation motion adjustments. Adjust rudder and shift/throttle controls as needed for current and wind conditions to move latterly away from dock. Practice makes perfect. I recommend practice in a completely open area... at least at first!

 

[Marin]

3. For making a standstill twin screw boat to move directly sideways to starboard or port (without thrusters)... the following works well: [Explantion followed]

Sounds great, been there, tried that, got the T-shirt, had a truly expert boat handler try it, then tried every alternative combination possible, he got the T-shirt. We then tried it all again with his own LCM-6 landing craft (twin Detroit 6-71s) Bottom line: doesn't work with a non-thruster GB or an LCM-6.

I can't say aye or nay for any other type of vessel.

 

[siestakey]

Talking about sideways, I watched a 70(?) Cheoy Lee come in today.
Skipper stood outside the wheelhouse door with a wireless remote smaller than my cell phone and brought that thing forward and sideways about 200 feet. The fenders didn't even squeeze as he settled it to the dock. He stepped off and secured it, Solo all the way.
So nice to watch.

At the Sarasota Boat show I watched several different brands do this some with Pods

But did see one older custom Hatteras CPMY the capt had what looked like a Ipad

 

[Baker]

I have seen a Sea Ray demo boat do it without pods. The computer uses the transmissions and rudders to do it. I will say this. When that boat is going straight sideways, it is in a very strange attitude to be able to go sideways without pods or thrusters. Healed about 20 degrees and not exactly perpindicular to its direction.

 

[AusCan]

I can do it in a 30 knot breeze on the beam. (one direction only)

 

[bayview]

Large rudders help a lot but even small rudders can get pushed sideways with judicious use of shifter for prop walk.
I couldn't get my ACMY to go side ways until I learned the trick of using the propwalk in short bursts to give a push. If I left it in gear the boat would turn as the engines were set regardless of the ruder position. "astern away" is the trick to figuring what to do.

When you put one trany in reverse with some rpms above idle the first thing the boat does is get a push to the other side. Quickly shifting back to neural will prevent forward momentum. Like wise shifting the other side to forward with some rudder will shove the stern toward that side , again briefly. Some rudder for the forward engine to push against helps a lot. Judicious bumping of the thrusts will get the boat doing what you want. Larger rudders and props make this easier small props and tunnels make it harder
but it probably can be done on your boat with judicious shifting.

IMO a big mistake often seen is allowing the boat to stop. Some momentum will help if you learn how to control it with bursts of prop side thrusts and twist. Knowing the center of turning of your boat is key because it is that point that you move toward the dock twisting around that point to align the boat with the dock.

To learn momentum control get in open water and try using fwd and reverse with some forward momentum to spin the boats center of rotation without changing the direction of travel. With varying amounts of fwd and reverse you will see the boats center of motion can be controlled independent of the direction the boat is pointing. Once you have this down docking is simply a matter of moving the center of rotation to the dock and adjusting the direction it points at the last minute to parallel the dock.

I do all this at 800 rpms with zero throttle adjustments, tyrannys only.

 

[caltexflanc]

My most recent (this Spring) difficult landing was at "my" boatyard. While I made a perfect landing, the strong side winds blew the boat away from the dock before my three-step journey to the midship line could be lassoed to the dock's cleat. Had to back away and try again. Alas, success although it took most of my strength to pull the boat to the dock as I was alone.

God invented spring lines so your strength need not be called upon... let Johnny Deere do that for you!

 

[FlyWright]

Okay, did a bit of research on the Michigan Wheel website (our props are Michigans) and it turns out that I was in fact taught incorrectly how to determine left and right-hand props. Can't remember who taught me that palm-on-the-blade method, but it was someone who should have known better (surveyor, perhaps?).

????????? You can't remember who taught you but who ever it was, they taught you wrong? Are you sure you didn't make a mistake....maybe just once... and learn it wrong? ???????

Maybe we could all learn a thing or two from the real pros.

 

[Marin]

????????? You can't remember who taught you but who ever it was, they taught you wrong? Are you sure you didn't make a mistake....maybe just once... and learn it wrong? ???????
.

Nope, sorry. For one thing, I never make mistakes, particularly with something as dead easy to deal with as a toy boat cabin cruiser , and second I distinctly remember squatting down behind the props on our boat in the yard and this fellow showing me the palm-of-the-hand-on-the-blade method I described earlier. Obviously, he was wrong based on what I just learned on the Michigan Wheel website thanks to Hawgwash's prompting yesterday.

I was taught the wrong method either in the yard in Tacoma after we liberated the boat from SFO Bay and trucked it up here or during our first haulout in the yard we initially used in Bellingham. So either 1998 or 2000. So it would have been one of the yard guys or the surveyor who did our first insurance survey.

There's a not-very-good-video I came across on the web last night illustrating how to determine a left or right hand prop. They keep calling it an impeller, but they do demonstrate a method of using the palm of the hand as a way to determine whether a prop is left or right hand pitch. At first I thought it was confirming the method I'd been taught but on watching the "palm demonstration" section again, in which they use their thumb to determine which hand the prop is, I could see it agreed with the Michigan distinction. The video is here:

 

[Capt.Bill11]

I would have thought it would have been obvious to you he was wrong when he was showing you that trick.

 

[Marin]

I would have thought it would have been obvious to you he was wrong when he was showing you that trick.

Why? We were brand new to this kind of boating. I'd never even HEARD of left-hand or right-hand being applied to a prop before. So what he demoed made sense to me.

If the term is tied to the direction of rotation, which part of the rotation do you look at if you don't already know, over the top or under the bottom? The top and bottom go opposite directions--- tough concept I realize but if one studies it hard enough they'll see that it's so--- and if one hasn't learned how the term correctly applies, both directions are equally plausible when applied to right or left rotation.

But the explanation I was given at the time didn't even consider rotation direction. It was simply based on the angle of the blades on one side or the other of the circle. Like the "thumb" demo on that little video. If he'd have shown me THAT instead of the flat-palm thing, he'd have been correct.

 

[psneeld]

The dog wasn't around to set everyone straight....

 

[markpierce]

Fortunately, after first hearing the concept of right and left hand propellers, I consulted an authoritative source (pages 177 and 178 in my Chapmans version). Mine's left-handed, explaining the starboard propwalk.