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Old 06-03-2020, 01:03 AM   #1
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Current Perpendicular to Dock

On a rising tide, not necessarily a bigger than normal tide, we often get a current flowing at right angles across the dock, from port(shoreside) to starboard. You feel it when you start positioning to line up the berth, the boat won`t do what you are tell it. Doesn`t happen every time.
Seen from the dock, leaves in the water or mud stirred up by vigorous maneuvering rapidly disappear to starboard, with the boat. You no sooner get lined up to reverse in than you`re a boat stbd of your berth.
Only solution I can think of is, when the "I`m not doing that" boat behaviour starts, position the boat up current to port of the berth, wait for it to drift sideways and try to judge hitting reverse at just the right time to reverse into the berth. Thoughts and contributions welcome.
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Old 06-03-2020, 02:13 AM   #2
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In my case my berth is parallel to the river current, but to get to the inner berth I need to go along a narrow-ish fairway and make a 90° turn before entering my berth. River current can make that little trip along the fairway 'interesting'. As I am usually single-handing, even when in the berth I don't want current moving me forward or back whilst hopping off the boat to secure lines.

The simple answer for me is to use periods of slack current (river is tidal)
to enter or exit my berth with minimal fuss. Yes, at times it can be inconvenient. But with slack water twice a day in daylight hours its no big deal to work around the currents.

I use the NAV function on my AP to give an ETA for the marina, and so I am typically able to just go straight into the berth on arrival at the marina. In other words, my solution to a problem such as you have is to just plan around it.
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Old 06-03-2020, 04:42 AM   #3
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On a rising tide, not necessarily a bigger than normal tide, we often get a current flowing at right angles across the dock, from port(shoreside) to starboard. You feel it when you start positioning to line up the berth, the boat won`t do what you are tell it. Doesn`t happen every time.
Seen from the dock, leaves in the water or mud stirred up by vigorous maneuvering rapidly disappear to starboard, with the boat. You no sooner get lined up to reverse in than you`re a boat stbd of your berth.
Only solution I can think of is, when the "I`m not doing that" boat behaviour starts, position the boat up current to port of the berth, wait for it to drift sideways and try to judge hitting reverse at just the right time to reverse into the berth. Thoughts and contributions welcome.
My first largish boat was a Uniflite 42 ACMY. I lived aboard near San Francisco's candlestick Park, a notoriously windy place where afternoon winds were commonly 30 kts. My slip was more or less perpendicular to the wind. While I avoided returning in the afternoon, I did find myself in uncomfortable situations, enough that it hindered use of the boat.

I can tell you from experience that the poke-and-hope method of side-sliding was not successful for me. Sideways momentum was just too great so landing was super sloppy. I'd try to stuff enough of the boat into the slip that I could just jam it home with tons of fenders. Was a great plan. Execution was awful.

Its hard for me to imagine your situation (Slip with piles? Fingers? Both sides or just one?), and I have no idea of your boat (single, twin, thruster, windage, etc), but if it were me on most boats, I would try to position the boat so I was working against the current - the side slide method has you working with the current. This might mean going past your slip and working back towards it. If there's an outboard piling or dock, tempting to land the aft quarter on it and pivot the bow, but if not successful, you will end up in a very difficult position pinned against neighboring slips/boats with no way to safely move. What's worse is there is a strong urge to power-up to extricate, which can be a very expensive and embarrassing urge as the stern swings into various fixed objects.

If the challenge is fairly moderate, and you can devise a reliable plan to use the current to your favor, do a ton of repetitions in practice during slack periods to build muscle memory. And practice aborting the landing to head back pit and reload. Honestly, backing a boat down a fairway scares me enough that I swear my DNA cell structure has been re-ordered a couple times, but sometimes that the way it has to happen. I never practiced it enough to get really comfortable with backing longish distances with obstructions on both sides.

But in the end, not all docking situations are solvable. If current is due to tide vs river, you may need to just wait it out. There is no magic bullet. If you don't have a thruster and this is common in your area, it might be a good investment, though even that is no guarantee if thruster is undersized or adverse conditions too great to overcome

In closing, I fancy myself a decent close quarter helmsman these days. I drove a 74-passenger dinner charter boat on SF Bay in the early 2000s for a while which really brushed up my docking skills - weather has to be really bad to cancel a run. Still, a couple months ago when I was in Ensenada and moved my Willard 36 from her berth, I totally misread the slight current (meaning I didn't even pay attention to it) and was about to be pinned. Thankfully, embarrassment was minimized due to mid week. And thankfully I had developed a good relationship with Victor, the dock worker who quickly came to my rescue.

EDIT - Bruce - on my PC I can see your picture with boat backed-in (not so on my mobile where I first responded). Boats pivot roughly 1/3rd way back from the bow, more or less beneath your feet on the flybridge. My first try would be to back towards your slip, but aim for the finger up-current, maybe even a little further depending on strength of current. You will want the stern of your boat close to your slip when you rotate to minimize the amount of time you're exposed to sideways current. My goal would be for the pivot point (beneath your feet) to line-up with up-current side of slip when your rotation is complete and you will indeed be crabbing slightly from left to right. Need to minimize this as best possible. It may not be pretty - practice, practice, practice. BTW - nice boat!

Good luck

Peter
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Old 06-03-2020, 07:15 AM   #4
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I can’t see in your photo if there is any fendering on the corner of your dock or not, but how about a dock wheel on the end of the dock. It may help you turn the corner if the current gets in control. You may be able to turn the corner and use the wheel as a means of turning without damaging the boat.
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Old 06-03-2020, 07:21 AM   #5
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If the slip is wide enough to allow it, back in somewhat diagonally, moving the boat up-current. Then you pivot the boat straighter as you back in. Might be a challenge with a single, but it's easy enough with twins. By not trying to move in a straight line backwards and not trying to move exactly perpendicular to the current, it's easier to compensate. It can still be a problem if the current is too strong, however.
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Old 06-03-2020, 10:50 AM   #6
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Originally Posted by rslifkin View Post
If the slip is wide enough to allow it, back in somewhat diagonally, moving the boat up-current. Then you pivot the boat straighter as you back in. Might be a challenge with a single, but it's easy enough with twins. By not trying to move in a straight line backwards and not trying to move exactly perpendicular to the current, it's easier to compensate. It can still be a problem if the current is too strong, however.
This is probably what I would try. Stern into the current, and try to keep my starboard quarter as close to the dock as I can while I shove the bow around. You have a thruster, right?

Or another option, head into the current until the end of the dock is close at your starboard quarter, and the dock line up is perpendicular to your centerline, get a line or two into the hands of someone on the dock, and then let the current take the bow to the left, while you tuck the stern in.

It's a tricky one, especially with a neighbor down stream.
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Old 06-03-2020, 12:35 PM   #7
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Peter wrote, "if it were me on most boats, I would try to position the boat so I was working against the current - the side slide method has you working with the current. This might mean going past your slip and working back towards it."

Exactly. A brisk wind and / or current can be your friend. In this case, you can use them as brakes on your boat's lateral momentum when entering the slip from down-current. That does require a certain level of confidence in your transmission, as you'll have to use sufficient power to keep way on while entering the slip from down-current, then quickly change the direction of thrust once you are inside the slip. But it sounds as though you have to do that sometimes, anyway.

Naturally, this would be easier docking bow-first, as your rudder would help fishtail the stern around the corner and into position. Apparently you must tie up stern-to, so you do have fewer tools at hand. Make the forces of nature become part of your toolkit.
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Old 06-03-2020, 03:42 PM   #8
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My boat shed is pretty much perpendicular to the afternoon sea breeze which often tops out at 12-15 MPH. Add that to whatever tidal current is flowing and the challenge to back my 14-foot beam Grand Banks 42 into a slip with pilings 16 feet apart was at times severe. As stated earlier, the idea of positioning the boat parallel and upwind(current) of the slip and poking it in there as it comes even with the slip would never work. In fact, that method was sure to end up with the boat getting wedged with about 1/3 of its length stuck into the slip and the rest being pushed forcefully downwind - no bow thruster.

The solution was to position the boat downwind of the slip and head directly into the wind with both engines in gear. At the chosen point, I put the outboard engine (the one away from the slip) in reverse and firewalled both engines with the rudders turned hard away from the pier. The approach distance off the pier was just enough that the stern cleared the outer pilings by ten to twenty feet. Then, in VERY rapid succession, the rudders were centered, throttles were idled, and the outboard engine was shifted into reverse (now both engines were running astern). The run up into the wind and sudden forceful twist generated enough momentum to counteract the strong downwind set of the sea breeze as the boat's beam was presented to it. There then existed a brief moment in time where, if I ended up aimed correctly, the boat backed neatly into the slip touching neither side (clutches being played like a piano) until it came to rest when its rub rail came gently to the downwind pilings.

This was a very aggressive method full of sound and fury not for the faint of heart, but really the only one that worked under those conditions. I was always ready to abandon a missed approach, and on more than one occasion resorted to clutching both ahead with full throttles to escape doom. After a while, I became quite proficient in the method and very rarely missed an approach.

I first learned the rudiments of this method when I conned a guided missile destroyer into a fueling fuel station directly off a beach in Punta Arenas, Chile where there was a strong alongshore current. This was a do or die landing as we were low on fuel down there in the southernmost city in the world with insufficient fuel to carry on north to Montevideo (avoiding Argentina because of the Falklands war). Since there were no pilings to either help or hinder us, I dropped the outboard anchor as the ship passed the fuel buoy just off the beach and backed the outboard engine full with the inboard at ahead 1/3. We came out of the turn high into the current where I ordered the other anchor dropped forming a nice vee with our chains as I backed into the buoy where a mooring line was quickly secured to the buoy. Whew! Based on that trick, my captain recommended me for command of my own destroyer.

I don't know if you have single or twin screws ot bow thruster, but the concept of using the ship's momentum and inertia works in many vessels. Maybe you have an assistant who could drop an anchor on the upwind side of the slip allowing you to twist the boat as needed to back into your slip.

Just some ideas from the cheap seats.
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Old 06-03-2020, 03:58 PM   #9
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Cross current and backing in without twins and or a thruster is very difficult.


Over one knot and all bets are off....width of slip/boat and obstructions sticking out past outer pilings or finger piers are also huge factors.


I used to have to tow boats and slingshot them into slips with cross current as well as dock single screw vessels in tricky slips too.


I have to say...there is no slick answer.


Every day with different conditions required different techniques.


Every boat handles different enough to require different techniques.


If there were pilings...or a finger dock with a wheel on the corner....then pivoting was the safest...not always the prettiest.


If obstructions stuck out on one side or the other...just raw speed worked but without a significantly wider slip than your boat....then backing in fast to overcome drift was a gamble with success only as good as boathandling skills or luck.


If the boat was an outboard or I/O you could use the directed thrust swing of the bow to swing up current while backing in and that was a bit sweeter...but I rarely had the ease of one of those vessel types.


Nope...its a treat with a cross current and only trying a bunch of things in a bunch of conditions and then a ton of practice will make it less than scary...but hardly ever routine.
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Old 06-03-2020, 04:10 PM   #10
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Very nice Rich. Glad you are on our side!
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Old 06-03-2020, 06:04 PM   #11
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Would need to know more, as others have mentioned, especially single (and which side the propwash takes you in reverse) or twin, and if a thruster is involved. Might be a combination of throttle and springline involved. Chapman's which I don't have handy, has a number of diagrams for various situations.
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Old 06-03-2020, 06:26 PM   #12
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I feel your pain. I have a single and it seems that where my slip is on the Manasquan River, there is always a current either going in or our and with wind like this past Sunday had me pinned on the pilings. If it wasn't for the bow and stern thrusters I would not have been able to get out. Getting in would have been impossible. Watching the guys get in with twins seems so much easier. Glad I have thusters. Sounds like they would help you out massive.
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Old 06-03-2020, 07:37 PM   #13
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His sig mentions a boat that has twins, and the avatar pic looks like floating docks, and possibly no pilings between him and the ship to port.

When dealing with a slip with pilings I'm not averse to using them to assist pivoting the boat against the outside piling, as a means to get enough of the boat into the slip to allow for taking a breath and then finishing the docking.

But with floating docks, bleh, not my favorite when it comes to docking unless the crew assisting me is good with working the fenders. Which is to say, not as often as I'd like! Can't "un-yell" at the wife so... it's more stress than ideal.

The downside to those dock wheel gizmos is they often end up marking up the side of the hull. That and I've not come across many that can take much force being worked against them. So the care you have to take to avoid wrecking them is nearly as much as you'd have to take to avoid the pier anyway. But my experience with them is limited, so ymmv.

Rich has the right idea. Using the power of the twins to yank the boat around instead of trying to a gentler approach. I used to have to do that on our last boat (34' twin gas engines), as at slow speeds it would wander way too much if there was any wind or current. Better to use firm bursts of power at 4-5kt kind of speed rather than letting it get pushed around at just 2-3kts. I'd get frantic arm waves from folks on shore sometimes, thinking I was coming in "too hot" but I knew very well how the boat could be hauled back to a stop. Better to power into position, avoiding being influenced "as much" by crossing current/winds and into the desired position for the next part of the docking.

This was a small marina and I had to power in through what could be a choppy sea wall entrance, with a strong wind off my side. Come in hot, tight against the wind, scoot past the outer row of slips, deep reverse to haul us to a slow, and a hard pivot to port to get into the fairway. Likewise having to watch it that it didn't get crabbed sideways getting down to the slip. Where, again, it was deep pulls of power to work the pivot to get reversed back into the slip. It took a fair bit of practice to really get comfortable with using more than just bump in/out of gear kinds of power. A key point that was ALWAYS on my mind was knowing when the situation was going to go past an easy point of recovery. Drifting too far over one way or the other, etc. And then knowing how I could use power to get the boat yanked back into a more workable position.

I had one detractor giving me some grief about that technique... so I had him come with me and try it the way his boat handled. And that failed. Thus he understood why I did it that way, for that boat.

Every boat is different. Getting to know how YOUR boat handles is the key.
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Old 06-03-2020, 08:52 PM   #14
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Thank you all for a broad range of possible solutions. Avoidance of the current condition is appealing,but sometimes I`ll have to confront the current.
The boat is new to me, but the issue was there with the previous boat. Both have twins, the new one has a bowthruster which could be stronger, but does help. The boats essentially have the same Harvey Halvorsen hull. Docking in fair conditions is a picnic. Facing out of the dock, there is a boat to port and a finger to stbd. No pilings. The berths are quite wide. The current is odd, it`s as if tide coming into the narrow long finger of water comprising "Sandbrook Inlet" bounces off the shore and runs at right angles across the dock.

I agree the "line up and gun it in" method has risks. For a start current speed probably varies. Fortunately it`s a "helping" marina where we leave what we are doing to help boats docking. We did get pinned against the corner or the finger last time, got it off with port reverse + thruster+ neighbour pushing, so a corner wheel might be a good move. No damage sustained.

I think getting in closer might help, but not too close or I risk touching the adjacent boat. Less distance reversed is less exposure to sideways current. It does require more power to overcome the current, but more power means a harder hit if something goes wrong. There is need to stay calm when the boat isn`t responding as normal. After the 3rd line up attempt I get a bit pissed but must keep cool. Knowing what`s happening helps. I`ve gained some useful ideas.
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Old 06-03-2020, 09:29 PM   #15
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....... how about a dock wheel on the end of the dock. It may help you turn the corner if the current gets in control. You may be able to turn the corner and use the wheel as a means of turning without damaging the boat.
Works for me when the tide is moving in or out.
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Old 06-03-2020, 10:32 PM   #16
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I feel you on the "need to stay calm" aspect. Especially when it comes to handling passengers. With our old boat and marina it was pretty much "no talking during docking" to maintain concentration. That boat, those conditions, ugh, it was a chore sometimes. You try not to show stress/irritation/panic to the passengers but it was exhausting some times.

More power does NOT have to mean hitting something harder. What it can mean, judiciously applied, is overcoming the forces of wind and currents on the boat for long enough to get situated into a more ideal position. Slowly creeping along, letting the wind/current push you around. Versus some confident, quicker motions to get the boat set up BEFORE the conditions can lead it astray.

If you know how well your props bite and what kind of distances you can get out of what kind of uses of power (both moving and stopping) it can often lead to less overall stress and docking do-overs.

I'll say this, what worked well for twin gas engines in a 34' cruiser did not directly translate to our present 47' with twin diesels. The props bite slower on the 47, but with a lot more momentum. The greater weight of the 47 and more keel are also factors. It doesn't get pushed around or wander as quickly as did the much lighter 34. But with time I've gotten reasonably familiar with being able to call on the power to get it docked with minimal fuss.
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