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  • Ship and Boat handling

    Starting this new thread about ship and boat handling, since that is a separate subject from anything else on CVF, and MAY be a subject for some future discussions.

    To kick it off, here is an ongoing discussion transferred from the Nordstjernen thread.

    Here is what has happened , so far:
    Originally posted by carinahansen View Post
    The second last time we saw Nordstjernen in Stamsund tonight..
    Great weather, lots of people, and a little daylight that made the photos more blue than black (finally)

    Originally posted by Clipper View Post
    Indeed, great photo Carina.


    Is this a "propeller walk" manoeuvre?
    Originally posted by ombugge View Post
    I would think this is more of a "spring walk". He has probably dropped Stbd. anchor and is now moving dead slow ahead, with rudder hard astarboard.
    That will bring the stern in towards the wharf, but at the same time controlled easing out of the anchor will bring the bow into contact with the wharf.
    Once the bow is firmly on the fenders the rudder angle will decide how fast the stern turn in or, if the wind or current is from Stbd. side, turning the rudder to Port can reduce the speed at which she hits the wharf.

    Classical manaeuvre for single screwed ships with fixed pitch propeller and reversible engine. (NX has Variable Pitch Propeller, which makes this operation easier, but doesn't change the procedure)

    With the old Gulf of Mexico type Supply Boats the "propeller walk" was used to "walk the boat". They were flat bottomed and twin screwed, with the propellers turning in opposite directions. By putting one engine ahead, the other astern and the rudders hard over, the boat would move sideways when coming alongside an anchored barge or drillship. The distance between the brest anchor wires/chains were sometime not much more than the length of the boat, so it took some skill to do this.
    Originally posted by Clipper View Post
    Aha, spring walk.

    I hadn't considered the anchor; two questions arise.
    • Would the captain delegate bow position to an anchor-man and concentrate on bringing the stern in; or would the captain actively involve himself in both stern and bow?
    • What's keeping the bow line tight as we see in Carina's photo?

    I would love to see a Gulf of Mexico boat doing that walking manoeuvre.

    Originally posted by Clipper View Post
    Thank you for your patience Ombugge. I understand how this works to bring a ship in (typically against an offshore wind) with bow line, momentum and forward power but I'm struggling to understand the forces involved when the anchor is also used. I can't find an illustrated example of exactly this configuration on the web.

    (Maybe we should take this to a more appropriate CV forum).
    We are talking about the Fwrd. spring line, not a bow line here. (Fwrd. spring line "pointing" aft, Bow line fwrd.)
    In Carina's picture you can see that the spring line is set and the heaving line has been thrown across to set the Bow line.

    I was just assuming that an anchor was used here. This would serve to ease the bow against the wharf in a controlled manner, rather than getting "slamed" into it by strong wind or current from the outboard side.

    If there were no strong wind or current he may just be easing the bow into the wharf, using the engine and rudder only.

    At least that is what it looks like to me, from a distance of 10,000 miles.

  • #2
    Re: Ship and Boat handling

    To elaborate on the subject of "walking the boat"
    With the old Gulf of Mexico type Supply Boats the "propeller walk" was used to "walk the boat". They were flat bottomed and twin screwed, with the propellers turning in opposite directions. By putting one engine ahead, the other astern and the rudders hard over, the boat would move sideways when coming alongside an anchored barge or drillship. The distance between the brest anchor wires/chains were sometime not much more than the length of the boat, so it took some skill to do this.
    Here is a little anecdote:
    In 1970 I was "Navigator" for Tidewater in Singapore, which involved me going on board any boat that was heading to new places of operation, or over long distances out of sight of land.

    Returning to Singapore with one of them, the Skipper jumped ship at Eastern Anchorage and asked me to take the boat around to Loyang Base, on the other side of Singapore island.

    He then jumped in a taxi and arrange a "welcoming comity" at Loyang.
    He arranged to have two boats tied up abrest, both Fwrd and aft of the space allotted to his boat.

    This was to test if this damn educated foreigner (read non-coona***) could manage to "walk the boat" into a slot not much wider then the length of the boat, something that would normally involve a lot of black smoke from the "smoke stacks" down on the aft deck.

    When I arrive they were all waiting, prepared to have a good time while watching my "boat handling skills", or lack there-off.

    At ebb tide the current was running strongly through the wharf, which was on wood piles, from the opposite side of where I had been instructed to tie up.

    Looking at the situation I slowed down a bit away, called the Indonesian Bosun to the Bridge to instruct him on the use of a spring line.
    I then proceeded to put the bow into the "gap" that was left me, set the bow spring and using both engine at relatively slow speed ahead, with the rudders hard over to get the stern to swing towards the wharf, while instructing Bosun to slack slowly on the spring line to ease the bow closer to the boats moored in front of us, and allowing space for the stern to swing clear of the boats aft of us.
    Bingo. Alongside without any dramatic antics and black smoke.

    This did not impress my fellow "boat handlers", watching from the other boats alongside, since I did not try to "walk the boat" against an impossibly strong current. Besides, there were no black smoke and no shouting.

    By the way, around that day the first Offshore boat with over 3000 ihp and a bow thruster had just arrived in Singapore. (The "Young America", which is still around as far as I know)

    Later on, when I became Captain of a small single screw cargo ship sailing between Singapore and lots of small ports with no pilot and no facilities in the east of Indonesia, this method was frequently used, incl. when coming alongside at Telok Ayer Wharf in Singapore, where the wharf booking was for LOA of the ship + 1 ft. extra at either end.

    This was a long time ago and a forgotten skill for most of today's "Ship handlers", with bow and stern thrusters and joystick operation.

    Does any of the Shiphandling Simulators or Games even allow for this method to be used???

    Comment


    • #3
      Re: Ship and Boat handling

      Interesting subject for a thread. I will admit now though that my boat handling skills are zero, i used to have enough trouble getting the RIB alongside, so no way i would have ever attempted to try it with Datchet - the vessel i used to work aboard. Four teleflex levers, steering, currents and the wind, nope, i would have got in a right mess with all that! Getting alongside is something i always left to the skipper, i would be the one climbing the quay ladder with a mooring line draped over my shoulder after the skipper had stuck either the bow or the stern quarter into the quay. (never any bugger on the quay to take a line).

      Forward spring on first was a firm favorite, rudders hard over then gentle power to pull her alongside. Then leave her in gear whilst we get the other lines ashore and secured. Our berth in Bideford had quite a large rise and fall in tide - up to about 6.5m if i remember correctly, drying at low water, so it was always important to get the length of the mooring lines just right because the boat would be left unattended over the following tide. Too much slack in the lines would mean problems for us if we came back at low water, she would be sitting off the quay too far for us to get aboard, lines too short would leave her listing at some crazy angle, or even result in a line parting. Once i knew the lines were just the right length for our regular berth i always marked them, i used to wrap electrical tape around them at the point where they took their first turn around the bits. That used to save a lot of messing about when getting back to the berth. (I used to use different coloured tape for different berths).

      Another favorite was to stick the corner of the stern in, get a stern line on, and then let her come alongside.

      The only time i have had to get her alongside myself was when some darn kids tried to let all her lines go one night, luckily they tried it when the tide was running, so by the time they got to the final line she had all her weight on it so they were unable to let the final line go. I got a phone call early one Sunday morning from someone in Bideford telling me the boat was out in the river with only her bow line on. The skipper was not contactable so i had to go and sort it out. Managed to pull her in close enough to jump aboard, then she just drifted out again with her stern out most. So i fired up, then sat there scratching my head for a minute or two before finally deciding going astern with full rudder would probably be my safest bet. Thankfully she done what i hoped she would, stern swung slowly in. Got my forward spring ashore and went ahead, all was well then, i was back in a situation i was familiar with. Darn kids, not what i was expecting to do on a Sunday morning! But i drove back home quietly pleased with myself that i had managed to get her back alongside without a problem.
      Your charts, your radar, your eyes and ears - if all 4 agree, you may proceed with caution.

      Comment


      • #4
        Re: Ship and Boat handling

        On how big ships is it realistic to use bow spring? The captain of Richard With told me on a bridge visit that they were too big for that kind of manouver, too big forces on the ropes.

        What about aft spring? I have a feeling that it's mainly used for departing manouvers?

        I don't quite understand the term "walk the boat", is it also a manouver?

        Comment


        • #5
          Re: Ship and Boat handling

          Originally posted by Tommi View Post
          On how big ships is it realistic to use bow spring? The captain of Richard With told me on a bridge visit that they were too big for that kind of manouver, too big forces on the ropes.

          What about aft spring? I have a feeling that it's mainly used for departing manouvers?

          I don't quite understand the term "walk the boat", is it also a manouver?
          With how large vessel you can use the above method on depends on the conditions and type of vessel. With strong wind or current setting against the outboard side the force required on the spring line would be considerable, especially with a large windage area, like on R.W.
          In calm weather, and with the benefit of Controllable Pitch Propeller, there should be no problem to use this method, but why would you, with all the thruster power available on R.W.??

          Using the back spring was a common method to get the bow to turn off the wharf, especially with a current running parallel to the wharf and from ahead. (Current = Pore man's Tug)

          If strong wind from outboard side, or current setting from astern, the method has limited effect. In that case it is best to set an anchor on arrival, to ensure that you can swing the bow out on departure.

          In the early days of Offshore Support Vessels in the GOM, to "walk the boat" was a common term used to describe the method of getting the boat to "walk" sideways by applying power on one engine ahead and one engine astern, thus inducing "Propeller walk" in the same direction, either to Port or Stbd.

          Which one ahead and which astern depended on which direction you wanted to "walk". The propellers had to be one inboard turning and one outboard turning when seen from astern and moving ahead both.

          The trick was to ensure that the engines picked up RPM at the same rate, otherwise the boat may start to turn, rather than "walk". Not all skippers had understood that. They would just put one throttle full ahead and one full astern, without watching the tachometers, claiming that "the damned boat wouldn't walk".

          Here is a typical GOM supply boat of the early type:


          In fact I saw one of them in Labuan a couple of weeks ago:

          Now used as a survey vessel, but still recognizable as and old Halter marine GOM boat.

          The early type that had Bow thruster looked like this:

          That made "walking the boat" a lot easier.
          Last edited by ombugge; March 19th, 2012, 11:47.

          Comment


          • #6
            Here is a nice piece of ship handling in timelaps fashion: http://gcaptain.com/watch-tanker-man...al-time-lapse/

            In more realistic speed: http://gcaptain.com/watch-tanker-man...al-time-lapse/

            And this is in very good weather. Now try to imagine what it is like in bad weather.

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