CFG
Deckhand
I used to be indecisive. Now I'm not sure.
Posts: 64
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Post by CFG on Nov 6, 2008 22:07:17 GMT -8
I was at the helm of the Burnaby once we had cleared the gap between Harwood Island and Texada Island as we were leaving Powell River until we were a ways out in the Strait. No course changes to be done, just had to keep her on a course of 250 degrees. Thats kind of what I thought you would say. That would mean she was turning to the north, into a current and or wind pushing down the straight towards Greater Vancouver from Campbell river and the narrows. It is kind of a difficult concept to understand, and even harder to explain it right But as a vessel passes perpendicular to a current in the water it will get turned to face bow into that current because the current pushes more on the stern of the vessel than the bow. This makes you end up with a kind of cat-walk happening as the vessel passes through the water. Note it must be moving under its own power or the opposite happens. The amount of drift also varies with the hull form at the stern compared to the bow. If there is a lot more area to take a side force at the stern than at the bow then it will have more affect. Confused yet? I am. Also kinda off topic which I know how much we all love
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Deleted
Deleted Member
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Post by Deleted on Nov 7, 2008 17:03:23 GMT -8
I had a very hard time explaining that theory.
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Post by oceaneer77 on Nov 18, 2008 20:33:16 GMT -8
The steering differences would be the telemotor servos out of adjustment. you do not steer the ship as a human does not have even 1/32 the horse power required to move the rudders in a timely fashion. the Human steers a small servo valve that acuates a larger valve, the larger valve(s) has an electric hydraulic pump that actually fills/empties the steering rams. So the Feel of the steering wheel is really not the feel of the ship. In the emergency steering station, you actually do move the rudders without any assistance, but it has probably 100 turns from port to starboard.
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Post by uricanejack on Dec 10, 2008 2:59:08 GMT -8
Hi
I think The Queen Of Naniamo recieved the OLD bow prop when it was lenthened originaly the V class were buit without bow thrusters. They were added to make dockings easier and safer when windy.
The other vessels recieved an additional bow thruster when they were raised due to increased windage.
The Queen Of Naniamo recieved a second bow thruster at the end of the 90's when she became the designated year round vessel on Route 9. prior to this the Queen of Tsawwassen was the designated vessel for route 9 and was replaced in early spring though the early fall by the Queen Of Naniamo due to increased traffic.
Around the time the Sydney was Decomisioned it was decided to leave the Queen Of Naniamo on Route 9 except for the anual refit when she would be relieved by the Queen Of Tsawwassen.
The Senior Master insisted he would require a second bow thruster if they expected the ship to make the landings in Tsawwassen and Otter Bay in winter strong winds.
The Queen Of Burnaby has a self centering wheel while the Queen of Naniamo does not. This means as you Turn the Wheel on the Queen Of Burnaby you have to overcpome some Hydrolic pressure which returns the wheel to center when released.
The Ships do Stear Differently and there are a nomber of theory why. most likly some minnor differnces in the hull shape.
The most likly reason the ship will tend to vere of in one direction on a twin screw ship is the engine revs are not quite equal and will be different each time the throtle's are set.
A little counter ruder is needed. Wind and sea will have an effect if strong.
The Queen Of Tswassen and Sydney were fixed Pitch direct drive with outboard rotating Screw's
The rest of the V Class were Variable Picth most variable pitch vessels are inboard rotating.
Almost all twin screw vessels have counter rotating screws so the transverse thrust or padle wheel effect will cancel out. If not you will have a great deal of difficulty stearing.
Most single screw vessels have right hand screws which rotate clockwise. this gives them a tendency to turn to port more quickly and to require a small amount of starboard ciunter rudder. The effect is most noticable at low speed through the water with higher revs. and most noticable when going astern.
A conventional right hand prop vessel will swing to Starboard when going Astern.
Ships are not built with of center screws. A few Old sailing Vessels had Auxilary moters installed of center but were notoriously difficult to handle.
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Post by Hardy on Dec 10, 2008 3:44:29 GMT -8
Welcome aboard 'Jack. Thanks for the insider view of things and the detailed explanations. One small 'gripe' that others may pick up on, is the option to hit the spell-check button before posting.
Hope to see more of your postings in the future.
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Post by DENelson83 on Dec 10, 2008 5:23:46 GMT -8
Twin-screw ships (and twin-prop planes) tend to have contra-rotating props, for the very reason of balancing "thrust". A single-screw, much like a mono-prop (think WWII fighter planes) tend to turn easier ONE direction than the other -- the direction of the rotation of their prop. On a lot of ships, it is overcome by having the "neutral" position of the rudder actually off-centre slightly to counter the effect. It isn't really hard to understand, even when Keyran-ized. Yeah. It's sort of the same effect as how a helicopter's fuselage will spin when the tail rotor is not working. Hmmm... Helicopter... I think we know which ships in the fleet have that kind of problem...
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Post by Low Light Mike on Dec 10, 2008 19:59:20 GMT -8
Hi Jack. Wecome aboard here. Thanks for your awesome post; I really appreciate the detail and your explanations of the various items. Thanks!
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Post by Taxman on Dec 10, 2008 22:40:59 GMT -8
Hi I think The Queen Of Naniamo recieved the OLD bow prop when it was lenthened originaly the V class were buit without bow thrusters. They were added to make dockings easier and safer when windy. The other vessels recieved an additional bow thruster when they were raised due to increased windage. The Queen Of Naniamo recieved a second bow thruster at the end of the 90's when she became the designated year round vessel on Route 9. prior to this the Queen of Tsawwassen was the designated vessel for route 9 and was replaced in early spring though the early fall by the Queen Of Naniamo due to increased traffic. Around the time the Sydney was Decomisioned it was decided to leave the Queen Of Naniamo on Route 9 except for the anual refit when she would be relieved by the Queen Of Tsawwassen. The Senior Master insisted he would require a second bow thruster if they expected the ship to make the landings in Tsawwassen and Otter Bay in winter strong winds. Well... that explains it
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Post by kerryssi on Dec 11, 2008 17:37:19 GMT -8
Most of what jack says is quite right. The Burnaby has a self centering wheel which makes it a pain to steer. We had a lanyard which we could slip over one of the spokes to keep it traveling sort of on course instead of manhandling the wheel. I think it is slight variances in the rudder which causes a ship to favour port or starboard. The Gulf Islands have some of the worst wind and tide conditions anywhere. As I have previously posted we came into Sturdies one time from TSA with the wheel hard a starboard, bow thruster( only one then) hard a starboard, starboard engine full astern, port engine full ahead and watched as she slowly turned to port. Missed the dock completely. At Village bay there is what we used to call the "Village Bay Two Step". Regardless of tide or wind you have to bring the ship in along the port leads. When it gets to the gap between the leads and the wing wall it steps off to starboard. If you have done it right you wind up "up the middle".
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Post by Variable Pitch on Dec 11, 2008 23:04:11 GMT -8
Hi I think The Queen Of Naniamo recieved the OLD bow prop when it was lenthened originaly the V class were built without bow thrusters. I am not sure that is correct, as I have a copy of the docking plans to the original "City of Vancouver" (1962) which shows the hull from the main car deck to the keel. I had a reduced copy made as a template for the scale model I built (which I donated to the Maritime Museum of B.C.). At the bow, there is clearly a bow thruster drawn and marked. In some of the old pictures, it shows the City of Vancouver at her launching at Burrard with the bow thruster in view as she slipped down the ways. As for the Sidney class, I am not sure if there was one or not (originally). On a lesser note, The Burnaby class never converted to Victoria class, despite stretching (and raising in the New West). V's and B's are a separate class unto themselves.
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Nick
Voyager
Chief Engineer - Queen of Richmond
Posts: 2,078
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Post by Nick on Dec 12, 2008 9:08:51 GMT -8
The Sidney class received bow thrusters sometime in the early 80s. Not sure on the exact year, but they didn't have thrusters for a good portion of their lives, and certainly didn't have them in the beginning.
I'm pretty sure that was one of the modifications they made to the plans when they were designing the Vs. Something to do with high winds at Tsawwassen....
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