Steering astern!

Sailor Steve · 12-06-13, 10:50 AM

Quote:

Originally Posted by CaptBones

Well, I don't really want to "torpedo" Sailor Steve's logic or contradict Jimbuna's experience

Why not? Other experiences and opinions are not only welcome, but vital.

Quote:

...but...steering with astern way on is extremely easy and very accurate in twin-screw destroyers and "Fleet" type submarines (probably just as good for U-Boats). I once backed the USS Laffey (DD 724) through the inner harbor of Grand Harbor, Valleta, Malta, to "Med Moor" at Fort St. Angelo.

How fast? It's my understanding that the big problem isn't slow maneuvering in harbor but maintaining a straight course at high speed. Then again, I was a humble radioman and never got to do fun stuff like steer the ship.

That said, I use sources which describe the real problems encountered, so it's not just theory.

Quote:

The pivot point in the mentioned ship types moves forward (toward the bow) when going in the astern direction with way on.

This source says the pivot point moves aft when travelling in reverse. I don't claim to know, but...

Quote:

I won the Pacific Fleet Shiphandling Award in 1974 by backing a single-screw "Knox" Class Frigate to starboard while making a "two bell" landing maneuver at berth B-26 in Pearl Harbor. I taught that maneuver to the students at Surface Warfare Officer School in San Diego for several years after that..."The Book" says it can't be done.

Them's some mighty fine credentials. I'll bow to your experience.

Aktungbby · 12-06-13, 11:40 AM

Aktungbby · 12-06-13, 11:47 AM

Quote:

Originally Posted by Sailor Steve

Them's some mighty fine credentials. I'll bow to your experience.

It doesn't count that I placed second at Omaha in the 5-axel Parallel parking event of a truck rodeo! 65' and 80,000 lbs., and there was NO power steering?!!!

Lordy, I'm datin' myself again!

CaptBones · 12-06-13, 09:16 PM

Hello again Sailor Steve...yeah, you might have gotten the short end of the stick in some ways by being an RM, but then you didn't have to experience all of the really unpleasant topside evolutions in bad weather that the BMs and non-rated seamen did...or did you have a line-handler billet during UNREP "events" (always a millions laughs there

)? Anyway, you're right, low to moderate speed was critical. The "Laffey" event was done at around 7-8kts max and I backed the "Grampus" (SS-523) up the channel to change berths at the D&S piers in Norfolk at about the same speed (or maybe it was the "Clamagore" (SS-343)...my memory sometimes confuses which ship goes with which event)...and just for "grins"...I'm amazed that two of those old sea duty assignments of mine are museum ships at Patriots Point in SC.

But, back to the subject. The reference material you provided a link to, is likely oriented to merchant ships, which for the most part have significantly different hull shapes than warships (and submarines especially). The merchant hulls are typically more "boxy" (have less dead rise in hull transverse cross-section and at the stern in longitudinal cross-section) and are almost all single-screw/single-rudder with a transom stern hull form.

The warship hull is more often multi-screw/multi-rudder with more dead rise and with skegs for each shaft-line. The physics of the action of the rudder(s) when going astern is also bass-ackwards, in that rudder angle going ahead produces a strong turning moment at the "trailing edge" of the hull, and rudder action going astern produces a weak turning moment at the "leading edge" of the hull. All that gives some advantage to the warship when going astern, but even with that it's seldom done at "high speed".

Another BUT...I also got my directions backwards

thanks to that memory issue; I was recalling the handling characteristics of a couple of types of ships with large bow-mounted sonar domes (those puppies really "anchor" the pivot point near the bow when going astern at any speed). You're right about the movement of the pivot point aft (towards the stern) when going astern, for older DDs and "conventional" type submarines. It doesn't move beyond a point roughly amidships though; it's that hull-form thingy again...

Another "yup" regarding speed is also due. Because you're dealing with that weak "leading edge" moment, in any sea state above 2 or 3, or going astern at more than 7-10 kts, a surface ship helmsman will have an unpleasant time trying to keep a steady course. The submarine can do much better; the "Fleet" boat because of the hull form and "uniformly" deep draft of the hull as well as that huge single rudder (at the very front of the hull when going astern) and I'd suspect the U-boat also...hull form and twin rudders.

In SH, I haven't used sternway at more than 4-5kts, but in RL the "conventional" boat does handle well at astern speeds over 10 kts. You don't want to do any more than that though; the forces exerted on the rudder/rudderpost and steering mechanism that way, can seriously damage them all, starting with wiping the rudder post bearings and seals. I suspect the game has only one method of calculating turn rate and it doesn't change with a change in direction, so it's likely to be too good for steering with sternway.

Leandros's second comment hit another key point WRT the game, but I have to add that the rudder control in the SH games is not at all correct. Every course change ordered, more than a few degrees, gets the same response - 40 degrees of rudder - I'd keel-haul the helmsman who did that (or rather the conning officer who allowed it to happen). In warships you have three standard rudder commands; "right/left standard rudder", "right/left full rudder" and "hard right/left rudder". You can also specify the rudder angle; "-- degrees right/left rudder". "Hard" rudder is only used in extreme circumstances (that's why it's said differently than the other commands...gets the helmsman's immediate attention); it runs the steering engine mechanism "into the stops" where an actual mechanical device prevents further movement of the yoke or crosshead that turns the rudder post. That's asking for a jammed rudder. "Standard" rudder is usually half the travel, in degrees, as "hard" rudder (that'd be 20 degrees for our SH U-boats) and "full" rudder is usually halfway between "standard" and "hard". "Standard" is "standard" because it's the best compromise between loss of speed and good turning rate and size of the turning circle. For best maneuverability in a tactical situation, you'll typically sacrifice a little speed to increase the turn rate and tighten the turning circle...using "full rudder", not "hard".

Lastly...Aktungbby is clearly in serious need of psychiatric help...or another six-pack of Hamm's...same difference. My hat's off to anyone who can handle a big rig without power steering, parallel parking at that (!), regardless of "only" placing second.

Well, enough...I've got a five year old grandson standing here asking to go to the SH3 Naval Academy to do some target practice...get 'em "hooked" while they're young!

Sailor Steve · 12-07-13, 11:31 AM

Quote:

Originally Posted by CaptBones

I'm amazed that two of those old sea duty assignments of mine are museum ships at Patriots Point in SC.

I was aboard USS Brinkley Bass (DD-887) in 1970. She was sold to Brazil in 1973, and served there until 1997, then sunk as a target in 2000.

Quote:

But, back to the subject...

I just wanted to thank you again for your input. There are always new things to be learned, and someone who has actually done it is the best possible source.

Quote:

Well, enough...I've got a five year old grandson standing here asking to go to the SH3 Naval Academy to do some target practice...get 'em "hooked" while they're young!

Oh yeah!

BigWalleye · 12-07-13, 08:17 AM

Quote:

Originally Posted by Aktungbby

It doesn't count that I placed second at Omaha in the 5-axel Parallel parking event of a truck rodeo! 65' and 80,000 lbs., and there was NO power steering?!!!

Lordy, I'm datin' myself again!

Only if you put your vessel on a (large) flatbed, a la U-505.

Aktungbby · 12-07-13, 01:34 PM

Quote:

Originally Posted by CaptBones

Lastly...Aktungbby is clearly in serious need of psychiatric help...or another six-pack of Hamm's...same difference. My hat's off to anyone who can handle a big rig without power steering, parallel parking at that (!), regardless of "only" placing second.

around.

BigWalleye · 12-07-13, 02:52 PM

Great story!

Quote:

Originally Posted by Aktungbby

in the dead of winter 'mit' crane and divers! Fortunately that little bar served ...Hamm's...

I just have one question: Did the bear help?

Aktungbby · 12-07-13, 06:50 PM

Quote:

Originally Posted by BigWalleye

Great story!

I just have one question: Did the bear help?

.U Betcha'

Andrewsdad · 12-08-13, 10:06 AM

Salute !!!

This course in steering and helmsmanship is fascinating !!! Now how about this question....

What happens when our boat is submerged. I know that a certain amount of speed is required to keep depth, but what are the ramifications of backing?

In game, if I am too close to the target track I will not reverse because I think that it is unrealistic and that the boat would probably swing too much as steerage way is lost and then regained and also holding periscope depth would be very hard.

Am I right?

Thanks,
AD

12-06-13, 11:40 AM	#2
Aktungbby Gefallen Engel U-666 Join Date: Jul 2013 Location: On a tilted, overheated, overpopulated spinning mudball on Collision course with Andromeda Galaxy Posts: 30,049 Downloads: 24 Uploads: 0	Aktung ASEA! __________________ "Only two things are infinite; The Universe and human squirrelyness?!! Last edited by Aktungbby; 12-28-13 at 01:35 AM.

12-06-13, 09:16 PM	#4
CaptBones The Old Man Join Date: Nov 2010 Location: Rockton, IL Posts: 281 Downloads: 208 Uploads: 0	Mo' betta' info... Hello again Sailor Steve...yeah, you might have gotten the short end of the stick in some ways by being an RM, but then you didn't have to experience all of the really unpleasant topside evolutions in bad weather that the BMs and non-rated seamen did...or did you have a line-handler billet during UNREP "events" (always a millions laughs there)? Anyway, you're right, low to moderate speed was critical. The "Laffey" event was done at around 7-8kts max and I backed the "Grampus" (SS-523) up the channel to change berths at the D&S piers in Norfolk at about the same speed (or maybe it was the "Clamagore" (SS-343)...my memory sometimes confuses which ship goes with which event)...and just for "grins"...I'm amazed that two of those old sea duty assignments of mine are museum ships at Patriots Point in SC. But, back to the subject. The reference material you provided a link to, is likely oriented to merchant ships, which for the most part have significantly different hull shapes than warships (and submarines especially). The merchant hulls are typically more "boxy" (have less dead rise in hull transverse cross-section and at the stern in longitudinal cross-section) and are almost all single-screw/single-rudder with a transom stern hull form. The warship hull is more often multi-screw/multi-rudder with more dead rise and with skegs for each shaft-line. The physics of the action of the rudder(s) when going astern is also bass-ackwards, in that rudder angle going ahead produces a strong turning moment at the "trailing edge" of the hull, and rudder action going astern produces a weak turning moment at the "leading edge" of the hull. All that gives some advantage to the warship when going astern, but even with that it's seldom done at "high speed". Another BUT...I also got my directions backwards thanks to that memory issue; I was recalling the handling characteristics of a couple of types of ships with large bow-mounted sonar domes (those puppies really "anchor" the pivot point near the bow when going astern at any speed). You're right about the movement of the pivot point aft (towards the stern) when going astern, for older DDs and "conventional" type submarines. It doesn't move beyond a point roughly amidships though; it's that hull-form thingy again... Another "yup" regarding speed is also due. Because you're dealing with that weak "leading edge" moment, in any sea state above 2 or 3, or going astern at more than 7-10 kts, a surface ship helmsman will have an unpleasant time trying to keep a steady course. The submarine can do much better; the "Fleet" boat because of the hull form and "uniformly" deep draft of the hull as well as that huge single rudder (at the very front of the hull when going astern) and I'd suspect the U-boat also...hull form and twin rudders. In SH, I haven't used sternway at more than 4-5kts, but in RL the "conventional" boat does handle well at astern speeds over 10 kts. You don't want to do any more than that though; the forces exerted on the rudder/rudderpost and steering mechanism that way, can seriously damage them all, starting with wiping the rudder post bearings and seals. I suspect the game has only one method of calculating turn rate and it doesn't change with a change in direction, so it's likely to be too good for steering with sternway. Leandros's second comment hit another key point WRT the game, but I have to add that the rudder control in the SH games is not at all correct. Every course change ordered, more than a few degrees, gets the same response - 40 degrees of rudder - I'd keel-haul the helmsman who did that (or rather the conning officer who allowed it to happen). In warships you have three standard rudder commands; "right/left standard rudder", "right/left full rudder" and "hard right/left rudder". You can also specify the rudder angle; "-- degrees right/left rudder". "Hard" rudder is only used in extreme circumstances (that's why it's said differently than the other commands...gets the helmsman's immediate attention); it runs the steering engine mechanism "into the stops" where an actual mechanical device prevents further movement of the yoke or crosshead that turns the rudder post. That's asking for a jammed rudder. "Standard" rudder is usually half the travel, in degrees, as "hard" rudder (that'd be 20 degrees for our SH U-boats) and "full" rudder is usually halfway between "standard" and "hard". "Standard" is "standard" because it's the best compromise between loss of speed and good turning rate and size of the turning circle. For best maneuverability in a tactical situation, you'll typically sacrifice a little speed to increase the turn rate and tighten the turning circle...using "full rudder", not "hard". Lastly...Aktungbby is clearly in serious need of psychiatric help...or another six-pack of Hamm's...same difference. My hat's off to anyone who can handle a big rig without power steering, parallel parking at that (!), regardless of "only" placing second. Well, enough...I've got a five year old grandson standing here asking to go to the SH3 Naval Academy to do some target practice...get 'em "hooked" while they're young!

12-08-13, 10:06 AM	#10
Andrewsdad Machinist's Mate Join Date: May 2001 Posts: 130 Downloads: 81 Uploads: 0	Salute !!! This course in steering and helmsmanship is fascinating !!! Now how about this question.... What happens when our boat is submerged. I know that a certain amount of speed is required to keep depth, but what are the ramifications of backing? In game, if I am too close to the target track I will not reverse because I think that it is unrealistic and that the boat would probably swing too much as steerage way is lost and then regained and also holding periscope depth would be very hard. Am I right? Thanks, AD