# Use of anchors on huge ships? **URL:** \ **Category:** Factual Questions\ **Created:** [December 28, 2011, 12:16am UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579 "2011-12-28T00:16:09Z")\ **Posts on this page:** 9\ **Page:** 8
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 21, 2016, 4:22pm UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/141 "2016-04-21T16:22:51Z")
> [@tonyfop](#): > > Oh, and **spifflog** can attest better to this part - every 100 feet of the anchor chain is painted a different color. I beleive that it goes red,white,blue repeating until you get to the last two lengths (shots?) which are yellow and red to warn you that you are coming to the end of the chain. From what I hear, if you see yellow, you are supposed throw the brake on, and if you see red, you need to get the \*\*\*\* out of there because if the anchor chain comes loose, its going to take a large portion of the fo’c’sle (sp? sorry, I’m not a Boatswain’s Mate) with it… Time to get the \*\*\*\* out of there: [http://youtu.be/lLLBhIJbVFs](http://youtu.be/lLLBhIJbVFs) ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 21, 2016, 4:29pm UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/142 "2016-04-21T16:29:51Z")
Annotated (analytical) vid of anchor free-fall mishap on USS Tarawa: [http://youtu.be/b7pRfix\_sNg](http://youtu.be/b7pRfix_sNg) ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [April 21, 2016, 5:12pm UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/143 "2016-04-21T17:12:58Z")
> [@Isilder](#): > > There are 4 deep basins in the Med, they are so deep they were thought to be literally the remains of an ocean, but now known not to represent anything so old, there’s some trenchs like the start of a new ocean, thats all. > > Well anyway, there’s heaps of anchorage depth sea … > The east of Spain has heaps, way out to around the Ballaeric Islands (Majorca). > > The east of Tunisia has two gulfs named, but they merge into a large area … this extends a long way out, 1/3 of the way to Italy… > > Most of the Adriatic Sea is shallow enough to anchor in, all the way north from Montenegro up to Trieste. > > There’s a large strip from Alexandria to Israel, and theres the sound (shallows between island and main land) formed by Cyprus … There’s numerous thin strips which are liable to be in the local nations control. Not sure what your point is here - these ships were too large for Suez, so would not be in the Med. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [April 23, 2016, 5:54am UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/144 "2016-04-23T05:54:14Z")
> [@silenus](#): > > _Theoretically_, a super-carrier might have to base is a lagoon somewhere during a shooting war. But given the speed and range of the ships, I really don’t think there is any _practical_ need for anchors these days. But it’s the Navy. They still teach celestial navigation and how to use a sextant. Also handy _theoretical_ skills to have. There’s a special aspect to the zombie nature of this thread. Aside his nonsense concerning large ships not utilizing anchors, the implied notion that the navy was mired in outdated methodology in navigation was just wrong. At the time of Silenus’s post five years ago, the navy was in fact, pursuing a total abandonment of training in celestial navigation, pursuant to current technological trends. The irony is, now that the fragility of satellite network geo-location has been realized, the navy is now reinstituting training in old school celestial navigation with a sextant for officers. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [April 23, 2016, 10:07am UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/145 "2016-04-23T10:07:48Z")
> [@bob\_2](#): > > Not sure what your point is here . I can’t help with your complaint that the facts don’t serve a clear purpose. You are wrong about large ships in the med. The old harbours of the med mean that the very largest ships aren’t used there, but the 2nd largest size is ! See [http://www.lr.org/en/\_images/213-35657\_30-ship-sizes.pdf](http://www.lr.org/en/_images/213-35657_30-ship-sizes.pdf) ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [April 23, 2016, 1:10pm UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/146 "2016-04-23T13:10:45Z")
> [@Francis\_Vaughan](#): > > For what should be the absolute last word on this try [here](http://alain.fraysse.free.fr/sail/rode/rode.htm), for a very solid mathematical treatment. (Follow the tiny arrow in the lower right hand corner.) For a one page summary try [this](http://www.rocna.com/kb/Scope_vs_catenary). (although the latter conclusions are mostly directed at smaller boats.) From the link above: > [@](#): > > The seabed acts on the boat via the anchor and the rode. If the anchor is not dragging, the bottom force is a reaction force, vectorially equal to the rode tension at the anchor pulling eye ((hopefully horizontal - see the static behavior chapter) + the anchor weight (vertical). If the anchor drags, the horizontal resistance decreases somewhat. Since dragging is the consequence of a rode overtension, this means dragging will continue unless the overtension stops or the anchor hooks something firmer! > > By the way, do not rely on the friction of the chain on the bottom to hold your yacht: it never exceeds a few dozens of kg or lb, except if it meets rocks, coral patches etc.! Otherwise, we would never need an anchor, would we? As we’ll see in the next chapters, **having a fair length of chain lying on the bottom is not intended to increase the holding power via the chain friction, but instead to keep the tension on the anchor horizontal when the rode tightens.** ---
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [April 23, 2016, 2:15pm UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/147 "2016-04-23T14:15:40Z")
> [@ZurBob](#): > > There’s a special aspect to the zombie nature of this thread. Aside his nonsense concerning large ships not utilizing anchors, the implied notion that the navy was mired in outdated methodology in navigation was just wrong. > > At the time of Silenus’s post five years ago, the navy was in fact, pursuing a total abandonment of training in celestial navigation, pursuant to current technological trends. > > The irony is, now that the fragility of satellite network geo-location has been realized, the navy is now reinstituting training in old school celestial navigation with a sextant for officers. You forgot to mention that LORAN (which had its own role in pushing celestial navigation to the wayside) had been phased out in favour of GPS also. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [October 15, 2016, 2:02pm UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/148 "2016-10-15T14:02:53Z")
Good mini-documentary on removal and repair of USS Nimitz (aircraft carrier) anchor and chains (350 lbs/link), starting 16:10: [The Scale Of Aircraft Carrier Maintenance Is Ridiculous](http://foxtrotalpha.jalopnik.com/the-scale-of-aircraft-carrier-maintenance-is-ridiculous-1787764141) ---
**Author:** ![SCAdian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scadian/32/3292_2.png) [@SCAdian](https://boards.straightdope.com/u/SCAdian)\ **Post date:** [October 16, 2016, 2:52am UTC](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579/149 "2016-10-16T02:52:20Z")
Since Leo woke the thread up… > [@LSLGuy](#): > > IANA big ship sailor. But I did live at the mouth of the Panama Canal for several years and both drive & fly over it daily. I also fly over NY, LA, & Long Beach harbors fairly frequently & have for decades. > > There were/are almost always (90+%) several big ships anchored at both ends of the Canal. Ditto on the outskirts of NY & LA / LGB harbor. Seeing a dozen anchored ships would not be extraordinary. And these represent several of the biggest & busiest shipping points on earth. The Panama Canal is like a two-lane road, with traffic going in both directions. Before it was remodelled in 2014-15, most of the Suez Canal was one-way. Ships transiting the canal would arrive the day before and drop anchor whilst waiting to start through the next morning. There were three convoys each day – two southbound and one northbound. The northbound convoy simply entered the canal and sailed through. The first southbound convoy would proceed as far as the Great Bitter Lake, then clear the channel and anchor until the northbound convoy passed. The second southbound convoy would anchor in the Ballah bypass (like a train waiting on a siding) until the northbound convoy passed. So every ship transiting the canal, no matter what size, spent time at anchor. [Previous page](https://boards.straightdope.com/t/use-of-anchors-on-huge-ships/607579.md?page=7)