What is Marine: Definition and 63 Discussions

The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combined arms, implementing its own infantry, armor, artillery, aerial and special operations forces. The U.S. Marine Corps is one of the eight uniformed services of the United States.
The Marine Corps has been part of the U.S. Department of the Navy since 30 June 1834 with its sister service, the United States Navy. The USMC operates installations on land and aboard sea-going amphibious warfare ships around the world. Additionally, several of the Marines' tactical aviation squadrons, primarily Marine Fighter Attack squadrons, are also embedded in Navy carrier air wings and operate from the aircraft carriers.The history of the Marine Corps began when two battalions of Continental Marines were formed on 10 November 1775 in Philadelphia as a service branch of infantry troops capable of fighting both at sea and on shore. In the Pacific theater of World War II the Corps took the lead in a massive campaign of amphibious warfare, advancing from island to island. As of 2017, the USMC has around 182,000 active duty members and some 38,500 personnel in Reserve.

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  1. BWV

    Methanol - H fuel cells for marine transport

    This privately held company developed a technology to extract H from methanol stored onboard marine craft, then the H can be used in a fuel cell for power. I assume the reason for a H fuel cell vs a direct methanol fuel cell (DMFC) in a marine vessel is that direct methanol cannot deliver large...
  2. T

    Cooling a marine engine while testing

    For my internship I have to test and certify a Marine diesel engine. We are trying to run a few tests in our workshop, but this obviously means we can't use the sea or a river as cooling. We bought an IBC tank, which can hold a 1000 liters of water. The water from the tank will be running...
  3. BiGyElLoWhAt

    Building a Low Power DiY marine bluetooth speaker set

    My dad has been asking about some speakers for his boat, something that will move a bit of air, not too big though. I'm thinking 1x12. He also wants it bluetooth and powered externally, so it doesn't drain the boat battery. So I'm thinking 1x12 speaker in a small box that can fit inside the...
  4. A

    Rotating waveguide antenna (rotating marine radar)

    I've seen these devices on shores as well as on ships , like a horizontal tube rotating slowly around it;'s axis. Now from what I know it's a type of radar, and unlike phased array it rotates it's beam physically by means of using a motor to rotate the antenna itself , what I want to know is...
  5. T

    Is there any way to find out how a US Marine died in WW2?

    I have a "first cousin, twice removed" who died in the Pacific theater of World War 2. He died on September 18, 1942. He was buried in Honolulu, Hawaii. He lived in Chicago, IL when he entered the service, so apparently the US Military did not bring bodies of killed soldiers back home in WW2. He...
  6. GiriBang

    Engineering Navigating a Career in Marine Engineering: Is It Unemployable?

    Right, I'm ambitious about joining the Indian Navy via Graduate entry scheme or at least some private companies like Maersk. But recently a relative who took Diploma in Marine Engineering said that the industry is flooded and it's currently unemployable. He said 4th Engineers are being fired...
  7. C

    Change in a marine mammal's lung volume when diving to 200 meters

    I attempt the solution on the attachment. The answer is 0.344 litre. Do I change 7L to m, so it is 0.007 cubic meters
  8. anorlunda

    Remarkable New Marine Propulsion Systems

    I recently came back from a cruise on MS Eurodam. The ship was equipped with two 17.6 MW Azipod propulsion systems. The captain explained a bit about them in a Q&A session, and I researched a bit more because I'm curious as an engineer. I'm sharing it here on PF for the benefit of other...
  9. Biscuit

    Programs Program Guidance for a Marine Biologist

    Hello, I am looking to change my major to become a marine biologist. As I view the different programs that are out there I have come into a couple of conflicts I was hoping you guys could help me with. The first being I have the option to either major in biology and get a masters in marine...
  10. anorlunda

    KISS Principle Marine Propulsion

    I"m a big fan of the KISS principle in engineering. I'm also a boater. I just found something I wanted to share. It is a permanent magnet motor in which the propeller itself is the rotor. The video hints that it works with simple reversals of polarity similar to a stepper motor. That...
  11. J

    Insulation monitoring in some marine isolated electrical systems

    Hi, In some marine isolated electrical systems I saw that only one phase insulation resistace is monitored. Why? If something happens on other phases I will have no information about that or...? Regards!
  12. U

    UPS, Marine Battery, as Sump Pump backup

    Hey there! I'm an IT guy and found this forum through searching on replacing UPS batteries with deep cycle 12v marine batteries. The reason I was looking is I happen to have 4 spare Compaq rack mount UPSs with dead batteries taking up space in my basement. I was thinking of putting in a backup...
  13. M

    "Immortal" jellyfish habitat range, Turritopsis dohrnii?

    What is the current habitat range of Turritopsis dohrnii or the "immortal" jellyfish? I know that there are multiple species of the Turritopsis genus and that the species dohrnii have recently increased its range by ballast water spread. What is the current range of the exact species dohrnii?
  14. F

    12V Marine Deep Cycle Battery Post is Moving -- Is the Battery Damaged?

    The battery post is moving up and down. It doesn't seem to want to come all the way out. Will the battery still perform properly or is it damaged? Can it be repaired? Pictures attached.Thanks in advance.
  15. Marco97

    I Marine Propeller Thrust: How Do I Calculate It?

    Hello folks! I hope all of you are having a good day. Here is my question: How can I calculate the thrust needed by a marine propeller to move a body of about 120 kg? Also, as long we are talking about marine propeller, our propulsion is in water and not in air, so what about the rpm? Are they...
  16. L

    Engineering Engineer switching from Mechanical to Marine

    Hi, I've had a longstanding interest in working at sea. The prospect of working as an engineer at sea is quite an exciting one. I have a degree in mechanical engineering and 2 years (non relevant) experience in design and manufacture in the oil and gas industry. Im just wondering if it's...
  17. M

    Earth Science / Marine Biology

    I'm in search for a career that is 'earth' related. I also have interests in the ocean. So, my choices come down to; Earth Sciences & Marine Biology / Oceanography. Was looking for a career in the space industry, or renewable energy, but found most of it to be engineering based. And I don't...
  18. weerakkodi

    Marine Propulsion: 4 Engine-Fast Gunboat Not Achieving 20 Knots

    I have a some problem about marine propulsion. Assume the 4 engine-fast gunboat is moved by forward two engines. The boat get 10 knots. Then if other Aft two engines operate gradually. You know the boat doesn't get 20 knots speed. What are the reason for that? Explain theoretically? Thanks for...
  19. wolram

    News F-18 Jet Crash: US Marine Corps Pilot Dies in Ely, Cambridgeshire

    http://www.bbc.co.uk/news/uk-england-cambridgeshire-34593948 Thank you for your service. RIP. A US Marine Corps pilot has died in an F-18 jet crash, close to an RAF base. The jet came down on farmland in Redmere, near Ely, Cambridgeshire, with the alarm raised at 10:30 BST. The Hornet...
  20. DaveC426913

    What is the Mystery Marine Creature Found in Cuban Waters?

    Just came back from diving in Cuba. These are some sort of jellyfish or other invertebrate but I haven't found any reference to it. They have no tentacles, just a round body like a kiwi fruit. Extremely transparent and incredibly fragile. Video...
  21. TBan

    Use of Gyro/Accelerometer for Boat Tilt Application?

    Hello, I'm looking to try to use a gyroscope to determine the rocking motion (just side to side - not back and forth) of a boat while it is traveling forward or sitting still in the water. Specifically, I'm looking for the boat's angle from vertical and this angle's velocity. Can I do this...
  22. Dostetres

    Multiple BLDC per shaft for marine propulsion

    New to the forum, and can't find this info or examples on the web. I'm interested in the possibility of coupling multiple DC brushless motors to a single drive shaft for main propulsion on a 45-50', twin screw boat. Lots of sail boat examples are given, but my interest is in a power...
  23. PrincessIceFall

    How to find the depth of immersion of this boat model?

    So I am trying to find the depth of immersion of this particular boat model, which has curvilinear edges (subparabolic edges) on each side. The figure of the pontoon is shown below So now when I place this pontoon in water, the height of the water that rises, called the depth of immersion is...
  24. Jason49

    I want to study marine biology

    Hi I want to study marine biology. I just want to know how long does it take to study this field
  25. K

    So I want to be a Marine Biologist

    Yes, I know "This is the Physics Forum KimG" BUT, this is science related so I figure it counts. I'm sitting here right now at 10:27 p.m. STILL trying to figure out my Physics homework (Which by the way if half of the reason I joined this Forum in the first place) and thinking to...
  26. T

    Maximizing Marine Power: Calculating Average Output of a 200km2 Tidal Barrage

    A tidal barrage contains an area of of sea of 200km2 and the tidal range 6m at spring tides and 2m at neap tides. What would be the average power output over the year? Any help would be great,
  27. G

    What is the difference between oceanography and marine geology?

    What's the difference between oceanography and marine geology?
  28. sophiecentaur

    Marine flares: disposal thereof.

    I don't venture onto this bit of PF, very often but I thought that someone might have some information on this subject. Out of date distress flares are an embarrassment to sailors. Local waste disposal services don't handle them and even most Coastguards won't touch them. It is sometimes...
  29. R

    Marine (nautical not marine corps) - forces acting on an interceptor plate

    Despite the name interceptor, this is marine as in water, not marine as in marine corps. Interceptor plate on a boat is like a horizontal flap (airbrake, alieron, elevator) on an aircraft but is mounted below the water. Usually it's a flat rectangle (not airfoil) that drops down from the bottom...
  30. S

    G10/FR4 Fiberglass Board vs Steel marine enviroment

    I was wondering if anyone knew of the potential downsides of using this material to replace a piece of 1/4 low carbon steel that is decaying and is a backing plate inside a hull of a 28 foot sailboat. I would be replacing it with 1/2" G10/FR4 fiberglass board minimum and could go to 3/4 inch if...
  31. N

    What is the correction use to determine marine gravity anomaly

    Dear sir/ma'am, I am a bachelor of Survey Science and Geomatic student from Malaysia. This is my final year and I have to complete a research, where my research is about to evaluate marine gravity and satellite altimetry data on coastal region. 1. Homework Statement I am in the middle...
  32. R

    Marine Boiler-safe working pressure after finding pitting marks

    On finding pitting on a water tube marine boiler, after inspection, how do i check for its safe operating pressure? Would it be safe to fire it and bring it up to its design pressure as stated by the maker?
  33. B

    Adam and Eve versus our ancestral marine organism

    Folks, Can anyone recommend any books regarding the argument of we unlikely came from 'adam and eve' (devine intervention) versus evolutionary evidence etc etc Thanks bugatti
  34. N

    Engineering Marine biology and engineering question

    What possible type of engineering could I major in that would also allow me to work with marine animals?
  35. _Tully

    Marine Corps Veteran, returning to school.

    Hello! I have found a lot of useful information on this sight since I've been lurking, but I have decided to merge from the shadows to ask a few questions. I have been an active duty Marine Corps Infantryman (MOS 0351 Assaultman) for the past four years. Now, finally at the end of my enlistment...
  36. S

    Calculating Rated Power Output & Energy Capture for Marine Current Turbines

    Hi i am trying to find rated power output for turbine for tidal, and energy capture per cycle i am putting limits to integration T1 and T2 i know i can assume period of 12 hours and 25 mints which is 745 mint for quarter cycle T1 would be 745/4 so T1 is 186.25 but i don't know how cani find...
  37. Evo

    Scientists discover new marine species - so cool

    Click on the right side of the picture to scroll through. http://www.telegraph.co.uk/earth/earthpicturegalleries/7875310/Scientists-discover-new-marine-species-in-the-hidden-depths-of-the-Atlantic-Ocean.html
  38. C

    Sonic Antifouling for Marine Vessel

    Need help with understanding with visual diagram how sonic antifouling for marine vessels work.
  39. MotoH

    News Father of US Marine killed in Iraq ordered to pay.

    If this doesn't make your blood boil, you've got something wrong with you. http://www.facebook.com/group.php?gid=355406162379&ref=mf" The money will go to help pay for this cost, and for other families of fallen heroes. Bill O'Reilly promised to pay all of the costs is Mr. Snyder does...
  40. M

    Engineering Marine engineering vs. Aeronautial Engineering

    Which is a better choice for a career? Which is more interesting? Which has more scope, both in terms of employement and development as an industry? If none of these, then what about robotech engineering (can I work for a space agency if I go into this field?) or geochemical research...
  41. T

    Questions about deep sea marine life.

    I wonder how marine life can withstand the enormous pressures at the bottom of the ocean without being crushed. The deepest part of the ocean, the Mariana's trench in the pacific, which is about roughly 30,000 feet deep, does have some rather strange-looking sea life inhabiting it. How do these...
  42. G

    Marine species under pressure 60 PSI

    just wonder if there any charts are available on marine species by depth and pref. location, esp. in depths with pressure between 60 and 150 PSI, or approx. over 100 feet
  43. B

    Video of my marine biology work

    I have wanted to review these ecosystems with other biologists for a while now, usually we just stay on aquarium web sites and just now I found yours. enjoyed reading through the threads and seeing the depth of the discussion, really great place. there is about 10 years dedication into...
  44. A

    A 25 Year Old's Dilemma in Marine Science and Astrobiology

    Hi... I actually graduated two years ago so maybe it's a little late to be posting this. I've been doing community work since leaving Uni but I miss science. I have a Masters in Marine Science and Management and a BSc in Environmental Biology. My dissertation was on genetics and I have some...
  45. DaveC426913

    Help w/ Humminbird Marine GPS unit

    Anyone here into sailing or boating? I haven't left my mooring yet, been testing it at anchor but my new Humminbird 383 insists I'm pointing NE when I'm actually pointing SW. It changes its mind every so often, occasionally it's correct, but seems to return to this position. I've left it...
  46. C

    Does Water Depth Affect Marine Propeller Resistance and Cavitation?

    Is there a noticable diffence in torque required to spin a marine propeller at a constant rpm (say 2000rpm) when under a different water column? (5m vs 35m)
  47. Astronuc

    HMS Victory Wreckage found by Odyssey Marine Exploration

    Wreck of renowned British warship found in Channel http://news.yahoo.com/s/ap/20090201/ap_on_bi_ge/shipwreck_discovery Odyssey has an ongoing legal matter with Spain over another wreck that was salvaged, the Spanish galleon Nuestra Senora de las Mercedes y las Animas, which sank off Portugal...
  48. N

    Is Microwave-Based Jet Propulsion Viable for Marine Vehicles?

    Hi, I'm new to the forums and I'd like to bounce an idea off of someone :biggrin: Although I've got a physics degree, I have successfully managed to forget a lot of it as people tend to do when not practicing, and I was wondering if someone would kindly pick some holes in an idea I've had...
  49. P

    Oceanography vs marine research

    Hi all, In a document, I read the two terms above and it really puzzles me. Please help me to see the difference between the two. Thanks
  50. B. Elliott

    Concussive effects of asteroid impact on marine life

    I was doing some reading on the effects of air blasts from asteroid impacts when I realized that I've never seen any data of the potential effect on marine life. Since sound travels farther and faster in a liquid, wouldn't an asteroid impact in a large ocean (liquid) have a more profound...