Merchant Marine Stability and Trim License Questions

Your vessel rolls slowly and sluggishly. This indicates that the vessel __________. A. has off-center weights B. is taking on water C. has a greater draft forward than aft D. has poor stability

Please keep in mind this applies to small angles of transverse inclination say no more than 5 to 8 degrees. As B moved transversely it travels in the path of an arc for a wall sided vessel. The center of the arc is located at M where B is acting upward through M, the Metacenter. The radius of this arc is BM, the Metacentric Radius. My favorite illustration is Fig. 16-2, on page 46, of the 4th Edition of "Stability and Trim for the Ship's Officer".

What is the definition of transverse metacenter? A. The distance between the actual center of gravity and the maximum center of gravity that will still allow a positive stability. B. The point to which G may rise and still permit the vessel to possess positive stability. C. The sum of the center of buoyancy and the center of gravity. D. The transverse shift of the center of buoyancy as a vessel rolls.

If the metacentric height is small, a vessel will __________. A. be tender B. have a quick and rapid motion C. be stiff D. yaw

Your vessel's draft is 24'-06" forward and aft. The MT1 of your vessel is 1000 ft-tons. How many tons of cargo must be loaded in number 4 hold, which is 100 feet abaft the tipping center, if she is to have a 2 foot drag? (Note: drag = trim by stern), (tipping center = LCF) A. 120 tons B. 240 tons C. 300 tons D. 480 tons

A vessel's KG is determined by __________. A. dividing the total longitudinal moment summation by displacement B.  dividing the total vertical moment summation by displacement C. multiplying the MT1 by the longitudinal moments D. subtracting LCF from LCB

Which will be a result of removing on-deck containers? A. KG will increase B. Metacentric height will increase C. KB will increase D. Reserve buoyancy will decrease

This poem first appeared in the Scots Observer in 1888, several years after the publication of the enormously successful adventure novel TREASURE ISLAND.        The sheets were frozen hard, and they cut the naked hand; The decks were like a slide, where a seaman scarce could stand; The wind was a nor'wester, blowing squally off the sea; And cliffs and spouting breakers were the only things a-lee. They heard the surf a-roaring before the break of day; But 'twas only with the peep of light we saw how ill we lay. We tumbled every hand on deck instanter, with a shout, And we gave her the maintops'l, and stood by to go about. Advertisement All day we tacked and tacked between the South Head and the North; All day we hauled the frozen sheets, and got no further forth; All day as cold as charity, in bitter pain and dread, For very life and nature we tacked from head to head. We gave the South a wider berth, for there the tide race roared; But ever...

Just select the language with the drop down  menu. Please try it out and let me know if you like it. Merry Christmas and Happy New Year!

Which statement about the free surface effect is TRUE? A. It increases in direct proportion to the length of the tank times the breadth squared. B. It decreases at increased angles of heel due to pocketing when a tank is 90% full. C. It decreases in direct proportion to increasing specific gravity of the liquid in the tank. D. In practice, the correction is considered to be a virtual reduction of KG.

Once the Holiday festivities have quieted down check out the Special Poem posted. Here is my my wish in the New Year: More people need to post the answers to the questions not just look at them. If you do not understand the question or the best answer just ask. You might be pleased with the understanding you gain. I would also like to ask that more people to share this site with their friends as well as subscribe. Happy Holidays and Happy New Year to All! William

Metacentric height is an indication of a vessel's stability __________. A. for all angles of inclination B. for large angles of inclination C. for small angles of inclination D. in no case

Which statement is TRUE of a tender vessel? A. It has a large GM. B. Its period of roll is long. C. It has a very low center of gravity. D. It has a good transverse stability.

Which abbreviation refers to the horizontal distance between perpendiculars taken at the forward-most and the after-most points on a small passenger vessel's waterline at her deepest operating draft? A. LBP B. LOA C. LWL D. LLL

Your vessel has a displacement of 24,500 tons. It is 529 feet long and has a beam of 71 feet. You have timed your full charge rolling period to be 25.0 seconds. What is your vessel's approximate GM? A. 1.25 feet B.  1.56 feet C.  1.98 feet D.  2.43 feet

When a vessel has positive stability, the distance between the line of force through B and the line of force through G is called the __________. A. metacentric height B. righting arm C. righting moment D. metacentric radius

A vessel is described as a two compartment vessel when it __________. A. has no more than two compartments B. has two compartments in addition to the engine room C. will sink if any two compartments are flooded D. will float if any two adjacent compartments are flooded

The center of flotation of a vessel is __________. A. the center of volume of the immersed portion of the vessel B. the center of gravity of the water plane C. that point at which all the vertical downward forces of weight are considered to be concentrated D. that point at which all the vertical upward forces of buoyancy are considered to be concentrated

My father taught me so I could teach others.  He was an U.S. ARMY Harbor Craft Master in WWII.   He could do it all except for Celestial Navigation.

Forces within a vessel have caused a difference between the starboard and port drafts. This difference is called __________. A. list B. heel C. trim D. flotation

Which statement about free surface is TRUE? A. A partially filled space with 40% surface permeability will have greater free surface effect than one with 60% surface permeability. B. Pocketing increases the loss of GM due to free surface effect. C. Cargo with a specific gravity of 1.05 has less free surface effect than a cargo with a specific gravity of 0.98. D. Pocketing occurs at small angles of inclination when a tank is 98% full.

The ship's tanks most effective for trimming are the __________. A. deeps B. domestics C. peaks D. settlers

Which is an indication of reserve buoyancy? A. Metacentric height B. Righting moment C. Rolling period D. Freeboard

The volume of a vessel's intact watertight space above the waterline is its __________. A. free surface B. marginal stability C. reserve buoyancy D. freeboard

Reserve buoyancy is __________. A. also called GM B. the void portion of the ship below the waterline which is enclosed and watertight C. affected by the number of transverse watertight bulkheads D. the watertight portion of a vessel above the waterline

Your vessel is damaged and listing to port. There is a short rolling period around the angle of list. The port side freeboard is reduced to 1 foot. There is no trim and the weather is calm. You should FIRST __________. A. press up a slack double bottom tank on the port side B. fill an empty centerline double bottom tank C. pump out a slack marine portable tank located on the portside amidships D. jettison the anchors and anchor cables

This is called a "SUN DOG" ( parhelion) . The American Practical Navigator, BOWDITCH, mentions this but does not tell you what it means when you see it. A SUN DOG normally is a small section of what looks like a segment of a rainbow concentric with the sun low in the sky. It is usually two points or 22.5 degrees on either side of the sun. This image was taken about 0900 in the morning at Commencement Bay, Tacoma Washington, USA. The weather was calm. As my father's story goes if you see a SUN DOG very bad weather will arrive in about 48 hours.  Well, 48 hours later there was a wind storm that knocked out electricity in the Greater Seattle Area for about 5 days with trees being blown down.

To prevent loss of stability from free communication flooding you should __________. A. close the cross connection valve between the off-center tanks B. completely flood high center tanks C. ballast double bottom wing tanks D. close any opening to the sea in an off-center tank

To increase the extent of flooding your vessel can suffer without sinking, you could __________.   A. ballast the vessel   B. increase reserve buoyancy C. lower the center of gravity D. raise the center of gravity

Of the following, the most important consideration for a tank vessel is __________.   A. GM B. the vertical center of gravity C. the longitudinal center of gravity   D. the stress on the hull  

Of the following, the most important consideration for a tank vessel is __________.     A. GM B. the vertical center of gravity C. the longitudinal center of gravity     D. the stress on the hull

What is the LCG required for zero trim for at specific draft?  (Hint no calculation is required.) To be clear a zero trim condition is that where the forward and after draft are equal provided there is no hull deflection. Why would you want to know this? Just consider receiving orders to take maximum cargo to arrive at a specific draft for discharging. If you know the required LCG it is easy to work backwards to determine the required sailing draft at the loading port as well as the maximum cargo to load.  Sadly, this is not a license question. I have found only about 1 in 100 Chief Officers and Vessel Master's know the answer.

The TPI curve, one of the hydrostatic curves in a vessel's plans, gives the number of tons __________ .     A. necessary to change the angle of list 1° at a given draft     B. necessary to change trim 1 inch at a given draft C. pressure per square inch on the vessel's hull at a given draft D. necessary to further immerse the vessel 1 inch at a given draft

What is the displacement of a barge which measures 85' x 46' x 13' and is floating in salt water with a draft of ten feet?   A. 1117 tons   B. 1452 tons   C. 500 tons   D. 17.5 tons

Which statement about the free surface correction is TRUE?     A. It is added to the uncorrected GM to arrive at the corrected available GM.     B. It is obtained by dividing the free surface moments by 12 times the volume of displacement.     C. It is obtained by dividing the total free surface by the total vertical moments.     D. It is subtracted from the total longitudinal moments before dividing by displacement to find LCG.

When cargo is shifted from the lower hold to the main deck the __________. A. center of gravity will  move upwards     B. GM will increase C. center of buoyancy will move downward     D. All of the above

What does NOT affect the value of the free surface correction?     A. Width of the tank     B. Length of the tank     C. Registered tonnage     D. Specific gravity of the liquid in the tank