Need help on a few CMM exam advanced stability questions


taking the CMM exam in a few weeks and am having a hard time figuring out questions 033064 through 033069 on the (upside down) attachment. they are also found on page 286 of Murphy’s Deck officer Study Guide #3 2011-2012 edition and correspond to: USCG questions # DS02900, DS02880, DS02880, DS02910, DS02950, DS02940, & DS02920.

i have been over these a number of times from different angles & keep coming up NIL.

any help & explantions would be appreciated.

thanks in advance,


ps boobs, beer, & fishing

sorry for not taking the time to fix the upside down attachment, but I’m grumpy, tired, and frustrated right now.

<!–[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]–><!–[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:“Table Normal”; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:“Times New Roman”;} </style> <![endif]–> You have loaded deck cargo and the vessel has assumed a 7° list due to
negative GM. Your salt water drafts are: FWD 16’ 00", AFT 16’ 02". If you
then load 1050 tons of cargo in the lower holds (/CG 11.0’) and take on
600 tons of bunkers (VCG 2.5’), what is the final GM?
(Use the reference material in Section 1, the blue pages of the Stability
Data Reference Book)

Mean Draft = 16’ 01"
From Deadweight Scale: Displacement = 7,920 tons

From Hydrostatic Curves: KM = 27’00" KB = 8’06" BM = 18’06" (18.5’)

(tan angle of loll)² = 2GM/BM

GM = (tan angle)² x BM/2
= (tan 7°)² x 18.5’/2
= .01507 x 18.5’/2
= -0.1

KG = KM – GM
= 27’- (-0.1)
= 27’ + 0.1
= 27.1’

w x d = moment:

Ship: 7,920 x 27.1 = 214,632

Cargo: 1,050 x 11.0 = 11,550

Bunker: 600 x 2.5 = 1500

New KG = Total Moments / Total Weights
= 227,682 / 9,570
= 23.79’

For new displacement (9,570) mean draft = 19’ 00”
For mean draft 19’ 00", new KM = 25.8’

KM = 25.8’
KG = 23.8’
GM = 2.0’

Studying to re-take CMM stability myself. Capt. Joes is the way to go - best money spent, and solutions to problems makes it possible to “reverse engineer” the question and easily see where the trouble is. and $90 I think - please correct me if I am wrong.
Memphis REC is also a great place to test. People are professional and friendly, room is comfortable and has all reference material available and in order. They don’t get many blue-water guys through there so I would suggest if doing stability bring your own copy of stability data reference that you can write on and have them look through it prior to approve it. (I believe the SDRB states that certain pages - particularly tables where you must create your own curves/tank capacities/floodable length, etc will be available for you to write on, but as I stated - they don’t get many in there taking tests requiring creation of stability curves).
Hope it helps. Only other thing I can add is - if your a slow as I am - allow all 3 1/2 hrs for the 15 question test.

Also - they open at 8 - not 7:30. Stay well clear of Econolodge which is only a couple of blocks way, make sure you try A&R BBQ just around the corner.

black_angel: it worked like a champ, thanks. luckily for me (and my confidence) i was very very close, i was only doing the last step wrong. other then this so far so good on stability, but i was always pretty good at math.

todd.harter: thanks for the heads re Memphis.i had actually wondered about taking a “blue water” exam there in “brown water” turf. in any event, I live in Manhattan NYC so I’ll just jump on the subway south a few stops to the NYC REC right next to the staten island ferry terminal. skirt watching & hot dog or kebab from street vendor for lunch as usual… life in the city. good luck on your re-take!!