PE · NCEES · Concept refresher

Briefs for all 13 knowledge areas.

One brief per knowledge area, weighted the way the NCEES specification is. What each area asks, the relations worth carrying, the mistakes that cost marks, and a recall list. The reference handbook is on screen in the exam — these briefs are for knowing what to look for.

ExamPE NA&ME
Areas13 briefs
Format85 questions, 8.5 h
01 Hydrostatics 02 Hydrodynamics 03 Ocean engineering 04 Structures 05 Arrangements 06 Propulsion 07 Piping 08 Auxiliaries 09 Electrical 10 Environmental 11 Outfitting 12 Materials 13 Rules
01 / 1310–15 questions

Hydrostatics & Stability

The largest single area on the paper. Nothing here is unfamiliar to a naval architect — the challenge is doing it quickly and in US customary units as often as SI.

What the paper asks

Displacement and curves of form; form coefficients; TPI and MT1; intact stability and the GZ curve; free surface; damage stability and subdivision; inclining experiment; and trim and draught problems.

The concepts, in order

Units are the difficulty, not the theory. The exam mixes SI and US customary freely. Long tons, feet, TPI in tons per inch and MT1 in foot-tons per inch appear alongside metric equivalents, and 35 cubic feet of sea water per long ton is a constant worth having by heart.

The reference handbook is on screen. Formulas are supplied, so the marks go to setting the problem up correctly and choosing the right relation — not to recall. Practise locating things quickly rather than memorising them.

Damage stability appears in outline. Lost buoyancy, permeability, and the criteria a damaged condition must satisfy. Deep probabilistic calculations are not asked; understanding what the index means is.

Free surface and the inclining experiment recur. Both are conceptually simple and both reward care: the correction that does not depend on quantity, and the experiment whose precautions all exist to remove something that would corrupt the measured angle.

Where marks are lost

  • Mixing long tons and metric tonnes. One long ton is 2240 lb, about 1.016 t.
  • Using 35 ft³/LT for fresh water. Fresh water is 36 ft³/LT.
  • Trimming about amidships. The ship trims about the centre of flotation.
  • Forgetting free surface in a damaged or partly filled condition.
60-second recall
  1. 35 ft³/LT sea water, 36 ft³/LT fresh.
  2. GM = KM − KG − FSC.
  3. TPI = A_W/420 (long tons per inch, A_W in ft²).
  4. Trim about the centre of flotation.
  5. Locate formulas in the handbook, do not memorise them.
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02 / 136–9 questions

Hydrodynamics

Resistance, propulsion and powering — the chain from hull form to installed horsepower, with the model-ship extrapolation that connects them.

What the paper asks

Resistance components and model testing; ITTC friction line; Froude scaling; propeller open-water characteristics; wake and thrust deduction; the efficiency chain; cavitation; and powering estimates.

The concepts, in order

The extrapolation procedure is the reliable question. Model at equal Froude number, compute friction separately for model and ship at their own Reynolds numbers, transfer the residuary coefficient unchanged, add a correlation allowance on the ship side only.

The efficiency chain runs from towrope to engine. Effective power divided by hull, open-water and relative rotative efficiencies gives delivered power; shaft losses give brake power. Knowing which power a question asks for is half the mark.

Propeller coefficients use speed of advance. J, K_T and K_Q are defined with V_a and with n in revolutions per second. Substituting ship speed or rpm is the classic error and it appears in this exam as it does in every other.

Cavitation is a pressure problem. Local pressure falling to vapour pressure on the blade back; cured by blade area rather than by blade shape alone. Burrill-type checks and the cavitation number are the examinable tools.

Where marks are lost

  • One friction coefficient for model and ship.
  • Scaling wetted surface by λ instead of λ².
  • Using ship speed in the advance coefficient.
  • Reporting effective power where brake power is wanted.
60-second recall
  1. Equal Froude number for the test; own Reynolds number for friction.
  2. C_F = 0.075/(log₁₀R_n − 2)².
  3. η_D = η_O·η_H·η_R.
  4. J = V_a/(nD), n in rev/s.
  5. P_E = R_T·V, before any propulsive loss.
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03 / 134–6 questions

Ocean Engineering

Waves, motions and the loads a structure sees in a seaway — a small area on the paper that draws on a large body of theory, so target the standard results.

What the paper asks

Linear wave theory and the dispersion relation; wave energy and group velocity; sea state statistics and significant wave height; ship motions and RAOs; encounter frequency; mooring and station keeping; and Morison loading on slender members.

The concepts, in order

Check the water depth before choosing a formula. Deep water above d/λ = 0.5, shallow below 0.05, and the full dispersion relation in between. Most errors in this area are a deep-water shortcut applied where the wave feels the bottom.

Energy travels at the group velocity, which is half the phase velocity in deep water. This governs how quickly wave energy propagates and appears in wave power and shoaling questions.

Sea states are described statistically. Significant wave height is four times the square root of the zeroth spectral moment; the largest wave in a three-hour storm is roughly twice the significant height.

Morison's equation splits wave load in two. A drag term in velocity squared and an inertia term in acceleration, ninety degrees out of phase with each other, with the Keulegan–Carpenter number deciding which dominates.

Where marks are lost

  • Using λ = 1.56T² in shallow water.
  • Taking group velocity as phase velocity.
  • Reading significant wave height as an amplitude.
  • Applying Morison to a large-diameter member. Above D/λ ≈ 0.2 diffraction governs.
60-second recall
  1. ω² = gk·tanh(kd); deep λ = 1.56T².
  2. c_g = c/2 in deep water.
  3. H_s = 4√m₀; H_max ≈ 1.9 H_s in three hours.
  4. ω_e = ω − (ω²V/g)cos μ.
  5. Morison: drag u|u| plus inertia u̇.
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04 / 137–11 questions

Structural Design

The second largest area. Hull girder bending, section modulus, buckling and fatigue — classical strength of materials applied to a very long thin box.

What the paper asks

Hull girder loading, shear force and bending moment; section modulus and stress; shear flow; column and plate buckling; deflection; fatigue and stress concentration; and an introduction to finite element analysis.

The concepts, in order

Treat the ship as a beam. Weight minus buoyancy gives a load curve; integrate once for shear, twice for bending moment. Shear peaks near the quarter lengths, bending moment near amidships.

There are two section moduli. Deck and keel are at different distances from the neutral axis, so the section modulus differs, and the smaller governs. Only continuous longitudinal material is included.

Check slenderness before using Euler. For a stocky member Euler predicts a stress above yield and the member squashes instead. Plate panels buckle by a different mechanism, with critical stress going as the square of thickness over stiffener spacing.

Fatigue lives at details. Hatch corners, bracket toes and weld terminations, with a stress concentration factor multiplying the nominal stress. High-strength steel does not improve fatigue resistance.

Where marks are lost

  • Quoting one section modulus for the section.
  • Neglecting the side shell's own second moment of area.
  • Using the wrong effective length in Euler's formula. It is squared.
  • Including non-continuous material in the hull girder section.
60-second recall
  1. σ = M·y/I = M/Z; compute both deck and keel.
  2. Neutral axis from ΣA·y/ΣA, then parallel axis for I.
  3. P_cr = π²EI/L_e²; check slenderness first.
  4. Plate buckling ∝ (t/b)² — spacing beats thickness.
  5. Fatigue starts at the detail, not the panel.
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05 / 135–8 questions

General Arrangements

Where things go and why: subdivision, access, tonnage and the human requirements that shape a general arrangement drawing.

What the paper asks

Subdivision and watertight boundaries; compartment arrangement and access; means of escape; tonnage measurement; habitability and accommodation standards; visibility from the bridge; and arrangement drawings.

The concepts, in order

Subdivision is driven by damage stability. Bulkhead positions follow from floodable length or from the probabilistic index, and the collision bulkhead position is prescribed by rule rather than chosen.

Escape routes are a design constraint, not an afterthought. Two means of escape from most spaces, dimensions and continuity of routes, and the requirement that they remain usable when the ship is heeled.

Tonnage is volumetric and dimensionless. Gross tonnage from total enclosed volume, net tonnage from cargo volume with corrections. It drives dues, manning and regulatory thresholds — not the ship's weight.

Bridge visibility is prescribed. The view of the sea surface ahead must not be obscured by more than the ship's length or two ship lengths, whichever is less, and blind sectors are limited — a real constraint on deck cargo and superstructure position.

Where marks are lost

  • Treating gross tonnage as a mass.
  • Placing accommodation without checking bridge visibility.
  • Forgetting the second means of escape.
  • Choosing the collision bulkhead position freely. It is prescribed.
60-second recall
  1. GT = K₁V; dimensionless.
  2. Two means of escape from most spaces.
  3. Bridge visibility: no more than 2L or 500 m obscured ahead.
  4. Collision bulkhead position is a rule requirement.
  5. Subdivision follows damage stability.
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06 / 136–9 questions

Propulsion & Power Generation

Prime movers, the shaft line and the ship's electrical plant — sizing the machinery to the powering estimate and to the loads it must carry.

What the paper asks

Prime mover selection and characteristics; shafting and bearings; gearing; propeller matching and the propeller law; electric and hybrid propulsion; power balance and generator sizing; and fuel consumption estimates.

The concepts, in order

The propeller law connects everything. Torque with the square of revolutions and power with the cube, so the engine and the propeller must be matched with a light running margin so that a fouled hull and heavy weather still leave the operating point clear of the torque limit.

Shafting is sized for torsion, thrust and vibration. Torsional criticals produce barred speed ranges; alignment and bearing loads matter as much as shaft diameter.

Electric propulsion decouples engine speed from propeller speed. That buys layout freedom, load sharing across several generators at their best efficiency, and redundancy — at the cost of conversion losses and a more complex electrical plant.

A power balance is a table. Every load, its rating, its load factor and its duty in each operating condition — at sea, in port, manoeuvring, emergency — with the generators sized on the worst case plus margin.

Where marks are lost

  • Sizing generators on connected load rather than on the load balance.
  • Forgetting the light running margin.
  • Comparing specific fuel consumption without correcting to reference conditions.
  • Ignoring barred speed ranges in an operating profile.
60-second recall
  1. P ∝ N³, Q ∝ N² along the propeller curve.
  2. Light running margin typically 4–7 %.
  3. Generator sizing from the load balance, worst case plus margin.
  4. P_B = 2πNQ.
  5. Fuel per day = P × SFOC × 24/10⁶ tonnes.
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07 / 135–8 questions

Piping System Design

Sizing a line, choosing a pump and proving the system will actually deliver — with the pressure drop calculation that decides all three.

What the paper asks

Pipe sizing and velocity limits; Darcy–Weisbach and minor losses; pump head and power; NPSH; system and pump curves; valve selection; materials and expansion; and system diagrams.

The concepts, in order

The duty point is where the curves cross. The pump curve falls with flow, the system curve rises as static head plus friction proportional to the square of flow. A pump does not have a flow rate; a pump and a system together do.

Friction goes as velocity squared. Doubling the flow through a fixed pipe quadruples the loss, which is why velocity limits appear in design rules and why the system curve is a parabola.

NPSH decides whether the pump will work at all. Available NPSH must exceed required with a margin, with the static term added for a flooded suction and subtracted for a lift, and vapour pressure the term that ruins hot duties.

Fittings often dominate. A short line with a strainer, several bends and two valves can lose more head than all its straight pipe, so equivalent lengths or K factors are not optional refinements.

Where marks are lost

  • Getting the sign of the static suction term wrong in NPSH.
  • Sizing a pump on static head alone.
  • Ignoring minor losses.
  • Using the speed affinity laws for an impeller diameter change.
60-second recall
  1. h_f = fLV²/(2gD); laminar f = 64/R_e.
  2. P = ρgQH/η.
  3. NPSH_a > NPSH_r, with margin.
  4. Q ∝ N, H ∝ N², P ∝ N³.
  5. Duty point = pump curve ∩ system curve.
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08 / 135–8 questions

Auxiliary Equipment Selection

Choosing the machine that meets the duty with the right margin — pumps, heat exchangers, HVAC, steering gear and deck machinery.

What the paper asks

Pump types and selection; heat exchanger sizing by LMTD and ε–NTU; HVAC and psychrometrics; refrigeration; steering gear requirements; deck machinery and winches; and compressed air systems.

The concepts, in order

Heat exchanger sizing is Q = U·A·ΔT_lm. Counterflow always gives the larger mean temperature difference for the same terminal temperatures, so it needs less area — and it is the only arrangement in which the cold stream can leave hotter than the hot stream leaves.

Steering gear requirements are prescriptive. Two independent power units where required, and the rudder from 35° one side to 30° the other in 28 seconds at maximum ahead service speed and deepest seagoing draught — the conditions are part of the requirement.

Air receiver capacity is set by starts. Enough for a defined number of consecutive starts of the main engine without recharging — typically twelve for a reversible direct-drive engine and six for a non-reversible one.

HVAC is a psychrometric problem. Comfort depends on dry bulb temperature and relative humidity together, and cooling below the dew point dehumidifies as a side effect — which is why reheat is sometimes required.

Where marks are lost

  • Pairing the wrong ends in an LMTD calculation.
  • Quoting the steering gear timing without the conditions.
  • Sizing air receivers on volume rather than on required starts.
  • Selecting a pump without checking NPSH at the duty point.
60-second recall
  1. Q = U·A·ΔT_lm; counterflow gives the larger ΔT_lm.
  2. 35° to 30° in 28 s, at full speed and deepest draught.
  3. 12 starts reversible, 6 non-reversible.
  4. COP_hp = COP_ref + 1.
  5. 1/U grows with fouling in service.
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09 / 135–8 questions

Electrical Systems

Sizing the plant and the cables, and protecting both — the marine electrical engineering a naval architect is expected to be able to check.

What the paper asks

Electrical load analysis; generator sizing; distribution and switchboards; cable sizing and volt drop; protection and coordination; emergency power requirements; grounding philosophy; and shore connection.

The concepts, in order

The load analysis is the design document. Every load listed with rating, load factor and duty in each operating condition, summed per condition, with the generators sized on the worst case plus a margin for growth.

Cables are sized three ways and the largest governs. Current-carrying capacity with derating for grouping and ambient temperature, volt drop over the run, and short-circuit withstand. Checking only the first is the common error.

Protection must discriminate. Time and current grading so that the device nearest the fault clears it and nothing upstream operates. Loss of discrimination turns a feeder fault into a blackout.

Marine LV systems are usually insulated from the hull. A single earth fault raises an alarm rather than tripping, and it must be found before a second fault on another phase becomes a short circuit through the structure.

Where marks are lost

  • Sizing generators on connected load.
  • Sizing cable on current alone, ignoring volt drop.
  • Forgetting derating for grouping and ambient temperature.
  • Assuming an earthed neutral because that is shore practice.
60-second recall
  1. P = √3·V·I·cos φ.
  2. Cable: current, volt drop, short-circuit withstand.
  3. Grade protection so the nearest device clears the fault.
  4. Emergency generator on load within 45 seconds.
  5. Insulated neutral: one earth fault alarms, two short.
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10 / 134–6 questions

Environmental Considerations

The regulatory constraints that now shape machinery selection as much as cost does — emissions, discharges and the systems that control them.

What the paper asks

MARPOL annexes and their limits; oily water separation and the 15 ppm equipment; sewage and garbage; ballast water treatment; air emissions, NOx tiers and sulphur limits; energy efficiency indices; and noise and vibration.

The concepts, in order

Discharge criteria have several conditions at once. Machinery space bilge water requires the 15 ppm equipment in operation, the ship en route, and an automatic stopping device — meeting one is not compliance.

Air emissions split into NOx and SOx. NOx limits depend on the engine's build date and where the ship operates, with Tier III in designated emission control areas; sulphur is a fuel matter met by compliant fuel or an approved equivalent such as a scrubber.

Ballast water is now a treatment regime. The D-2 standard requires a type-approved system; D-1 exchange was transitional. System selection is a design decision with real space, power and back-pressure consequences.

Energy efficiency has a technical and an operational index. EEDI and EEXI are design attributes; CII is calculated annually from fuel consumed and distance sailed and rated A to E.

Where marks are lost

  • Confusing EEDI, EEXI and CII. Design, existing-ship technical, and operational.
  • Quoting a NOx limit without the build date and operating area.
  • Assuming 15 ppm is the only condition for discharge.
  • Ignoring the power demand of a ballast treatment system in the load balance.
60-second recall
  1. Annexes I–VI: oil, NLS, packaged, sewage, garbage, air.
  2. 15 ppm, en route, equipment running, auto stop.
  3. Sulphur 0.50 % global, 0.10 % ECA.
  4. Tier III in NOx ECAs, by keel-laying date.
  5. D-2 treatment standard for ballast water.
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11 / 134–6 questions

Hull Outfitting

Everything attached to the hull that is not machinery — anchoring and mooring, closures, lifesaving, coatings and insulation.

What the paper asks

Anchoring and mooring equipment and the equipment numeral; windlass and winch design; watertight and weathertight closures; lifesaving appliances and their arrangement; coatings and cathodic protection; insulation and fire boundaries; and access equipment.

The concepts, in order

Anchoring equipment follows the equipment numeral. Class rules compute a numeral from displacement, exposed profile area and superstructure, and the anchor mass, cable size and windlass capacity follow from a table — not from judgement.

Watertight and weathertight are different requirements. Watertight resists a head of water from either side; weathertight resists spray and green water from above. The closure appliance and its testing differ accordingly.

Corrosion protection is a system. Coating for the barrier, cathodic protection for the gaps — sacrificial anodes or impressed current — and the coating specification and surface preparation determine most of its life.

Fire boundaries are classified. A, B and C class divisions with defined insulation and integrity times, arranged by the fire control plan. The insulation is structural fire protection, not thermal comfort.

Where marks are lost

  • Selecting anchors by displacement alone. The equipment numeral includes windage.
  • Treating weathertight closures as watertight.
  • Specifying coating without surface preparation. Preparation is most of the life.
  • Confusing A-60 with a thermal insulation requirement.
60-second recall
  1. Equipment numeral drives anchors, cable and windlass.
  2. Watertight resists head; weathertight resists spray.
  3. Coating plus cathodic protection, together.
  4. A, B and C class divisions with integrity times.
  5. Surface preparation determines coating life.
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12 / 134–6 questions

Materials, Corrosion, Welds & Connections

What the ship is made of, why it fails, and how the pieces are joined — with weld and bolt design as the calculable part.

What the paper asks

Steel grades and notch toughness; aluminium and composites; corrosion mechanisms and prevention; galvanic series; weld types and design; fillet weld strength; bolted joint design; and non-destructive testing.

The concepts, in order

Steel grade is about toughness, not strength. Grades A, B, D and E in normal strength, AH to EH in higher strength, with the letter denoting the temperature at which the steel still absorbs energy rather than fracturing in a brittle manner.

Galvanic corrosion needs two metals, an electrolyte and a connection. The more anodic metal corrodes, and the area ratio matters enormously — a small anode connected to a large cathode corrodes fast. Aluminium superstructures on steel hulls need an insulating joint for exactly this reason.

Fillet weld strength is carried by the throat. Throat is about 0.7 times the leg for an equal-leg fillet, and weld metal volume goes as the square of the leg — so oversizing is expensive in consumable, time and distortion.

Bolted joints fail in several modes. Bolt shear, bearing on the plate, tension in the net section, and tear-out at the edge. All four are checked, and the smallest governs.

Where marks are lost

  • Choosing a steel grade on yield strength alone.
  • Ignoring the anode-to-cathode area ratio.
  • Using the leg length as the throat in a weld strength calculation.
  • Checking only bolt shear in a bolted connection.
60-second recall
  1. Grades A/B/D/E denote notch toughness.
  2. Small anode plus large cathode corrodes fast.
  3. Throat = 0.7 × leg; strength is on the throat.
  4. Check shear, bearing, net section and tear-out.
  5. Surface defects MPI/PT, internal UT/RT.
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13 / 135–8 questions

Rules & Regulations

Which authority sets which requirement — and the difference between a class rule, a statutory requirement and a professional obligation.

What the paper asks

Classification societies and their rules; USCG regulations and the Code of Federal Regulations; IMO conventions; ABS and other class rule structures; the load line and tonnage regimes; and professional practice and ethics.

The concepts, in order

Class and statutory are parallel regimes. Classification is a contractual matter about the ship's structure and machinery against a rule set; statutory certification is the flag state's legal requirement, frequently delegated to the same society as a recognised organisation.

In the United States the Coast Guard is the flag authority. Its requirements sit in Title 46 of the Code of Federal Regulations, and knowing which subchapter applies to a vessel type is the practical skill — the exam asks which body governs as often as it asks what the limit is.

IMO conventions bind through the flag state. The IMO itself neither inspects nor detains; port states enforce against visiting ships, and coastal states exercise rights under UNCLOS.

Professional practice is examinable. The engineer's obligation to hold public safety paramount, to practise only within their competence, to disclose conflicts of interest, and the meaning of sealing a drawing.

Where marks are lost

  • Saying the IMO enforces its conventions.
  • Confusing class rules with statutory requirements.
  • Sealing work outside your area of competence.
  • Assuming a class approval satisfies a statutory requirement.
60-second recall
  1. Class is contractual; statutory is legal, often delegated.
  2. USCG requirements sit in 46 CFR.
  3. IMO legislates; flag and port states enforce.
  4. Public safety is paramount.
  5. Seal only what you are competent to seal.
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Now sit it

The handbook is supplied. Knowing what to look for is not.

Take a timed practice set on the same area straight after the brief. Results save to My Progress so you can see where the weight of the paper is falling.

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