Practical owner-side overview for a production aluminum catamaran. Costs are typical 2024–2025 ballpark ranges (USD) for portable / field-capable gear and commercial training in North America or similar markets. Actual prices vary with brand, new vs used, digital vs analog, and local labor. Always follow the applicable welding code and class society rules (AWS D1.2, ABS, DNV, Lloyd’s, etc.), not a website summary.
Equipment cost: $50–$8,000. Flashlight, weld gauges, magnifiers, and mirrors are nearly free. A decent videoscope/borescope for tight catamaran spaces is $1,500–$8,000. High-end digital measurement cameras cost more.
Training: 8–24 hours for a focused VT course; often bundled into CWI / welding inspector programs. $400–$2,500. ASNT Level II VT typically ~24 hours classroom + experience hours.
Defects detected: Surface only — undercut, overlap, incomplete fusion at the toe (if visible), porosity that breaks the surface, misalignment, weld size, crater cracks, underfill, burn-through, distortion. Cannot see subsurface lack of fusion or internal porosity.
Top sources: AWS (B1.11 visual guide), ASNT, CWI (AWS QC1). Tools: Gal-Gage, Bridge Cam gauges, Olympus / Evident IPLEX videoscopes, FLIR / Seek thermal for some heat-related clues (not a substitute).
Equipment cost: $200–$15,000. Soap-bubble / low-pressure air with gauges and regulators is cheap. Vacuum boxes, calibrated pressure kits, or dye-in-water setups cost more. Full hydrostatic of large hull volumes needs pumps, manifolds, and safety relief — often yard-owned rather than inspector-owned.
Training: 1–5 days. $300–$2,000. Formal ASNT LT Level II exists but many marine teams use procedure-based training plus a competent supervisor.
Defects detected: Through-thickness paths only — leaking porosity, cracks that go through, incomplete penetration that opens a path, failed fillet/seal welds on tanks and voids. Does not size or locate non-leaking internal defects.
Top sources: ASTM E1003 / E432 family, class society tightness tests. Hardware: inflatable test plugs, vacuum boxes (e.g. from NDT suppliers), simple manometers. For boats this is often a shipyard production test, not a “NDT van” method.
Equipment cost: $4,000–$25,000 for a portable digital flaw detector plus a set of dual-element, shear-wave, and delay-line probes suitable for aluminum. Calibration blocks (IIW, DSC, alloy-matched) extra $300–$2,000.
Training: Level I ~40 hours; Level II another ~40 hours. $1,500–$4,500 per level plus required experience (months of logged work). Aluminum-specific practice is essential — do not assume a steel-only tech is ready.
Defects detected: Subsurface lack of fusion, incomplete penetration, cracks (orientation-dependent), porosity clusters, laminations, and remaining thickness. Weaker at very near-surface defects and at some geometries (T-joints, small fillets, access from one side only).
Top sources: Evident (Olympus) EPOCH series, Sonatest, Baker Hughes / Waygate, Dakota. Training: Hellier, NDT Classroom, ASNT, ISO 9712 providers. Technique: AWS D1.2 / D1.1 UT procedures adapted for aluminum.
Equipment cost: $25,000–$90,000+ for a portable PAUT instrument (OmniScan X3 class or similar), probes, wedges, scanners, and software. Used units exist in the $15k–$40k range. Encoders/scanners for reproducible hull scans add cost.
Training: On top of conventional UT: typically 40–80 hours PAUT (plus TOFD if used). $2,000–$6,000. Competent Level II PAUT on aluminum marine structures is a specialist skill — budget weeks, not a weekend.
Defects detected: Same family as UT but with better imaging, length/height sizing, multi-angle coverage, and recorded data. Excellent for lack of fusion, incomplete penetration, and many cracks. Combined PAUT+TOFD is the usual industrial replacement for radiography on butt welds.
Top sources: Evident OmniScan, Eddyfi M2M / Gekko, Zetec Topaz. Training: same houses as UT plus vendor academies. Codes: ASME Section V, ISO 13588, class society UT/PAUT approvals.
Equipment cost: $150–$3,000. Visible-red kits are inexpensive. Fluorescent systems need a UV-A lamp ($400–$2,000) and darker viewing conditions. Consumables (cleaner, penetrant, developer) are ongoing cost.
Training: Level I often 4–8 hours; Level II ~8–16 hours classroom. $400–$1,800. Easy to over-train relative to the method’s simplicity — process control (dwell, cleaning, temperature) matters more than theory.
Defects detected: Surface-breaking only: cracks, porosity, cold laps, crater cracks. Extremely sensitive if the surface is clean. Will not find subsurface lack of fusion. Paint, oxide, and grease hide indications. Not ideal on very rough as-welded aluminum without prep.
Top sources: Magnaflux, Sherwin, Met-L-Chek, Ardrox. Specs: ASTM E165, AMS 2644. Widely used on aluminum because it is cheap and matches the “surface crack” risk after welding and grinding.
Equipment cost: $5,000–$35,000 for a portable instrument plus probes (including weld probes and arrays). Conductivity meters are cheaper add-ons.
Training: Similar to UT — ~40 hours per level. $1,500–$4,500. Aluminum is a natural ET material (conductive, non-ferromagnetic).
Defects detected: Surface and near-surface cracks, some pitting/corrosion under thin coatings, conductivity changes (heat damage, alloy mix-up). Limited depth. Geometry and lift-off (paint, oxide) affect signals. Complementary to PT, not a full volumetric method.
Top sources: Eddyfi, Evident Nortec, Zetec, Fischer. Good for painted or coated aluminum where PT would require stripping.
Equipment cost: $25,000–$150,000+ depending on portable X-ray vs gamma projector, film vs computed/digital radiography, and darkroom or scanner. Gamma (Ir-192, Se-75) adds source exchange, security, and licensing costs that dwarf the camera itself. Annual compliance is expensive.
Training: 40–80+ hours plus radiation safety officer (RSO) requirements, dosimetry, and jurisdiction licenses. $2,000–$6,000 training plus ongoing program cost. Not a casual owner capability.
Defects detected: Volumetric internal defects — porosity, inclusions, incomplete penetration (if aligned), some lack of fusion. Cracks are orientation-sensitive (easy to miss if the plane is wrong). 2D shadowgraph; no depth without extra shots or computed tomography (not field-practical on a hull).
Top sources: Carestream, Fujifilm, Waygate, Yxlon, QSA Global (gamma). Heavy regulation: NRC / equivalent, local health physics, transport of sources.
Yes, in most aluminum catamaran production programs you can — and many serious yards already do. PAUT (often with TOFD on accessible butts) plus VT, PT on critical surface zones, and leak/tightness tests covers the defect types that actually sink or crack cats: lack of fusion, incomplete penetration, root issues, surface cracks, and through-leaks.
RT remains useful for some one-sided joints, very thick sections, or when a class surveyor or contract still mandates film. It is a poor fit for a thin-to-medium aluminum hull: radiation exclusion zones stop production, gamma is a security/safety headache, and many planar lack-of-fusion defects that matter in aluminum are easier to miss on RT than on a well-qualified PAUT scan.
Expect a mixed picture. Larger or class-oriented yards (and those used to export/superyacht or commercial work) usually have VT in-house, often PT, and either a UT tech or a standing subcontract with a mobile NDT company. Smaller fabrication shops frequently weld to “looks good,” maybe soap-test tanks, and hire a third-party inspector only when the owner or class surveyor insists.
Do not assume in-house PAUT or a documented written practice (SNT-TC-1A / ISO 9712) exists. Ask for: written NDT procedures, operator certifications, calibration records, and sample reports from a recent aluminum hull — not a verbal “we check everything.”
Both. The yard is responsible for process control (WPS, welder quals, in-process VT, their own NDT). The owner / design authority should have independent inspection: hold points, random PAUT/PT, review of records, and a right to reject. Class (if the boat is classed) is a third layer, not a substitute for owner oversight.
Independence matters because the yard is paid to finish the boat. Your inspector’s job is to protect the structure you will own for decades. Put inspection hold points and NDT percentages in the contract, not in a side email.
Specialized inspection robots already exist: magnetic or vacuum crawlers, drones for external visual, encoded PAUT scanners on rails. A general-purpose humanoid that can access a catamaran’s tight interiors, prep aluminum surfaces, run qualified PAUT/PT, and sign a code-compliant report is not here.
Optimistic industrial timelines put capable humanoids in structured factories later this decade; marine interiors, variable geometry, and certified NDT judgment are harder. Plan on human techs plus better scanners for the next 5–10 years. Do not wait on humanoids to write your inspection program.
During build (mandatory): in-process visual, after critical welds, after fairing/grinding (which can hide or open defects), before closing tanks, and a final tightness/NDT package before launch. Repairs get re-inspected.
In service: not “never again.” Aluminum cats see fatigue at high-stress welds (crossbeams, hull-to-deck, engine beds, foil/daggerboard cases, chainplates). Classed commercial or passenger boats have periodic hull surveys. Private yachts should still plan:
Manufacturing NDT finds process defects. In-service NDT finds fatigue, impact, and corrosion-related cracking. Both belong in the life of the boat.
| Method | Why | Rough owner budget |
|---|---|---|
| VT + photos/videoscope | Every weld, every day | $2k–$8k |
| PT kits + UV | Surface cracks after grind/repair | $1k–$3k + consumables |
| Leak / tightness | Tanks, voids, hull integrity | Yard + $1k–$5k kit |
| PAUT (own or contract) | Volumetric replacement for RT | $30k+ own, or $150–$400/hr contract |
| ET (optional) | Coated surfaces, crack screening | $8k–$25k |
Most owner teams should contract PAUT rather than buy it until they have enough hulls to keep a Level II busy. Buy VT/PT and the right to watch every scan.