A heavy-lift vessel moves what nothing else can — transformers, port cranes, offshore modules, jackets, yachts, and entire process units. It’s the top of the project-cargo fleet, and also the most misunderstood, because “heavy-lift” covers several very different ship types. What decides whether a given ship can take your job isn’t deadweight; it’s the crane SWL at radius, whether two cranes combine for a tandem lift, how strong and open the deck is, and whether it can hold position offshore. This guide covers what to check before you buy or charter to buy.
Three kinds of “heavy-lift” ship
Match the ship type to the cargo and the operation first:
| Type | How it lifts/loads | Best for |
|---|---|---|
| Geared heavy-lift (with cranes) | Own revolving cranes; often tween decks and box holds like an MPP | Break-bulk + project units it can self-load anywhere |
| Deck / module carrier (gantry or bridge crane) | Open, very strong deck; gantry/bridge crane and/or roll/skid-on; often DP | Large modules, port cranes, offshore structures on an open deck |
| Semi-submersible (float-on/float-off) | Ballasts down to float cargo on/off — no lift at all | Floating cargo: rigs, other vessels, giant modules |
The right choice depends on whether your cargo is lifted, rolled/skidded, or floated on. In-stock heavy-lift tonnage includes modern DP2 deck-cargo carriers with a bridge/gantry crane, very high deck strength, and unrestricted (world-wide) trading.
See current availability on our heavy-lift vessels for sale page.
Crane SWL — and the combined (tandem) lift
For geared and crane-equipped ships, the crane figures decide the ceiling:
| Spec | Why it matters |
|---|---|
| SWL per crane at radius | Maximum safe load falls as the hook reaches out — get the full load chart, not the headline |
| Combined / tandem SWL | Two cranes lifting one unit together — the real ceiling for the heaviest pieces; confirm the certified combined figure |
| Outreach | How far past the hull the crane can place a load — critical for quay/barge/offshore work |
| Lifting height | Clearance for tall units |
| Crane type (revolving vs. gantry/bridge) | Revolving = flexible placement; gantry/bridge = very heavy, precise travel along the deck |
Tip: For the heaviest cargo, the certified combined lift — not the single-crane SWL — is the number that matters. Confirm it’s on the class/crane certificate, not just the brochure.
Deck strength, area, and configuration
Heavy cargo is as much about the deck as the crane:
- Uniform deck load (t/m²) — the real limit for heavy point loads (modules, crawler cranes, transformers). Strong open-deck carriers reach into the low tens of t/m².
- Clear deck area (m²) — whether your units physically fit and can be arranged/sea-fastened.
- Tween decks & box holds — geared heavy-lift/MPP types flex between break-bulk and full-depth holds; see our MPP buying guide.
- Sea-fastening & lashing points, and roll/skid capability — for ro-ro’d or skidded modules.
- Weather-deck vs. holds — where and how your cargo travels.
For flat, open-deck project cargo without a crane requirement, compare a self-propelled deck cargo vessel; for fixed lifting at the worksite, a floating crane.
Dynamic positioning, ice class, and trading area
- Dynamic Positioning (DP1/DP2/DP3) — essential for offshore installation and station-keeping without anchors; DP2 adds redundancy for critical work. Confirm the DP class and its survey/trials status.
- Ice class — for high-latitude and wind-farm work in seasonal ice.
- Navigation/service area — unrestricted (world-wide) vs. coastal — caps where the ship can trade.
- Stability during lift/float — review the stability and (for semi-subs) ballast/deballast systems.
Class, certificates, and due diligence
Before committing, confirm on paper and under NDA:
- Class & status — in class with a recognised society (e.g. CCS, ABS, DNV, BV, LR), no overdue surveys or outstanding Conditions of Class. Look for relevant notations (deck cargo/heavy-equipment carrier, DP, ice class, PSPC, AUT, in-water survey).
- Lifting-appliance certification — crane register, load-test records, combined-lift certificate.
- GA, deck strength plan, crane load charts, stability booklet, and DP documentation.
- Statutory & survey position — Load Line, Tonnage, Safety, pollution; special survey/drydock dates.
- Clean title — no liens, mortgages, or maritime claims.
Survey: cranes, deck, and DP all get tested
Commission an independent pre-purchase condition survey, plus a drydock survey for any serious purchase. On a heavy-lift vessel the surveyor focuses on:
- Cranes — load-test and combined-lift records, wires, hooks, slew bearings, hydraulics, foundations.
- Deck & structure — thickness gaugings, deck strength in way of heavy cargo, sea-fastening points.
- DP system — thruster condition, DP trials/FMEA, redundancy testing.
- Ballast / (semi-sub) deballast systems — pumps, valves, and stability control.
- Hull & propulsion — twin-screw machinery, steering, and ballast tanks.
Tip: A cheap heavy-lift ship with a worn slew bearing, an out-of-date combined-lift certificate, or a DP system needing overhaul can cost far more than a dearer, well-certified unit once you add repairs and lost project days. Test the cranes and DP before the price tempts you.
Total cost of ownership
Budget beyond the purchase price: survey, crane load test and any class rectification, crane/DP overhaul reserve, delivery/repositioning, flag and class transfer, insurance, and modifications (grillage, sea-fastening, crane pedestals) for your specific cargo.
Quick pre-signing checklist
- ☐ Ship type (geared / deck-module carrier / semi-sub) matched to lifted vs. rolled vs. floated cargo
- ☐ Crane SWL at radius and certified combined (tandem) SWL confirmed
- ☐ Outreach and lifting height suit your loads
- ☐ Uniform deck load (t/m²) and clear deck area adequate, with margin
- ☐ Tween-deck/box-hold or roll/skid capability as needed
- ☐ DP class (and trials status) and ice class suit your operations
- ☐ Navigation area (world-wide/unrestricted) confirmed
- ☐ In class, no overdue surveys / Conditions of Class; special survey priced in
- ☐ Independent condition survey (+ drydock); cranes, deck, and DP tested
- ☐ Full documents under NDA; clean title confirmed
- ☐ Total cost of ownership budgeted (crane/DP overhaul, sea-fastening mods)
Frequently asked questions
What is a heavy-lift vessel? A heavy-lift vessel is a ship built to carry and handle exceptionally heavy or oversized cargo — transformers, port cranes, offshore modules, jackets, even other vessels. It may use its own heavy-lift cranes, a strong open deck with a gantry/bridge crane and roll/skid loading, or a semi-submersible float-on/float-off method.
What’s the difference between a heavy-lift vessel and a multipurpose (MPP) ship? An MPP is a versatile geared cargo ship that also carries some project/heavy cargo. A dedicated heavy-lift vessel goes further — higher crane SWL and combined-lift capability, much stronger and more open decks, and often DP for offshore work. Many geared heavy-lift ships are effectively high-end MPPs; deck/module carriers and semi-subs are distinct types.
What is a combined or tandem lift? A combined (tandem) lift uses two of the ship’s cranes together to raise a single heavy unit. The certified combined SWL — not the single-crane rating — sets the heaviest piece the ship can lift on its own, so confirm it on the crane/class certificate.
Why does deck strength (t/m²) matter? Heavy modules and machinery impose high point loads on the deck. The uniform deck load in tonnes per square metre — together with clear deck area — determines whether your cargo can be stowed and sea-fastened safely, often more than the headline deadweight.
Do I need a DP heavy-lift vessel? For offshore installation and station-keeping without anchors, yes — dynamic positioning (DP2 for critical redundancy) is essential. For quayside and port project cargo, a non-DP crane vessel or deck carrier may be enough. Match DP class to your operation.
Looking for a heavy-lift vessel now? Golden Shipyard carries in-stock and newbuilding heavy-lift and deck-cargo carriers, including modern DP2 tonnage around 27,800 DWT with a bridge/gantry crane, high deck strength, ice class, and unrestricted trading. Browse current availability on our heavy-lift vessels for sale page, or learn about our ship sale & purchase brokerage services. To receive full particulars under NDA, email [email protected].