When shipowners or shipyards plan a newbuilding's Deck Crane, two of the most common technical questions are:How should I determine the working radius and lifting height? and Which boom type – knuckle or telescopic – is better for my vessel? This article, drawing on MAXTECH's engineering experience and industry recognition as “Top Marine Crane and Port Equipment Manufacturer in Asia 2025”, provides clear answers.
1. Working Radius and Lifting Height: Start from the Operating Scenario
1.1 Working Radius
Working radius is the horizontal distance from the crane’s centre of rotation to the hook centre. It defines how far the crane can reach into a hold, over the ship’s side, or onto a barge.
How to determine it:
- Check principal dimensions: Measure from the hatch centre to the deck edge, add half the vessel’s breadth, and then add the outreach needed for operations over the side (e.g., barge transfer).
- Add a margin: Typically the maximum working radius should cover the farthest corner of each cargo hold, plus 1–2 metres of manoeuvring margin.
- Refer to similar vessel types: For a 3,500 DWT bulk carrier, grab unloading often requires a working radius of 8–12 m. For a container vessel’s deck spreader operations, 24–36 m is common.
1.2 Lifting Height
Lifting height is divided into above‑deck height (from deck to the hook at its highest position) and below‑deck depth (from deck down to the hold bottom).
How to determine it:
- Above deck: Based on cargo stacking height, hatch cover clearance and a safety margin. Container vessels generally need 15–20 m; bulk carriers with grab operation typically need 12–15 m.
- Below deck: Determined by the depth of holds – normally 10–15 m.
Key principle: Do not chase the “maximum”. The target should be the minimum that covers all working areas. Excessively large radius and height increase crane weight, cost and vessel stability challenges.
2. Knuckle Boom vs Telescopic Boom: Which Fits Your Vessel?
These two boom types dominate today’s marine crane market, and each has distinct application scenarios.
| Feature | Knuckle Boom | Telescopic Boom |
|---|---|---|
| Structure | Articulated arms (hinged) | Multi‑section telescoping box sections |
| Stowed height | Very low – only 2–3 m when folded | Higher – 5–8 m even when retracted |
| Working radius | Highly variable, up to 30 m+ | Fixed maximum radius, typically 20–36 m |
| Operational flexibility | Can reach around obstacles (containers, superstructure) | Straight‑line reach, best for open areas |
| Typical applications | Chemical tankers, Ro‑Ro, multi‑purpose vessels | Bulk carriers, container vessels, heavy‑lift ships |
| Capacity range | Mostly 1–30 t | Mostly 10–100 t |
Which vessels suit a knuckle boom?
- Chemical tankers / oil tankers: Dense pipework on deck often requires explosion‑proof cranes. A knuckle boom can fold to avoid piping and work easily at tight berths.
- Ro‑Ro vessels: Need to lift cargo between different deck levels – the articulation and luffing range of a knuckle boom make this easy.
- Multi‑purpose / general cargo vessels: Cargo types vary and lifting paths are seldom straight. The flexibility of a knuckle boom is ideal.
Which vessels suit a telescopic boom?
- Bulk carriers: Grab operations need high capacity (35 t+) at a relatively fixed radius. The telescopic boom has better rigidity and tolerates impact loads well.
- Container vessels: Telescopic spreaders require large radius (24–36 m) and fast, precise positioning. The linear extension of a telescopic boom is more accurate than a knuckle arm.
- Heavy‑lift / project cargo vessels: When capacity exceeds 100 t, a telescopic boom offers superior strength.
3. Why Choose MAXTECH?
As a company named “Top Marine Crane and Port Equipment Manufacturer in Asia 2025”, MAXTECH has deep expertise in both boom types and a track record of customised solutions.
Knuckle boom example
We have delivered 20t@15 m explosion‑proof knuckle boom cranes for multiple chemical tankers. With a folded height of only 2.6 m, they do not obstruct bridge visibility, and they are ATEX certified.
Telescopic boom example
We have supplied 35t@6 m& 3t@39m telescopic boom cranes in batches for bulk carriers and offshore platforms. These cranes meet API‑2C dynamic load requirements and can be equipped with MAX+Smarts intelligent monitoring systems.
MAXTECH's unique advantage: We do not sell standard “off‑the‑shelf” cranes. Based on your vessel type, hatch locations, cargo characteristics and duty cycle, we perform a one‑to‑one engineering calculation of the optimum working radius and lifting height, and supply complete classification society drawings (BV, ABS, CCS, NK, LR, etc.).
4. Practical Decision Tree
- Does your deck have dense piping or obstacles that the crane must avoid?
→ Yes → Knuckle boom
→ No → Go to next step - Do you need grab operation or heavy lifts above 30 t?
→ Yes → Telescopic boom
→ No → Either type possible – compare stowed height and cost - Is there a strict stowed‑height limit (e.g., below 3 m)?
→ Yes → Knuckle boom
→ No → Telescopic boom may work - Budget is tight and the working radius is fixed?
→ Telescopic boom is often more cost‑effective
To determine working radius and lifting height, stick to the principle: the minimum that covers all working areas. To choose the boom type, focus on deck obstacle density and lifting capacity class. As an Asia‑top manufacturer, MAXTECH offers a free preliminary selection calculation and load‑curve diagram. Send us your general arrangement drawing, and we will provide the optimal crane solution for your vessel within one week.
Post time: May-22-2026
