engineering

Heave compensation

Heave compensation is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Heave compensation rather than just read about it. In short: Heave compensation is motion compensator technology applied to minimizing the vertical movement of a load supported by lifting gear mounted on a heaving platform. Techniques include active heave compensation and passive heave compensation—the two traditional types of heave compensation—as well as balanced heave compensation.

Key takeaways

Heave compensation belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Heave compensation to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Heave compensation from memory before moving on to harder problems.

Reference excerpt

Heave compensation is motion compensator technology applied to minimizing the vertical movement of a load supported by lifting gear mounted on a heaving platform. Techniques include active heave compensation and passive heave compensation—the two traditional types of heave compensation—as well as balanced heave compensation. Devices that perform heave compensation are known as heave compensators.

Description Heave compensation is move compensator technology used to minimize the movement of a load in one direction. This direction is often vertical, as for a load supported by lifting gear mounted on a heaving platform. In offshore drilling, heave compensation is used to reduce the impact on the drill system from motions, including those of waves and the vessel.

Types There are two traditional basic types of heave compensation are active heave compensation and passive heave compensation. Balanced heave compensation is also used, and differs from the two traditional approaches.

Active heave compensation

Active heave compensation has a control system that uses power to drive the lifting gear to keep the load stabilized along the vertical axis to compensate for any movement of the platform specific point, using power to gain positional accuracy.

Passive heave compensation

Passive heave compensation uses a relatively soft spring which isolates the load from most of the vertical force variation to reduce transmissibility of transient loads.

Adaptive passive heave compensation Adaptive passive heave compensation is an improvement to passive heave compensation, that allows stiffness and damping to be adjusted during usage. It is particularly useful when doing a lifting operation that starts topside and moves through the splash zone, through potential resonance and finally landing at deep waters.

Balanced heave compensation

Balanced heave compensation converts the non-linear force of a gas spring or hydro-pneumatic spring into an adjustable, substantially linear force supporting the load.

Crane shock absorbers

Crane shock absorbers are low cost compensation devices that are used to mitigate dynamic shocks that can occur for example during pile hammering. Incidents offshore have caused significant damage to both cranes and equipment when no shock absorber was present.

Compensators A heave compensator is a kind of motion compensator. Whereas most motion compensators will compensate for movement in all directions, the heave compensator will compensate for movement in only one direction, for instance, for vertical movement. In practice, the words motion compensator and heave compensator are used interchangeably. Sensor technologies being used are inertial sensors and GNSS (example: iMAR Navigation) or image processing. The simplest motion compensator is the anchor chain of a ship. Not only does the anchor prevent the ship from drifting, but the chain itself dampens the movement of the ship due to undulating motion of the waves. Generally, motion compensators are implemented as springs. For very large forces (dozens to hundreds of tonnes), the springs are implemented as gas springs: hydropneumatic devices — a plunger cylinder buffered by a volume of gas. Examples of heave compensators include:

Drill string compensators Riser tensioners Conductor tensioners Guideline tensioners More advanced heave compensated systems are often specified as systems with passive heave compensation or active heave compensation or combinations of these. A new approach to advanced heave compensation systems is offered by balanced heave compensation, increasing safety while lowering energy consumption and spring adjustment times.

References

Worked examples

Example 1 — a first encounter with Heave compensation

Start with the simplest possible case. Write down what Heave compensation claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Heave compensation before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Heave compensation ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Heave compensation

In research: Heave compensation appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Heave compensation in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Heave compensation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mechanisms (engineering), so understanding it makes those chapters shorter.
In everyday life: Look for Heave compensation outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Heave compensation in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Heave compensation means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Heave compensation out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Heave compensation in simple terms?

Why does Heave compensation matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Heave compensation?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Heave compensation.