a group of sailboats docked in a harbor

Requirements and Documentation for the Spanish Maritime Authority (Capitanía Marítima)

The documentation required by the Spanish Maritime Authority (Capitanía Marítima) for vessel legalization depends on the type of structural modification, technical alteration, or administrative change carried out.

In Spain, a naval technical project must generally include:

  • A descriptive technical report

  • Updated vessel drawings

  • Justification calculations

  • Verification of compliance with Spanish maritime regulations

Proper preparation of the technical file prevents administrative objections, delays, and rejections

When Does Capitanía Marítima Require a Technical Project?

The Maritime Administration may require technical documentation in cases such as:

  • Engine replacement or modification of the installed power

  • Structural reform of hull or deck

  • Change of vessel registration (cambio de lista)

  • Installation of new technical systems

  • Alteration of weight distribution

  • Administrative regularization

Each intervention must be technically justified according to applicable regulations

a group of people on a boat in the ocean
a group of people on a boat in the ocean

Typical Technical Documentation

A complete technical file usually includes:

  • Descriptive technical report

  • General arrangement and detailed drawings

  • Structural calculations (when applicable)

  • Stability study if the modification affects safety

  • Applicable regulatory justification

  • Installation or execution certificates

Consistency between the technical report, drawings, and calculations is essential.

brown wooden table and chairs
brown wooden table and chairs

Specific Requirements by Vessel Type

Requirements may vary depending on:

  • Recreational vessels

  • Yachts and superyachts

  • Commercial-use units

  • Authorized navigation type

  • Vessel length and displacement

Applicable regulations vary by the vessel’s administrative and operational category.

Boats are docked at a harbor near mountains.
Boats are docked at a harbor near mountains.

Stability Study: When Is It Mandatory?

A stability study may be mandatory when:

  • The weight or center of gravity is modified

  • Installed power is increased

  • Vessel use or registration category changes

  • Significant structural reforms are performed

The study must include:

  • Hydrostatic curves

  • GM (metacentric height) calculation

  • Verification of intact stability according to applicable technical criteria

Man on boat with spanish flag enjoys ocean view
Man on boat with spanish flag enjoys ocean view

Frequent Errors in Project Submission

Administrative objections often arise due to:

  • Incomplete technical reports

  • Inconsistency between drawings and description

  • Absence of justification calculations

  • Lack of regulatory references

  • Documentation signed by a non-qualified technician

A poorly prepared file can significantly delay approval.

Boats docked at a sunny marina with buildings behind.
Boats docked at a sunny marina with buildings behind.

Standard Administrative Procedure

  1. Preparation of the technical project

  2. Submission to Capitanía Marítima

  3. Administrative review

  4. Correction of requirements (if necessary)

  5. Technical inspection (when applicable)

  6. Issuance or update of official certificates

Correct preparation reduces both processing time and costs.

A boat docked at a pier with a flag on it
A boat docked at a pier with a flag on it

Technical Guarantee and Legal Security

A properly prepared naval technical project:

  • Complies with Spanish maritime regulations

  • Ensures structural safety

  • Allows legalization without administrative incidents

  • Provides technically defendable documentation

The involvement of a chartered naval architect and marine engineer guarantees professional rigor and administrative validity.

a flag on a pole
a flag on a pole