KDS Offshore
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Capability · 06 / 09 · Naval architecture

Vessel Conversion Engineering

Remotorisation, repurposing, capacity uplift.

Lead time · 4–10 weeks (design)Fixed-fee, fixed-scopePrincipal-ledAuthor · Sérgio Ribeiro e Silva, PhDLast reviewed ·
✦ TL;DR

Vessel conversion engineering is the redesign of an existing hull for a new role — remotorisation, capacity uplift, hybrid-propulsion retrofit, scientific or commercial repurposing. KDS Offshore handles the stability re-issue, structural reinforcement, class- and flag-state liaison (DNV, BV, RINA, LR, DGRM), and yard tender support. Fixed-fee feasibility first; design only when the engineering case closes.

Overview

What this service is

A conversion is a different problem from a new build: the geometry is given, the structure has a history, and the budget has to compete with replacement. We do conversions where the engineering case actually closes — not because we want the project, because the operator does.

Typical jobs span the full range we have either delivered or quoted: tanker → FPSO conversion; hybrid dual-fuel LNG–Diesel–Electric propulsion retrofit; remotorisation (the gearbox usually wins); passenger or cargo capacity uplift; additional accommodation-block installation; OPS / shore-power fitting; stand-by vessel hull conversion; and scientific-research conversion. We handle the stability re-issue, the structural reinforcements, the class- and flag-state liaison, and the yard tender support.

Our reference jobs are the Belize I remotorisation for Nautiber (2023, delivered on schedule) and the Libries motor-sailer conversion for Blue Geo Lighthouse (2022, on-time, on-spec).

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Outcomes

Numbers we expect to defend

On schedule
Belize I delivered
Nautiber, catamaran remotorisation & capacity uplift, 2023
On-time, on-spec
Libries scientific-tourism conversion
Blue Geo Lighthouse, motor-sailer conversion, 2022
Fixed-fee
feasibility study before design commits
most projects either move or stop at feasibility
4–10 wk
typical lead time for the design package
after feasibility decision
Deliverables

What you get

01
Conversion design package
02
Re-engining feasibility
03
Updated stability book
04
Structural reinforcement design
05
Class & flag-state liaison
06
Yard award tender support
Fit

When this is the right call

✓ When to use
  • Remotorisation, hybrid-propulsion retrofit, or accommodation upgrade where the hull is sound and the role is shifting.
  • Passenger or cargo capacity uplift requiring structural reinforcement and re-issued stability.
  • Scientific-research or tourism conversion of an existing commercial vessel.
  • Yard tender preparation — the operator needs a yard-ready specification before bid.
✗ When not to use
  • When the new role asks for a hull the existing vessel cannot give within structural or stability limits — we say so in feasibility, not after steel is cut.
  • When the operator wants a brand-new design without reusing the existing hull — use Naval Architecture instead.
Methodology

How we run a project

  1. 01 / 04

    Feasibility

    A short, fixed-fee study answering one question: does the conversion close on engineering, schedule, and budget? Most projects either move or stop here.

  2. 02 / 04

    Design

    Updated stability book, structural reinforcement, GA, system updates, and a yard-ready specification.

  3. 03 / 04

    Tender support

    We help the operator put the work out to yards, evaluate the responses, and brief the winner.

  4. 04 / 04

    Site supervision

    Optional. Inspection, gate reviews, sea trials, and acceptance testing.

Tools & methods

Software stack we use

  • Maxsurf · stability
  • AUTOHYDRO
  • SESAM · FEA
  • Ansys
  • STAR-CCM+ (when hydrodynamics change)
  • Class-society liaison: DNV, BV, RINA, LR
Regulatory context

Frameworks we help you satisfy

  • SOLAS Chapter II-1 (damage stability)Re-issued damage cases after any subdivision or compartmentation change.
  • MARPOL Annex VI (NOx / SOx)Emissions compliance for remotorised propulsion plant.
  • IACS Common Structural RulesWhere reinforcement intersects CSR-applicable structure (tankers, bulkers).
  • EU MRV / FuelEU MaritimeOperational fuel-consumption baseline before and after retrofit.
  • Decreto-Lei 96/2017 + DGRM (Portugal)Direct liaison with the Portuguese flag-state authority for PT-flagged conversions.
Vessel types

Where this discipline applies

  • Catamarans (passenger, tourism, working) — Belize I
  • Motor-sailers and yachts — Libries
  • Working boats and supply vessels
  • Tugs and harbour craft
  • Small ferries and RoPax
  • Specialist conversion (scientific, expedition, hospital)
Selected work

Where this discipline was used

·01"Belize I" remotorisation & capacity upliftNautiber2023↗·02"Libries" scientific-tourism conversionBlue Geo Lighthouse2022↗
Common questions

FAQ

When is conversion the wrong answer?

When the new role asks for a hull that the existing vessel cannot give you within structural and stability limits. We say so in the feasibility, not after the steel is being cut.

How do you handle hybrid-propulsion retrofits?

Energy audit of the operating profile first — if the duty cycle does not have meaningful low-load hours, hybrid does not pay back. When it does, we size the battery and the genset around the actual load profile, not a generic one.

Do you handle the flag-state side as well as class?

Yes. For Portugal-flagged conversions we liaise directly with the Direção-Geral de Recursos Naturais, Segurança e Serviços Marítimos (DGRM); for foreign flags we work with the operator's flag-state representative.

Other capabilities

Eight other disciplines, one office

✦ Brief this service · Conversion

Tell us about the vessel.

A 30-minute call with a principal. No deck, no sales engineer. Two engineers, your problem, an honest answer about whether KDS is the right firm.

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