Rebuilding a Boat Deck

March 10, 2026 by

Federico Solutions, Myrko Federico

Rebuilding a Boat Deck in Sapele Mahogany (CNC)

Field: Marine joinery / CNC fabrication / Boat restoration

Period: 2017

Client: Personal project (Kranchi boat)

Status: Completed — in service

Background

In 2017, the deck of my Kranchi boat (original fibreglass floor) was completely rotten — cracks, delamination, water ingress. Repair was out of the question: it had to be rebuilt from scratch.

Goal: Replace the fibreglass deck with a solid wood deck that is both attractive and resistant to the marine environment, using CNC for precision and finish quality.

Problem

Technical challenge:

Original fibreglass deck: complex geometry, curves, precise cut-outs for seats, table bases and hatches
Wood species: find a timber suited to the marine environment (resistant to salt water, UV and humidity)
Marine finish: a treatment that lasts without excessive maintenance
Precision: cut-outs, grooves and decorative patterns (compass rose) with tight tolerances

Design challenge:

Reproduce the geometry of the existing deck
Integrate a decorative motif (engraved compass rose)
Anti-slip grooves (marine teak style)
Precise cut-outs for fittings, hatches and bases

Solution

Phase 1: Choosing the material

Species chosen: Sapele mahogany

Why?

Marine resistance: excellent performance in humid and salty conditions
Dimensional stability: little movement with changes in humidity
Appearance: fine grain, warm colour (reddish brown)
Durability: class 2 timber (natural resistance to fungi and insects)

Treatment: Marine oil

Penetrates the wood (no surface film to peel)
UV protection + water repellent
Easy maintenance (re-oil once a year)
Natural matt finish

Phase 2: Design & CAD

Survey of the existing deck:

Accurate measurement of every cut-out
Tracing of the curves and complex geometry
Locating seats, bases, hatches and fittings

Complete CAD drawing:

3D model of the deck
Integration of the compass rose motif (central engraving)
Anti-slip grooves (evenly spaced, teak style)
Optimised CNC toolpaths

Phase 3: CNC fabrication

Operations carried out:

1. Cutting the boards

Sapele mahogany ripped into boards of suitable width
CNC cutting of the outer shapes (deck geometry)

2. Grooving

CNC-machined anti-slip grooves
Even spacing (classic teak deck style)
Controlled depth for water drainage

3. Engraving the compass rose

CNC-engraved central motif
Controlled depth for relief
Fine detail (star points, circles)

4. Specific cut-outs

Seat positions (round cut-outs for swivel bases)
Hatches (access to compartments)
Fittings (flush screws)

5. Assembly

Boards fixed to the underlying structure
Invisible joints
Perfectly flush finish

Phase 4: Finishing

Marine oil treatment:

Fine-grit sanding (up to 220)
Application of marine oil (2-3 coats)
Drying between coats
Natural matt finish

Result

Deliverable:

Boat deck entirely rebuilt in Sapele mahogany
Total surface: [Kranchi deck dimensions]
CNC anti-slip grooves
Central engraved compass rose
Precise cut-outs (seats, hatches, bases)
Marine oil finish

Impact:

Premium look: natural solid wood deck vs. the original fibreglass
Marine resistance: Sapele mahogany suited to salt water
CNC precision: flawless cut-outs and grooves
Durability: still in service after 8 years (2017-2025)
Easy maintenance: a yearly re-oiling is enough

This project demonstrates:

The ability to restore a boat (complete deck)
Command of CNC for marine joinery: cutting, grooving, engraving
Selection of materials suited to the context (Sapele mahogany for a marine environment)
Aesthetics + engineering: engraved compass rose + function (anti-slip grooves)
End-to-end project: CAD design, CNC fabrication, marine finish