Jesse Cannon, freelance marine geophysicist

Know the seabed before you build on it.

Magnetometry for UXO, side-scan sonar and sub-bottom seismic, processed, checked and interpreted by a geophysicist with twenty years in marine geophysics. Aboard your vessel, in your site office, or remotely from my home office.

Taking on contracts: offshore, site office or remote

Where the name comes from

Look up from below the surface and the whole sky squeezes into one bright circle: Snell’s window. Its rim is the critical angle of water, 48.6°. Beyond it, light can’t get out and the surface becomes a mirror. Under the seabed, the same physics bends sound along buried layers. That’s the world I map, and the name of my company.

Where the name comes from

Look up from below the surface and the whole sky squeezes into one bright circle: Snell’s window. Its rim is the critical angle of water, 48.6°. Beyond it, light can’t get out and the surface becomes a mirror. Under the seabed, the same physics bends sound along buried layers. That’s the world I map, and the name of my company.

Jesse Cannon

Twenty years at sea, and on the data

I’m Jesse Cannon, a British marine geophysicist and the founder of Critical Angle. I started offshore on exploration seismic crews for major oil and gas clients and rose to Chief QC Geophysicist on 3D ocean-bottom cable surveys. In 2014 I moved into near-surface geophysics: the seabed and shallow geology that wind farms, cables and pipelines are built on.

Since 2016 I’ve freelanced on eighteen contracts, aboard survey vessels, in site offices and, more and more, from home. Clients have always reviewed my work positively, and I intend to keep it that way: thorough, data-driven and honest about what the data can and can’t tell you.

Particulars

Name
Jesse Cannon
Flag
British
Operator
Critical Angle SLU, Spain
Type
Marine geophysicist: magnetics, side-scan sonar and seismic
Trading area
European waters, or remote
In service
Since 2006
Freelance record
18 contracts since 2016: 8 aboard, 2 in site offices, 8 remote
Offshore wind
10 wind farms
Certificates
BOSIET with CA-EBS to July 2030, OEUK medical to June 2028, NEBOSH IGC

What I bring to a site survey

Six steps from deck to deliverable. The data on screen is simulated, but it’s the kind I process and interpret every day.

  1. Online QC on deck

    Data quality is decided while the vessel is still on the line. I’ve run online QC of side-scan sonar on a pipeline route, processed magnetometer and side-scan data aboard, and spent nine years in QC on exploration seismic crews, deciding when lines had to be reshot. Safety comes first, on every rotation.

    Experience
    9 years of offshore seismic QC; 8 freelance contracts aboard
    Safety
    NEBOSH IGC with credit; BOSIET with CA-EBS
    Online QC logSimulated
  2. Magnetometry for UXO

    Unexploded ordnance is a real risk on many North Sea and Baltic sites, and the magnetometer is how you find it. I process magnetic data in Oasis montaj: QC, filtering, gridding, target picking and anomaly reporting, aboard or from home.

    Software
    Oasis montaj
    Contracts
    9, of which 7 for UXO
    Magnetic anomaly grid and line profileSimulated
  3. Side-scan sonar

    Boulders, debris, wrecks, cables and bedforms: side-scan sonar shows what’s lying on the seabed. I process, mosaic and interpret it in SonarWiz, from online QC on a gas pipeline route to contact picking for wind farm sites.

    Software
    SonarWiz
    Contracts
    11
    Side-scan sonar waterfallSimulated
  4. Sub-bottom and high-resolution seismic

    Pingers, parametric echo sounders such as Innomar, chirps, boomers and sparkers. I process high-resolution seismic in RadExPro, where I built one company’s template project and processing sequence from scratch, and interpret it in Kingdom.

    Software
    RadExPro, IHS Kingdom, ProMAX
    Sources
    Pinger, parametric, chirp, boomer, sparker
    Sub-bottom profileSimulated
  5. Multibeam and GIS

    Bathymetry gives the seabed its shape. I interpret multibeam alongside side-scan and bring every layer together in QGIS and ArcGIS Pro, ready for charts and client deliverables.

    Software
    QGIS, ArcGIS Pro, ArcMap, Global Mapper
    Projects
    Pipeline and wind farm interpretation, remote
    Multibeam bathymetry coverageSimulated
  6. Interpretation and reporting

    From reflectors to geological units: picking horizons, correlating vibrocores and samples, mapping hazards, and writing the reports that cable routes and foundations are designed from.

    Experience
    Geological interpretation, vibrocore analysis, survey reports
    Quality
    Set up ISO-controlled technical procedures from scratch
    Interpreted seismic sectionSimulated

Remote by choice, offshore when needed

Since May 2021, every contract has been delivered from my home office, for Fugro and GeoXYZ.

The office is set up for production geophysics: a high-spec computer, backup power, 1 Gbps symmetrical internet and three screens. I work in your software, to your procedures and reporting templates, with the same QC discipline I bring aboard. It keeps me close to my family, and I’m still glad to join a vessel when the job needs someone on deck.

Workstation
High-spec computer, triple-screen display
Power
Backup power supply
Connection
1 Gbps symmetrical internet
Data security
Cybersecurity bootcamp, Ironhack, 2026
Remote record
8 contracts, 2021 to 2025

Freelance weeks per year, by where the work was done

Site characterisation contracts, 2016 to 2025

  • Aboard a vessel
  • Site office
  • Remote
Show as a table

From Brittany to the Gulf of Bothnia

Eighteen freelance contracts since 2016, for survey contractors including Fugro, GeoXYZ, MMT and NSEA, on projects such as Arkona, Borssele, Neart na Gaoithe, Saint-Brieuc, East Anglia THREE, NordLink and the Northern Endurance Partnership.

  • Offshore wind farms10
  • Power cables6
  • Gas pipelines2
  • Offshore switching station1
  • Fibre-optic cable system1
  • Carbon capture and storage1
Open the plotting sheet
Project positions, freelance site surveys 2016 to 2025. Positions are indicative.

The software I work in

SoftwareUsed forExperience
SonarWizSide-scan sonar processing, mosaics and contact picking11 contracts
Oasis montajMagnetic data processing and UXO target picking9 contracts, 7 for UXO
IHS KingdomSeismic and sub-bottom interpretation4 freelance contracts, plus EGS International, 2014 to 2015
RadExProHigh-resolution seismic processingBuilt a full template project and processing sequence
ProMAXExploration seismic processing and QC6 years offshore
QGIS, ArcGIS ProGIS, charting and deliverablesWell experienced
ArcMap, Global Mapper, WorkbenchGIS and data reviewFamiliar
Kilo in the International Code of Signals: “I wish to communicate with you.”

Tell me about your survey

Whether you need someone aboard next month or a remote processor for a backlog of side-scan, send a few details and I’ll get back to you.

Company
Critical Angle SLU

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