Marine Draft Surveys

What is a draft survey?

A draft survey calculates the weight of cargo loaded or discharged from a vessel by measuring the change in displacement before and after the operation. It is the recognized independent method used by shippers, receivers, charterers, and P&I clubs to settle bill-of-lading quantities.

Focus cargoes

Gulf Coast Surveyors concentrates on the dry bulk trades that dominate the Sabine–Neches and Houston ship channels:

• Petroleum coke (green & calcined) — calciner-direct and storage-pad loadings; sulfur, moisture, and HGI sampling per ASTM D6970.
• Sulphur (granular & prilled) — moisture and fines monitoring, IMSBC Group C with MHB corrosivity considerations.
• Fertilizer — urea, ammonium sulfate, DAP/MAP and AN-based blends; hold-coating verification and segregation checks.
• Grain & agribulks — corn, soy, wheat, sorghum, DDGS, soybean meal under USDA/FGIS and the IMO International Grain Code.
• Soda ash — hygroscopic loading, grain-clean hold standard, FDA food-contact rules where applicable.
• Sodium sulphate — Glauber's salt / salt-cake loadings; bone-dry holds, hatch sealing, and tight weather windows.
• Sand & frac sand — IMSBC Group A, TML certificate and moisture content within 7 days of loading.

Our process

• Six-point freeboard / draft readings on arrival and departure, both sides.
• Ballast soundings (or ROB measurements) cross-checked against the vessel's tank tables.
• Density samples taken at multiple depths; trim, list, and hog/sag corrections applied.
• Calculations referenced to the vessel's hydrostatic tables and stowage plan.
• Signed survey report delivered the same day, with figures auditable to the underwriter.

Ports served

Beaumont, Port Arthur, Orange, Sabine, Houston, Galveston, Texas City, Corpus Christi, and Lower Mississippi (New Orleans / Baton Rouge). Coverage available 24/7; dispatch typically within two hours.

Request a survey

Call +1 (409) 866-4403 or use the marine survey request form to schedule attendance.