Semper Offshore

Frequently Asked Questions — Charlestown, MA

How far do you travel and how does mobilisation affect the bid?

Most commercial diving contractors work from a home port and serve a regional footprint, but mobilisation can cover hundreds of miles. The mobilisation line includes vessel transport, dive spread setup, and crew travel; in Charlestown, MA, it can easily exceed the diving day rate for a short inspection. Bundling multiple structures or tasks into one mobilisation is the most effective way to lower the cost per unit.

How do scheduling and permits work for subsea work in a working waterway?

Expect to coordinate with the US Coast Guard, Army Corps of Engineers, and sometimes local port authorities for work in navigable waters. Diving operations must comply with OSHA 29 CFR 1910 Subpart T and ADCI standing practice, so the contractor handles the permit and safety planning. In Charlestown, MA, tide, river traffic, and environmental windows (like fish migration or in-water construction windows) often dictate the working schedule.

What inspection reports and data deliverables should we expect?

A standard subsea inspection deliverable includes a narrative report, condition coding, photo and video logs, and NDE data such as ultrasonic thickness measurements. For bridges, the report must meet 23 CFR 650.311 and be prepared under an FHWA-NHI qualified team leader. You should also get a database-ready summary that lets your engineering team compare findings against previous inspection cycles.

When does it make sense to do in-water work instead of hauling out a vessel or structure?

In-water inspection and repair is faster and cheaper than drydocking for ships, and it is the only practical option for offshore platforms. The USCG accepts in-water hull exams under 46 CFR 71.50-3 when visibility, sea state, and hull condition allow; otherwise haul-out is required. For fixed structures, in-water work is routine because there is no haul-out, but you need to accept the limits of diver access and water clarity.