Small Boats, Big Rules: Why Survey Is So Hard (and What We’re Doing About It)

If you’ve ever thought about putting a CNC Marine hull into survey for charter work, rescue, or commercial fishing, you’ve probably heard the same thing over and over:

“Small boats in full survey are hard.”

In this episode of the CNC Marine podcast, Marsh, Pete and Liam sit down to unpack why that is using a few real projects as examples and answer a listener question we get all the time:

“Will a CNC boat sink?”

Let’s dive in.

The 7.0 Walkaround: Massaging a Great Boat Into 2C Survey

One of the recent projects on the go has been a 7.0m walkaround — the 7010 WA you might have seen online as “Fantasy”, the big orange plate boat doing the rounds on YouTube and Instagram.

Originally, the follow-up build started as a standard recreational design. Then the owner came back and said:

“I want it in full 2C survey.”

That simple request changed everything.

To get the 7020 WA into 2C survey, Pete and Liam had to:

• Redesign the hull for twin outboards

• Rework fuel tank systems to meet survey requirements

• Push the beam out to 2.7m, largely driven by stability rules

• Tweak deck heights, steps and internal layout so the boat would scrape through the stability calculations

From the outside, the boat still looks like a tough, stable 7m walkaround — because it is. Jump on the 7010 WA and it feels rock solid, barely moving through the big “wind heel” stability tests.

But on paper, under the current rules, it’s right on the edge.

That’s the big frustration:
the boat is stable and fit for purpose in real life, but the way the rules are written for small vessels makes compliance a constant game of millimetres, deck heights and exemptions.

What Makes Small Boat Survey So Tough?

When people think “survey”, they often picture ticking boxes:

• Add a bulkhead here

• Beef up a stiffener there

• Add an auxiliary engine or twins for offshore work

If it was just structure and systems, life would be pretty straightforward. Structure rules are relatively reasonable: if something isn’t strong enough, you make it stronger.

The real battle is stability, especially for small boats.

The wind problem

One of the biggest drivers in the current stability rules is wind. Small survey boats are assessed against very high, static wind speeds — think the equivalent of 50 knots of wind hitting the side of the boat in flat water, then measuring how far it heels.

In reality, the kind of operators using 6–7m plate boats offshore:

• Are watching forecasts

• Aren’t choosing to head out in 50 knots

• Have real-world conditions and judgement limiting their day

Pete’s frustration (which we share) is that:

• We’re not seeing real-world data showing these boats rolling over from wind alone

• Most serious incidents come from bars, seaways, or damage (water ingress), not just wind heel

• The rules are so tight that a boat that feels incredibly safe to stand on can still fail on paper

So when a customer rings and says:

“I want my 7m hull in full 2C survey for charter fishing.”

…we can’t always give a simple yes/no answer up front. The tolerances are that tight.

Who Makes the Rules?

In Australia, commercial vessel rules sit with AMSA (Australian Maritime Safety Authority), who apply the NSCV (National Standard for Commercial Vessels).

Those standards:

• Were built years ago by committee

• Pull from various international standards

• Haven’t really been optimised for modern small plate boats

Meanwhile, places like Europe work under well-funded standards such as ISO, which are constantly being updated, reviewed, and refined off real-world data.

Pete’s view?

• Australia wants its own rules (fair enough — our coastline is unique)

• But we don’t have the same funding or update cycle

• The small-boat stability problem has existed since NSCV landed

• Even AMSA has had to create exemptions just to get some designs through

The result is a system that can actually penalise new, well-designed boats, while older boats remain in service.

Old Boats vs New Builds: The Grandfathering Issue

One of the most confusing things for owners and operators is this:

“My mate runs a similar-sized boat offshore with X people in survey. Why can’t I?”

Often, it comes down to grandfathering.

• Boats that were already operating when AMSA took over can usually keep operating under their existing approvals

• They may not have to meet the current stability rules if they don’t change how and where they operate

• They can even be sold and continue in operation (within certain limits)

So we’re in a world where:

• A 20–30-year-old boat can legally carry the numbers it always has

• A brand-new, rock-solid 7m plate boat might struggle to get the same numbers approved under today’s rules

From a safety point of view, that doesn’t make a whole lot of sense.

The 6.1 Centre Console: Fighting for Small Charter Boats

Another example the team talks about is a 6.1m centre console for a small coastal charter operator.

The idea was simple:

• Run a mum-and-dad style charter

• Operate up to around 15 nautical miles offshore

• Take a small number of passengers in a proper plate boat

• Keep it trailerable — not a 10m+ monster that needs a truck to tow

You can:

• Go offshore as hire-and-drive under Australian Standard 1799

• Go offshore as commercial fishing (3C) under exemption

• Go offshore as crew-only (no passengers) 2C under exemption

But the moment you add passengers + skipper and call it a charter, you’re back to full survey requirements — and that’s where small boats hit the wall.

Pete has been:

• Trying to use existing exemptions logically

• Applying the same standards used safely in hire-and-drive and fishing

• Proposing operational limits (distance/weather) to keep things sensible

So far, no simple win. It’s a lot of box-ticking, exemptions, and re-interpretation attempts just to get a safe, fit-for-purpose 6.1m charter boat through.

Again, this isn’t about dodging safety. It’s about:

• Keeping boats genuinely safe at sea, and

• Making it possible for small operators to run viable businesses in modern plate boats

We’re Not Just Complaining — We’re Trying to Change It

It would be easy to shrug and say “that’s the system”.

Instead, Pete and the CNC Marine team are actively involved in trying to move things forward:

• Pete sits on the review committee for AS 1799 (the Aussie standard used for recreational builders plates)

• He’s involved in AMSA working groups and boards

• We spend a lot of unpaid time working through edge cases with AMSA, builders, and owners

The goal isn’t to drop standards.

The goal is to:

• Keep people safe at sea

• Ensure the boats we design actually feel safe and behave well in real conditions

• Make the rules fit-for-purpose so small commercial operators can run modern, well-designed boats — not be forced into old, grandfathered hulls or imports

If we’ve had anything to do with a boat, our goal is simple:

Everyone climbs back on the trailer or into the pen at the end of the day.

Listener Question: Will a CNC Boat Sink?

To finish the episode on a slightly lighter note, Liam reads out a question from Wayne on Instagram:

“Will a CNC boat sink?”

Fair question.

The answer lives in a couple of key concepts: flotation and buoyancy.

Basic vs Level Flotation

In Australia, if you’re building a boat under 6 metres, your builder’s plate will refer to one of two things:

• Basic flotation

  • The boat may float in an awkward attitude if swamped (e.g. bow up, engine down in the water)

  • But it should not sink

• Level flotation

  • Even when full of water, the boat should stay roughly upright and level

  • People can stay inside the boat rather than clinging to a hull that’s half-submerged

At CNC Marine, we design with foam flotation to achieve flotation outcomes. You can also use sealed air chambers — which is where pontoon-style hulls come in.

Foam vs Pontoon-Style Hulls

Pontoon boats often use lots of sealed compartments around the perimeter. It’s a bit like the old Titanic example: if you can flood one compartment and still stay afloat, that’s “one-compartment subdivision”; flood two, that’s “two-compartment subdivision”.

In aluminium plate boats, we lean heavily on:

• Correct hull geometry and freeboard

• Internal structure and sealed spaces

• Foam strategically placed to achieve the flotation required under the standards

So, will a CNC boat sink?

• Built and fitted out as designed, with flotation correctly installed:

  • It’s designed not to sink, even if swamped

  • In many cases, it will maintain a useful attitude in the water so you can stay with the boat

Like everything, it depends how it’s built and what’s been changed — but the design intent is clear: we want you on top of the water, not under it.

Thinking About Survey or a Commercial Build?

If you’re:

• Looking at putting a CNC design into survey

• Wanting to start a small charter, rescue, or commercial fishing operation

• Or just curious what’s realistically possible with a 6–7m plate boat in today’s rule set

We’re in the thick of this every day — working with builders, AMSA, and operators to squeeze the best boats we can out of the current system (and hopefully improve that system over time).