Specification, General Arrangement and the Design Freeze

After signing: which document wins, drawing approvals and deemed approval, 499 GT and weight margins, the design freeze, plus a free xlsx register and tracker.

A yacht contract is signed on a specification and a general arrangement that are not finished. The months after signature turn them into hundreds of approved drawings, and somewhere in that period the Owner has to stop changing the layout so the Yard can order glass, joinery and everything else that depends on it. This lesson covers how to run that period: which document wins when two disagree, how drawings move through approval, how weight and gross tonnage are kept inside their budget, and what the design freeze means for every change after it. It ends with a register and a tracker you can use on your own project.

The general mechanics are covered elsewhere and are not repeated here. Revision control, drawing status (issued for approval, issued for construction, as-built) and review protocols are in Document Control and Technical Data Packages. How to read a GA as a planner is in Reading a Ship's General Arrangement for Planners. The contract questions about approvals were raised in Reviewing a Yacht Yard House Contract; this lesson shows how to run the answers.

This is not legal or naval architecture advice. The contract, class, the flag and the naval architect decide. The project manager's job is to make the process visible and keep the dates.

Illustrative project: Project YP-48 is fictional. Its parameters are chosen from publicly reported industry ranges so the numbers are realistic, but no real yard, owner or yacht is described.

YP-48 at signature

YP-48 is a 48 m full custom motor yacht with a design target of 499 GT, for private use and charter with 12 guests, built to the Red Ensign Group Yacht Code Part A (July 2024 edition). The contract runs 30 months, the flag is the Cayman Islands and the class society is Lloyd's Register, both illustrative choices explained in Rules Before Lines, and money is shown as an index where the contract price is 100. The parties (the Owner, the owner's representative, the Design Studio, the Yard and its naval architect) are introduced in Anatomy of a Superyacht Newbuild and Who Does What on a Yacht Build.

At signature the Owner holds four technical documents: the contract, the technical specification, the contract general arrangement and the makers list. The YP-48 master schedule then gives the design side its dates:

Two things stand out. Steel is cut three months before the design freeze, so the hull structure is fixed well before the layout. And interior design carries on for seven months after the freeze. A design freeze is therefore not one moment when everything stops. It is a set of dates, each fixing a different layer of the design, and the rest of this lesson treats it that way.

Which document wins

The contract package will contradict itself somewhere. The contract deals with that through an order of precedence clause, which How a Shipbuilding Contract Works explains for commercial ships: usually the contract terms first, then the specification, then the plans. One publicly filed commercial newbuilding contract states it in two sentences: where the specification and the plans are inconsistent, the specification prevails; where the contract and the specifications are inconsistent, the contract prevails.

Yacht house contracts are bespoke, so read the clause rather than assume it. For YP-48 the agreed order is contract, specification, contract drawings, makers list. Where the makers list sits varies; some contracts make it part of the specification, which changes nothing in practice as long as everyone knows.

Three working rules follow from the clause.

Precedence settles conflicts, not gaps. If the specification says nothing about a detail and the GA shows it, the GA is not in conflict, it is the only source. Gaps are filled by design development, and that is where most arguments about "what was included" start.

An approved drawing does not quietly amend the specification. The commercial article notes that supervisors' approval of a detail does not usually relieve the yard of its obligations, and the contract review lesson asks whether owner approval shifts responsibility. The mirror image matters just as much: if a drawing departs from the specification and the owner's side approves it without noticing, the departure is now on an approved drawing but not in the contract. The register at the end of this lesson has a column for exactly this. Any drawing that departs from the specification leaves the drawing route and goes through the change route, where price, time, weight and tonnage are agreed in writing.

Log conflicts when you find them. Each entry records the two documents, which one wins under the clause, and whether the Owner wants the losing version instead. If the Owner does, that is a change request.

Three illustrative YP-48 conflicts:

The drawing approval cycle

Every drawing that needs an answer follows the same loop: the Yard prepares it, submits it, receives comments, and either issues it for construction or revises and resubmits. On a yacht two things make the loop harder than on a commercial ship. There are more reviewers on the owner's side (the representative, the Design Studio, sometimes the captain), and many drawings go to class, and through class or the flag to the code, at the same time.

Agree the route for every drawing at kick-off. The drawing list should say, drawing by drawing, whether it goes to the Owner, to class, to the flag or its Recognised Organisation, or to several of them. The UK Ship Register's advice on large yacht surveys recommends submitting the drawing list for the sections it surveys early in the project, to avoid problems once construction is complete. The split between class and flag is set by each flag, which is why the second lesson in this series insists on knowing it before the register is built.

Use one set of response codes. YP-48 uses A (approved), B (approved with comments, which go into the next revision), C (not approved, revise and resubmit) and I (for information, no approval needed). Yards use different letters; what matters is that the codes are agreed at kick-off and that a C starts a new review period for the new revision.

Comments must point to a requirement. "Owner not happy with the saloon ceiling" is not a comment the Yard can act on. "Ceiling height at frame 22 is below the 2.10 m in specification section 7" is. A comment that asks for something the specification does not require is not a drawing comment at all. The delegation letter for YP-48 lets the representative make drawing comments within the specification, and sends anything that changes scope to the Owner.

Send the owner-side answer through one channel. The Design Studio and the naval architect review, the representative sends. Two sets of comments on the same drawing, one from the designer and one from the representative, is how a Yard ends up building the wrong one.

The owner's side is not the only reviewer that takes time. Class plan approval of a shafting arrangement or a structural fire protection plan runs to class's own procedure. The Yard plans with an assumed period, and the register should track class items against that assumption, because a late class answer delays the same work as a late owner answer.

Review periods and deemed approval

The contract usually gives the owner's side a fixed number of days to answer each submission and says what happens if it does not. In the publicly filed commercial contract mentioned above, the buyer has 21 days and the buyer's site representative 14 days, and drawings not returned within the time limit are deemed approved without comment. The contract review lesson flagged this as a typical risk on yachts: short periods with deemed approval turn a busy owner's late reply into a permissible delay for the Yard.

After the review, YP-48's contract gives the owner's side 14 days for technical drawings and 21 days for interior drawings, with no deemed approval for finish and colour items. Those figures are illustrative. For the project manager they create three habits.

Every submission gets a due date on the day it arrives. Not a clause reference, a date. The register calculates it from the submission date and the period, and the owner's side works to the date. Check whether your contract counts calendar or working days and when the clock starts (on receipt, or on a complete submission).

Watch for batches. A Yard that sends forty drawings on the same Friday has technically complied. Agree at kick-off how batches are handled, for example a maximum number of drawings per week or a longer period for large submissions.

Deemed approval is a deadline, not a convenience. If a period is about to run out and the owner's side cannot finish, ask the Yard in writing for an extension before the due date. Letting a drawing be deemed approved means accepting whatever is on it. The contract binds the Owner and the Yard; it cannot make class approve anything by silence, so deemed approval only ever applies to the owner's side.

The register also carries a "needed by" date for each drawing: the start of the schedule activity that consumes it. The difference between the reply date and the need date is the drawing's float. In the YP-48 example, the class answer on the shafting arrangement is two months overdue, but the float to main engine installation is still about three months. That is a reminder to chase, not yet a delay.

Weight and gross tonnage

On a 499 GT yacht, the design is managed against two budgets that are easy to confuse.

Gross tonnage is volume. Under the International Convention on Tonnage Measurement of Ships, 1969, gross tonnage is a function of the moulded volume of all enclosed spaces: GT = K1 × V, where V is that volume in cubic metres and K1 = 0.2 + 0.02 × log10 V. Weight does not enter the formula. The practical consequence, worked out from the formula, is how little room there is near the line. Around 499 GT the enclosed volume is roughly 1,880 m³, and each additional GT takes only about 3.65 m³. Enclosing a 4 m by 3 m area of open deck to a height of 2.3 m adds 27.6 m³, or about 7.6 GT. Treat that arithmetic as a sense of scale: the actual measurement follows the convention's rules, including spaces that may be excluded, and the naval architect's tonnage calculation is the figure that counts.

Why the line matters. The first lesson in this series sets out the reported cost of crossing 500 GT. The Yacht Code itself shows the scope of it: Part A has separate chapters for yachts under 500 GT and for yachts of 500 GT and over on machinery, electrical installations, steering gear, bilge pumping, structural fire protection, fire appliances and safety management. A yacht that crosses the line late in design is not adding paperwork; it is moving into different technical requirements while half its drawings are approved.

Weight is mass. Stone floors, thicker glass and heavier structure add weight without adding a cubic metre of enclosed volume. Weight drives displacement, draught, speed and stability. A 2022 master's thesis on weight estimation of superyachts notes that when weight deviates from the early estimates, the result is mainly unwanted changes in speed and stability.

Where the weight story ends. Under the Yacht Code Part A, the lightship weight and the vertical and longitudinal centres of gravity are determined from an inclining experiment carried out in the presence of the Administration, and the results must be approved before they are used in stability calculations. The UK Ship Register's advice notes expect its surveyor to witness the stability tests when construction is about 98% complete. By then every kilogram is on board. The purpose of tracking weight monthly is to have no surprises on that day.

The naval architect owns both numbers, as the RACI in the second lesson shows. The project manager's part is procedural: every change request and every variation order carries a line for its GT effect and its weight effect, filled in by the naval architect before anyone decides, and the monthly report shows both margins.

Reading the YP-48 example:

• The budgets. At signature the naval architect estimates 488.0 GT against the 499 GT target, a margin of 11 GT. Weight is shown as an index where the estimate at signature is 100; the budget, including the design margin, is 105. Both budgets are illustrative.
• Month 3, CR-01. The Owner asks to enclose part of the bridge deck aft as a gym, 4.0 by 3.0 m. At about 7.6 GT that would use more than two thirds of the remaining margin. After the tonnage check the Owner accepts a 3.0 by 2.5 m version, about 4.7 GT.
• Months 5 and 6. Class plan approval asks for heavier structure around the tender garage opening, and the Design Studio specifies stone floors in the bathrooms. Both add weight and no tonnage.
• Month 9, VO-02. After the freeze, the Owner asks for 150 mm more headroom in the wheelhouse over 38 m². That is 5.7 m³, about 1.6 GT, and it goes through as a signed variation order.
• Month 14, CR-05. A request to enclose a bar on the sun deck, 23 m³, would add about 6.3 GT and take the estimate to about 502.6 GT, over the line. It is rejected. By then the GT margin is 2.7 and the weight margin 0.6, both inside the warning band.

The design freeze

The design freeze is a dated milestone after which named parts of the design are fixed. In the YP-48 schedule it sits at month 7 and covers the GA and the interior layout. Glazing, exterior doors and the joinery package are linked to it, so a late freeze moves those orders, and the master schedule lesson shows how close some of them run to the critical path.

Because the design is fixed in layers, YP-48 gives each layer its own date:

What changes at the freeze. Before the freeze, developing the design inside the specification is normal work: the Design Studio refines, the Owner chooses between options, the Yard draws it up. A change to the specification is a change at any time, but before the freeze it usually touches drawings rather than work already ordered or built. After the freeze, any change to a frozen item is a change request: it is priced, its effect on the delivery date, weight and tonnage is stated, and it becomes a variation order before the Yard acts on it. The freeze does not make changes impossible; it makes their cost visible. Industry guidance on yacht contracts makes the same point from the contract side: the fewer variations needed after signing, the fewer knock-on effects on the build, which is why the specification should be as complete as possible from the outset. The yard-side mechanics of pricing a variation are in Change Order and Variation Order Processes; the owner-side change process gets its own lesson later in this series.

What must be true on the freeze date. Treat the freeze like a milestone with a definition, in the same way as the payment milestones in the payment plan lesson. For YP-48 it means:

• the GA revision to be frozen is approved by the Owner, with class comments on arrangement items such as escape routes closed;
• the naval architect's tonnage estimate and weight estimate for that GA are issued, with the margins stated;
• the interior layout drawings are approved (not the finishes, which have their own later date);
• every specification item still marked "to be agreed" has a decision date in the schedule;
• the Owner has signed the freeze record, listing what is frozen and what is not.

When the Owner is late. A freeze that slips is an owner decision that slips. The contract pillar article lists late approval of drawings beyond the agreed turnaround among the buyer's delays that can entitle the builder to more time, and a yacht house contract is likely to treat it the same way; check yours. The owner's side should see the freeze coming: the register shows which freeze drawings are still open, and the schedule shows what moves if the date moves.

The template: T7 Drawing Approval Register and Weight / GT Tracker

The workbook has two working sheets, each in a blank and an example version.

• Register. One row per drawing or document that needs a reply: number, title, discipline, approval route, revision, submission date, review period, need date and the schedule activity that needs it, response date and code, class or flag status for dual-route items, and whether deemed approval applies. Formulas give the due date, the status (Not submitted, Under review, Approved, Approved with comments, Resubmit, Overdue, or "Deemed approval?" where the contract allows it), days late against the review period and float to the need date. Counters at the top show how many drawings are overdue, due for a deemed-approval check, answered after their need date, or departing from the specification.
• Weight & GT. Starting estimates, target, limit, budget and warning margins at the top, and a log of every change or estimate update with its GT and weight effect. Formulas give the running estimates, the margins left, a warning when a margin falls below its threshold, the margins if pending items are accepted, and whether each change came after the freeze. A rule-of-thumb column converts added volume to GT near 499 GT, only to show scale.

The YP-48 register example is shown as at month 9, with twenty drawings: one deemed-approval check, two overdue items and one departure from the specification. The weight and GT example is shown as at month 14, with a pending request for a larger tender garage door.

Download: Drawing Approval Register and Weight / GT Tracker (T7), xlsx

The register complements the Owner / Yard / Class Communication Matrix, which sets who reviews what and through which channel. The matrix is the rule; the register is the record.

Before the design freeze

Before the owner's side signs the freeze record, check that:

• the order of precedence in the contract is known to everyone who reviews drawings, and conflicts found so far are logged with their outcome;
• every drawing has an agreed route, and the register shows a due date and a need date for each;
• no owner-side drawing is past its due date without a written extension;
• no approved drawing departs from the specification without a signed change;
• the current GT and weight estimates are issued by the naval architect, with both margins above their warning levels;
• every change request raised so far carries its GT and weight effect;
• each later freeze layer (superstructure, interior details) has a date in the schedule.

The next lesson in this series, The Master Schedule for a Yacht Build, puts the design freeze and the orders that hang on it into the full 30-month programme.