NAVAL ARCHITECTURE & SMALL CRAFT DESIGN
Naval Architecture, in simple terms, is the design of floating structures. This covers anything from a simple barge to a mega-yacht. Small craft design focuses on smaller vessels (typically < 24.00m) which can be displacement, planing or sailing craft.
The Naval Architecture design process is commonly described by a design spiral. The design goes through several iterations until a final, optimal design is reached.
Different types of vessels will have different task to be completed (e.g. sail versus engine power). Also, the priority of different tasks will also change. For example, a racing boat will place more importance on weight and resistance, whereas a ferry will consider seakeeping and stability more important.
In reality, the design process is not as simple as shown by the spiral; it is more a squiggle. To complete a resistance calculation, a weight calculation needs to be conducted. However, a weight calculation requires details of the engine for example (from the resistance calculation). So each task requires input from other tasks. One of the roles of the Naval Architect is to manage this flow of information.
HULLFORM DESIGN & DEVELOPMENT
Design of all hullforms, from displacement (slow speed) to planing craft (high-speed).
HULLFORM GENERATION (MODELLING EXISTING VESSELS)
Using a special process and dedicated Naval Architecture software, we can generate 3D hullform models of existing vessels. This model can then be used for various calculations.
We can develop detailed General Arrangement drawings in AutoCAD. These drawings show the layout of the vessel and the allocation of the various spaces.
RESISTANCE & PROPULSION CALCULATIONS
We can provide initial powering predicton calculations (resistance curves, powering curves) for standard hullforms. We use proven resistance algorithms best suited to the hullform being assessed. More detailed calculations require in-depth Computational Fluid Dynamic (CFD) analysis and/or scale model tank testing.
A seakeeping analysis predicts how a vessel will respond when encountering different sea states. Initial sea-keeping analysis is carried out using a method known as Strip Theory, which is well suited to conventional hullforms. Unique hullforms and detailed sea-keeping analysis are best performed by tank testing scale models.
Using specialist Naval Architecture software we can determine a vessel's stability characteristics (how likely it is to capsize). The stability can then be compared against preselected criteria to assess if the vessel is expected to be safe in operation. Advice regarding changes necessary to help make the vessel comply can be offered. Both Intact and Damaged stability (deterministic and probabilistic) can be assessed.
Initial structural assessments will calculated the required shell thickness and stiffening arrangements. Calculations are performed to ISO 12215 or specific Classification society requirements.
Using estimating techniques we can provide an initial weight estimate for a design. Then, as information increases and the design matures, the weight calculation can be refined. The final weight is confirmed using a Check Lightweight survey when the vessel is built.
Using our 3D model including tank definitions, and information from the weight calculation, we can determine how the vessel should be loaded safely. As a minimum, three conditions are checked (departure, mid-voyage and arrival).
We can assist in the creation and updating of Stability Booklets. The Stability Booklet typically details the main particulars of a vessel, along with the hydrostatics, stability characteristics, and loading conditions. Our Stability Booklets are created in accordance with international guidelines (IMO A749, Intact Stability Code 2008).
A concept design usually involves one loop around the design spiral (each of the above tasks addressed once). This is to identify if the concept is feasible. More detailed design studies are then performed as the design matures.
RECREATIONAL CRAFT DIRECTIVE (RCD)
We have in-depth knowledge regarding addressing the requirements of the RCD for both design and construction. We can help advise on compliance with the RCD and checking if an existing vessel would be compliant with the Directive.
Gordon Design has a growing interest in Small Craft Surveying, and aims to become a member of the Yacht Brokers, Designers and Surveyors Association (YBDSA). Please contact us for more information or to arrange a survey.