The Nauti-Craft technology is a hydraulic suspension system for multihulled vessels. The system separates the hulls from the superstructure which allows the hulls to react rapidly to wave inputs and conform to the ocean surface without transmitting high forces and accelerations of the hulls to the deck and superstructure. This provides increased levels of ride comfort, control and stability whether stationary or travelling at speed. The improvements to stability and maintaining a level attitude can be further enhanced with active control of the suspension system. This has great potential applications for commercial, military and recreational vessels.
The need for marine suspension.
• Reduced slamming and jarring motions
- Improves comfort and safety.
• Reduced roll and pitch motions.
- Reduces sea sickness.
• Improved planing speed in rougher conditions
- Improves speed comfort and efficiency.
• Cost Versus Performance
- Allows a smaller vessel to provide seakeeping typically only found in larger vessels while having the lower operating costs of a smaller vessel.
Graph showing comparison between Nauti-Craft's 2Play prototype and a standard catamaran of similar size
• Passive Reactive System.
- Hydraulic interconnections provide beneficial functionality without requiring power when underway or at rest.
• The elegant and devious combination of interconnections provides a PASSIVE mode decoupled solution for optimal tuning for comfort and safety
- Allows the hulls to individually conform to the ocean surface or accommodate wave inputs while maintaining the stability of the body (deck and superstructure).
- Permits the hulls to move rapidly with high accelerations while reducing the acceleration levels on the body.
- Reduces load inputs to the body and reduces the torsional loading on the body.
- Permits simplified active control of roll and/or pitch attitude at (low) body frequencies while allowing the passive reactive system functionality to react to and distribute loads from (higher) hull frequency inputs.
• Auto adjustable for different load conditions and sea states.
- Self-levelling of the body with adjustable height.
- Electronically auto adjustable controlled variable damping.
• Optional active roll control for fast efficient and stable cornering.
• Optional active pitch control.
• Optional DACS (active ‘skyhook’ Deck Attitude Control System)
• Uses standard marine, aeronautical, agricultural & automotive types of components.
- Using well proven component types along with FEA and FMECA during the design process ensures safety and reliability.
Deck Attitude Control System
The Nauti-Craft DACS (Deck Attitude Control System) actively adjusts and maintains the horizontal attitude of the deck at low speeds and when manoeuvring relative to fixed structures or coming along side larger vessels like ships. DACS enhances the intrinsic “passive reactive” and stable deck features of the nauti-craftTM technology by providing additional control inputs in response to monitoring the movement of the deck.
The Design Process
To date Nauti-Craft have built and tested a number of prototypes, including a 4 hull craft "4Play" and most recently an 8.5 metre catamaran 2Play. Part of the design process has been an extensive dynamic simulation program. Using MSC ADAMS software and Nauti-Craft's proprietary dynamic models, our engineers are able to calculate, analyse and validate a range of forces and motions in a range of operating conditions.
The video below shows an ADAMS dynamic simulation of a pylon docking sequence. This model includes the full hydraulic systems with active enhancement, hull water contacts, engine thrust and pylon contact and friction forces.
The simulation shows our one third scale N-C catamaran removing the roll and pitch components (which make one sea-sick) while its deck remains horizontal with moderate heave motion (vertically). This is achieved using our own DACS (Deck Attitude Control System) which actively adjusts and maintains the horizontal attitude of the deck at low speeds and when manoeuvring relative to fixed structures or coming along side larger vessels like ships. The video then goes on to stabilise the front end of the deck at a precise / given height before touching the wind turbine pylon. Once contact is made and maintained the engineers can safely step across.
The video below shows an ADAMS dynamic simulation of active roll and pitch systems operating at 10 knots