We have found through testing that 4m length is long enough to support the larger helmsman, without being too much of a handful for small sailors to launch and recover.
An overall beam of 1.4m conveniently fits a normal roof-rack.
We have always felt that a chined hull is the correct approach, giving the sailor more reserve stability.
The chine peels off the spray when sailing down wind and at the same time gives greater dynamic stability.
The flatter hull panels of a chined hull allow construction from normal flat sheets of PU foam, reducing the weight of the core bond (cores designed to mould around tighter curves “absorb” more resin into their score cuts or honeycomb).
The original prototypes had a higher chine, however through development the chine has dropped to just below the water line amidships. This has proved to have several advantages:
A 35kg sailor gains the benefit of approximately the same waterline beam and hence the same hull form stability as a heavier sailor
The waterline beam and wetted surface does not change significantly with an increase in helm weight
We have found that because the RS Aero is so light there is less inertial mass to pull against when trying to sit in if there is a lull or a header. This is compensated for by the flatter hull and increased form stability due to the buoyancy in the chine area
The chine has a small lip (or land) in order to reduce spray drag and for precise positioning of the computer cut foam panels during construction
The RS Aero has a fine bow for upwind sailing, stable mid-ship sections and a relatively wide transom.
The transom shape has been fine tuned to ensure that the RS Aero planes bow up (analogous to the trim tabs on a powerboat stern).
Vertical bows are common in “box rule” dinghy classes and yachts built to rating systems. We chose a raked bow for this one-design dinghy because those measured waterline length pressures don’t apply and:
It leads to greater flare in the forward 20% of the topsides, giving reserve buoyancy and forgiving handling in waves – it is easier and more efficient during the lamination process, leading to cost and consistency efficiencies in volume production – it makes the Aero’s valuable stacking system possible.
As the RS Aero is relatively narrow we have optimised the width by adopting the modern approach of running the gunwale parallel to the centreline in the aft half of the boat. This has a number of advantages:
Maximum righting moment wherever the helm sits out, irrespective of fore and aft position
When capsized the topside buoyancy is kept to a minimum – ie. the boat floats lower allowing easier reach to the daggerboard (particularly important with a very light boat)
In plan view, the abrupt change of deck line at the front of the cockpit allows a fine bow without pushing out the overall width or the topsides forward, as would happen with a fair curve
Easier to sit alongside a RIB or the dock
More space to tie the mast sections alongside the boat on a roof-rack
The boat can be stored or transported more easily on its side
The hull and deck are joined with a conventional gunwale. We have used the “biscuit tin” (smooth) join for close to 10 years on the RS Elite, but chose a U section gunwale for the RS Aero because:
It creates an important carbon laminate “box frame” around the boat and distributes rig loads through a light, efficient structure – it makes righting the boat from inverted faster and safer - the gunwale gives a significantly drier and more pleasant ride upwind & tight reaching – it makes the boat much easier to hold when launching and recovering, especially in waves.
Flat panel deck
We have used, where possible, a chined flat panel deck to minimise weight and keep straight load-paths with structural corners.
Numerous deck profiles were tested to maximise sitting out comfort whilst maintaining good “kick off” surfaces when roll tacking - and a feeling of security when sailing downwind in a blow. We have resisted the styling led temptation to cutaway the deck at the transom – it is useful to sit on when bearing away in extreme conditions.
During construction, the mast step is located in the hull by a vertical pin, thereby ensuring mast rake and rig position are identical from boat to boat.
After manufacture, the pin is removed to leave a drain hole for the mast tube.
There is a stainless steel protector at the base of the mast tube to prevent wear.
The RS Aero is designed to stack – the hull above sits perfectly into the deck below.
This allows three boats to be stacked on a conventional road trailer base with small carpet-type pads between them – double and triple trailers are unnecessary.
Efficient stacking allows over 30 boats to be loaded into a 40’ shipping container – minimising freight cost and carbon footprint in transport to dealers or regattas.
Every aspect of the simple shape has been considered to minimise weight and maximise cost-efficient manufacture:
Flatter panels on the chined hull allow construction from normal flat sheets of PU foam, reducing the weight of the core bond
“Chine” angles on the deck add form stiffness without additional weight
Low surface area reduces weight and material costs
Simple shape reduces time in the manufacturing process
Epoxy resin is used for its high strength and low water absorption properties.
Woven glass matt is used throughout the hull.
Carbon fibre is used in all high load areas such as both hull and deck around the mast step, the hiking region of the deck, all around the gunwales and the transom.
Due to its ultra-light weight and the high elongation at break (shatter resistance) of the epoxy resin system, the RS Aero has proved to be remarkably durable.
Yet the boat is so astonishingly light it is possible when landing to deliberately capsize the boat and to carry it up the beach single handed, by holding the top of the daggerboard and the boom! Pulling the boat up the beach on a trolley makes you smile.
Young sailors and small women can lift the RS Aero onto a roof-rack.
The tooling has been CNC machined to give maximum control over shape and symmetry.
RS Aero–Dynamic Three Rig System
From day one we have assumed a requirement for three rigs of differing sail areas to cater for the desired crew weight range: S Aero 5 – RS Aero 7 – RS Aero 9.
We have developed rigs with sufficient control to totally flatten and twist the head of the sail upwind reducing the healing moment. This allows a greater sail area to be carried – a big benefit downwind and in lighter conditions.
Working closely with a world-leading carbon fibre tube manufacturer (the largest windsurfer mast and fishing rod manufacturer worldwide) we have produced the three rigs using a common top-mast and boom, yet radically differing stiffness bottom sections that are still compatible with the top-mast. The differing bend at deck level and stiffness of the three rigs ensure the boat remains well balanced, without resorting to a permanently pre-bent lower section for the smallest sail.
It is worth noting that even with the smallest RS Aero rig the sail-area : hull-weight ratio is significantly higher than most existing hiking single-handers, due to the incredibly light weight of the RS Aero hull. So even the RS Aero 5 enjoys the amazingly responsive feel that makes the boat so exciting.
Racing will take place as separate fleets – in fact it is expected that there will be some variation in events schedules – for example the RS Aero 5 programme may include some of the fantastic RS Tera’s events due to its natural pathway.
The largest rig is 5.5kg lighter than the equivalent in aluminium alloy and the cutting-edge production method provides for very tight control on mast stiffness and weight.
The original prototype rigs had a sleeved luff mainsail – this proved impractical with the big headed mainsail making it difficult to step on windy days. There were also problems with the inboard end of the full length battens. Most sailors preferred the convenience of a main halyard on a tracked mast.
The RS Aero rig is positioned well forward in the boat to provide for a good distance between the mast and the centre-mainsheet to reduce sheet loads and for ease of gybing, without the risk of snagging associated with a transom led mainsheet.
This is the greatest area of conflict between styling pressures and the performance requirements of the RS Aero.
It is not possible to produce a Mylar sail that will cope with the wide range of mast bend of a responsive carbon rig, in different wind strengths and on different points of sailing. This is due to the lack of bias (diagonal) stretch of the fabric. Mylar film is stable in all directions.
We have, therefore, chosen a high denier Dacron sail fabric with a low filler content that offers good durability and a high level of user-friendliness.
RS Aero- Foils
The RS Aero has a vertical daggerboard for ease of use.
The daggerboard is of a glass/carbon construction from CNC milled tooling, to a modern section developed successfully to reduce downwind drag whilst still generating enough lift upwind.
The unusual profile is designed to fill the daggerboard slot in the hull until the point where the knuckle is reached – minimising drag.
The tapered tip below the knuckle reduces tip losses.
There is some evidence that a leading edge knuckle can provide greater stability of flow - it is not uncommon in birds!
Evolved during testing, the rudder blade’s low drag section and surface area are extremely effective.
We tested numerous rudder stocks and it became apparent that due to the downwind speed of the RS Aero none of the injection moulded rudder stocks provided enough stiffness.
We have designed a custom, low pressure die cast, high grade alloy stock of minimalist size.
The rudder blade can be rotated to vertical whilst ashore and is well supported at all angles whilst afloat.
Early Aero prototypes had single ended control systems for vang, cunningham and outhaul cleated near the centreline for simplicity, however the majority of test sailors wanted cleats on the side decks – we bowed to public demand.
Fit-out is, nevertheless, simple whilst providing all the rig control you need and enabling the boat to be rigged in moments.
The centreline toe-strap is well padded for comfort and adjustable to suit hiking style and sailor size.
Functional and beautiful custom designed carbon fibre RS Aero options include brackets for Tack Tick or Velocitek electronics, a GoPro camera mount and tiller extension.