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Wednesday, December 31, 2014

Farewell 2014

Some images looking back on a year of regrouping, transition and growth:

Production L rudders, proven at the A Class Catamaran Worlds 
Mould for experimental T rudder elevator with junction bulb. Part of extensive R&D work on appendages
Rudder gudgeon assembly with 'between races' rake adjustment
Experimental gudgeons with 'on the fly' rake adjustment
via tiller extension twist-grip
Billet rudder cassette. Our concept of 'dagger' rudders with offset axis has been widely adopted
First A Class 'V' foil concept. 'Inspiration' for current Z foils
Retrofit foil case kit with rotating bearings

Moth bow swivel fitting developed with Scott Babbage. Production version available here:
Moth bellcrank developed with Scott Babbage. 
Production version available here:
Bolts with streamlined heads. Used on UAVs and various sailboat classes
Experimental Finn mast chocks for NB Sailsports
18' Skiff rig spanners for Allmarine. Available here:
Tasar fittings for NB Sailsports.
Available here:
Trophies for A Class Catamaran Nationals

Wednesday, December 10, 2014


We have received many questions regarding the differences between ‘active’ and ‘passive’ foil systems for full foiling.
So here is a look at the principles with respect to performance.


An active system consists of a foil with variable camber or variable angle of incidence controlled by a sensor that measures heave position (ride height).
The input can be via a mechanical device such as a wand/float or an electronic sensor.

Usually the main lifting foil is fully submerged. In order to minimise the total lift necessary, the submerged foil should be angled to provide both vertical and horizontal force components.
The vertical component holds the boat up and the horizontal component resists leeway.
Moths achieve this vectoring by heeling to windward.
By vectoring the lift from the submerged/active span, the vertical struts are not significantly loaded so surface-piercing effects are minimised.

It is interesting to note that where active T foils have been tried on catamarans the results have been less than promising because vectoring was difficult to achieve. Sideforce was provided by the surface piercing vertical struts. These got smaller with increasing ride height. Also their pressure field interfered with the main lifting foil degrading efficiency.

With twin Ts it may be possible to set the hulls up for differential ride height (set the neutral point on the respective sensors differently for windward and leeward foil) thereby encouraging the platform to stabilise at a heeled ride height. However the downside is that the windward foil will have a long span of submerged strut (since the foils are far away from the centreline, the difference in immersion from upright to heeled is large).

One concept we tested, designed by Dave Lister, showed promise by combining active heave control and lift vectoring via angled fully submerged lifting spans for minimum wetted area.

On an active control setup, lifting foil area does not change with heave. The submerged portions of the vertical struts get shorter but this has little effect on total lift. Instead lift is controlled by changing the lift coefficient of the main foil, either through altering angle of attack or, most effectively, through adding camber by deflecting a flap.

A flap alters camber and changes the angle between chord line (light blue)
and oncoming flow (dark blue)

This solution comes in different forms. Variations on V configurations rely on a decrease in immersed foil area with heave.
Other solutions such as the acute L/V rely on a coupling between heave and leeway such that increasing leeway reduces the effective angle of attack of the main lifting surface.
Where leeway values are very small, an L/V foil can also use a reduction in lifting area (inboard tip breaching the surface) as a last-resort means of limiting ride height.


Mechanically it can be argued that the overall complexity is similar: Active systems have swivels, pushrods and bellcranks that require significant refinement and must be looked after correctly. Passive foils require hull and deck bearings and means of adjusting depth and rake.
So ultimately the cost differences are minimal.
Active foils need some form of articulation built in (a shaft or flap) so they are more complex to produce. But they tend to be made from straight segments whereas passive foils tend to have curved spans so their tooling is more expensive.
Again, on balance cost is not a deciding factor.

Active foils with mechanical sensors tend to be at a disadvantage in light winds and marginal foiling conditions because there is a drag penalty associated with the control system.
In non-foiling conditions the sensors can be disconnected and retracted. But then no lift is available so any puffs would see the passive boat move ahead in foil-assisted mode.
Arguably the active setup is also heavier depending on where the sensors are located and how they connect to the foils.

So on a small cat the passive foil would have the competitive edge in very light winds.
The exact crossover remains a subject of investigation and will be found to depend on variables such as displacement/length ratio, sail area/wetted area ratio and the exact design of the foils...

Once foiling the active system requires less deliberate correction by the skipper.
This favours the less advanced sailor but probably makes little difference to the nuanced expert who is constantly making adjustments by muscle memory.

The crucial difference is this: An active foil can be smaller for a given takeoff speed because lift coefficient can be maximized when needed and dialed out when not required.
You can have an aggressively cambered foil on takeoff and a flat low-drag one at high speeds.

This is not impossible with passive foils. For example, the section used in the upper portion can have more camber than the one used near the tips.
But the compromise is more critical.
It is more difficult to have early takeoff and low drag at high speeds.

If the rules are tested and the A Class decides that active controls are not desirable, then passive systems will evolve rapidly and the problems will be solved.
Hopefully the decision will be an informed one based on a good understanding of the options rather than on prejudice and fear of the unknown.
In either eventuality the development process will continue to be fascinating.

Graph from UNSW Team 1: Sam Paterson, David Kirkby, Byrce Edmonds, 
Ashley Thornton, Felicity Kelleher, Nick Tenison, Syafiq Nazarudin 
And Team 2: Jarred Grimmond, Nay Myo Lwin, Stephen Narunsky,
Julia Shields, Tyler Steer, Hu Su

Friday, November 28, 2014


New Moth bow mechanism developed with Scott Babbage now available from SailingBits.
CarbonicBoats worked with Scott to develop a system with less friction, almost zero play, and built-in adjustment of gearing and wand length.

Four prototypes incorporating different shapes and bearing materials were created and tested before the production version could be signed off.
A great project for learning about the complex tradeoffs between mechanical efficiency, weight, reliability, repeatability of tolerances and cost effectiveness.

Milled from a single block of aluminium the new design takes out the wobble and play from other systems. With a larger diameter axle, and bronze bearings, the bow mech takes away the opportunity for unwanted movement that develops in other designs.

Incorporating adjustable gearing, adjustable wand and a large fast-point variation, you have a large range of adjustment to get you through the full range of conditions.

And for all those aero junkies, it incorporates and aerofoil maystick to reduce drag.

Available in Black, Silver, Red, Blue, Purple & Yellow.

Order yours now by going to:

Saturday, November 22, 2014


The nature of our UAV work is such that we don’t regularly get to share it with the public.
Confidentiality is often an important consideration in the aerospace game so it is exciting that on this occasion we can reveal images of a recent project.

These are the first airframes of the Cometa UAV, designed by d3 Applied Technologies for surveillance and 3D mapping missions.
We worked closely with Gonzalo Redondo and the d3 team to develop tooling, details and fittings best suited for their design.

The beautifully integrated and streamlined airframe is demountable in the field so it can be transported in a compact package.
It can operate with landing gear or from a catapult with parachute landing.
The aerodynamic treatment, informed by in-house d3 CFD capabilities, is exquisite.

Wednesday, November 12, 2014

Checking In

Click here to read a Q&A Session with Martin Vanzulli who is doing a great job of keeping the A Class website up to date as well as running the Catsailingnews blog.

The interview covers our V3 Paradox A Class design (nearing production) as well as our ongoing foil R&D work.

The final questions are about how some of our recent experiments with control system foils fit with the A Class rule. We reiterate that our design decisions for production are informed by proactive consultation with the Technical Committee to make sure we are always within current rule interpretations when introducing innovations to the market.
Experimental work goes on in parallel. It is aimed at demonstrating what is possible and, increasingly, at satisfying market demand for 'pure' full foiling solutions.
Personally my hope is that fair, objective, literal and consistent rule interpretations will allow further development within a knowable and predictable design space.

Tuesday, November 4, 2014


You can now listen on demand to the show we guest-hosted on Sunday night:

Wednesday, October 29, 2014

Higher Learning

Earlier today two teams from the University of NSW presented results of an inquiry into theoretical hydrofoil stability and performance.
The teams undertook to assess three candidate foil types on an A Class catamaran and investigate relative characteristics of lift, drag and change in lift with ride height/leeway.
A more detailed report is being prepared, but initial indications are in line with experimental observation.

Thanks to Dr Qing N. (Shaun) Chan for structuring the project.

Saturday, October 25, 2014

Working the Angles

Our Paradox Version 3 A Class cat platform design is complete and tooling is underway.
The foil housing arrangement in the new boat is designed to accommodate virtually any shape with full interchangeability of parts using a new version of our proven system of hull and deck bearings.

Now focus is on foil design.
The plan is to offer the boat with a foil package that prioritises ease of use. 
Design constraints were imposed to keep the overall arrangement symmetrical (so the foils need not be raised/lowered/trimmed at every tack or jibe) and to minimise part count.

An alternative foil package with flaps to control heave is being developed in parallel.
Owners will have the option of fitting either foil package depending on preference.
Full interchangeability is being implemented from the earliest stages of design.

Looking at the simple 'no moving parts' option, the most promising concept is the Z foil, itself a development of our 'comma' foils, in turn inspired by Hydroptere.

Studying the Z foil in detail reveals some interesting tradeoffs that the reader will appreciate.

Since the A Class has a maximum beam limit and an inboard limit for all immersed portions of the boat, there is a theoretical maximum available horizontal (projected) span.

To take advantage of the full available width, the 'working' part of any lifting foil should ideally start at maximum beam and end at the inboard limit.
This can be achieved in a number of ways including:
a) Mount the supporting strut right out at max beam.
b) Use a T foil.
c) Cant the strut outward so it exits the canoe body somewhere inboard of the hull maximum width, goes down and outboard until it hits maximum beam, then connects to the lifting span.

Option a) has the drawback of poor interference drag characteristics at the junction between hull and foil. Since the foil leaves the hull tangentially where the topsides roll into the 'shoulders' of the bilge, the included angle between the inboard face of the foil and the bottom of the hull is very acute.

Option b) could potentially be promising but it is difficult to overcome the drag of the T junction. The two free tips of the lifting element also give higher lift-induced drag.

Option c) leaves us with some interesting trades to make.
Moving the junction inboard gives better 'end plating' and less interference drag. 
These two factors also discourage ventilation when transitioning to full flight.
However moving the exit point inboard requires either more outward cant or more depth of the vertical strut to achieve the same span of working foil.

More outward cant means less draught and less overall foil area. But in some conditions the outward canted strut can generate downforce, negating some of the gains and adding induced drag.
Less outward cant means more draught and more overall foil area. But also more total lift.

Overall characteristics of lateral resistance (and optimum effective toe-in) are also affected by the above tradeoffs.
Cant angle of the upper strut also has an effect on the rate of change of effective dihedral with heave.
Which is a measure of heave stability (decreasing dihedral angle with ride height gives positive heave stability).

Surprisingly the best combination may well be to give up some horizontal span in order to limit outward cant and/or draught without moving the exit point too far outboard.

Other considerations are the 'droop' angle of the main lifting segment and the shape of the tips.
Interactions of these parts are quite complex as there is significant 'wraparound' of the pressure fields.

Fascinating as always.

Tuesday, October 14, 2014


Here is the first production item emerging from our development work in collaboration with Moth guru Scott Babbage.
Billet machined bellcrank now available from
The brief was to develop control system components that minimised play (manifested as slop/bumps in the foiling ride) while maintaining full adjustability.
More bits are under development and will be available soon.

Saturday, October 4, 2014


Here is an extended mix showing some early runs with experimental control system foil configurations.
Though there is still vast untapped potential, these sequences give a flavour of what is surely to come.
Everyone who tried it commented, through a persistent grin, that it is easy and feels secure.

As often repeated on this site, the goal is performance, not foiling at all costs.
Passive systems such as L/V foils give some measure of heave stability at the cost of some additional lift-induced drag. If properly designed they are competitive and manageable. The key is to design the system to work with the hull so that the highly foil assisted mode remains fast. In the right conditions and with the right technique the skipper can then push beyond a 99% lift share and transition to full foiling.
So far this has only been proven to pay downwind in flat water when fully powered up. But undoubtedly the profitable flight envelope will steadily grow, expanding to lighter winds and upwind.
By all accounts engaging this mode is hard work and requires judgement to give net gains in VMG. But since gains are definitely available, it is a challenge to be relished.
V, comma, and now Z foils have improved performance, added a challenge and made the A Class safer to push hard, without taking away from the delicious responsiveness of this lightweight boat.

The difference between a passive system and a control system is that the latter is simply relentless. The boat will remain foilborne essentially until it stops, allowing for the skipper to look around, sit in, change gears and ride out lulls... All while the ride height is directly reacting to changing inputs.
So enjoy this first glimpse into just what is possible under this great class rule!

Make no mistake: there is a concrete measurable difference between current passive systems and truly stable foiling. As long as speed gains are out there, people will experiment and discover ways of realising them. Whether this is made easy and safe or expensive and dangerous is determined by how the rule is administered.

Wednesday, September 10, 2014

Bel Paese

Some great images of Andrea Ferrari racing his Paradox V2 in Italy

Monday, August 25, 2014


Another symbolic milestone: the last batch of Katana Marblehead hulls from the existing tooling is here.
The old moulds have been 'retired' and work will begin soon on updated tooling.
Deliveries are expected to start again in mid 2015.
Get in touch for more details...

Saturday, August 2, 2014

Back to the Future

I have hinted in previous posts that the new home of Carbonicboats is in a rather special place.
Now the bulk of the preparation work is behind us, the Sydney International Boatshow is as good an occasion as any to reveal a bit more about our choice of this little known but fascinating location.

Image source
Cockatoo Island is a UNESCO World Heritage Site in the heart of Sydney. It is steeped in shipbuilding history. It was a place of great industrial production and innovation where many a destroyer with the proud 'HMAS' prefix was constructed and commissioned.
It was a key piece of infrastructure in supporting the Pacific Fleet during WW2.
Great technological innovation also took place there with notable presences such as de Havilland aircraft in the 1930s and naval submarines in more recent times.

Image source
After a period in limbo following the relocation of heavy industry, the island is being revitalised under the auspices of the Sydney Harbour Federation Trust. The many unique spaces it offers now play host to art exhibitions, concerts and film crews. A Marine Centre is also being readied with dry stack boat storage, food and entertainment.

Angelina Jolie directing Unbroken on Cockatoo Island. Image source
Such a place was a natural fit for our company.
Direct access to the water for testing, the convenience of being right next to Sydney city, security and relative privacy, are all great practical benefits.
But the significance of continuing an awesome tradition is deeply inspiring.
My greatest wish as a director of Carbonicboats is to foster a corporate culture where innovation and quality are valued highly. Being surrounded by the legacy of past creativity and being in the presence of similarly innovative companies will certainly help.