Rohak edited this page Feb 4, 2017 · 4 revisions


Cesar HARADA, contact@cesarharada.com
Guillaume DUPONT, guillaume@scoutbots.com
Kwanyuk Agnes CHAN, Agnes@scoutbots.com



“Birthday” and “Classic” :

  • Total length : 84 cm
  • Total Hull height : 42 cm
  • Total mast height : 89 cm
  • Area of main sail : 1 424 cm2
  • Area of jib : 828 cm2



  • Total weight 4.5Kg
  • Sail (including mast and boom) : 245 Gr
  • Control box : 700 Gr
  • Hull + Ballast : 3.5 Kg (approx)
  • Hull (without ballast) : 1.032 Kg
  • Ballast (lead) : 2.468 Kg


  • Total weight : 5.163 Kg
  • Sail (including mast and boom) : 245 Gr
  • Control box : 700 Gr
  • Hull + Ballast : 4.218 Kg (approx)
  • Hull (without ballast) : 1.75 Kg
  • Ballast (lead) : 2.468 Kg

Electronics (identical)

  • Remote controller : FS Sky. FS-GT3C
  • Receiver : FS Sky, FS-GR3E (3 channels)
  • Servomotors : ?
  • Power in boat : 4 AA battery (1.5V each, standard)



We built a whole new gear system that is equipped with 2 speed controllers, feeding 2 powerful DC geared and worm geared motors - one for the sail - one for the hull control.

It worked great in the workshop but required a much longer procedure to start up (4 switches to flick in a specific order). The system did not work on the water.

The very large Hobby battery, the larger motors could hardly fit into the dry box and were very heavy.

Even if this configuration provides more power, it is hard and expensive to:

  • Find this kind of battery
  • Use these speed controllers (145HKD each)
  • The motors may even be too powerful for the application risking to damage the hull.


  • New control box (10.5.7)
  • Sail : 1 geared DC Motor, 6V , 70RPM
  • Hull : 1 Wormgeard DC Motor, 12V, 30RPM
  • Battery : 11V, 2200MAh, NiMH
  • Speed control (x2) : WP-1040 Brushed Waterproof
  • Receiver: FS Sky, FS-GR3E (3 channels)


2 3 4 5



The commercial boat could not handle the relatively strong wind and went flat on the water and drifted away. Protei “Classic” Sailed well but it could not tack. Protei “Birthday” could tack and jibe - most maneuverable of the three, but was a little slower than “Classic”. The round hole in “Classic” hull is to reduce it’s side force so it provides a side force similar to Protei “Birthday”.

So we have decided to abandon that design and stick with the simple 2 channel RC to regular servomotor - more standard.

Test report

  • Wind condition : Average 2.5m / sec. Gusts at 5m / sec.
  • Current condition : .5 to 1 knots
  • Wave height : max 30 cm, high frequency, disorganised 3d waves


  • Successful, the boats sailed easily and against the wind
  • Wind conditions were good
  • Little waves
  • Current was quite strong
  • Protei “Birthday” (The articulted one) can tack - the regular (solid hull) could not tack - Shape shifting was more maneuverable !
  • Both Protei “Birthday” and “Classic” can go upwind.
  • Classic is faster
  • Both boats are too heavy
  • Protei “Classic rudder should be be bigger.
  • Both “Classic” and Birthday were approximately equally maneuverable in low and high wind
  • We tested “university club” sailboat, it was crap. Cesar had to swim to get it back : http://youtu.be/AailPjvkYo4?t=6m31s


  • Fiberglass spine works well ! Good find Guillaume ! 2 layers or regular 300gr / m2, bidirectional.
  • Thin slicing the hull was good for bending - but no so good for hydrodynamics as here is still too much water turbulences between the section
  • The floatation line could be lower (float higher) on “Birthday” - it was ok on “Classic”
  • Water stocks in the “dry compartiment” - not good.
  • The hull is not curving enough
  • Cable guides
  • The attachment of the hull bending are too loose. we need a more solid attachment point on the “flexible spine”
  • The side view of hull would be more like a banana
  • Not a cross section rectangular but more like a circle profile


  • Hydrodynamic, maybe a little bit too heavy

Motor (Hull & Sail)

  • The Servomotor box from previous Protei worked very well. Super water tight, and 4AA batteries lasted a good 40 minutes of sailing without weakening.
  • The Powerful “Speed controlled” gearbox did not work. It did work in the workshop - not in the water. Not again. Very expensive and time consuming trial - that we should save our clients. Let’s stick to RC for simplicity and reliability sake.
  • The control box should have 1. Switch 2. lights 3. cable inversion 4. cable guides


  • Bright orange sail is well visible and safe
  • A lightweight fabric could be used for the sail.
  • The windvane was not giving us a good information about direction or strength
  • Sails area is ok for this wind
  • add a boom for the jib

Control Box

  • the control box is not easy to open- reverse the tube to other sides


We designed, built and tested 2 hulls of the same dimension, same electronics, same weight (ballast), same sail. The major difference is that one is a solid rigid hull “Classic” and the other one is a shape shifting hull “Birthday”. We also tested a commercial sailing boat called University club (sales at 950 HKD - expensive for poor performance).

Overall we are satisfied and we have a clear list of actions to improve. We are currently simultaneously building 3 new prototypes with the approximate same dimensions.

Next Step

See Protei-10.6.1

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