47751 Michigan Ave., Laguna Heights, Texas, Tel.: 956-943-5150

Kite-sailer main hull


The main hull of the kite-sailer is the last component we build - as such expect a few changes / modifications along the way

The general dimensions are :

Length overall :32'

Waterlength : 29'

Max width at waterline : 36"

Max width midship : 48"

Draft : 18"

Displacemnt empty : 0.9 t

Max displacement : 1.5 t

Construction : "Nidacore" core material  with bi-axial carbon fiber in epoxy resin hand-laminated over the core in the interior and exterior surfaces till the waterline -Fiberglass cloth in the above waterline / cockpit area.

Wave piercing deep bow area for maximum lateral resistance and minimum frontal resistance.

Balancing the kite forces - while keeping him in line of sight

Kite propulsion causes less heeling force than using sail propulsion. Due to the lower  distance between the CoG and the center of pressure of the kite (the hauling point of the kite on deck of the boat ) 
As well as  due to the fact that the lift of the kite and its heeling force cancel each other nearly out if the attachment point is at the right location .
The windward side ( side facing the wind ) of the hull will not be lifted and therefore the kite sailer ( kite-boat) is able to sail almost upright and significant more stable than any other sailing vessel.
Just how do we achieve a shifting pressure point of the kite in a simple and fool proved way while not running after him ...
We need to shift the kite hauling point to leeward of the boat hull and be able to shift back if we change course without getting the lines and the kite controller tangled up in each other ...
If we can move the Kite Hauling Point leeward ( facing away from the wind ) :
windward ( side facing the wind ) side will not be lifted -
less heeling force on the main hull - stabilizer / floats / Ama will be less immersed and create less drag which results in higher speed -
the lift and heeling force should cancel each other out on average .
Best solution to this problem appears to be a bend sailing track which allows the kite hauling point to run around the kite controller  which keeps the kite always in direct line of sight and moves the kite hauling point to the right location on the deck of the boat.

Open cockpit area for at least 6 passenger which give basic protection but would allow the  use of paddles as alternative propulsion to approach sensitive wild life areas and not chase the birds away before you can actually see them.


Helms man control area - aft in the main hull which should allow to control all navigation necessary instruments and steer the course of teh kite-sailer.

Rudder and jet drive - as the kite-sailer has sufficient width for a dual retractable rudder set up - we will choose this approach as it would allow to set  the rudder surface to the vessel speed without disturbing a clean water flow from the jet exit nozzle.

First step is to build and collect all the small custom build components for the main hull from the Harken track - to the seat and rudder blades ...


Additional detail on the main hull :


Propulsion :

For the prototype kite-sailer we want to evaluate the best combination of propulsion for this kind of vessel.
As such we will have four different from each other independent propulsion systems :

  1. Kite power - is seen as the main propulsion for the kite sailer and should allow the vessel to approach most all of its desired destination except straight against the wind.

  2. Electric drive - which is located in each Ama / Stabilizer aft of midships in a designated engine compartment which can be manually lowered through a door in the Ama floor and controlled  by the  helmsman in the main hull for RPM. Basically trolling motors with a Pulse Width Modulation speed control (PWM). A PWM accomplishes two things:(a) maintains motor torque at any speed setting which results in propeller rotation (b) only delivers usable power to the motor without any waste power going to "speed coils" which are effectively resisting in the motor designed to carry a portion of the power and leave the remaining power go to the motor. The electric drive should allow the kite sailer to approach sensitive wild life areas without disturbing their nesting routine while the passenger of the kite sailer can enjoy precious wildlife first hand up close without creating a major impact in these sensitive areas. And should allow for easy docking or port maneuvers as they are set 16 feet apart.
  3. Jet drive - aft in the main hull of the kite-sailer to allow in calm or dead calm condition to get within reasonable time from point A - to point B
  4. Last but not least there are oars which should always work assuming you have enough crew and rum aboard ... as the free-board is set for easy paddle fun.

Back to main page

Back to main page

Technical drawing of Kite-sailer KS32F, not to scale, Kite boat for protected inland waters.


Back to main page

Construction of Kite sailer KS-32F main hull

Most recent status :
  temporary alignment of Kite sailer hulls

The main hull of the kite sailer is out of the shop and reset -
The Amas need to get aligned and crossbeam attachment checked for alignment
Winter will slow us down but we can start with the outfitting on the cold days and fairing on the warm days ...there is some light at the end of this tunnel ...

Main hull of the kite sailer ...kite boat


Interior divider get installed , laminated and faired before the first coat of epoxy primer will seal the surface from UV exposure ...
As winter is approaching in South Texas our shop gets to cold for swift and proper cure ..
Time to get the hull out of the shop and in the sunshine.

Interior divider on the kite sailer


The Nida core floor panels get laminated against the rib structure and cutouts for the inspection hatches installed.
Bi-axial Carbon fiber along the hull joint and fiberglass cloth over the the core seal the surface and give the kite sailer the required stiffness in the water line.
Since the deck has a curve all hatch joint surfaces need to get brought back to a leveled surface - first test of the hatches.
The side walls get laminated in fiberglass cloth and we can step up to the interior components.

Cockpit floor for teh kite boat KS32


The Kite-sailer has like any other boat floor supports which give the hull additional strength while providing the support for the access hatches.
Theoretically we are ready for laying the Nidacore floor panels on the finished frame work is time as we are in the middle of the hurricane season ...
All supports get sealed with two applications of epoxy resin to seal any moisture out.

Floor support in the cockpit area of the Kite-sailer


After building the seat cowling we can install the forward crossbeam pivot points which should allow to lower or raise the crossbeams with  stabilizer / floats or Amas according to sea and wind conditions .
The stabilizer / floats or Amas are already finished and you can see their construction here  :

Also the support for the Kite controller track (bend sailing track)  gets installed . This will  allow the kite hauling point to run around the kite controller  which keeps the kite always in direct line of sight and moves the kite hauling point to the right location on the deck of the kite sailer .

The support
for the Kite controller track is also the forward wave breaker support which will increase its strength without adding any further weight to the vessel .

The first 8 feet of our Kite Boat are ready for the first application of epoxy primer ...looks like there is some light at the end of the tunnel ..

Bow section of Kite sailer with crossbeam connection

The first fit of the kite controller seat is like 4th of July fireworks ... so far so good all works out.
The seat is a modified Kawasaki Jet ski body - build in carbon fiber ....
Since the ergonomics of these skies allow a more or less comfortable ride - why shall we try to reinvent the wheel ...

First fit of the kite controller location / seat


The main floor stringer are getting installed as well as the base for the seat of the kite controller.
It still looks a bit rough ... but so far the shape works out fine
The floor boards get laminated to the hull with bi-axial carbon fiber which will give the hull the final strength  extra impact support gets installed and we are off to take the part of the modified Jet ski.

Internal support for the kite control location


The finished bi-axial carbon fiber laminated hull provides a nice balance between strength and extreme low weight ...
I have to admit that I am more than pleased ...after the laminate is finished the fairing and painting starts to make sure the core is properly protected for the next working step

Finished carbon fiber lower hull of the kite sailer creats a light weight kite boat hull


After cleaning the hull well and making sure there are no wires from previous working steps the internal bi-axial carbon fiber cloth  gets laminated  in epoxy resin.
The Spanish cedar stringer are under the laminate and provide a slight challenge to have good adhesion of the heavy cloth as such we lay in two sections with overlap in the keel area.

Internal biaxial carbon fiber laminate in the kite sailer hull

Once the hull was turned and secured we see the rest of the work ahead of us ..

All the dust in the hull is now in the unprotected bilge - some cleaning and sealing the Nidacore core material will be the first priority ...

Hope no rain will fall before that and soak in the core .

hull turned and secured , ready for more work

3 weeks of preparation just to make sure the 3 seconds of the actual turn don't end up in a "ups"

Challenge still was to lift the hull high enough so it can swing through  without hitting the concrete or to turn before anticipated ...thereafter ...hope ..

Lifting the kite sailer hull for its turn
March 2013

During the winter season, progress slowed due to lower temperatures , as such it took longer than  expected to fair the aft section and lay the carbon fiber - still we got that aspect finished as well and reached the point to lay the last layer of glass on the exterior and apply the first  barrier / anti-fouling coat of copper poxy

Copper poxy barrier coat onmain hull


After the bow area is finished for the final copper-poxy application we can concentrate ( as far as the weather will allow it ) on the stern section of the hull.

We always wanted to try a jet drive on a sailer for a few reasons -
No prop under the boat which gets fouled up ,
No outboard on the transom which puddles in the air if you go through a wave or comes out of the water in reverse,
Smooth lines and smooth waterflow...

But we expect certain drawbacks as
Low reverse thrust
Unit needs to be above the minimum water line and stay out of the water if at rest
Some kind of intake duct to feed the water into the unit ...
But all starts with getting first a jet unit installed into the hull as seen in the photo.
Thereafter we will fair the hull and lay the carbon fiber

Back to main page

Kite-sailer - laminate jet drive unit into the hull


Final fairing of the hull does not allow any power tools - perhaps a random orbit sander excluded and should take the last 1/8" imperfections out of the hull surface.
Manual sanding-boards provide a better finish on the hull - are a bit more time consuming and require a high amount of muscle power but you will be a lot more pleased with the final lines of your hull.
Do not sand into the carbon fiber strands - and if it helps add a small amount of tracer color into your fairing mix.
Allow the fairing compound to cure full to ensure a easy surface to sand.

Back to main page

Kite-sailer forward bow section faired to final finish


The Kite-sailer is a composite hull where the skin carries the load as such it is important to have a perfect laminate on the outer bi-axial carbon fiber skin and inner bi-axial carbon fiber skin.
In case you are on a similar project here some tips : sand the surface as smooth as possible and make sure you have no high spots.
Brush the surface dust free and pressure wash the surface after sanding to make sure there is no sanding dust/contamination left on the surface. Let dry.
Wipe the surface down with a clean shop-towel with Acetone. Do not use shop-towels which are brand new or washed with fabric softener ( Teflon based) .
Make sure you have enough roller, brushes, squeegees, and shop towels within easy reach -
Check for pinholes - if they are present ( which happens often after applying fairing ) apply the first coat of resin with Cabosil or solid Microballoons.
Thereafter saturate the surface with resin - while unrolling the fabric, saturate the side facing the hull ( especially on heavy cloth as 10oz/sqy and up) - make sure the cloth is laying as smooth as possible on the hull surface before you saturate the outer surface.
Apply resin to the outer surface and use the more flexible "Bondo" squeegees to distribute the resin equally over your cloth - allow 10 - 15 minuets for the resin to penetrate and follow with the stiffer polyethylene squeegees to force any excess resin out of the laminate.
Watch for color / reflection change on your cloth to detect dry spots or over saturated sections - follow up for up to 1 hour before you should have a perfect laminate and allow the cure to proceed.
Allow to cure for 2 - 4 hours ( or till the resin is cured to the point of a chewing gum feeling ) before laying a fairing ( Resin hollow Microballoons ) coat over the fabric to close the low spots in the fabric weave.
Thereafter sit back and grab a beer ... yup you still have to clean up.

Back to main page

Kite-sailer forward biaxial carbon fiber laminate wetted out


After the initial fiberglass cloth on the core material - several layers of fairing take the edgy look / feel off the hull and created the smooth hull shape we desired.

We decided to lay the carbon fiber in two sections - forward 16' and aft 16' just for simplicity and to make use of the currently still great weather conditions -
the forward 16' are ready for the laminate - so lets get mixing....

Back to main page

Kite-sailer forward core hull


Several layer of carbon fiber reinforce the bow section - as we want a smooth sailing through the waves and some resistance against the basic obstacles on our journey. The lines from forward facing aft line up nicely and after several layers of fairing we we can start to apply the carbon fiber in the underwater ship.

Back to main page

Kite-sailer bow lines and carbon fiber reinforcement


The previous prepared bow foam core gets laminated to the Nidacore hull / bow rib and the primary fairing process can start.

The Nidacore hull gets the first layer of fiberglass cloth in epoxy resin before the initial fairing gets applied to take the "edge" off the core panels.

We want the hull 80% smooth before laying the outer bi-axial carbon fiber skin. As winter is approaching so does the cure time of the resin require more time.

Back to main page

Kite-sailer bow foam core gets laminated to the hull




Slowly the boat hull shape emerges after the Nidacore boards are secured to the hull.
The consistency of the Nidacore panels is more like a slice of  toast you desire to shape over a Watermelon without destroying the cell shape of the toast ...
Quite some effort will be required to pull / push the core in place before laminating the first layer of fiberglass cloth over it


Back to main page

Kite-sailer hull emerges after the core skin is applied .. it starts to look like a kite boat


The skin core is held in place by the stringer joint - thereafter the epoxy / cabosil fillet gets fiber-glassed with fiberglass tape to creat the more or less solid structure which needs final shaping before laminating the core material

Back to main page

<Kite-sailer hull to bulkhead joint during construction


Once the Nidacore boards are cut they get shaped in one direction against the boat hull and secured from the exterior against the stringer.

After 24 hours the epoxy is cured and the temporary brace removed.

On the interior the stringer get laminated with fiberglass tape against the core panels which provide sufficient strength to hold the core of the skin against the bulkheads a temporary grid structure for the next step.

Back to main page

Kite sailer core installation

kite boat internal stringer


This little saw attachment ( Cummins 4" saw attachment ) does a halfway decent job in the shallow cuts through the core and inner skin - just after a few cuts the blade gets hot and it creates a non-organic cotton candy coating on the teeth - which creats high torque resistance and a uneven cut width.
Time consuming in a southern climate with 95 degree base temperature



Back to main page

core cutting device for nidacore honeycomb material


Sheeting the boat hull of the kite-sailer with the Nidacore core material provided a new set of problems.

Even if Nidacore has great physical properties - to conform to the tight radius of the kite-sailer hull required quite some effort.

Calculating the outer circumference of the Nidacore board surfaces on the boat hull and inner circumference will give you the difference between outer skin length and inner skin length.

The boards need to be cut to the outer circumference length and thereafter on the inner surface reduced via cuts to the inner circumference length to allow the board to bend to the desired shape.

The difference divided by the cut width of your blade will give you the amounts of cuts you need
Quite a few cuts in each sheet as you can see on the outlines and it will still leave a certain "edgy" shape.

Back to main page

Cutting layout of Nidacore hull material for the kiteboat kite sailer KS32F


Main ribs on the kite-sailer are build out of Nidacore honeycomb - Nidacore panels are a polypropylene co-polymer with a scrimp fabric on both sides and our prefered core material for boat hulls.

A layer of fiberglass cloth is hand-laminated to both surfaces before the stringer for the future floor boards are laminated to the finished cut ribs / bulkheads.

We build the kite-sailer upside down - as such you see the keel up.
Length stringer will help to bend the outer core skin over the ribs and are Spanish cedar which served us well in the past in our tropical environment and are very light weight.

Back to main page


The foam core gets shaped and sealed with a epoxy / CAB-O-SIL Fumed Silica putty - sanded and laminated in fiberglass cloth .

The inner core has a 2 lb density foam and the outer skin a 4 lb density foam ... foam below the water line is 4 lb throughout the workpiece.

Back to main page

Bow-section of the kite-sailer during construction with approximately 250 lb of active flotation.



The bow section of the kite-sailer is a solid urethane foam core with a internal ply rib structure - we hope that in the worse case scenario  it will absorb impact or break / crush.

The foam is poured in its liquid form and expands to approximately 16 times its fluid volume.



Back to main page

Rib-structure of the kite-sailer bow section with partially filled flotation foam - Kite boat crush zone with flotation foam


4wings Main page - 4wings Yachtservice - - Site-map