Beams under construction

The cross beams are key components of every multihull. Proasis’s beams are made from plywood and timber in a hollow construction. The outside is reinforced with glassfiber. Each beam is 4.5 m long and weights about 25 kg.

Closed beam on the left, open cross section on the right.
It doesn’t matter how many clamps you have . . . you will run low! We clamped 40 on each beam and could have used 60 ore more.

Work on the hulls started

Glassing some bulkheads for the leeward hull

Doesn’t look like a boat yet but we aim to finish the bigger hull of our proa by end of October.

If you like to take a look by yourself feel free to visit us in our workshop:

Its located 15 km from Kiel. The easiest way to get there is to catch a train to Flintbek (regular trains between Hamburg and Kiel stop there). If you take a car leave the A 215 at Blumenthal.

You will find us there every afternoon for the next couple of weeks. Don’t be shy, we are happy about all guests and visitors!

We’ve got a boatyard!

Thanks to some friends we’ve got access to a very nice workshop close to Kiel!

Work on Proasis will start there later this month. If you want to learn how a boat is built feel free to visit us and join the construction team! Everyone is very welcome to become a part of the Proasis team!

Our new boatyard. Boat is almost finished. Just need to magnify it 25 times.

Rig production is going on!

As promised in our last post we managed to the sail this week!

As sailcloth we got a strong PE sheet (also known as polytarp). That’s exactly the sort of stuff the people in Micronesia using for there sails.

Exceptionally we bought it new but spend only 40 bucks.

Nice place for lofting! Thanks to STS, our sailing club, for their gym!
Laying out everything to get the shape.
Cutting the cloth
Sewing. We used a very cheap DIY sewing machine, nothing special for sails. It worked well but but professional machines would give a better result.
More cutting . . .
More sewing . . .
Finished !

We hope to setup the sail for test purpose during the next days. Read more in our next weekly update!

Rig production started

Maybe an odd way to start building a boat, but the very first part of proasis will be the rig (naval term for mast, sail and all other parts belonging to them). Why? That’s a bit of a story:

Originally, proasis was supposed to get a free standing carbon mast (free standing means no shrouds to hold it up) with a soft wing sail on it (see a video of something similar here).

1:5 model of the originally planned wingsail

Aside of the not very sustainable carbon part we never got happy with the design:

  • Much additional work for the mast construction
  • High expenses for the materials
  • Even more work for sewing the sail (it needs sewed in shape!)
  • High bending moments in the leeward hull around the mast bearing
  • Unsustainable design, many new and non degradable parts involved

We thought about many workarounds and fancy designs but eventually came back to the (Marshallese) oceanic lateen sail!

Marshallese canoes with oceanic lateen sail

Proofed for centuries on the pacific, the biggest ocean of our planet. For us the best sail possible:

  • Decent performance (we measured the performance of marshallese canoes!)
  • Simple and cheap to build (spars and flat cloth only)
  • Low center of effort
  • Low stress in the sailcloth

For the spars we were lucky to get tons of old windsurfing mast for free by our sailing club:

Old windsurfing mast, ready for recycling!

The windsurf mast were simply transferred into mast and booms and laid out to test the geometry for shunting:

Geometry of our sail

Next week we will get some cloth and sew the sail. Stay tuned!

Windward hull mockup

Now, after the 1:5 model proa proofed our general concept by amazing sail performance it’s time for something in real size!

To get an impression of what the living conditions on proasis will be we made a full size mockup of the accommodation compartment in the windward hull. In manufacturing and design, a mockup is a scale or full-size model of a design or device, used for teaching, demonstration, design evaluation, promotion, and other purposes. It is probably best known from the automotive industry for show cars, but is an important part of yacht design too.

Our mockup taught us a lot about usability, ergonomics and structural design of the cabin.

As you can see, its a quick and dirty construction from scrap wood and paper boxes. All of that was recycled by us and therefor for free!

Preparing ribs and bulkheads . . .
. . . and finished with paper sheets on! We made only one bow due a lack of material . . .
For comparison: this is how the windward hull looks like from above in a simple CAD model . . .
. . . and this is real life!
Having lunch in the surprisingly spacey insight of proasis! Four adults could sit there comfortably and sheltered for meals, two sleep in the cozy bunks in each bow over night.
The design office got transferred into the mockup for a couple of days: after spending a lot of time inside there we are confident to build a suitable accommodation!
Simulation of the galley/stove area

Scale model (1:5) under construction

The 1:25 scale model turned out to be very promising. As intended, it gave us a better feeling for the shape and led to some changes (extension of the beams to leeward i. eg.).

Next step: a 1:5 full functional model!

Originally planned to be radio controlled, we realized that the shunting process would be very difficult to build and stepped back from that idea. The 1:5 model (1,8m long btw) is now manually controlled and secured by a kite line.

Water bottles for proper scaled weight trim
Beams are lashed on for controlled flexibility

The model will be used to experiment with two different types of rigs and various rudder/leeboard configurations: aside of a traditional oceanic lateen sail (also known as crab claw sail) a newly developed softwing gaff sail with unstayed mast will be tested. The platform is prepared to sail a double rudder configuration (oversized rudders are used for steering and leeway prevention) and leeboard/rudder configuration (leeboard to prevent leeway, small rudder for steering).

Softwing gaff sail
Traditional oceanic lateen (crab claw) sail with double rudder configuration.
Leeboard configuration. The ducktape is not the final solution, the leeboard is supposed to swing back and forth for lateral trim.
Huge SUP board as capsize prevention
Ready for a sail!

Stay tuned, we will post some sailing videos soon!