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So the catamaran is made from pipes, not like the pipe boats, which are essentially plastic replacements for bamboo, but from big tubes. But a sea going vessel must be able to slice through the sea, unlike the practical pipe rafts of Taiwan, so one needs some pointy shape. And this is the technique: use some 3D geometry.

Listening to well meaning and highly experienced ship’s mechanics state that it does not work and it cannot work reminds me of mathematicians who, very clever as they are, are caught within their axiom systems and cannot get outside them. So in January Markus started putting the tips on his cat in the right kind of way.

The bow section

The top cutout for the bow section is complete, the bottom cut has been made but the section is still not removed.

In the image you can see the bulkhead door between the bow section and the next section of the vessel. These bulkhead doors help make the whole system safer by ensuring that the whole vessel cannot flounder and go under – some buoyancy should remain,even if the whole catamaran flips, and that is a common problem with catamarans. Initial stability makes them super comfortable to cruise on, but once they start to tip the righting moment (the force that tries to pull them back down to being flat on the water) decreases, unlike monohulls whose deep fins have an increasing righting moment as the boat heels (tips), making them stable. Several catamarans and trimarans have been rescued from the southern ocean as contestants race them as hard as possible around the world; once flipped there is pretty much no way to get them back up again without outside help.

But the safety issues of catamarans are not our interest here, applied 3D geometry and a wonderful trash boat are!

You can also see on the left hand side the light coming through the vertical slit. When the bottom section is removed, these slits, through all but about 10cm of the tank wall, allow the whole forward section to be drawn together and welded shut.

The front-most edge of the bow area is straight, which would mean that a certain section of the bow would remain open. However it can be seen that the 4 cuts that arrive at the bow are equally spaced, so a second piece of hull can be cut out of the removed sections and used to fill in the missing area at the bow.

The bow of one of the hulls, showing the extra sections welded into place and the threaded rod used to pull the sides together for welding.

So we end up with a collection of three dimensional cylindrical cuts that fit together to form a flattened cone shape that gives a relatively good water-cutting capacity, not too sharp an entry and the ability to shed water from above easily.

These issues have been discussed at length with several boat builders and other boat people. The whole combination of factors come together in an interesting way – who knows whether the nose is now too fine and will be pushed under by the sails driving it into waves or whether it is a great, speedy shape.

Only time will tell.

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