SS Hydrograaf, 1/100 3D, hydrographic ship, Royal Dutch Navy

[wefalck]

And from around 1860 hydraulic presses were used to form the iron/steel panels for Francis' patent boats. These were used as lifeboats on board of ships and the German Lifeboat Association (DGzRS) founded in 1865 used Francis-boats from its beginnings.

Hydraulic presses were also used early on to compress cotton-bales for shipment.

The principle was know in antiquity, I believe.

[DrPR]

Hydraulic motors have advantages over electric motors.

1. Hydraulic motors are very powerful for their size. Small hydraulic motors can deliver the power of a large electric motor.

3. When hydraulic motors stop they will not rotate - the hydraulic fluid in the lines prevents them from turning. So they hold the position where they stop. Cut the power to an electric motor and it will spin freely.

3. Hydraulic motors do not generate sparks. They are safe to use in areas with flammable gasses or liquids and around explosives. Electric motors produce sparks.

4. Hydraulic motors do not generate electromagnetic interference. Electric motors do.

These are some of the reasons hydraulics are used extensively on ships.

Phil

[Iceman 29]

The hull is almost finished.

At this level of design, the devil is in the details... especially the design of the sheets which must perfectly fit the skin of the hull. This is a necessary step.

The design of the metal sheets adds to the precision of the model compared to a smooth hull, as do many other small details that contribute to the overall effect and give a real impression of realism on the retina.

This is a far cry from the beginning of the project and the initial sketch which is rather insipid. The 3D drawing makes it possible to apprehend this phenomenon of scale, the more precise the details, the more "alive" the model will be.

But the second step, printing, must restore all this visual information, in a real ship...

Here again nothing is simple, the path between the drawing and the final printing is full of pitfalls, the printing and painting procedure must be prepared well in advance when choosing the 3D drawing, it is necessary to anticipate.

Questions arise, which object to print apart from painting and gluing it easily, the adjustments are also to be closely monitored, this is not the strong point of resin printing. etc..

Then there is the method of assembly of the model, because the parts are nevertheless numerous at the end.

This is where the experience gained from drawing and printing plays a major role.

Don't think that drawing and printing a complex object such as a ship can be done by snapping your fingers, as some might think. Not so simple.

That's the beauty of it, otherwise there would be no interest in the end for the model maker. �


The sketches of the design at the beginning of the project:









The hull is hollowed out to avoid the use of resin, and especially to avoid printing problems, suction of the part and deterioration of the surface of the edges.





I have provided a very flat layout for easy positioning of the superstructures. Feedback from the SS Nomadic.



You can see the holes for positioning the windsocks and some accessories not present on this drawing for the moment, mast, ventilation sleeves, chimneys of the coal stoves for heating, compasses .

[Maarten Sch�nfeld]

Good morning, Pascal,

I fully agree that your 3D drawing of the hull is truly a work of art, and not something that's be done in a jiffy. All your effort pays off I'm sure!

May I humbly point at the propellors: you still need to swap starboard and port? But as these will be separate components at printing, that can also be done at assembly time of course.

Btw: is that you, standing on the forecastle, overlooking with a shipwright's eye the progress of the build?

Maarten

[wefalck]

Are you sure that the propellers are the wrong way around ? Normally, looking from the engine, the starboard propeller should turn clockwise and the port propeller anticlockwise, so that flow is directed towards the rudder. If I am looking at Pascal's rendering, then the propellers seem to be right ... unless my geometric imagination goes wrong.

[Maarten Sch�nfeld]

Are you sure that the propellers are the wrong way around ? Normally, looking from the engine, the starboard propeller should turn clockwise and the port propeller anticlockwise, so that flow is directed towards the rudder. If I am looking at Pascal's rendering, then the propellers seem to be right ... unless my geometric imagination goes wrong.

Hi Wefalck, I'm afraid the latter! And if the Starboard propeller looking from the engine turns clockwise, then indeed the flow is directed towards the rudder. But that's the whole point: when looking forward from behind, it then turns anti-clockwise! Looking backwards from the engine doesn't make sense in describing the motion of a ship. In most aircraft though, it's a different matter (having tractor propellers).

For most efficiency, it should be the opposite: it should turn outward, not inward. Please have a good look again to the picture in drydock. When turning inward, the surface wake of the two screws would be pushing towards eachother, creating a wave crest which doesn't help propulsion but only causes loss of energy. Hence the rule that side propellers should turn outward (but there are definitely some well documented exceptions, the Spruance class destroyers and Tico class cruisers being the most prominent I know of.)

Hydrograaf-1-225x300.jpg (20.79 KiB) Viewed 923 times

And have a close look at the port propeller on the drawing: it really turns outward, not inward! Look closely at the shape where the blades meet the hub.

Hydrograaf Port propeller .jpg (65.34 KiB) Viewed 923 times

Bottom line: 'clockwise' or 'anti-clockwise' is irrelevant and arbitrary, because it depends on your viewpoint (looking forward or backward.) The whole issue is about turning outward vs. inward (and that's not arbitrary). Many people seem to think that the direction of turn is something by convention, but it isn't, there is a good physical reason why props should turn outward.

For centreline props it's a completely different matter: for these indeed it's a matter of convention. UK, USA and several other nations favour 'clockwise' (when looked from behind!!) but German and French shipbuilders opted for 'anti-clockwise'. And when chosen, then the engines are also committed, so you'll never change it over the lifetime of the ship (or the engine).

And now I'm open for a discussion on the Exceptions!

[Maarten Sch�nfeld]

And a final quibble on the propellers: Pascal, I think you selected a 'standard' prop for your design? The Hydrograaf typically had propeller blades with a straight trailing edge, not the typical 'mouse ears' of the props you used.

[Iceman 29]

From what remains of my courses at the merchant navy school and later from my years as chief engineer and a good ten technical stops of ships in dry dock, including 2 ships with 2 lines of propeller shafts.

For the rotation of the propellers we simply speak of divergent or convergent propellers, seen from the back of the ship, it is very simple and it is the norm for the shipyards and the marine mechanics.

You look at the top of the propeller from the back and turn it forward, if the top of the blade goes inwards it is convergent, if it goes outwards it is divergent.

Converging: the propeller on the starboard side turns anti-clockwise. The port side, clockwise.

Divergent: the propeller on the starboard side turns clockwise.The port side, counter-clockwise.

We can see here on your recent enlarged photo (modified propulsion with 2 diesel engines) that you provided us that the propellers are divergent if we follow the rule above.

I will last change the direction of rotation following your advice a few days ago, but I notice that the program has put them back in the wrong direction.

As for the shape of the blades, I will see if I need to redesign the propellers. You can see from your photo and the original plan that it is not the same design.

But beware, because the propellers on the general plans are often schematic propellers, which do not correspond to the original propellers fitted at the shipyard during construction.



Corrected:

[Maarten Sch�nfeld]

Super! And I agree with you the photo and the plan show different propeller blade shapes, although generally similar. Your observation that the plan was not the final source for the prop blade is of course correct, these items were still under design when the ship plans were ready for the ship itself already to be started on the slip.

It seems that the 'solidity' of the blades (the percentage of the blades covering the circle) was increased from the ship plan to the current propellers. As the ship is 110 years old ther might have been some upgrades in the intervening years of course. That would be quiet some research to discover that. If you like, I could approach the current ship owners (in Dutch) if they have a history on the maintenance and changes to the ship.

[Iceman 29]

Thanks Maarten.

You can try your luck with the ship owner, the propeller plans are normally provided in the plan library on board, exactly 2 sets on board, some time 3, and one copy at the owner office..

But in 110 years, the plans may have disappeared little by little.

But I think that the propellers of Hydrograaf must be probably close in design to those of the SS Nomadic which is the same age and which are original.
They are very similar to the one in your picture.

https://www.chambre-experts-fluviaux.fr ... s-nomadic/

[Iceman 29]

It took me a few more hours to perfect the 3D print file of the half-hulls.

I cut the ship in half and placed reinforcement pillars inside, and made a hole to glue a small threaded rod to hold it on its support once finished.

The ship is 40 cm long, so I made two 20 cm elements to fit in the printer.

I also made a vent in the cut, the half circle that you can see to avoid a suction effect that occurs between the part, the printing plate and the film in the tray. This suction can take off the part during printing, a catastrophe, and if it does not take off, it can make lines on the outside of the hull, damaging the surface of the hull and even deforming it, it's very ugly.

It took me a while to find this vent trick. The hole will be filled with putty later on during assembly.

This is a test print, getting it right the first time is rare, but it happens. �

It takes 20 cl of resin (a beer with a false neck..) to print these two pieces with the supports in 10h30, for a total cost of 7 euros.

A litre of standard grey Elegoo resin is around 34 - 35 euros.

Verdict tomorrow morning when I wake up! �

https://www.amazon.fr/dp/B08PD13JP5/ref ... UTF8&psc=1

[Maarten Sch�nfeld]

Fingers crossed for the result, Pascal!

[JIM BAUMANN]

Once again-- staggeringly good work !!
have just read the whole process in one go;
its a beautiful vessel and your modelling so far is exquisite!

Bravo!!!

Jim Baumann

[Iceman 29]

Thanks Maarten & Jim !

The printing is very good, without any hitches, for this first one of this very nice ship. One of my best.
It's that you get better with experience, probably.

The quality and stability of this printer is also a big part of it.

I've had time to glue the half-shells, it's always tricky to sand the section to remove the 3 layers of adhesive and stay flat.

I'll still have to work on the cutting area but it's not bad.

The day started well this morning when I woke up.

It's always magical to materialize a virtual thing that you've worked hard on for dozens of hours on a screen. It's a shock to touch it in real life! It's like a gift we give ourselves every time, like a child.

[maxim]

The hull looks really impressive!

[Maarten Sch�nfeld]

Congratulations! That looks VERY good indeed! Worthy of all the effort you put into it.

[Devin]

Very nice indeed! I'm very curious as to how your surface finish turns out. I've taken to printing large items without surface detail, so that sanding to remove printing artifacts, layer lines, and support attachment points, doesn't damage any detail. Then I add it in with strip styrene, smaller printed parts, etc.

What printer are you using? I have an Epax E10, but haven't tried anything really huge on it yet, my side-business of HO scale detail parts keeps the printer busy pretty much all the time, not allowing me a lot of time to play with it.

[wefalck]

The printing results look really neat.

Not having any practical experience with 3D-printing, I was wondering why you needed the elaborate support structure above the deck ? To prevent the hull from being warped due to overhang of the forecastle ?

Another point that I noticed were the deep vertical seems between the plates in the out-strakes. I noticed them already in the drawings, but though that they might disappear during the printing. Normally, these plates would butt smooth against each other and would be backed on the inside by seam-strips that also fill the distance between the plates and the frames. Are the seams visible like this in photographs of the prototype ?

[Iceman 29]

Thanks all!

@Wefalck

The brackets are effectively the starting point for the printing of the forecastle, or more precisely in this case the floor.
If it is not in place, the printing of the printing table will be very badly done and the printer could be damaged.

For the sheet metal plates, indeed I cheated a little bit on this level, I created a space between the plates to see the plate, the groove is 0.3 mm, less once printed and even less once painted.

It gives relief to the hull, it's not perfect, but it looks very good when painted. It's very thin.
I could spend more time on it, but the 3D program would be overloaded. It requires a lot of calculation for the software.
I still have the anti-roll keels to draw and print.

I admit it's a bit conventional.



@Devin

I used the Anycubic Photon Mono X. Excellent printer.

[Fliger747]

Pascal:

Very nice result, I can appreciate that realizing the design in reality is quite satisfying. Good to mover from the virtual world to the one of touch and sight!

Regards: Tom