IonAguirre

If I say I can, Its that I can. In fact, anybody with just a brieff knowledge about geometric analisys can do it. It does not mind if the world is plannar, spherical or egg shaped. The shape of a "world" doesnt mind, its even irrelevant if we are speaking about an Euclidian vectorial space or not. Everything is reduced to projections and coordinates conventions, that, if are "consistent" will work and return accurate results, no matter wich kind of projection and/or dimensions could be used. Astronomical Navigation can be used as far as its a matter of solving a matrix product and finding the director cosines. Once solved, results can be used into any map if the projection is known, and the conversion matrix is found. In the case of OW, the problem can be approached from an Euclidean R3 or an R4 space, it depends. I'll not keep on this discussion. Studying is a solution that solves most doubts my friend. About the map. In fact we have one, and by the way, a Navigation software that works from NA data giving even the ETA to destination. And .... it works my friend. And ..... the same way we made it, others surely have done it yet. Nature and computers share the same lenguage, MATHS. Thats only a matter of finding the right "words"

I agree with the sextant idea, but it requires a real sky map moving with time. With such a stars map, having a watch and an astronomical ephemeris table is also required. With these tools and the corresponding knowledge is how one of the fixing procedures is performed. It sounds complex, but it isn´t. The Sun is the other key aster for navigation allowing for the fastest and simplest fix procedure. At local midday, from a watch, the observed Sun height angle, and the ephemis of the Sun, longitude and latitude can be resolved very fast. For those interested, I can develop the whole thing. Using astronomy for position fix during coastal navigation, would be appart from a wrong practice, like killing ants with a canon. I'd like to be able for taking bearings to the coast (in fact, I'm actually using this procedure). Actual OW compass has a very low accuracy, but if we had a better one, location can be accurately obtained from two bearings, and speed and location from three ones. By night, if lighthouses are included the procedure results even easier than by day.

Quite a nice work ¡¡ Thanks a lot

Sorry freddy. If you read my post again, you'll see I've changed it. I wrote it thinking on Jorge Juan and on, ages designs. The Gaztañeta years belong to the earlier, traditional, more rounded, bows design. Here is a drawing from Gaztañeta. Bow and stern framing is included at both sides and can be used for 3D modeling. This approach with gunports at every deck is an early design, and was never built that way.

Hi Freddy: First thing to say is ... "Congratulations". I know how complex and long can be a detailed ship hull modeling process. I have some historical comments for Cavero. Cavero: The Jorge Juan construction system is not the English, but the Jorge Juan one. It was the result of a personal development and integration he made from Traditional, Spanish, English and French systems. The work was derived from theoretical analisys and experience, as he was a Seaman as well as a Scientist and a Naval Architect. Justification of his designs can be found at his: "Examen Maritimo Teorico Practico" Vols 1 and 2, published -1743. Your model seems to be a design from Antonio Gaztañeta Iturribalzaga, and hence, belongs to the pure traditional Spanish construction system. Original drawings from Gaztañeta can be found at our Naval Museum, and surely in the Net. If you want to be accurate, compare all `plans before starting the work, as most plans in the net belong to comercial models, and not to the original ship design. Don't trust on that kind of plans. Check this link ..... http://www.todocoleccion.net/lineas-navegacion/planos-navio-san-fernando-museo-naval-ver-foto~x16319926 Regards

Im working on a Radio Control Sloop. Still at the mechanics and electronics stage and only the keel and some frames are done for the hull work. I'll post pics when I have more than some aluminum rails and servo arrangement. About the question for 3D modellers. I'd not say Im an artist, as none of my models have nothing from myself. All I've done is suited for Technical/Historical research, hence are built from original plans (when available) and able for CFD and technical analisys. Its more a matter of how the ships behave, and how they were built, than of how they look like, albeit I try to make them (from the looking point of view) as similar as the original, as documentation allows for.

Really, really nice models. Aracno, may be it's not on your plans, but those Frigates had a Keel shoe for making the submerged "Lateral area" deeper. The addition of that part added a better counter drift effect. May be that's why you see the shape a little bit wrong. Anyway, just a great model.

Nice frigate. As Cavero pointed above, she was only a project by Julian de Retamosa that was never built due to strategy concerns. Thanks for posting her plans.

Hi Maturin: Thanks for your appreciation. Julian de Retamosa is a relatively modern Architect which original documents are duly conserved at out National Naval Museum, located at Madrid. There is even a Naval Dockyard model of her. For the hull lines I've used original drawings and after the 3D main body model was built, I made all calculations regarding stability, wind effects, hull speeds, theoretical polars and RAOs. Numbers fit reasonably well with those resulted from the official sea trials, which documentantion is also conserved at the same Museum. Anyway, Im for any data confirmation, advice or comment ........ Kind regards

Diana Frigate again: 3D Model in progress. Albeit they have the same name, the English and the Spanish figates have nothing to do.

Woudn't it be useful providing some lighthouses for night navigation ? If each lighthouse had a particular lights pattern (as real ones), navigation would be quite improved. It would even be possible taking bearings and setting ship's location.

Hi Mikedabay. Hull copper planking started around the middle of the XVIII century.

Thanks Sir: I've been testing OW with a professional Chart Plotter (SPS, Ship's Planning Station by Stentec Marine) and CM93V2 official charts installed. As fas as I've been able to explore in only two days, the Open World scenery is surprinsingly accurate. Predictions by SPS are complied by the Game, planning in SPS works for the game ..... Once again, developers .... Well done guys ¡¡ Regards

Hi MacJimm: I agree, an analogic XVIII century compass is better for a "final release", but at the actual development state, and from the software development point of view, a difgital one is simpler and could solve the problem by now.

I guys: I tested the OW yesterday for my very first time. I found maps quite accurate and shore view quiet nicely modeled as well. But ..... As there is no help for a possition fix .... it would be nice having, as a minimum, numeric indications of the ships heading in degrees, and another for the rudder angle. Without those simple tools, its quite hard to travel along the Open World. The actual compass with marks every 30º, together with no rudder indicator, makes travelling quite a complex thing. Im not for a big compass but for a numeric three digits one only, located above the actual one. It would be enough for navigation. Another thing developers could take into account if a kind of ECDIS or Plotter is an idea flying around your heads, could be using an NMEA standard stream for navigation data output. That way, any chart plotter (Some of them are free), could read the ships data and plot it on a scanned or digital chart. Thanks and regards

May I know what those coordinates mean ? Where is the 0,0 ? What are the units ? How are they defined ? Thanks a lot.

FLOODING EFFECT Flooding effect is decreasing the metacentric height, or what is the same, the same effect than loading a weight at a high location. That "virtual" rise of CG is a function of the water moment of inertia, that depends on volume and shape. For the seek of simplicity and the game requirements, the hull can be assumed to have a constant cross section that can be defined as a parabolla which general equation is: Y= ax²+ bx +c, where Y is the flood sounding and X is the flood breadth. As we did before coefficents a,b and c can be calculated from three known points of the reference hull cross section. Once those values are known, computing the breadth for any sounding is trivial. Taking into account that we are only looking for a reasonable behaviour and not for a scientific simulator, the flooded volume can be computed as a prism, which lenght is the lenght of the ship (LPP) and which breadth ( is the one computed from the parabollic assumption above. Then, its moment of inertia with respect to the rolling axis (X) is given by: Ix= (LPP * B³)/12 And the "virtual rise" of CG by: GGv= water density * Ix/Displacement(in Kilograms) The new stability GZ curve, or corrected GZ will result from: GZc= GZ - GGv*sin(X) where X is the heeling angle. Now, with a flooding sounding of 2.7m the ship (DIANA again) would capsize for a heeling of 75º. But due to the added weight, total flooding will happen before .....new draft would be: From all assumptions made before (No bulkheads, free flow of water inside the hull, etc .....), or in a more technical term .. Permeability=100% At the same time, new submerged volume can be assumed as a prism, which base is the inial waterline breath. Hence, the heigth of such prism which volume equals the flooded one is: h= Flooded volume/waterline breadth And new draft would be: Final draft= Initial draft+h Final draft= 5.2+2.56= 7.76m, well above the maindeck .... If a more accurate prediction of this draft is wanted, .... Assumtion of new volume as the addition of a triangular and a rectangular section along LPP. Integration of the parabolla between Yo=old draft, and Y=new draft and equaling to the required section area increment, compute Y. Below: Left: Parabollic section, with intial water line, blue, and flood, green. Right: Corrected Static curve of stability Permanent heeling=44º (And now its checked ¡¡) due to flood and wind Vanishing stability at 75º

Dear Maturin: YOU ARE RIGHT ¡¡¡ I made that graph bery quickly and had a very BIG mistake. My Apologizes Heeling and righting moments are not in the same units. While the first is in Kilograms, the second is in Newtons. Here you have the corrected graph with the corresponding source data table. Now results are a lot more logical. Thanks a lot for pointing me to the very big heeling angle. Im a lot shamed for publishing such a nosence. The sails names are in Castilian. This is a lot more logical. A wind of 11 m/s would heel the ship to the lower battery deck limit. As you can see, I've set all yards to the same angle. Graphs: Upper right: Heeling moment due to each sail Lower left: Righting arms with and without wind. Lower right: Aerodynamic coefficients aligned with the Ships reference axis. The dotted vertical line corresponds to the averaged angle of attack for all sails. My apologizes again, and thanks for your comments. Im a lot absent-minded.

Yes it does, 5m/s approx=10 Knots. But don't forget that the assumption is for the "worst" case, that supposes that each sail will receive the "full" wind, that is not true. Anyway yes, 10 knots is too much for full rigging, at around 20º the water plane reaches the first battery. This big heel is due to the very high masts. The frigate is not designed for using topgallants under this abeam wind.

Nop. Keep M above G GM<0 = capsize The ship in the example, is supposed to have a fully watertight main deck. In the real case, flooding would make the ship sunk. At the curve, it would be seen as an abrupt curve ending for the flooding heeling angle.

34 guns Spanish frigate DIANA Launched 03/10/1792 Architect: Julian de Retamosa. LPP=43.12m BOA=11.14m T=5.2m D= 1151 mT Retamosa Original drawing Stations Rebuilt drawings for quality improvement Visible decks Upper deck Main deck Rigged side view Hull 3D view

A CORRECTION HAS BEEN POSTED BELOW. From now on, stability means "TRANSVERSAL STABILITY" All units in metrics (I.S.) KN values for a fixed displacement only. How the ship's stability changes into flood conditions ? What are the effects of wind on the ship's stability ? Everything around these questions starts from the Cross Curves set of each hull, but as I posted a few days ago, here is my proposal for a simpler way, which could avoid having to build tables with curves values and interpolation algorithms. A way I think could be a reasonable approach is using a third degree polinomy instead of real cross curves. A general form could be: Y=Ax³+Bx²+Cx+D Where Y is the cross value (KN stability arm) and X is the heeling angle. The key is solving for A,B,C and D for each ship. Four coefficients A,B,C,D require four equations. The system can be solved by using four points from the real KN curve of the ship. Or, as I've done, from three points and the condition of tangency at the origin for the initial stability value GM. Naval building theory says that a straight line, tangent to the stability curve at the origin, will reach a value=GM for x= 1 radian. Where GM= metacentric height Hence, making the first derivative of the polinomy, and forcing x=0, will return that the equation of that line is given by: Y= Cx And we know that: KM= 57C (Where 57 is 1 radian in degrees) As the whole information has been referenced to the Keel and not to the center of gravity, instead of using GM, we must use KM: KM= KG+GM Now, we have four equations and four unknowns. It can be solved. From KN= Ax³+Bx²+Cx+D, With X as the heeling angle in degrees, KN values will result. Lets now take into account the height of the center of gravity ... The righting arm of stability is normally named GZ. For each heeling angle. GZ= KN- KG sin(X) Where X is the heeling angle again. Effect of wind: Wind works against stability, hence we must compute the heeling arms. The angle from which the wind blows, relative to the ship, will be denoted as W. The angle at which the yards are turned as V The angle of attack of the wind on the sails as Aa From simple geometry: Aa= W-V Once the angle of attack is known, its only a matter of having the sails aerodynamic coefficients. Fortunately, in the very good and clear work presented by William C. Lasher and Logan S. Flaherty about the Suvivability of squared rigged sailing vessels, good approaches to those coefficients are included. For each combination of wind and yards possition, a different angle of attack will result. From the resulting angle of attack, LIFT and DRAG, CL and CD, coefficients of the sails joint can be obtained. But lift and drag mean nothing in a ship, those coeficients must be converted to propulsion coefficient Cx and Heeling coefficient Cy. The conversion is given by: Cx= Cl sin(W) - CD cos(W) Cy= Cl cos(W) + CD sin(W) I'll not explain what to do with Cx that has nothing to do with heeling and capsize. Lets forget it by now, and lets go with Cy. Cy relates the shape of the sails with the force that wind exerts on them, in such a way, that force will come from: Fy= 0.5*1.24*Cy*Area*WindSpeed² Where 1.24 is the averaged air density. The point at which this force is applied is called the pressure center, lets say it is at a heigh Z from the keel, and lets call this distance as KZ. Working against the wind, there is another force, the Lateral resistance of the hull, that can be assumed to be applied at a point half way from the keel to the water surface. Lets call the height of this point from the Keel KL Then, the wind will exert a heeling moment (WM) given by the force Fy and the distance between both points. WM= Fy*(KZ-KL) Lets now see how to obtain a heeling arm for each heeling angle in order to include its value in the final stability calculation. Heeling arms are usually denoted as HA. With D as the ships displacement in kilograms. HA= [WM* cos(X)^(1.3)]/D X= heeling angle Then, final righting arm under wind conditions will be given by: GZ= Ax³ +Bx²+ Cx +D - KG sin(x) - [WM cos(x)^(1.3)]/D The value of WM will depend on: Sails area and height of the resulting pressure center (Two or three fixed values joints could do the work for the game) Wind speed Wind angle Yards angle (The same than for surface and center of pressure) In very simple way, as well, flooding could be included. NOTES: No aerodynamic sails interaction is taken into account. But for the seek of simplicity its not required. CL and CD curves can also be approached by polinomials, avoiding the table/interpolation issue. In the graph below there are some calculations for the Frigate DIANA. Displacement= 1151 mT KG=2.85m GMo= 3.53m Mean draught= 5.2m Wind speed= 5m/s Wind angle= 85º Yards angle= 45º Sails area= 7470 m² (full rigged) Pressure center height= 26.38 m Sample points for coefficients calculations: Heeling=0 ---> KN=0 Heeling=45 --> KN=3.92 Heeling= 90º -> KN= 4.27 Heeling= 57º --> KM= 5.93 (The equation is the first derivative of the polinomial) Results: A=0: B= -0.0001: C= 0.1034: D=0 Resulting curves: GZ (green) Righting arms from real stability information. No wind. GZs(black) Righting arms from the polinomial expression. No wind. YR (blue) Tangent line at the center, returning GM for X=57º GZfs (dashed red) Righting arms under wind conditions. GZflood(violet) Flooded Righting arms. Water sounding 4 meters. Permanent heel due to wind= 40º Permanent heel Wind + flood= 45º It looks reasonably well for a game. Any question, dont hersitate asking ......... Regards

Its quite interesting how Spanish, English and French ships evolve to deep hull designs approaching a V shaped hull, while Nord sea ships follow the counter tendency, making bottoms more and more flat. Those nothern seas around the Channel and Baltic sea have many shallow waters areas and lots of channels, while European atlantic shores are mostly formed by cliffs, stepped sea floors and deep waters. Ships design is like Nature, in the same sence than animals which addapt to their environment.

I've visited the Wasa museum in real life, and despite the fatal errors in her design, she is quite a beautiful ship. By the way, she is a constant source of infomation about how ships were built during those ages. Anyway, this ship is outdated if the time period were NA takes place is kept as it is. Regards and thanks for the plans and information.

Once again ........ Are OW points coordinates taken from a real map ? Or are just an invention ? If yes, you are right, if not, you aren't. Take two places at, lets say, 23º North latitude. One of them is at 83ºW and the other is at 84ºW. Whats the distance between both points? Lets now take another two points. Now both located at 45º North latitude. Longitudes are the same than above 83º and 84º west. Once again, whats the distance between both points ? Solve it without using a ruler on a map, but only from the provided numbers. Try with no correction ¡¡ Calculation does not depend on the map projection. It doesn't mind if OW is plannar or not. What minds is only if real world coordinates have been used, or what is included in the game is just an invention. Its not a matter of drawings nor games, but a matter of geometry.