Counter Stern
- This topic has 34 replies, 5 voices, and was last updated 6 years, 10 months ago by
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Hi All,
I’m a retired Marine Engineer. I am trying to model a steam tug which I restored as a working passenger vessel some time ago.
I have more or less achieved the main hull form but the bar keel, stern post, (which is a solid casting going forward from the AP) and the counter stern overhang have got me beat.
How do I input these into delftship free?
Thank you in advance
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Hi Jurgen,
Thank you for taking the time to respond. I am still very much a learner and as yet I have not fully understood adding points edges curves etc. I managed to delete quite a few, much to my dismay but I will get there.
I have started my model using LBP and now I think I need to add a box to manipulate the transom overhang from the AP.
Thanks again
Bob -
Hi, here I am again, I’ll do not bother you with nerdy details at your stage of apprentice but focus on grid management and how to obtain proper shaped solids by tweaking points and edges position.
When you’re modeling, check it out with wiew of interior edges – see proper button on hull display section – it will show the actual stress of the surfaces.
Experiment with added boxes and relay ever on Delete, it’s a lifebuoy. Go deep in layer’s assignement tool, it’s not a cosmetic but a true asset to manage separate parts of the design.
What you call Transome I think it’s actually a fantail stern, to be designed carefully if it’s like:I can give an ex. in an actual tug design:
Sorry for quality, not a big definition, I know. As you can see it’s obtained extruding edges and so on, if you keep on the basics and rely on DS “manual” – click on ? on every fuction, it’s exaustive – you can draw quite everything.
Bye, Jurgen.
P.S. If and when you can spare some time I really like some details on that tug: construction year, dock, steam engine type…
I’m interested, thanks. -
Hi Jurgen,
Thank you for your continued help and inspiration.
Yes that which I am calling a transom is very very similar to the fantail you show.
OK the vessel:
St Yelta………………….(yelta, aboriginal word from one of their languages meaning sea bird)
Built by Cockatoo Docks & Engineering Sydney NSW Australia.
Ship no 192 laid down in 1947 and commissioned for Adelaide Steam ship Co. in 1949.
Main particulars LOA 102.75 ft
LBP 94.5 ft
Beam 25 ft
Mean Draft 10 ft
Maximum speed 13 knots at 140 rpmPowered by 1000 hp triple expansion steam engine, supplied by 3 furnace Scotch Marine boiler at 200 psig. Was converted from coal to oil in 1957.
4 blade cast iron propeller 8 ft diameter 11 ft pitch.
Retired in 1976 and sat idle until taken over by the South Australian Maritime Museum in 1986. Between then and 1996 was restored and transformed, (by mostly volunteers), into a licensed passenger vessel. Now operates school holidays from Port Adelaide cruising passengers up and down the estuary form a 1.5 hr trip, also available for charters.
Alas all I have to work with is a photocopy of the body plan plus a photocopy of the general arrangement.
Best Regards
BobThis is as far as I’ve got!
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Well, I’ve done a bit of homework, to clear, I hope the core of your difficulty.
Arranged a .pdf because definition is better so you can have a clear look at gridpoints and try to apply a somewhat similar arrangemet in your drawing.
Two problems arouse: first there’s an issue of proportions but it could be irrelevant, second I lack informations (of course) on general aspect- there are some railings marked where I draw a plate – but again what really matters are waterlines.Well take it easy anyway, at least we are not on a salary for this, just send me a virtual pint of Forster.
Cheerio, Jurgen -
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Hi Jurgen,
Having had a more in depth look at your PDF, as well as my earlier comment about the aperture, below is why I think you feel the proportions are wrong. I know I don’t really know but here is what I believe:
The vessel is trimmed such that the drafts are as follows:
Draft at frame 54 which is taken from the keel base at frame 48 = 8.926 ft
Draft at frame 27, (Midships), is 10.253 ft again from the keel base.
Draft at frame 0 is 11.984 ft.The vessel has a bar keel and stem post which is 6″ deep below the frames and 6″ forward of the stem post. The hull plates are 3/8″ and overlap and are riveted to the keel
The stern post casting tapers at the bottom from 3″ to 1-3/4″ and is butt strapped and riveted to the keel at its’ forward end.Attached are some slipped photos.Best Regards
Bob -
Hi Jurgen,
Having had a more in depth look at your PDF, as well as my earlier comment about the aperture, below is why I think you feel the proportions are wrong. I know I don’t really know but here is what I believe:
The vessel is trimmed such that the drafts are as follows:
Draft at frame 54 which is taken from the keel base at frame 48 = 8.926 ft
Draft at frame 27, (Midships), is 10.253 ft again from the keel base.
Draft at frame 0 is 11.984 ft.The vessel has a bar keel and stem post which is 6″ deep below the frames and 6″ forward of the stem post. The hull plates are 3/8″ and overlap and are riveted to the keel
The stern post casting tapers at the bottom from 3″ to 1″ to match the keel at its’ forward end.Attached are some slipped photos.Best Regards
Bob -
Attached is my file of Yelta
Still haven’t sorted out the stern and aperture 4 days of failure. There is something I’m not grasping yet, the penny has not dropped!!
I went through a similar period with 3D CAD but finally the penny dropped as to where the Z axis is and now I would not design any other way. I’m hoping for something similar here so if anyone can give my penny a push………… Wonderful.
Jurgen has been a big help………..I would not have got this far without this.
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“In South Australia She Was Born, Sadly Never Made ‘Round Cape Horn”
Here we are for another chapter of Yelta’s Saga.
Do not blame me: think it’s time for a small tutorial:A warning. when creating faces check ever the normals, for ex. if hydrostatics props are correct or reversed, correction could be done selecting the wrong portion in >>interior edges wiew and pressing >>flip normal in the face section.
Try to focus on smoothing the mesh by adjustments of control points.By the way this will interest you:
http://freeshipplans.com/wp-content/uploads/2013/04/ACTIF.pdf
It’s the grandfather of your tug, launched in A.D.1939, I foud very useful the transverse sections to upgrade my Yelta’s drawings.Up for now, godspeed.
Jurgen. -
Hi Jurgen,
Thank you once again for your invaluable help. I have downloaded your tutorial and the ship file now I’m off to practice and learn some more…………….who said you can’t teach an old sea dog, (Старый морской волк), new tricks?
And not only that you are a poet of distinction. Move over Chekov.
Kindest Regards
Bob -
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Business as usual, first of all last update:
It’s a change on size and position of the propeller, muzzle aspect and fairing, import as .part then delete the old layers.
For easy process make visible only the layer to del. then in >>hull disply>>interior edges select with>>Ctrl+left click and send them to dustbin.
Check and eventually Redo. Your drawing is quite good, nothing to criticize at first glance.
The lack of crease edges – the red ones – I prefer to draw a knuckle or a sharp edge doubling normal edges so close to obtain a kind of chamfer; sometimes it’s not so precise but if you need a nice rendering an as real picture it’s a way.
Deck positioning – my fault, or better a wrong guess.
As for the propeller and stabilyzers I pick proportions by the .jpeg – we say take measure with the nose – and sometimes the scent is wrong!
Anyway Yelta’s Saga is in progress, maybe ’till Easter we can manage to create a proper model.
Bye, Jurgen -
An addition: when I extude an edge(s), at the end of the process i.e. 1 or more extr. steps, I select in >>edges section >>set crease, so only the last one – the actual real edge of the mesh – remains crease (red).
Finally if you think the propeller is not so… well remember it’s a sketch, the design of an efficient propeller involves Black Magic, Voodoo tricks and the sacrifice of a virgin at full moon. Or a proper expensive prog. …
And for a true end, I wish to enforce the use of >>move, rotate, scale, in >>tools>>transform section.
It’s a Jack of all trades: remember only that every transf. is relative to 0,000 0,000 0,000 coordinates.
Jurgen.
Oops, my previousattachement has failed…
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Hi Jurgen,
The background image is a jpg of my cad 2d lines plan drawing which I made from the bodyplan drawing and some basic measurements from the profile drawing.
It was not faired just used splines by fit point after measuring the bodyplan. So be warned pencil and paper is not quite accurate like CAD or delfship.
Best Regards
Bob -
Hi
I’m one of those people that is absolutely pants at any sort of technical design software. I have had a go at this but it would seem that the scope and complexity is beyond me, which is unfortunate as I have been looking to have a fantasy modern Battleship modeled. I have a general layout sketch (MS Paint) and a relatively detailed description but I am pretty confident I wouldn’t be able to do it, especially with my lack of skill at this kind of software.If anyone would like the challenge, I would be extremely grateful
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Hi Bob, the last for now, better we keep it in freezer for a while: do not want to bore to death all the Forum…
As you can see I started from scratch, it,s not so precise especially at the bow, but take an inspiration to the stern grid alignement, the mesh is remarkably smooth.
Another thing to point out: propeller and rudder assembly were imported as a part by the old drawing then scaled and moved, so it’s an example of what is possible with those tools.
I avoided the deck just not to be criticyzed…
But you have seen already “how to”.
Godspeed, Jurgen. -
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Have a look if it can help you:
For info on details just ask.
Bye, Jurgen.Hello Jurgen,
maybe a little bit deviating and off topic.
But seeing this image you posted I am intrigued how you constructed the shaft tube, i.e. the half-cylinder that penetrates the shell at the deadwood.Of course, the obvious way to me was to use the create cylinder primitive.
But I couldn’t work out how to apply this function to only obtain a longitudinally split half-cylinder.
And when I construct the half-cylinder “freehand” I usually don’t obtain a perfectly circular shape.of cross-sections and lid.Regards,
Ralph -
Hi, ralph.
first of all a credit I must pay, the hull’s image comes to an interpretation of a beautiful dutch workboat that I picked in “show me your ship” forum topic, the author will please forgive me but I forgot his name…
Anyway, that and all the axle fairings I draw before and then, came by the same process: Freehand as you calll it.
Specify a center, radius, number of edges, take note of offsets and carefully fillet the mesh to the hull.
It starts extruding faces by having in mind a precise – as above – roadmap: no tricks, only routine.
I’m glad, no bombshells this time.
By, Jurgen. -
Sometimes it is too clumsy to apply in a drawing that’s not clearly a workshop sketch…
As you can see in my ST Yelta’s drawings I just draw a cylinder – properly shaped – then barely added as a Layer.
BUT in the same drawings you can find the sternpost shaped with an axle passage carefully designed “freehand” the result can not meet a tough tolerance, as it was drawed basically for rendering purposes…
Indeed, if you really want, you can do it but as Mr Mike cleverly pointed out some days ago, Delftship is a modeller, NOT a construction program.
Nice days to you, Jurgen. -
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I’ll take this, the author can reply if he wants…
It seems Mr. Bob has made a mismatch, just select hull control faces and >>>flip normals.
Imagine a glove being turned inside out, that happens frequently when you extrude new faces by selected points and/or edges.
It is not what we have here but is important to check normals doing these ops. the way the mesh is extruded depends on spacial succession of points or edges selected and you have to think a bit before clicking OK.
Hope it will help you, bye, Jurgen. -
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