Print at Apr 20, 2019 7:13:56 AM

Posted by okh at Jul 9, 2018 1:43:04 PM
Re: Holes in the ground
Oh, now I see. True, true, you are right. SH3D cannot calculate and adjust the waterline around a hull at various loads (elevations).

Calculating exact displacement/waterline/draft/freeboard for many different loads and at different water densities (fresh/salt) is a science in itself. Not to mention if you put the hull in motion through water. And you are right, the waterline perimeter is indeed significantly different between loaded and normal/standard displacement, at least for a cargo vessel.

But for a house boat, I think there sort of is an answer to your challenge as different displacements are standardised. And once you know a more or less official displacement you can calculate the 'standard' waterline. Which it seems to me would be the correct cutout to use. And for a house boat with a relatively large hull (inland cargo vessel), it is hard to see that the waterline would vary much within the permitted limits for passenger load + baggage + provisions. My guess, but I may be wrong, is that it would be well within the margin of error allowed for displacement calculations.

Your question is interesting for a number of reasons. For me, because I play with displacement and waterlines for different hull shapes from time to time, albeit at an amateur level. One thing is where to put the masking tape for the anti-fouling, but it is also interesting for determining hull speed, propeller dimensions and motorisation. Lots of lovely theory to study. In the realm of naval architecture, that is, and there are probably many suitable tools for this. Some of which might even help you intersect water surface with hull at different loads and speeds.

Traditionally calculation of waterline and displacement and other factors was done on experience, rule-of-the-thumb, slide-rule and tables. Amazingly, the guesstimates were usually very good, with some notable exceptions like Wasa. But then, world moves on with some impressive estimations done by clever engineers and computers, such as Oasis_of_the_Seas passing under the Great Belt bridge in shallow waters at high speed (squat effect) with marginal clearance. Not much room for calculation errors...

But the real questions you ask are different, assuming I have not misunderstood again.
1) Should SH3D calculate automatic cutout for 'staircase' type models?
2) And furthermore, should SH3D calculate the cutout to the perimeter at the exact level where the model intersects with a floor/ground?

1) Possible auto staircase cutout was mentioned in connection with the release of SH3D 4.2, thread 4444. Even if this could possibly be useful in some contexts, non-rectangular staircases and swimming-pools, the reason I asked was not because the feature would be important to me. The question was more about whether I should bother to add SVG for L-shaped staircases. And as Puybaret mentioned, the actual cutout for a staircase is often different from the outer perimeter of the total staircase.
2) A cutout that also considers perimeter at a certain height, I think is a new suggestion. In your case, I can see it might be useful. But then, that is probably the only case I can think of. And how would this work with a staircase?
.. in my opinion, this is only a workaround, and sorry, I'm a perfectionist, and workarounds are only temporary solutions and for me not aceptable.
So, this is where I disagree. I do not see manually adding SVG for advanced models as a workaround. Quite the contrary. For models with complicated shapes, it will be better if SH3D does not make assumptions about how to cut / intersect with other surfaces. Letting the model maker (or the user) is - I think - much more professional, or perfectionist if you like.

But as you may have understood from the stuff above, I think your house-boat project is really interesting and I hope you will keep posting images and solutions. I hope your dream of travelling the canals of Europe comes true.

ok