A Professional Bathtub: The Ship Towing Tank

[@serowing]

Nice brief review, but I guess the most misterious and valuable process of a Towing tank is the extrapolation of the model data in full scale....verytimes with a sort of magical aura surroinding it!

[@DatawaveMarineSolutions]

That is on my list to create a video for! I actually started this video with that intent . . . but I'm still working on the right combination of mathematics and approachable explanation.

[@MrOttopants]

I do like how these tank rails have to be made to match the curvature of the earth.

[@Hellndegenerates]

No they don't, that's insane, The water is formless and cannot support itself, 0.6mm of curve 😄😄😄

[@MrOttopants]

@@Hellndegenerates "...the tracks are not straight in the usual sense, but follow the curvature of the earth.” According to the American Society of Mechanical Engineers: “To meet requirements for uniformity … the rails on the basin walls upon which these carriages will run had to be far straighter and more level than the most perfect railroad track. In fact, to eliminate the effect of gravity on the motion of the towing carriage, the tracks are not straight in the usual sense, but follow the curvature of the earth.” It's cute that you think you can know things without actually researching though. Thanks for playing the game. I don't debate reality with morons who think the entire world is conspiring against them, so you're muted. But please, by all means, respond. I enjoy knowing I won't see your frustrated flailing. Bye.

[@microbeta]

There are several tow basins that are so long they require the rails for follow the curvature. 😉

[@nterry894100]

I love your videos Nick. The principles involved are easy to grasp, but those "special mathematics" scare me to death.

[@potatopants4691]

Love your videos Nick! Though, it feels like I've been transported back to 2004.

[@medhelal]

Thanks Nick for this informative video, love your work and a big fan

[@henryh.448]

What would be the cost comparison for a towing tank test versus a CFD simulation? And how long do they take?

[@DatawaveMarineSolutions]

Stay tuned. I have that comparison in a future video. (Originally it was going to be in this video, but by the time the I reached one hour, I realized that it needed to be segmented.)

[@henryh.448]

@@DatawaveMarineSolutions Hehe, no problem. I was hoping you would make a detailed answer. Video is the best way. Thanks again for all you do.

[@nterry894100]

Nick who makes these models? What are the most dimensionally stable materials for making them, which must be important if they are required to be stored for long periods of time?

[@DatawaveMarineSolutions]

The towing tanks often make their own models. Or you may find a fabrication shop that specializes in model construction. Typical process for model construction: we stack and glue blocks of high density foam in the rough shape of the hull. And then a CNC mill cuts out the exact shape from the foam blocks. We then cover that in a few layers of fine mesh fiberglass and add some paint coats. Then the final model goes for dimension verification to ensure all the dimensions match their specifications within a few small tolerance. The fiberglass is fairly dimensionally stable, provided you use a resin that doesn't absorb moisture. But even then, the model may change slightly over the period of several years. One towing tank told me that after a year, they normally expect the old model to be distorted out of tolerance and unusable.

[@TonyOlsenFerris]

There appear to be very few towing tanks like this in the world. Is there a good resource to find the professional towing tank that's closest to me?

[@AlenHR]

cool, i live next to one in zagreb, croatia.. it is 276m long, 12.5m wide and 6m deep.. it can tow up to 14m/s.. there is also some big circular tank, 32m in diameter, but i don't know what is it for.. some military testings, they say..

[@DatawaveMarineSolutions]

That big circular tank would be a maneuvering basin. More on that to come in future videos.

[@charmio]

Danm, that's a simple idea. Thoes giant testing gantries pulling the ships seem darn complex though. What was wrong with a rope, some pulleys and a weight?

[@DatawaveMarineSolutions]

A rope pulleys and a weight was the original towing tank. But the demand for accuracy increased as ships got larger. Think about the consequences if we calculate the wrong number for resistance. The ship gets either too large or too small of an engine. It can't make the scheduled route, or requires more fuel due to the oversized engine. All that translates into higher shipping rates, which ultimately increases the price on nearly every product you buy. Towing tanks are one component in a chain of professionals, including the vessel crew, that work hard to deliver your cargo safely and at an affordable cost.

[@cliffcampbell8827]

Are there tests for small to huge wave tests? Let's face it, the ocean is rarely calm and smooth.

[@drkjk]

You made note of how precise the temperature of the water, is the water saline, and if so, is it held to the same level of precision?

[@DatawaveMarineSolutions]

Typically fresh water, taken from city water supply. The tank will frequently measure the water density and correct their measurements back to standard salt water density. That is why the temperature control matters. We need density to remain constant throughout the day.

[@HughCStevenson1]

Water viscosity varies quite a lot with temperature too!