what was wrong exactly with design of old sailing "ships"?

I agree.

It seems like, in the days of sail, crew were almost always difficult to come by.

I think that is very understandable. The work was hard and often dangerous. The working conditions were miserable.

On top of that, the captains often operated like petty tyrants, and had little accountability up until at least the mid-19th century. Beatings an floggings were common, to enforce the captain's absolute authority.

Interesting also is that a model of cooperative business arrangement occurred, in the late 17th and early 18th century, on sailing ships. Those were the pirate ships (not to be confused with the privateer ones).

Often, they got started when the crew mutinied and threw the captain and his officers overboard, and took over the ship.

Other times, the crew would desert their ships and link up with others who had done the same.

Pirate ship captains could be fired by their crews. And all of the crew was entitled to a share of the "profits".

I think the early steam ships won out, not because of crew problems for the sailing vessels, as much as they had the ability to keep more predictable schedules.

Those early ships were really sailing ships still, but with auxiliary power. The engines then produced only about one hp per ton of engine weight (which included the boiler and condenser). But they could keep more reliable schedules.

As the 21st century wears on, and assuming there will be a strick anti-C02 regime, sailing ships may make a comeback, at least in smaller vessel sizes.

They will most likely all be schooners, with two to four masts, with strong auxiliary engines.

 

About the crew. Astonishing to think the design crew for Cutty Sark was 26 including Master, Mate, Carpenter and cook! One trip from the far East the actual enlisted crew was 19!

 

That might be how many they arrived with....they may have departed with more...

 

various arts & sciences seem to have developped at different speeds during human history:
architecture seems to me to have been at the speartip of development (gothic cathedrals of unsurpassed beauty were built when other technology hadn't progressed passed the treadmill & block & tackle), whereas
medicine seems to have been one of the tail-end-charlies: the break even point, from which on medical "intervention" was statistically beneficial (as opposed to detrimental) was in the early 20th century!
& shipbuilding somewhere in between?

 

That is a bit more than what a super container ship has for crew. The Cutty Sark carried 1700 tons. A super container ship carries 165,000 tons.

 

That is a good comparison.

My Dad was a ships doctor for a while with the Blue Funnel Line (Alfred Holt) in Britain in the 1950's - the ships that he was on were the Elpenor (7,339 gross tons, 9,246 tons deadweight, built in 1954)
ELPENOR - IMO 5102451 https://www.shipspotting.com/photos/2643536

And the Glengyle (8,887 gross tons, 9,580 tons deadweight, built in 1939)
GLENGYLE - IMO 5132004 https://www.shipspotting.com/photos/2334944

Both vessels carried passengers - and I remember my Dad telling me that each ship had about 70 or 80 crew members on board. All of the officers, along with the ship's doctor, and the passengers, had their own stewards.