Thread: Boating rules

Originally Posted by NavyDiver

Sydney to Hobart train wreak 98 would rank as a WOW in the sailing sense. RIP sailors
.......

Interestingly, from my analysis at the time, it seems a major factor in the carnage, apart from the weather itself, was that this was the first real test of the widespread use of carbon fibre in yachting.

What many of the designers apparently failed to fully appreciate is that the advantage of carbon fibre is not that it is stronger than glass,but that it is a lot stiffer. This means that where glass reinforcement, being elastic, allows stresses to spread, enabling you to get away with structures that have built in stress concentrations. But if you do this with carbon fibre, it will not spread, and you will get failure at the stress concentration. This is why you have things like a yacht where the backstay pulled out the entire transom, but it also seems to be behind many other failures.

Designers and builders (and possibly scrutineers) have apparently learned from this, and we don't seem to have had a repeat.

What many people do not appreciate (but designers should) is that for almost any structure, the overall strength/mass ratio of the structure is dependent not on the strength of the material, but its elasticity or stiffness, measured by Young's modulus - some parts depend on tensile strength, but that is the easy bit. And in structures on boat in rough seas, most loads are alternately compression and tension.

The reason for this is that failure of compressional structural members for almost any realistic structure will almost always be due to what is called Euler buckling. And the only material property involved in calculating this strength is Youngs modulus.

An interesting feature of most realistic materials for building things like cars, planes, boats is that the ratio of density to Youngs Modulus is almost identical. Almost the only exception to this is carbon fibre reinforced plastic, which is a lot stiffer than would be expected from its density. This means you can make panels for example thinner and hence lighter for the same strength, but where building in fibreglass you could assume that if it is strong enough in compression it is plenty strong enough in tension, the same may not necessarily be the case in tension, especially if you do not properly manage stress concentrations. This explains the transom failure mentioned above, but also some of the mast failures etc.

The great quality of Viking ships was their flexibility. They would twist and flex but not break. Kept the crew busy bailing though as the clinker hulls leaked a good bit with the flexing and twisting.

Originally Posted by NavyDiver

Sydney to Hobart train wreak 98 would rank as a WOW in the sailing sense. RIP sailors

Give some idea of the power those who have sailed know is so much bigger than us. Yet we keep sailing and blue water allure is compelling.

Suspect my wow plus beside ghosts of my recovery jobs, is still our amazing Great Australian Bight. Words cannot describe what I saw. Just imagine the MCG disappearing in front of you, reappearing and disappearing again and again and again..... and you have a smidgen of an idea of the wonder our oceans gifted me.

Bass Strait is bad enough, but not as bad as the Great Australian bight at its worst. The only time I've ever been truly frightened at sea. And I've seen the Tasman sea at it's worst, been in a Typhoon near Japan , and two cyclones off the West coast in a patrol boat, 15 metre seas, gale force winds. All a doddle compared to the bight when the sea is angry.

Allan Villiers wrote some great books on the days of sail. He was a sailing ship man. They would take those big sailing ships down to the Roaring Forties and Furious Fifties looking for wind. Find them in your council library. He wrote of the big German ships and their masters who were noted as hard ship drivers. Their reputations were made by the amount of time they could keep the lee rail under water. He wrote a hefty book on Cape Horn and the Drake Passage under sail. He reckoned it was the most dangerous place on the world's oceans where a ship could disappear in the blink of an eye.

Hi,
Another brilliant read is books by Tim Severin , who re creates various voyages.
Cheers

More at timseverin.net

Originally Posted by 4bee

James it's not him you should be bothered about, just stay clear of Gibraltar.Killer whales launch ‘orchestrated’ attacks on sailing boats | Marine life | The Guardian

James I am glad you weren't born & out sailing when this little bugger was around.


True size of the prehistoric megalodon shark revealed - CNN

Originally Posted by bob10

Bass Strait is bad enough, but not as bad as the Great Australian bight at its worst. The only time I've ever been truly frightened at sea. And I've seen the Tasman sea at it's worst, been in a Typhoon near Japan , and two cyclones off the West coast in a patrol boat, 15 metre seas, gale force winds. All a doddle compared to the bight when the sea is angry.

I remember when the Bight was feared as being rough as buggery for Coastal Shipping. Passenger Liners not so much.

Have seen Video (taken by the the ship's Bridge cameras) from one of the latest Queens leaving Port Adelaide's (Outer Harbour) not showings any rough conditions at all & was a smooth trip to Fremantle. Friends of ours vouched for that small "journey". It seems it can certainly change state very quickly. They also had big problems before they left here with one of the Vessel's Propulsion Units (Pods) which delayed them by nearly a day. Progress huh?

Originally Posted by Bigbjorn

Allan Villiers wrote some great books on the days of sail. He was a sailing ship man. ....

Yes, I think I have all of his books.

But when you think of sailing one of the great iron sailing ships through Drake Passage, spare a thought of the 16 - 18th century sailors who used Drake passage, upwind, not really knowing what they were up against, and in ships far less seaworthy than the ones Villiers sailed in. Read the accounts (preferably the contemporary ones) of Drake, Anson, Dampier etc. Even Cook had some "interesting" passages, especially when trying to map Antarctica, although he had a pretty good idea what to expect, knew where he was all the time, and was in a far more seaworthy ship.