Cyclone Debbie

[44'cruisingcat]

Originally Posted by PaulinOz

Ex-Tropical Cyclone Debbie will continue to generate areas of very heavy rain over the Wide Bay and Burnett, Southeast Coast districts and parts of the Capricornia and eastern pasrt of the Darling Downs and Granite Belt over the next 24 hours.

Currently the heaviest rainfall is occurring over parts of the Wide Bay and Burnett region near Seventeen Seventy and Bundaberg with rainfall rates of 50-100m in 1 hour. Parts of the Southeast Coast district are also see very heavy rainfall rates .

Widespread 24 hour rainfall totals of 150 to 250 mm are expected, with significantly higher accumulations in excess of 400mm possible locally, mostly about the higher ground in southeast Queensland. This rainfall will be very intense at times, leading to a risk of severe localised flash flooding. Locations that may be affected include Gladstone, Kingaroy, Bundaberg, Brisbane, Sunshine Coast and the Gold Coast.


The fun just keeps on coming, Quote"Flying away might not be a bad thing though, if you landed where the weather was better".

Would need to fly a long way to get away from this weather at the moment.
Its stretching from Townhsend Island in The North down South to near Eden which is over a Thousand Nautical Miles as the cat flys.

Yeah, but the ISS is just a multi caught in a breeze isn't it?

[daletournier]

Originally Posted by PaulinOz

Ex-Tropical Cyclone Debbie will continue to generate areas of very heavy rain over the Wide Bay and Burnett, Southeast Coast districts and parts of the Capricornia and eastern pasrt of the Darling Downs and Granite Belt over the next 24 hours.

Currently the heaviest rainfall is occurring over parts of the Wide Bay and Burnett region near Seventeen Seventy and Bundaberg with rainfall rates of 50-100m in 1 hour. Parts of the Southeast Coast district are also see very heavy rainfall rates .

Widespread 24 hour rainfall totals of 150 to 250 mm are expected, with significantly higher accumulations in excess of 400mm possible locally, mostly about the higher ground in southeast Queensland. This rainfall will be very intense at times, leading to a risk of severe localised flash flooding. Locations that may be affected include Gladstone, Kingaroy, Bundaberg, Brisbane, Sunshine Coast and the Gold Coast.


The fun just keeps on coming, Quote"Flying away might not be a bad thing though, if you landed where the weather was better".

Would need to fly a long way to get away from this weather at the moment.
Its stretching from Townhsend Island in The North down South to near Eden which is over a Thousand Nautical Miles as the cat flys.

Im in the sandy straits , I can assure you its raining hard .

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[44'cruisingcat]

Hamilton island is still seeing gusts around 50 kts.
They must be wondering when it's going to end.

[daletournier]

Originally Posted by IslandHopper

Wind and rain has eased significantly here in Bundy over the last thirty minutes or so, the sun is even shining....

Good to hear, that means it should here soon.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[kmacdonald]

Originally Posted by Jim Cate

Umm, not wanting to get mixed up in this silly argument, but I think you may have things reversed in the above statement. If flow across an airplane wing caused a downward pressure, it would be kinda hard for it to fly, being pressed into the runway as it tried to take off. I believe that Mr Bernoulli would agree with that.

I suspect that the few cases of airborne multihulls that exist, it wasn't lift over a horizontal deck that elevated the boat, but rather the wind getting under the deck as the boat pitched and the primarily drag forces generated did the heavy lifting.

However, I am but a ignorant monohull sailor, opining about multihull vessels that I've never owned so just ignore me...



Jim

I agree. When the bow or stern rises with a large wave, the underside of the bridgedeck is exposed to the full force of the wind. If you have watched NASCAR racing and seen some of the "spectacular" crashes you would understand a little better.

[PaulinOz]

Originally Posted by IslandHopper

Wind and rain has eased significantly here in Bundy over the last thirty minutes or so, the sun is even shining....

Looks like Bundy has seen the last of the rain for a while. In Brisvagas the wind is a constant 25 gusting 30 was from the North got a bit more East in it now. If anything it looks like it now is moving quicker than they predicted earlier.

Hunkered down or if you use the Oz TV news reporters of the past few days vernacular, bunkered down for the duration playing on the internet.

[IslandHopper]

Originally Posted by daletournier

Good to hear, that means it should here soon.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

Yep, just spoke to my brother on Bribie Is and he's starting to feel it now, clearing up nicely here....

256 km Gympie (Mt Kanigan) Radar Loop

John...

[handmer]

Originally Posted by Jim Cate

I think you may have things reversed in the above statemen

Factor is saying that the underside of the bridge deck could act like the top of the wing - so the cat is working as an upsidedown wing (compared to a plane), pushing it down.

That is correct in that it is possible, but you are correct that an airborne multi is likely from drag, not lift.

Wind hitting the cat creates an aerodynamic force. Drag is the component of that force parallel with the flow of the wind. Lift is the component of the force perpendicular to the flow of the wind.

So drag push the boat back in the direction the wind is flowing. Lift will either push the boat up, or down.

At the most basic, lift is re-directing the direction of the airflow. By pushing the air in one direction, you push yourself in another (Newtons third law, for every action there is an equal and opposite reaction).

Whether or not the cat will experience lift pushing it up, or pushing it down, depends on the shape and the angle the wind hits it. In other words, whether it re-directs more air upwards or downwards. Lift is going to be minor compared to drag anyway, since the cat is not a very good aerofoil.

If the wind is not parallel to the water, then drag would be the major force moving the boat away from or towards the water.


Of course, none of which makes a cat or a mono more or less of a dog

[Jim Cate]

Factor is saying that the underside of the bridge deck could act like the top of the wing - so the cat is working as an upsidedown wing (compared to a plane), pushing it down.

Perhaps that is what he meant, but (surprise) not terribly clear to the reader.

However, comparing the shape of a cat's structure as viewed from ahead to the profile of a wing is a big stretch IMO. The interaction of the nearby water surface with the flow field around the lower surfacce of the deck, and the completely disrupted flow over the house, davits, rig and other impediments reduces the idea of downward lift to t he ridiculous. Plentyof drag, though!

Anyhow, I dunno what Factor had in mind... all I commented upon was what he appeared to write.

Jim

[handmer]

Yeah not well worded. I suggest we put every cat into a wind tunnel post haste and find out for sure

[Factor]

One of these surfaces is a Bernoulli curve, and in this case an enclosed one.

Also trying to work out how this discussion point started - is there a single reported case of a multi getting airborne during debbie?

[tuskie]

Originally Posted by PaulinOz

Hunkered down or if you use the Oz TV news reporters of the past few days vernacular, bunkered down for the duration playing on the internet.

You aren't up in the FLY- bridge getting ready for take off?

[kmacdonald]

It's OK now. The cat owners group has decided to tie their boats down and not tie them up. The rest of us should be fine now. Thanks cat owners!!!!!

[Factor]

Originally Posted by tuskie

You aren't up in the FLY- bridge getting ready for take off?

Yes - I think you should be lodging a flight plan with CASA, for 1700, that is when the strongest winds in Manly seem to be likely. They are forecast northerly, so maybe a landing at Southport may be appropriate. If you get lucky when the southerly change comes through you can fly half way back, its not as strong

[kmacdonald]

Did we take the mystery out of UFO's?