Downflooding

[Boathook]

Jazzcat is more stable upside down than the right way up, but short of that, downflooding isn't an issue. Yes, if we did heel to 90 deg, it's likely the forehatch would fail, allowing water in, but we wouldn't stay that way for long, so that would be the least of my worries. Fortunately, I am unaware of anyone who'd succeeded in flying a hull, let alone capsized a Catalac, and I believe it's never been done.

Not a standard one. A modified one with 'keels' added did trip over many years ago.

 

[Stemar]

Keels on a Catalac. That sounds a bit like "I'll take the keel off my mono hull so I can go faster" If you want that kind of excitement, just buy an Iroquois

 

[zoidberg]

Lots of beer...

But do store it where it does some good.... close to hand and keeping cool!

 

[capnsensible]

Well I'll stick me neck out and say beer should be on the shore or on a boat tied up somewhere......

 

[Stemar]

Well I'll stick me neck out and say beer should be on the shore or on a boat tied up somewhere......

That's a long way to go for a pint mid-Atlantic...

But closer to home, you're tight, of course

 

[capnsensible]

That's a long way to go for a pint mid-Atlantic...

But closer to home, you're tight, of course

Last thing I've ever wanted mid Atlantic is a pint of beer.......

Well, I suppose there are other things like for example, rabies, but glopping at sea isn't ever going to enhance crew ability to deal with any emergent problem. But others are free, of course, to do whatever.

 

[Boathook]

Last thing I've ever wanted mid Atlantic is a pint of beer.......

Well, I suppose there are other things like for example, rabies, but glopping at sea isn't ever going to enhance crew ability to deal with any emergent problem. But others are free, of course, to do whatever.

I've enjoyed the odd beer or G&T whilst sailing but it never much more than a single drink. I was doing a RORC across the north sea years ago and G&T appeared at 1800 hours. I was most upset at this. No ice and in a plastic mug .....

Proper sessions are when at anchor or tied up etc.

 

[Chiara’s slave]

No alcohol on Chiara whilst under way. Mooring up is usually the most stressful part of the day, so we like to get that over with. Stability is far from the top of our list, and downflooding doesn’t make the list at all. Mooring up in a stiff breeze still has the power to scare the crap out of us

 

[boomerangben]

I would suggest that the angle of downflooding in most leisure yachts is largely irrelevant. Drips and dribbles from leaky fittings and hatches are sufficiently annoying to ensure water tightness of anything exposed to the weather deck. I suppose opening hatches are an issue, but again water is likely get in before the angle of downflooding is reached. Wet sleeping arrangements are a good motivator for hatch discipline!

 

[Chiara’s slave]

I would suggest that the angle of downflooding in most leisure yachts is largely irrelevant. Drips and dribbles from leaky fittings and hatches are sufficiently annoying to ensure water tightness of anything exposed to the weather deck. I suppose opening hatches are an issue, but again water is likely get in before the angle of downflooding is reached. Wet sleeping arrangements are a good motivator for hatch discipline!

I can think of a few classics where downflooding could maybe happen, but modern boats, you’re quite right. Classic wise, I can recall a Robert Clarke ketch being lost in the Needles fairway in 1992, an otherwise sound boat overcome in very short order via the main hatch. I knew the owner.

 

[Frank Holden]

I have a stability book that was put together for a Westerly Oceanlord that was going into charter/sail training.
It misses out on 'Class 1'(?) by 1 º. There is a note that if a Firdell Blipper is fitted at the very top of the mast then its AVS will be just above 120º .

 

[Chiara’s slave]

I have a stability book that was put together for a Westerly Oceanlord that was going into charter/sail training.
It misses out on 'Class 1'(?) by 1 º. There is a note that if a Firdell Blipper is fitted at the very top of the mast then its AVS will be just above 120º .

And without? You’d expect the buoyancy of the blipper to count for something by the time it’s immersed.

 

[PhillM]

Having spent 15 years deep sea with a basic understanding of Naval Architecture and stability, it concerns me that some are happy to set off across Oceans with dinghies hanging off the stern on Davits. Perhaps I just sail too smaller yachts to think I may need my dinghy to go ashore for my take away mid ocean?????

One did on this years ARC. Davit failed (I dont know the exact circumstance of the failue) resulting on loss of dinght and a couple of holes in the stern where the bolts had been. Boat retired to Cate Verde for repairs and didnt complete the crossing as the ARC crew would have missed their flights home for xmas from Saint Lucia.

 

[Frank Holden]

And without? You’d expect the buoyancy of the blipper to count for something by the time it’s immersed.

As mentioned above, without the blipper it was just under 120.

 

[capnsensible]

It's too late when the blipper is wet.....

It's the weight up the mast that counts in stability measurements.

 

[capnsensible]

Try this:

rya stability category application form for yachts - Google Suche

Look for RYA form SS1

 

[Chiara’s slave]

It's too late when the blipper is wet.....

It's the weight up the mast that counts in stability measurements.

It might prevent a rollover. Though of course that is dynamic rather than simply pressure.

Frank, the 120 is with the blipper you said. Misses out on class 1 by 1 degree without it. What angle is required to be class 1? Presumably we are talking about static AVS. That surely cannot be the only stability measure, or no multi could ever achieve class 1. Perhaps they can’t. I don’t know.

 

[capnsensible]

It might prevent a rollover. Though of course that is dynamic rather than simply pressure.

Frank, the 120 is with the blipper you said. Misses out on class 1 by 1 degree without it. What angle is required to be class 1? Presumably we are talking about static AVS. That surely cannot be the only stability measure, or no multi could ever achieve class 1. Perhaps they can’t. I don’t know.

SS 1 is available as a pdf download. I did it but don't know how to put it on here. It may help you.

I've never coded a multihull so can't help there. Skippered one on local charters, did a delivery on another. So it can be done.

 

[zoidberg]

I'm intermittently amused by the 'old wives tales' of effective yacht radar reflectors which persist, year on year, in denial of a large collection of reliable tests by the likes of QinetiQ that they are about 1/Root .'sod all use'....

But, like many 'yottie favourites', they're part of a belief system. Not to be challenged on any logical. engineering or sacience basis.

Like the twin 4" reflectors device which came fitted to the top of my old boat's mast. It comprises a pair of 'semi-spherical' Luneberg lenses in tandem ( what-is-a-luneburg-lens-antenna/ ) and - I have reason to know - is effective/efficient in two narrow directions. Only two. It has been retained 'cos it affords a convenient mount for my tricolour light. Another, the '3LENZZ', has three semi-sphericals, which is effective in 3 narrow directions - and 1/ Cube root. effaffaluse in all the others.

As for other types e.g. the stacked tube reflector...

"Probably one of the best selling reflectors as they are relatively cheap, easy to install and come in halyard mount or with deck mount bracket fitted.
Refer to www.ussailing.org where they found these units to be 'invisible: a useful addition to a stealth bomber'.

Then there's the venerable aluminium-plates corner reflector which is carried on just about every elderly boat by equally-elderly owners who 'swear black is white' about how effective their chunks of metalwork are in avoiding being run down by cross-channel ne'er-do-wells in white caps. They're favourites of Stockholm tar-chewing Old Gaffers, principally 'cos they're 'Unmeasured Sail Area' and add almost measurably to VMG Downwind, like an extra mizzen sail.

I remain persuaded by the guidance of a Master Navigator and doyen of the RIN who advised "The higher the frequency of the sensor, the better the definition and the earlier the target definition. Whenever possible use that part of the EM spectrum around 10^15 Hertz i.e. visible light, using the paired sensors on either side of your nose.
In other words, See and Be Seen."

 

[Marsali_1]

Can radar reflectors cause down flooding or is this ^ misposted?