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Old 13-10-2022, 10:29   #1
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Dorades?

Does anyone know if there is a mechanism for sealing dorade's in the event of a capsize?
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Old 13-10-2022, 10:38   #2
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Re: Dorades?

The boat's righting moment.


Unless it's a submarine, it's not designed to float upside down.
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Old 13-10-2022, 11:11   #3
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Re: Dorades?

Many boats float for hours or even days once capsized. This is enhanced by multiple bulkheads and a watertight pilot house. I suppose a manual flap would not be too difficult to engineer. Something automatic would be nicer.
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Old 13-10-2022, 11:24   #4
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Re: Dorades?

I found these clever enough to bookmark them.


https://www.air-onlyventilators.com/products/
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Old 13-10-2022, 11:34   #5
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Re: Dorades?

What do you mean by capsize? Presumably you mean a "knock-down", i.e. the boat being put on her beam ends, but not rolled over. In a knock down, the doreades will handle the situation just the way they are, though of course a bit of water might come in. Just a nuisance, not a danger.

Monohull do NOT stay "upside down" if rolled over. Once they are past something called the "point of vanishing stability" they are, by the nature of their hull shape and ballasting, NEGATIVELY STABLE, i.e., they will return to their "upright", normal way of floating. Provided they have any openings in the structure above the sheer reasonable well sealed they will not take on sufficient water to sink them. What water does come in, the (manual) bilge pump should handle.

The danger of a rollover and even a knockdown is the damage it can do, and likely will do to the rigging, and the danger of heavy items below deck such as batteries coming adrift and being thrown around.

IMO you are wasting emotion on worrying about the Dorades, but if you like, you could obviously make cover plates for the inboard side of the air downtakes. If you are a cruising man, spend your energy on learning meteorology and weather forecasting rather than on worrying about the Dorades. Then stay out of the sort of conditions that can knock you down :-)

You might like to read Adlard Coles' Heavy Weather Sailing. Heavy going, but worth it :-)!

All the best,

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Old 13-10-2022, 11:58   #6
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Re: Dorades?

Some dorades do have a closer. When water came in through ours during a knockdown, I managed to stuff a towel into it, which greatly slowed the ingress.

While capsize events do occur, they are rare events, and one would generally be in damage control mode, and very glad one kept their rig up to date, in good nick.

Ann
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Old 13-10-2022, 12:13   #7
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Re: Dorades?

Thank you both for the excellent information. I am well aware of the importance seamanship and a well built boat play in avoiding such circumstances. I.e. weather forecasting, routing, and righting moment. That being said I did read of a circumstance where a boat turtled for some time, took on a significant amount of water, then when it was finally righted it sank. If I remember correctly the crew left the companionway door open.
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Old 13-10-2022, 12:45   #8
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Re: Dorades?

Boats rarely capsize for no reason. Usually you will have plenty of warning of impending conditions sever enough to cause a capsize. Its then relatively easy to seal the dorades from the outside as a precaution. Mine can be replaced by screw caps and the drainage holes sealed with some quickly applied sealant, but even large amounts of gorilla tape will do in a pinch. Your not looking for complete watertightness, just a sufficient reduction of inflow in the case of inversion to keep the boat afloat long enough for it to self-right or for help to arrive. There are lots of ways of achieving that.
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Old 13-10-2022, 14:22   #9
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Re: Dorades?

My thoughts exactly.
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Old 13-10-2022, 14:56   #10
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Re: Dorades?

Quote:
Originally Posted by TrentePieds View Post
What do you mean by capsize? Presumably you mean a "knock-down", i.e. the boat being put on her beam ends, but not rolled over. In a knock down, the doreades will handle the situation just the way they are, though of course a bit of water might come in. Just a nuisance, not a danger.

Monohull do NOT stay "upside down" if rolled over. Once they are past something called the "point of vanishing stability" they are, by the nature of their hull shape and ballasting, NEGATIVELY STABLE, i.e., they will return to their "upright", normal way of floating. Provided they have any openings in the structure above the sheer reasonable well sealed they will not take on sufficient water to sink them. What water does come in, the (manual) bilge pump should handle.

The danger of a rollover and even a knockdown is the damage it can do, and likely will do to the rigging, and the danger of heavy items below deck such as batteries coming adrift and being thrown around.

IMO you are wasting emotion on worrying about the Dorades, but if you like, you could obviously make cover plates for the inboard side of the air downtakes. If you are a cruising man, spend your energy on learning meteorology and weather forecasting rather than on worrying about the Dorades. Then stay out of the sort of conditions that can knock you down :-)

You might like to read Adlard Coles' Heavy Weather Sailing. Heavy going, but worth it :-)!

All the best,

TrentePieds
Most boats are stable upside down or their angle of vanishing stability would be 180 degrees. The range of the angle that they're stable upside down and the area of that curve are so small that if the waves were big enough to capsize you upside down they would roll you enough that the boat will eventually right.

The "D" example boat in the link is wide and will spend much more time upside down than other designs.
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Old 13-10-2022, 21:00   #11
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Re: Dorades?

Thank you for the link cal40john.
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Old 13-10-2022, 22:06   #12
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Re: Dorades?

The Yachting World interviews showed one Golden Globe racer shoving a nerf football in the dorade vent when concerned about knockdowns.
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Old 14-10-2022, 06:19   #13
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Re: Dorades?

My kind of racer!
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Old 14-10-2022, 07:42   #14
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Re: Dorades?

Quote:
Originally Posted by Weatherbird View Post
I found these clever enough to bookmark them.


https://www.air-onlyventilators.com/products/
Those look great, however in the capsize scenario I don't think they would block water. Upside down, the balls would want to float (which when upside down is towards the base of the unit ) and keep the vent open. The problem is you ned something that will
1. stay open when the boat is upright
2. block water rom waves when the boat is upright
3. close off when inverted and the boat is upside down.

That is a bit of a challenge.
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Old 14-10-2022, 12:54   #15
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Re: Dorades?

Quote:
Originally Posted by Mattdewizard View Post
Thank you both for the excellent information. I am well aware of the importance seamanship and a well built boat play in avoiding such circumstances. I.e. weather forecasting, routing, and righting moment. That being said I did read of a circumstance where a boat turtled for some time, took on a significant amount of water, then when it was finally righted it sank. If I remember correctly the crew left the companionway door open.
Yeah, the companionway will be a MUCH bigger problem. But as seen, there are dorades that have a closure when inverted. I think the Nerf ball is a good idea to have on hand though.
I wonder if you have read the book "God Forsaken Sea"?
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