I think the idea of a self-draining cockpit is a bit over sold here.
There are alternatives. Especially for boats with gross displacements under say a thousand pounds.
The pdracer fleet took capsize recovery safety seriously since its very beginning.
The pdracer approach was what they called "air-boxes". These were sealed on all sides, but typically had a hatch on top, or an inspection plate on the inward side.
The air-boxes usually extended across the boat or along its length. The advantage of the latter was that the boat usually ended up free of water after it was righted. The disadvantage was that, if the sides were high, the boat was hard to get back into.
With the air-boxes extending across the hull, the advantage was that the boat would sit lower in the water, due to a considerable amount of water still aboard and would be easier to get back into.
My personal boat, a scow, but longer an narrower than a pdracer, does not have airboxes. Instead, it has 12, one gallon milk jugs lashed under the side decks. This is to make it easier to board after righting. I can pull the side down and swim over it.
Once aboard, I can bail the water out, as the water in the boat will be supporting most of my weight, not the 12 milk jugs.
I Sailed an old FJ for many years, and always wished I could sail the water out of the hull. I had seen Flying Dutchman and other boats with the flaps in the transom and wondered if that would work on my FJ. Did you retrofit the FJ you pictured. I also remember seeing a device in the bottom of the boat in the stern that looked like a one-way valve that would sail the water out of the hull.
Great explanation of "free surface" effect. And how it's possible to mitigate it, even in an open boat. Now I know what I need to watch for if I add water ballast. Thanks, Mike, for the info and the extra link.
Looking at the third drawing, if the outside two compartments are difficult to close off water tight as on a clinker built hull, would it not be easier to seal off the center section and have drains with flap closures on the other two compartments? You would still have a lot less FSE and a lot more flotation.
I think the idea of a self-draining cockpit is a bit over sold here.
There are alternatives. Especially for boats with gross displacements under say a thousand pounds.
The pdracer fleet took capsize recovery safety seriously since its very beginning.
The pdracer approach was what they called "air-boxes". These were sealed on all sides, but typically had a hatch on top, or an inspection plate on the inward side.
The air-boxes usually extended across the boat or along its length. The advantage of the latter was that the boat usually ended up free of water after it was righted. The disadvantage was that, if the sides were high, the boat was hard to get back into.
With the air-boxes extending across the hull, the advantage was that the boat would sit lower in the water, due to a considerable amount of water still aboard and would be easier to get back into.
My personal boat, a scow, but longer an narrower than a pdracer, does not have airboxes. Instead, it has 12, one gallon milk jugs lashed under the side decks. This is to make it easier to board after righting. I can pull the side down and swim over it.
Once aboard, I can bail the water out, as the water in the boat will be supporting most of my weight, not the 12 milk jugs.
I Sailed an old FJ for many years, and always wished I could sail the water out of the hull. I had seen Flying Dutchman and other boats with the flaps in the transom and wondered if that would work on my FJ. Did you retrofit the FJ you pictured. I also remember seeing a device in the bottom of the boat in the stern that looked like a one-way valve that would sail the water out of the hull.
Useful information. Matches my own experience.
Great explanation of "free surface" effect. And how it's possible to mitigate it, even in an open boat. Now I know what I need to watch for if I add water ballast. Thanks, Mike, for the info and the extra link.
Looking at the third drawing, if the outside two compartments are difficult to close off water tight as on a clinker built hull, would it not be easier to seal off the center section and have drains with flap closures on the other two compartments? You would still have a lot less FSE and a lot more flotation.
Thank You for the additional information and thoughts. Now I understand the cockpit floor in my DS 2.
JW