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Old 03-04-2018, 16:29   #16
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Re: Dorades ! need your ideas.

A mushroom vent on the inside pipe? But turning them so they face aft when offshore works very well for the most part.
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Old 03-04-2018, 16:32   #17
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Re: Dorades ! need your ideas.

To open/close the top cover, use a piece of all thread. Attach it to the cover - a block of PVC, threaded to match to rod and glued to your top cap will work. Make up a bar with a threaded hole to match your all thread in the middle. The bar is a close fit on the ID of your inlet pipe. Mount the bar to the pipe with screws thru the pipe and into the bar, 2 screws per side. Then put a handle on the threaded rod below the bar, and above the bottom of the pipe. A gasket on the bottom of the top cover is a good idea, or you can machine an o-ring groove in the top of the pipe and install an o-ring there.
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Old 03-04-2018, 16:44   #18
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Re: Dorades ! need your ideas.

Gosh, the ideas are coming in fast now.
The Bronze vents are a thing of exquisite beauty, but alas, they will not do.

Ours is a wet boat, she is flush deck, and has never pounded, except once leaving Cuba by the Windward Passage. We often get green water over the deck if were in too much of a hurry. Our present system even if the mushroom vents are screwed down will admit water. When open, they are not the best at breathing either. Then we leave them open for a few months, and the thread seizes...its not working.

I will make the dorades soon, and experiment, and post comments and pictures once the job is done. (Even if not 100% successful)
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Old 03-04-2018, 16:53   #19
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Re: Dorades ! need your ideas.

I think a fair few dorades have drains that are way too small. Big drains with rubber non return flaps on the outside might help.

There are some rollover proof dorades that have tubes running right down to the bilge. Prehaps a bucket with a drain under the vent to capture spashes might work. Other ideas are those 90mm PVC pipe screw on end caps. Screw them up from the inside and remove them with a bucket to catch any collected water.

It is also possible to get pipe bungs that just fit inside the pipe and when you tighten up a screw the rubber insert expands and seals the pipe.
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Old 03-04-2018, 17:06   #20
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Re: Dorades ! need your ideas.

Something like this.
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Old 03-04-2018, 17:58   #21
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Re: Dorades ! need your ideas.

how about smth like a toilet plunger, instead of all that complicated threaded stuff? you push it in from the inside, when you're done you pull it out (maybe you'll have to mop up some water after that).

how bad are you anticipating the weather to be?
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Old 03-04-2018, 19:31   #22
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Re: Dorades ! need your ideas.

The ideas keep pouring in like the water does....

Were not expecting bad weather, but it always happens...
When you are crossing an ocean, there will be at least one storm.
When we beat hard to weather, our decks are very wet. That is why we have to close the mushroom vents inside the existing cowls. In tropical and temperate waters it becomes very hot and stuffy down below. We want to have our dorade vents open in those conditions, facing aft, as extractors.

I have been delaying this long enough. Now is the time to do something. Is only taken 20 years of cruising to get my lazy ass in gear!
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Old 03-04-2018, 21:26   #23
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Re: Dorades ! need your ideas.

Hi, sy gilana,

Make sure the dorade boxes have for and aft and port and starboard drains. They need to let a lot of water out fairly quicklly. Our two have 13-14mm drain holes, and they have never let a drop in. Ours have friction fit plugs, but the inside part is engineered so water just plain can't get there. The friction fit plugs are loose enough that they leak air when it is cold, so they, presumably could leak water if we rolled. Sometimes we jam dish towels up them, to cut off the draft.

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Old 04-04-2018, 08:48   #24
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Re: Dorades ! need your ideas.

Our fireplace chimney has a spring loaded cover attached to a length of SS aircraft cable that drops down the chimney into the firebox. Attached to the other end of the cable is a collar followed by a short piece of chain that feeds through a slotted bracket mounted to the wall of the firebox. The default position of the cover is OPEN, held that way by the springs. When rain or snow storms come through I pull on the chain, securing the collar below the slot. This closes the door over the chimney above the roof line and keeps everything water tight. Seems to me that you could construct a similar cover in your Dorade box out of PVC flat stock (3/4" Kleer board stock would work). The spring could be made from solid, tubular or banded polymer material like band saw "tires" for instance. In your case the springs would be attached from the top of the PVC piece to the underside of the dorade box.
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Old 04-04-2018, 09:34   #25
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Re: Dorades ! need your ideas.

What exactly is your reason for not wanting the usual arrangement i.e. deck plates that screw into the mount for the scoop when the scoop is off?

Dorade boxes have a baffle inside between the scoop and the air intake into the cabin, usually @ 50% the height of the box, to further help airflow and prevent water intake.
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Old 18-04-2018, 18:47   #26
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Re: Dorades ! need your ideas.

Hi Sujin, the method you mention is not what I have got, I have no way of screwing in a plate. I want to be able to open and close from inside the boat. In storm conditions I like to limit my time on deck to a minimum. Sometimes they bow up too fast, especially like on a 20+ day crossing, or anywhere in the Med in September, you get very little warning.

We are now on the hard, and searching for a suitable toolbox to make the mold.

Will take photos and keep you updated.
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Old 15-05-2018, 19:56   #27
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Re: Dorades ! need your ideas.

UPDATE:

As you might know, we are on the hard doing our 7 year haul out....yes, we get 7 years on our anti fouling paint.

As I had too many things going on during the haul out, I subcontracted the making of the Fiber(fibre) Glass boxes that will form the main volume of the Dorades. In the attached photo in the background is a ship, originally called Shuttle Goteborg. It is now being used as a shed, to build an 80 ft party catamaran.

While chatting to the workers there, they offered to help by making the boxes. They threw my idea of the toolbox right out as it would not be rigid enough to mould the glass and resin, instead making a mould out of Melamine clad chip-board.

I paid $36.00 each for these beautiful boxes. Note, they are still to be cut along the base to the camber of the deck, drain holes have to be made, and the vents and cowls fitted.

More photos will come as the job progresses when we are back in the water, and at anchor somewhere nice. Full details to follow....
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Old 16-05-2018, 06:28   #28
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Re: Dorades ! need your ideas.

Quote:
Originally Posted by sy_gilana View Post
UPDATE:

As you might know, we are on the hard doing our 7 year haul out....yes, we get 7 years on our anti fouling paint.

As I had too many things going on during the haul out, I subcontracted the making of the Fiber(fibre) Glass boxes that will form the main volume of the Dorades. In the attached photo in the background is a ship, originally called Shuttle Goteborg. It is now being used as a shed, to build an 80 ft party catamaran.

While chatting to the workers there, they offered to help by making the boxes. They threw my idea of the toolbox right out as it would not be rigid enough to mould the glass and resin, instead making a mould out of Melamine clad chip-board.

I paid $36.00 each for these beautiful boxes. Note, they are still to be cut along the base to the camber of the deck, drain holes have to be made, and the vents and cowls fitted.

More photos will come as the job progresses when we are back in the water, and at anchor somewhere nice. Full details to follow....



That IS beautiful, and what a steal! I was happy to see this thread, since I MUST install a dorade vent as part of our refit.


I was just looking at the same system you have (for about the twentieth time) at Defender. Is your primary complaint that it admits water, or that it doesn't catch enough wind?



And how much water are we talking about? We have no headliner; is it possible we might be okay with what you currently have, or would you advise to stay away regardless?
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Old 16-05-2018, 06:53   #29
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Re: Dorades ! need your ideas.

I would avoid them like the plague!

There are fundamental design errors that I have tried to work around.

1. When a large wave comes over, even if they are facing aft, there is a return wave as the boat pitches forward into the next trough, there simply is not enough VOLUME in the base, to swallow that amount of water, bearing in mind that the stand pipe under the mushroom is only about 3/4" high. Result is about a quart of water in a deluge.

2. The drain slots are so aligned that a minor amount of deck wash, say 1/2" thick, sliding across the deck enters the drain slot, which is perfectly aligned to jet that water against the stand pipe, with its radius, it shoots the water up under the mushroom and in. About a tablespoon at a time.

My new design will be much better, and I will post detailed photos and an honest report. I intend to locate a bucket under the vent, and I am going to simulate wave entry with another bucket, 3-4 gallons per chuck. It has to be stress tested prior to trusting them.

In the tropics, the boat gets incredibly hot inside after a day or two of everything battened down.
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Old 16-05-2018, 08:16   #30
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Re: Dorades ! need your ideas.

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Originally Posted by sy_gilana View Post
I would avoid them like the plague!

There are fundamental design errors that I have tried to work around.

1. When a large wave comes over, even if they are facing aft, there is a return wave as the boat pitches forward into the next trough, there simply is not enough VOLUME in the base, to swallow that amount of water, bearing in mind that the stand pipe under the mushroom is only about 3/4" high. Result is about a quart of water in a deluge.

2. The drain slots are so aligned that a minor amount of deck wash, say 1/2" thick, sliding across the deck enters the drain slot, which is perfectly aligned to jet that water against the stand pipe, with its radius, it shoots the water up under the mushroom and in. About a tablespoon at a time.

My new design will be much better, and I will post detailed photos and an honest report. I intend to locate a bucket under the vent, and I am going to simulate wave entry with another bucket, 3-4 gallons per chuck. It has to be stress tested prior to trusting them.

In the tropics, the boat gets incredibly hot inside after a day or two of everything battened down.

Okay then! I will heed your advice, and I can't thank you enough for it!



My next idea was to use one of the common SeaTeak dorade boxes, but with which vent, I'm not sure. I need to create the most ventilation possible, but on a tiny boat like ours, the size of the box and cowl could pose challenges.



I'll stay tuned to this thread. I definitely want to get this right the first time. Thanks again.
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