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Go Back   SailNet Community > General Interest > General Discussion (sailing related) > Hatches facing backwards???
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Thread: Hatches facing backwards??? Reply to Thread
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Topic Review (Newest First)
05-02-2008 06:07 PM
witzgall So one more question - What kind of goo should I use to seal the flange to the deck?Lewmar specifies a sealant, as opposed to an adhesive, but they don't go as far as to recommend a particular one.
05-02-2008 04:01 PM
Jeff_H "Witzgall - the forward hatch in the picture is going to break or develop a severe leak quickly."

Well there's a statement that i completely disagree with. The majority of production boats have their forward hatches mounted with the hinges aft and they rarely, if ever have a problem. The dog side of the hatch (vs hinge side) usually has the better seal since the dogs compress the gasket making a forward facing hatch more watertight when hit with green water (half blue-half yellow) when closed. An open forward hatch will catch jibsheets whichever way it faces.

In terms of ventilation, I had a boat which had a forward hatch that could open either way (you shifted the hinge pins) and it clearly had better ventilation when opened to the rear. There is a theory of ventilation that suggests that the area of the exhaust end of a non-compressed ventilation system should have 50% more area than the intake end. On my boat the forward hatch has its hinges facing aft (opening facing forward) and the main cabintop mounted hatch has its hinges facing forward (opening facing aft) which when combined with the area of the companionway seems to be consistent with that theory.

I do leave the midships hatch with the forward hinges open when sailing in moderate or less conditions and it does not seem to take spray down below.

Jeff
05-02-2008 03:48 PM
witzgall Now that I think about it some more, I think that you are looking at an optical illusion - I don't think the forward hatch will hit the smaller one. THe lens I used to shoot this is VERY wide, and can introduce distortion and perspective issues easily. At least that is what I am hoping.
05-02-2008 03:48 PM
Zanshin I have a deep dent in my fiberglass from my forward hatch flying open (even though it has a big steel spring preventer), which is why I noticed it in the picture. I have a similar ventilator to the one in the picture, and that is what is hitting first. I think I will put some sort of a rubberized door stopper on the cabin top, in your case it would have to be mounted pretty high so that the hatch would clear the other hatch. As you noted, putting the hatch the other way may do even more potential damage, although the chances of a gust coming from that side are lower, at least while at anchor.
05-02-2008 03:28 PM
witzgall Never thought of that. Otehr than moving the hatch for the head, any ideas on how to keep this from happening?

The hatch does has a leak now, not bad mind you, and the boat/hatches are over 20 years old.

Maybe this is a good reason to put the hatch in reverse? But then, there will be nothing to support it in your scenario, and it could put extreme stress on the hinges.


Quote:
Originally Posted by Zanshin View Post
Witzgall - the forward hatch in the picture is going to break or develop a severe leak quickly. One day it will be partially open to catch the wind, then a gust will flip it back open. It will land (with extreme force) on the other hatch with it's left corner and bend/crack. Perhaps not the first time, but it will happen.
05-02-2008 03:08 PM
Zanshin Witzgall - the forward hatch in the picture is going to break or develop a severe leak quickly. One day it will be partially open to catch the wind, then a gust will flip it back open. It will land (with extreme force) on the other hatch with it's left corner and bend/crack. Perhaps not the first time, but it will happen.
05-02-2008 02:54 PM
witzgall Thanks all for your input. I wwil install the new hatches in the same orientation.

I wonder if the specific design, and or length (50-85ft) of Dashew's boats made a difference.

Chris
05-02-2008 02:41 PM
Cruisingdad
Quote:
Originally Posted by witzgall View Post
The question was, with the hinges forward, hatch open 90 degrees and the companionway open (under a dodger) would the airflow at ANCHOR (again, not sailing, for you speed readers) be better, then having the opening of the hatch facing forward.



Chris
The answer is no.

The type of hatch is irrelevant. Boats point into the wind when anchored, unless there is an opposing current stronger than the wind. You will get more ventilation with the hinges as shown, in the rear, hatch facing forward when open.

- CD
05-02-2008 02:09 PM
Valiente
Quote:
Originally Posted by Faster View Post
We have two hatches forward of the mast, the lower foredeck hatch has hinges fwd, the one in the cabin top has hinges aft and acts as a ventilation scoop.
I have the same set-up: The forepeak hatch (the forepeak is isolated forward of a collision bulkhead) has the hinge forward, but has a small opening flush port set into its steel plate so you can close it but still get ventilation.

The cabin top hatches are about 18 feet back from the bow, are 19 x 19" A&Hs on four inch teak surrounds and open towards the bow with the hinge at the aft for the same reasons.

I would think the logic of one over the other would be dictated by the "offshore factor" of the boat's intended use, and the design of the foredeck regarding camber of the deck, height of the cabin house, and height of the cabin hatches, wave breakers, etc. above the cabin top.

I know that close-hauled in ten foot seas, my foredeck barely got damp, whereas we caught a fair bit of spray blown aft on to the higher, more exposed aft deck. I also noticed not a lot of spray on the pilothouse forward windows. Off the wind, we got spray only. Running, it was pretty dry. Your results might vary.

On a C&C design, by contrast, the "spoon bow" with the flush forward V-berth hatch stayed dry, but we got green water sweeps aft close-hauled in 35 knots. The seas would board at the low point in the sheer and just fly back into the cockpit on the low side. But the foredeck was merely wet, not inundated.
05-02-2008 01:10 PM
christyleigh
Quote:
Originally Posted by witzgall View Post
The question was, with the hinges forward, hatch open 90 degrees and the companionway open (under a dodger) would the airflow at ANCHOR (again, not sailing, for you speed readers) be better, then having the opening of the hatch facing forward.
My answer would be No, absolutly not. With the hinge forward as mine are when the hatch is vertical it is Blocking the wind at anchor. With the hinge aft and the hatch open the hatch itself is acting as a Wind Scoop. Both situations are assuming the normal anchoring with the wind on your bow.
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