forehatch design

[lilianroyle]

I'm currently thinking about a new forehatch for my smack. If I make a hatch which fits snuggly over the coaming, obviously it will not hinge. Has anyone used the kind of hinge that would allow you to left the hatch up vertically a couple of inches and then open . Is this a good idea. What is this kind of hinge called? Any better ideas. Thanking you in advance
Pete

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[tillergirl]

I've had a look in my copies of the 'Woodworker's Pocket Book' and Collins Complete Woodworkers Manual and I can't see what you seek. The only one described with a 'cranked throw' (I thought he played for Sri Lanka), is a cranked centre hinge which is no good to you as it fits in the wrong plane - i.e. imagine a goor - the centre hinge would be fitted to the top and base edges not the side.

My hatch fits over coamings using a piano hinge at the forward edge. It works although I couldn't claim the hatch is a snug fit to the coaming and I guess my coaming is not as high as yours. I do have, however, a space for any water getting through the mating edges of the hatch to be drained away. This is achieved by having the hatch outer edges mating to a timber flange. There is then a gap on each side and rear (with drains) before the coaming. The weakness is the forward edge of course but its not too bad.

Hope this helps

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[mcrem]

I have seen such a hinge used on an attic skylight. The skylight was pushed upwards and then swung out. I think it might be called a 'friction hinge' but I could be wrong about the name.
Suggest you talk to a local Velux window supplier or have a look on the screwfix.com site.

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[Mudplugger]

It is possible that a Friction Hinges would work as a pair of hatch stays, but please be advised that F/Hinges are designed to close on the hinge side with reasonable compression, as the hinge opens, so the movement is is cantelevered to allow cleaning of the glazing when in the open position..... The hinge stile moves across & out. The maximum opening angle would be limited to 90degrees. Any size over 400 (16") is more likely to be restricted to around 30degrees. Maximum weight for a 90deg. Hinge (pair) about 24kilos. They are availabe in Austenitic. PM if you want any more details.. Regards Tony W.

<hr width=100% size=1>Tony W.

 

[tugboat]

If you're open to an alternative idea, I can recommend the Maurice Griffiths double coaming design such as I had on a wooden boat. I changed the standard hinges for the lift-off type for doors. If you fit the bottom half of the hinges on both for'd and aft sides of the hatch you can turn the lid round the other way to catch the breeze at anchor.

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[Mirelle]

Very good idea.

The Maurice Griffiths double coaming forehatch really does work; using the lift off pattern hinges is a new one to me but since the hatch cannot slide sideways when it is closed it seems like a very neat idea.

<hr width=100% size=1>Que scais-je?

 

[Stemar]

Re: Very good idea.

Just make sure you get solid brass hinges.

I didn't try very hard, but the only lift-off types I could find were BZP or brass plated, which won't last five minutes.

If anyone knows of a supplier, I'm interested

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[spark]

As others have said the double coaming hatch is the way to go. A 'snug fitting' single coaming hatch will let water in in some circumstances - capillary action will let the water climb up between the lid and the coaming. The double coaming design breaks the capillary and lets any water drain back out onto the deck.

Davey do brass lift-off hinges but only deal with the trade. Classic Marine should be able to get them for you ( www.classicmarine.co.uk ).

Something else worth thinking about is building ventilation into the hatch coamings which I have done on Spark and is a great success. The vents are either side of the hatch and are dorade-type with the openings aft facing<A target="_blank" HREF=http://www.qei.co.uk/sparkdeck.html>( see pics here).</A> Spark is a very dry boat - if you take water over the bows you might want to build the coamings/openings a bit higher.


<hr width=100% size=1><A target="_blank" HREF=http://www.sail-spark.co.uk>Spark's Summer Voyage 2004</A>

 

[Mirelle]

Re: Very good idea.

"No advertising on YBW" but I've no connection with them except as a customer:

http://www.classicmarine.co.uk

<hr width=100% size=1>Que scais-je?