At anchor in a hot climate, a wind scoop fitted in you boat's fore hatch will transform living conditions below. There are several different designs available if you want to buy one, but here's a simple and effective version that can be easily and cheaply made up from a single piece of light fabric.
Sadly, I can't take any credit for the design of this; I believe - although I'm not certain - that this should go to the renowned cruising couple, Lynn and Larry Pardy.
As you can see, it's made from two pieces of nylon spinnaker cloth stitched together and attached around the outside of the foredeck hatch surround.
Attached thus, you can close the hatch from below when it starts to rain.
An ordinary domestic sewing machine will be able to handle this easily, but for maximum durability you should use a zig-zag stitch and UV-resistant thread.
If your hatch is hinged at the forward edge as shown above (the most seaworthy approach), a partially closed hatch - as in the above pic - will still provide ample ventilation whilst preventing rainwater from getting below.
The first step is to measure the outside dimensions of the fore deck hatch surround - the length and the width - to determine the length of the foot of the wind scoop.
The first piece is shaped as shown below. It's a right-angled triangle, the longest side of which is curved.
The length of the foot is half the WIDTH plus the LENGTH of the hatch surround as measured in the first step. The height is about three times the length of hatch surround - that's usually around 5 feet (1.5m) or so.
The curved edge should approximate to the shape shown. Allow 1" (25mm) all round for seaming.
The second piece is a mirror image of the first one, so use one as a template to draw the other.
Then cut them both out and stitch them together along the curved edge as shown below. Ideally, you'll use a zig-zag stitch for this.
Then turn in the remaining seams and stitch them together. Just two more things to attend to:~
On Alacazam, the fore hatch is bedded on a teak surround which makes holding it down with lift-the-dot fasteners a cinch.
Two of these are fitted to each of the three sides, the male part screwed into the surround, and the female part pressed into the seam around the foot of the windscoop. No special tools are needed.
Using a halyard to hold it up just doesn't work - you need to hold it both up and forward. First though you need to provide an attachment point on the windscoop for a light line - a short loop of webbing strap stitched on is ideal.
If you're lucky you'll have a convenient forestay, cutter stay or babystay to attach it to. Otherwise you'll have to be a little more creative. One solution would be to take a halyard down to a deck fitting just ahead of the hatch.
You'll find that this wind scoop will direct an impressive breeze throughout the boat which you can vary by adjusting the position of the hatch cover.