The same size rectangle can fit either at the rear of the boat (in the love seat area) or on the upper deck below the boom.
The water captured can be diverted to bucket, or via hoses of various lengths into the tanks
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Since Footprint often finds herself away from civilization, and recently has found that water, when found, must be paid for, and the tanks don't last forever, we decided it was time to find someway to capture the water that falls from the sky to fill our tanks.
We've just made our first rain catchers, and before leaving the BVI for our 8 day passage to Bermuda, we were able to fill our tanks, solar showers and spare water jugs in just a couple of afternoons of good rain. It might not be perfect but it works, and we are happy with it - here is some general info in case it can help someone else. It was amazing to watch the water find its way down the funnel, along the pipes, and into the various storage areas, and watching the water level slowy climb in the tanks., now I understand why Kyle gets so excited watching the wind gernerator pump amps into our batteries.
I researched a lot, and sought a lot of advice (thanks to all those that helped, especially those at SailNet). The best rain catchers are gutters built into the boat permanently, with a tap to direct the captured water either overboard or to directly into the tanks (or elsewhere). I hurt my brain trying to find a way to fit gutters, or make use of current water flow aboard our Gemini 105Mc Footprint - but I could not do it. Tony Smith (the designer of the Gemini) suggested simply opening the rear locker on the steps and letting the water that drans back, fall into there and into a bucket. Though that may work, I really don't fancy opening my (mostly dry) locker to the rain, nor hanging around on the back steps, nor finding a way to keep that locker door open against the wind. We decided we'd have to go with a canvas/material based water catcher. Also it's placement should not interfere with sailing, nor with safe passage/access around the boat.
Other suggested that the sails and the mast are a great source of water collection - you just need to be able to place something under them to capture the water. Again, I agree, But.... I'll only have the sails up if I'm underway, now if I'm underway and it's raining do I really want to go forward and rig something? Will it interfere with reefing? How would I secure a bucket in that area and keep the water in the bucket? or how best to route a hose back to the tanks? Most of the time I'm simply at anchor and the sails are not up. I'm still thinking that something should be possible using the sails/mast, but I've yet to solve that problem - someone suggested installing some kind of cone at the base of the mast and directing that output to a bucket/hose.. I believe it should work, but I haven't tried that yet.
It is easy to make a canvas/material rectangle - insert some grommets on the corners and edges, and sew in a material "funnel" in the middle... So far so good. If you can't make it, it should be quite cheap to have made. The ideal size was bigger than any bits of material I had left aboard Footprint after a number of other sewing projects, so I decided I'd experiment and prototype and if I found something that worked, I could then improve on that later. It would be much easier if I could actually capture water and THEN decide how to improve a system, than to design and build the perfect system first time.
So - next issue is where to put it? I expect it mostly to be used at anchor, but it might also be used underway on really long passages, so I wanted the rain catcher not to interfere with general foot traffic - I didn't want to suddenly have to step over new lines placed at trip level, nor to scramble under things - I wanted to keep easy, safe passage around the boat. I also didn't want the rain catcher to interfere with the sailing of the boat. Note we will always set off on a passage with sufficient water aboard, but if we can capture additional water, it means more showers, and less restrictions on water use generally. I decided two locations were good
I made a rectangle from the material I had (actually I made two, with two different types of materials, one heavier, but they are both the same size). I found the best place to attach it was at the cleats on the davits for the dinghy, and from the forward corners around the rear cockpit enclosure poles and secured with a good knot to the hand rails above. I was amazed that this works really well. When at anchor this area is in a wind shadow, so it doesn't billow and throw the water off too much, but it does seem to capture a reasonable amount of water. We find we never use our love seat so it is not in the way for us on Footprint. From here the center funnel that directs the water can be inserted into a bucket (that we secure to the boat) or with a longer hose directed right into the water tanks either side of the mainsheet track.
The funnel is made from canvas/material and sewn into the center of the rectangular rain catcher. Permanently attached to the end of the funnel is a male pipe fitting - to which I can attach various lengths of hose to direct water to the area needed. Also embedded in the filter/ male pipe fitting is a primitive filter (which can be removed and cleaned, or replaced, by removing the hose clamp and disassembling).
Funnel fittings. In the canvass itself I've attached a male fitting, and I have a variety of lengths of hose with female fittings to attach to that: It will connect to short hose, medium hose, or long hose (the same type I use to fill water from a dock). It would have been easier to install the "quick release" hose fittings, however I could not find them in the hardware stores available when I was making my rain catcher - I may well make that small conversion in the future. For now I screw on my various fittings, but that can be cumbersome with the medium length hose as I have to twist the whole hose with the fitting, not just the fitting on the end (again, finding a better fitting would help here, and I long for a decent hardware store).
Filtration - I've installed mosquito net (folded into 4 layers) at the hose fitting hose clamped to the funnel end. I also plan to experiment with needlepoint rings - these are two rings that fit perfectly one inside the other, between which you can clamp material. Their main use is in needlework, and cross stitch to hold the material taught for working on. I think that they should work in the funnel area, to hold a filter that the water has to pass through. I found some wooden ones with brass tightening nuts ($1.50), but I'm really on the look out for plastic ones so they won't decay and rust on me. In this setup I can install any type of filtration material, possibly even coffee filters. For now, I've got the basic filter, and I can direct water into a bucket and filter from there before putting in the tanks if I feel it necessary. If the water is clear/clean, I can just direct hose right into the tanks.
Bleach - note we have always used a small amount of bleach in our water tanks whenever we fill with water (about 1/8 teaspoon per 2 gallons, a table spoon per tank). We did this even when filling from drinking water supplies in the US - we certainly do this when capturing rain water to stop any unwanted growth of the local wildlife in our water tanks.
Directing output - When directing the output directly in to the water tanks - I found the hose shoved into the water tank was tight enough so it did not get pulled out. When directing the output into a bucket I found the weight of the hose connector in the funnel helped to keep the shape of the installed catcher, but in really windy conditions I simply use a longer hose so the water exiting the funnel won't find itself without a bucket below it).
Attachment points
Key dimensions - The key dimension turned out to be the width of the dingy davits (distance between the cleats) and this is where I put my corner grommets (actually on my original they are a little further out, so I had to adjust mine, but if I was making again, this is what I'd do) - this is almost identical to the distance between the and rails with the tangs on the Gemini cabin - so the same rectangle can be used in either areas. I hook the grommets directly onto the cleats and then secure it in place with the line - when placed forward, I simply tie the lines on the grommets to the tang area. Currently my rain catcher is approximately 52" x 86". Place grommets in the corners (on the 86" length) to match the distance between the davit cleats and attach a line to secure it in place. Once I matched this up, I realized the corner grommets were too far apart to secure a good taught edge, so I installed extra just in a bit from the corners (I could just make the whole rain catcher narrower). The other dimension could have been bigger, especially for the forward (hand rail tang) location, but not too much bigger for the love seat location. I have grommets on all 4 corners, and the mid points of each length - on the longer sides I also have grommets at the 1/4 points. I probably don't need all of these, but it was easy to do them all at the same time and worry about what I needed later.
Next steps / future enhancements
