Water Collection?

Anybody here collect rain water?

I've been living on the hook on a Marine Trader 44 CPMY for 3 months now, based in Miami. Watermakers are pretty expensive, require engine room space, and maintenance. Once i looked up a chart of how much rain we get in Miami monthly, I've been convinced all I need is a simple catchment system.

My boat has 250gal of tankage, and hardtops over both the sundeck and flybridge, cummulatively about 200 sq ft of roof. An inch of rain yields .6 gal per sq ft. For simplicity, lets just assume I can collect 100gal per inch of rain. Miami avg monthly rainfall (inches): Jan 2, Feb 2, Mar 3, April 3, May 5, June 9, July 7, Aug 9, Sept 10, Oct 6, Nov 3, Dec 2. I expect the "dry" months would yield about just enough for my needs...in the wet season it seems i could be downright wasteful.

My tankfill is on my cockpit floor, so its as simple as diverting the water off the roof and into a pipe/hose that threads into the tankfill. Should I go with actual small gutters? Or just rim my hardtops with some sort of lip and cut drain holes at the low points? Curious if anybody has done this, and also what kind of external (pre-tank) filter i should install?

Done it but not on a boat. One problem is keeping the roof and gutter system clean. Birds are the worst. Just rats with wings. They carry all kinds of disease and worms. Either they poop or stand on the roof eating their latest prize.

You have to filter and sanitize the water or you'll probably get sick. And what are you going to use for gutters? House gutters? It will make the boat look crummy, greatly reduce the selling price, more than the cost of a small watermaker. You can make a watermaker for under $1000.

Even with a clean collection system the rain water must be filtered before going into your tanks.

All rain drops contain dirt , "condensation nuclei ", that is required for the water to form from water vapor...

Not hard to filter with a std house filter .

Not hard to sterilize with a lil splash of bleach. Plus im not too concerned about maintaining pristine aquifer purity for the water I bathe & defecate in.

And boats are depreciating assets, so im not worried about what the next owner wants -- I'll probably live on it til it sinks anyway.

If i go the gutter route, i was hoping to find a mini version of house gutters (maybe for RV's). But like i said, the other option is to install a raised rim (which wouldnt be noticeable).

Roof collectors are very common in tropical and high rainfall areas. Large tankage for storage is normal. As mentioned, Filters, UV etc are commonly used for cleanup. Drinking water can be made with a small RO unit.

Price out the options taking into account drought events. Compare to an RO unit and your path should appear.

We have used a Sunbrella awning as a rain catcher. Aluminum poles in sleeves at fore & aft ends with a flexible PVC pole in the middle. Bulkhead fitting with hose barb sewn in the middle. Tie high enough to whatever you have overhead. If not raining pull middle upward with rope to arch for shade. When raining release rope, awning will go to a catch rain position. After first flush, hose water to tank.

Works well. We have a sewing machine so homemade, was 10x8, but design is flexible to fit your boat. Wind stable with sufficient tie points. Used while cruising for years with a 100 gal water tank when only other alternative was 5 gallon jugs during dinghy trips ashore.

Hot tub chlorine will help keep it clean also. I’m also considering such ideas. We don’t have much in the way of pesky birds here.
Personally I’d dump the rain water into a simple screen initially, then a more complex filter inline on the tank output side. If you put a pool chorine tablet on the screen as it washes into the tank, it will slowly dissolve and probably keep you right where you need to be with nasty bugs.

Birds are always taunting us