Marnine Boat Fan

February 2008 -- Putting little fans all over the boat has been on my list for a while,
but every time I priced out "marine" 12V fans I put it off.

I went to a local computer superstore to pick up some 12V fans to play with. We're going to have a little "Fan Off" competition. I took them all to the boat and connected them up to a 12V circuit to see which would work best.

Key specifications are air movement, measured in Cubic Feet a Minute (CFM,) Power Consumption in Amps at 12V, and Noise in decibles (dBA.) Decibles are non-linear. The difference between 40 and 50 dBA is significant,
but the difference between 10 and 20 is much less noticeable.

This, the cheapest one, moves 100 CFM
but makes 48 dBA of noise.
It's also bigger and wider than the others.

It pulls .35 Amps. But, it's cheap.
The wider housing focused the air in a tighter beam, and I could feel it six feet away.

But it really was loud. After about ten minutes, it was annoying. Since I'll have eight of these things around the boat, it would be really annoying if multiple fans were on.

It was loud enough that I couldn't hear what was going on outside the boat.

So this one is out.

This was the most expensive.

It moves 72 CFM, but only makes
14 dBA noise, and pulls only .18 Amps.

That's attractive, if it's going to be
on all the time during hot weather.

Compared to the first one, this one seemed almost silent. The thinner case, and perhaps the design of the blades, disperses the air in a wider pattern. I could easily feel it moving air from three feet away,
in about a 140 degree arc.

That actually would be perfect for a fan mounted above a berth.

This one's a keeper.

This one is interesting.

It has three speed settings. At the high end, it moves 79 CFM, makes 30 dBA noise. At the low end, it moves 39 CFM and makes 25 dBA noise.

No power consumptions specs were provided, and I forgot to check with a multimeter. Oh well, later.
The 30 dBA was noticeable, but it seemed to move more air than the super silent one. Logically, the difference between 79 and 72 CFM shouldn't be noticeable, so maybe it was just my imagination.

I liked the little three speed switch. In the middle setting, it still moved a fair amount of air but was really quiet, and at the low end it seemed silent. Yet, at the low end I could still feel air moving from three feet away.

Perfect for sleeping. This one's a keeper.

This one comes with a variable speed adjustment, which I forgot to take with me to the boat. Oops.

My experience with rheostats on board is not very positive, though. They can create a hum in
the radio and stereo. It moves 110 CFM max, makes between 17 and 40 dBA, and pulls .5 Amps.
Wow, that's a lot of juice.

When I fired it up, at max setting only, it was as loud as the first fan. That, and the power consumption,
knocked this one out of contention.

Besides, the reheostat violates the KISS principle.

This little bracket was designed for security cameras. It's actually solid black powder coated, and nearly invisible. I just tweaked this picture to make it more visible on a computer.

Manufactured by Clover, model MBK003.

It supports up to five pounds, can be adjusted and locked in any position, and has a standard 1/4"-20 connection.
(That's what's on the bottom of all cameras.)

It cost $5. It also took me a month to get the idea. I was looking at "ball mount brackets" and all kinds of wierd stuff that cost way too much money. I also considered must making some cool universal bracket out of wood, but didn't want to make
such a big deal out of this.

All the parts are supported
by a wood bracket.

Using a large 4-1/2" hole saw,
I cut scallops out of the
edge of some scrap.

Fortunately, I have lots of little pieces of teak and mahogany in my scrap bin.

The switches came from a
nearby model train shop.
I'm not into model trains, but there's a hobby shop dedicated to trains next to my favorite sushi place.
It's full of interesting stuff, but this is
the first time I ever spent money there.

Sure enough, they had tiny little low voltage switches for a reasonable price.
The electronics superstore wanted way too much money miniature switches, but these are cheap.