Wind Scoop

[brackish]

Anyone using a forward hatch wind scoop they're fond of?  I think that coupled with a riding sail might be just the ticket for comfortable summer nights aboard.  Wonder if the smaller forward hatch on Compacs would allow reasonable setup for a scoop.  Had one on my last boat, but it had a larger forward hatch. 

What about those all direction scoops, anyone use them with a good outcome?

[Mundaysj]

I just bought one for Blond Ambition at the boat show this year.... but I have not had a chance to use it yet.  I will let you know how it works around August.
)
Sherie

[capt_nemo]

I've used both types on sailboats (21,25,32 & 35), and a single direction type on a 36' Trawler.

The single direction type works reasonably well swinging at anchor, but adding a riding sail would certainly maximize its efectiveness. Look for it in various sizes and choose the one that fits your forward hatch best. Keep in mind that the large WIDE channel (scoop) formed above the cabintop for capturing as much breeze as possible  just needs to be secured inside the cabintop after being SQUEEZED somewhat by passing through the hatch opening. In my opinion, larger is better as long as it fits - just think funnel!(and MORE air)

The multi-directional type, is supposed to work best at dockside with boat stationary and wind direction variable. It might possibly work OK with a riding sail but I'd opt for the single direction type for anchoring. The multi-direction type has FOUR channels only one of which is used by wind from a given direction. The problem I had was that with so many cloth panels the cloth on the working sides would partially collapse in light or variable winds and interfere a little with air flow below. Even at dockside I preferred to change the orientation of the single direction type to face the wind.

[brackish]

Thanks, think I'll go with a single scoop, it will be used at anchor for the most part, I've got power at the dock can always use a fan there.  As I recall, the challenge has always been how you secure it to the hatch.

Sherie, good to hear from you, hope you've been well.

[HideAway]

I use a single scoop as well.  I find it necessary to tie the jib halyard used to raise the scoop off to the forestay to keep a better shape.  If the sea breeze stays up it s actually quite cool down below at night even in the summer.  We also have electric battery fans.  If there is no wind we just sleep in the cockpit.  Matt -  Welcome back Sherrie!

[Glenn Basore]

Sherie !

Great to hear form you................

Sure have missed reading some of those Blond Ambitions Stores of the past............

Would love to hear a few new stories.........

Glade to hear from you again.

Glenn

[curtisv]

We used the commercial one size fits all type scoop in the Vrigin Islands where the air flow in the cabin is really needed.  These are roughly triangular and made of very light nylon.  It was hard to keep the top tied just right so that the scoop would stay filled.

If I needed a scoop (on Cape Cod you don't, you need a sleeping bag at night), I'd sew a bulgy rectangle with some light dowel, preferably bendable plastic rod, along the edges so it stayed fully open when the wind was intermittent.

The commercial ones might work well with Compac since the hatch is centered and a line to the forstay would work.  The boat we were on in the Virgin Islands (was big and ..) had two hatches, one to either side of the mast, so tying to the forstay alone didn't work.

Curtis

ps - Sherie - good to hear from you.

[capt_nemo]

The one I used on my Trawler did not require a halyard or tie off at all. It was a collapsible single direction type that had a bendable batten (or two) that formed a semi-circle for the forward edge pulled down by a line that was secured to a wooden dowel long enough to fit across the hatch below.The nylon cloth sides were attached to a plastic frame that went around the hatch. It's been a long time so I hope I got it right. But, you get the idea. It worked so well that I wished I had it for my previous large sailboats. It SHOULD probably still be available somewhere. If not, you could probably make one using Jo Ann Fabrics Rip Stop Nylon, which is what I use for making my own light air sails.

[brackish]

The one I used on my Trawler did not require a halyard or tie off at all. It was a collapsible single direction type that had a bendable batten (or two) that formed a semi-circle for the forward edge pulled down by a line that was secured to a wooden dowel long enough to fit across the hatch below.The nylon cloth sides were attached to a plastic frame that went around the hatch. It's been a long time so I hope I got it right. But, you get the idea. It worked so well that I wished I had it for my previous large sailboats. It SHOULD probably still be available somewhere. If not, you could probably make one using Jo Ann Fabrics Rip Stop Nylon, which is what I use for making my own light air sails.

Is this the one you are referring too?:

http://breezebooster.com/breeze.html

if so, were you able to close your hatch with it installed? and could you take it down from the hatch without going on deck in the event of a high wind storm?

[capt_nemo]

Yes, it sure looks like it, and the name "Breezebooster" does strike a bell!

As long as the strings coming down into the cabin are not too thick (and I don't think they are) I believe you can move the hatch to partially or even fully close it.

And, once you release the dowel across the hatch opening inside the cabin (under tension) and feed it back outside, if you can reach up and out to grab it all and collapse it, you should be able to bring it all down below. Don't know how small your hatch is but I think you only have to reach out with one arm to colapse and retrieve it (while holding on to the dowel with the other arm to prevent loss).

If offered in different sizes be sure to get the one that fits your hatch best. Slightly larger is OK but too large could present problems.

Good luck - and let us know what you finally decide to do.

capt_nemo

[brackish]

Thanks, Capt. Nemo for that recommendation.  Bought a Breeze Booster, medium size and used it on the BEER cruise last week.  It is great!! 30 second setup and take down.  Its best feature is that in the middle of the night when the big storm comes up you can take it in without having to go up on the rocking and rolling wet deck to remove and secure a halyard.  I got to experience that benefit twice while on the cruise.  In a light rain, you can close your hatch and leave it up.  Great product.

[capt_nemo]

brackish,

Glad it worked out for you. As I recall it is indeed a great product.

The sharing of information and experience is what this Forum (CPYOA) is all about!

capt_nemo

[skip1930]

" Keep in mind that the large WIDE channel (scoop) formed above the cabin top for capturing as much breeze as possible  just needs to be secured inside the cabin top after being SQUEEZED somewhat by passing through the hatch opening. In my opinion, larger is better as long as it fits - just think funnel!(and MORE air)"

1~Could a folding fiberglass tent type rod be used to form the entrance horn of a sewn and pocketed [ to push the rod through and to form the shape ] wind scoop ring? Always difficult to find a place for 'stuff' when not in use. Why not fold it up?

2~A couple of the four Fan Laws for moving air can loosely be applied here...understand it is far more difficult to turn air 90 deg then to turn say, water 90 deg. "High volume, less weight, more difficult" and "High volume, more weight, less difficult".

Side Bar:-->One cubic foot of air at 70 deg F. weighs about 1.087 lb. per cubic foot.  One cubic foot of air at 600 deg F. still weighs 1.087 lb per cubic foot BUT takes up the space of TWO  cubic foot. So the coefficient of expansion at 600 deg F. is '2'.

Which is why when pushing air through a forced air heating burner, with a motorized supply fan, the running motor amps drops when pushing heated air as compared to the cold start motor amps pushing cold air. The heated and expanded air flows through a larger square foot discharge duct leaving then when entering the air heater cold. The air velocity remains the same cubic fpm at both ends of the air heater.

Question? What weighs more per cubic foot? Heavy moist air or light dry air?
Answer. Light dry air weighs more as an air molecule is so much smaller then a water molecule, more air molecules can be packed into a dry cubic foot. Which is why 'they' call it HIGH PRESSURE. It weighs more. It pushes the mercury up the tube a few more inches in a barometer.
With LOW PRESSURE air is damp, and does not weigh as much per cubic foot. It weighs less. And is pushed away by high pressure. It does not push the mercury up the tube so much.
I just described to you the making and source of the WIND that pushes our boats, which of course is non renewable. What makes light dry air? The sun heating it.

3~So to get that large volume of cool scooped air into and through the square foot of the shoot, the volume of air [ cubic foot ] must turned 90 deg [ adds resistance ] and be sped up to get through the next choked down area of the smaller hatch. For air to speed up with it's associated increasing resistance [ resistance squares as speed doubles ], resistance must be overcome.
To have the same volume of air from the 'big' opening flow through the 'small' opening, air has to move faster through the smaller opening. What makes it do that?

I puzzled. skip.

[Tim Gardner]

Simply put skip, there is no more air being pushed, just higher velocity air moving.  Think Bernouli here. The air being fluid and compressible changes from a low velocity constant mass gas to high velocity constant mass gas as the control volume decreases from the scoop size inlet to the hatch size outlet. Inertia (velocity head) provides the force needed.

TG

[Billy]

also, when air is compressed, it gets cooler.
when you blow to cool off food, verse trying to fog up a mirror. same air from your lungs just leaving a diff. size hole.

and....compressors are what makes AC cold, and the fridge too!