Where is my spa cover? Ever have to ask yourself this question after a wind storm? I have had people tell me they have found their cover a quarter mile from their home. I do not know how they knew it was their cover. Maybe in some parts of the country people write things on their spa covers to help them recover them after a storm. I suppose you could write, If Found Please Call, on the bottom. Maybe, Hope This Spa Cover Did Not Land On Your Sister.
Personally I think it might be time for a different type of spa cover. I found a posting on a spa cover dealers website claiming that they had several covers that made it through Hurricane Katrina. That is a little like saying there were some calvary survivors after Custers last stand. There is a big difference between having some going undamaged and having no losses.
The question to ask is are they selling anything different? So far I have found stronger straps as their solution. Well you could build a solid roof that attaches to the spa but in case you did not notice solid roofs were flying right off houses. The answer is not stronger tie downs for the wing you use to cover your spa but get rid of the wing.
Find a design that does not offer a rigid surface for the wind to lift on. The reason rigid foam spa covers fly is that they make a good wing. Our armed services fly planes with less aerodynamics than the typical rigid foam spa cover.
What causes a spa cover to fly? When wind comes at the spa, some of it hits the side of the cabinet and has to go around. As the air is pushed around the spa it some of it goes up over. As it breaks over the top of the rigid foam cover it starts a little ripple or swirl action that begins to suck upward on the rigid surface. Like when your riding in a convertible, if you have hair like I used to, it does not blow backward like you expect but forward because of the windshield diverting the air flow. If you had no windshield your hair would be blown straight back. This swirl action pulls the foam cover up off the spa.
It does not need to move it very much, just enough to create enough of a gap for some of the air to get under the cover. The second reason rigid foam spa covers fly is they have a nice air space between them and the water surface they are supposed to be keeping warm. Once air starts to flood into this air space it creates pressure. The air rushing in can not push down on the water so it takes the only thing it can move, the spa cover. Once this action starts it is only a matter of what velocity is required before lift off occurs. The first movement of the flying spa cover is straight up.
The pressure in the space between the water of the spa and the bottom of the cover pops the cover straight up. It takes a lot less force than you might think because it is lifting on the entire bottom area of the rigid foam cover at once. Even a saturated rigid foam spa cover that is too heavy for one person to lift will fly when the air is pushing on the entire bottom surface. Once a heavy spa cover gets airborne watch out because anything it runs into is going to get damaged.
So are these spa cover dealers offing anything different? Are they offering a spa cover that is not designed like a wing? Are they selling a spa cover that does not require straps and truck ratchets to secure it to the spa? I propose looking for a different kind of spa cover.
The internet has put the world at your finger tips. Instead of settling for the same old thing, shop the web for a design that makes sense. Look for a design that does not use a rigid foam board resting across the top of the spa. A better design would rest right on the water surface first because the water is what you intend to keep warm and second because this would remove the void that would build up pressure to pop the cover off. If the flexible and dome shaped rather than flat and rigid it would resist lift and deflect even the strongest winds. If you are tired of worrying about your spa cover every time the wind blows, you owe it to yourself to find a better spa cover.
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