Golf Ball Fluid Dynamics

[kingofsportsIII]

Originally Posted by Ari

. . .For a boat, good streamlining of the hull will overcome this problem.Canoe shape hull. To introduce thin layer of air in between the hull and water surface might make the hull more slippery but to have those bubbles deeper in the water will cause the boat to sink deeper, water density is what supporting the boat to float, if aerated and contains tiny bubbles, water density will drop, thus the ability to float the boat.In a water treatment plant, where air is injected into the water and form tiny bubbles..even a rescue float will sink to the bottom when thrown in into this tank.

This was a very enlightening response. Makes me wish I had applied myself in physics instead of going for the easy bonehead liberal arts degree.

I thought of using a flat bottom on the main hull of my next boat because in my limited experience having the flat bottom makes it really easy to haul out and dry dock without having to construct special supports. The boat I have now is tall and long and its important to distribute the weight evenly to avoid damaging the hull- a long flat bottom and ten 12”x12” beams makes the once per year process a snap.

So, if I was going to have a 80’x 6’ flat bottom I was thinking about a slightly concave bottom (to trap the air pocket in the flat section) and a ‘airstone’ strip on the bow end so the bubbles travel the length of the hull with the theory that this cushion of air would reduce drag to about 1/3 of the wetted surface of the main hull.

Ari’s mythbusting logic seems to be based on pure science which I am completely unqualified to debate. Thanks for your comments!

[ron17571]

I liked the coating the hull in chapstick idea!i read about a teflon anti fouling stuff you brushed on,seemed like a slippery idea.my expierience was finding out that under laser class rules using dish detergent was an agent thats illegal,palmolive does more than clean dishes.

[kingofsportsIII]

maybe my crazy air bubble idea wasn't so crazy after all! Check out. . .

http://www.newscientisttech.com/data...9/25391601.jpg

[Verytricky]

Originally Posted by kingofsportsIII

maybe my crazy air bubble idea wasn't so crazy after all! Check out. . .

http://www.newscientisttech.com/data...9/25391601.jpg

No - this idea is crap.

To maintain the curtain of bubbles the ship would need to travel at planning speeds.

Also, if there were sufficient bubbles to maintain the curtain at displacement speeds, the ship would sink into the bubbles, as the bubbles are air, and metal sinks in air...

I have checked, and there are sources online of bubble curtains sinking ships - even touted at one point as a defence barrier!


It may be possible to run a planning hull on a curtain of bubbles, but not a displacement ship. Displacement ships only float because they weigh less than the water they displace. ( duh ) If you surround the ship with a bubble curtain, the ship will sink into the bubbles, because the weight of water/air mixture creating the bubble curtain is now less than the ships weight, and thus the displaced substance is less than the weitght is the ship displacing it, thus glug glug glug...

[yipster]

than how about the encapsulated bottom bubble displacement designs ive seen, i think there must be gains in the idea somehow