Recent content by ken

Agreed there is technically reduced power in the horizontal plan proportional to cos 5 but that's pretty insignificant. Someone also pointed out that when a round hull with transom (most planing dinghies) is heeled to windward, the aft contact point with the water moves to windward. This has...

I made a mistake, I squared the inverse change in area/drag, should have taken the square root. Velocity increase would then be 1.014% which is not enough to account for the reported speed increase. Ken

Hi I believe Russ is talking about the way cross flows change with heel. When heeled to lee, there is an upward component of cross flow toward the peak of the sail there the chord is generally narrower. When heeled to windward, the flow is directed more downward toward the foot or boom...

Hi Russ, nice to hear from you again. That's a good thought. I haven't experienced this myself but the claim is for as much as 10% increase. If your guess is correct, It will not work so well with eliptical sail plans as with triangular sails. Also should not work above the design wind as...

Hi, There is some evidence that on a silboat going to windward in moderate to strong wind, heeling the rig over to windward (the reverse of normal) gives significantly increased speed. It works on narrow hull boats but only on wide hulls where the rig is heeled independantly of the hull...

Bernoulli principle is way too weak an effect to explain filght. It's just a simple easy way to explain it to school kids. Ken

Usual practrice in aerodynamics is to work in "indicated airspeed" by assuming sea level density (1.225 kg/m^3). If you want actual velocity you need to account for density. General formulae: L = 1/2 . p . v^2 . S . Cl D = 1/2 . p . V^2 . S . Cd Where : L = Lift Force D = Drag...

Yes I understand that. I realize you may suspect I have another agenda so I'd like to explain I sometimes like to play devils advocate and push such points to see if people really can give an adequate answer to things like this. Just saying it has not been seriously challenged in 50 years...

That's disappointing. I've been trying to clarify my original question and then you raised the question of magnitude of effects so I tried to clarify the order of magnitude that would be considered significant. I hope you don't have a problem with somethig I wrote? Though you say...

Hi Well from what I've read I think C14 dateing has some bigger problems in it's base assumptions. Assumption 1 : The level of C14 in the environment has been stable for a very long time. That is to say that the rate of production form cosmic radiation in the upper atmosphere is the...

Yes, Inter molecular forces relating to water being a polar molecule. This is the reason for surface tension. Well it's not my point in fact it is an assertion form others that wax reinforces surface tension in contact with the hull. It is also well documented that adding substances to the...

OK Beading is not just a function of surface quality though it is one factor. Dull wax will still cause beading. If you spray water on a waxed surface, the water will bead due the polarity of water and non polarity of the wax molecules. The polar water molecules of align strongly to form...

Yes but given equal surface finish, is there a difference between a surface that beads and one that sheets? This is to do with molecular polarity isn't it? So how does this effect boundary flow? Ken

So there is a slight hellical rotation in the fan airstream which is generally ignored. Ken

Hi Sailing 30 yrs ago we used to wax and polish hulls to maintain a protective and as gloss a surface as possible. However some say that anything that beads water such as wax causes more drag than a smooth surface that water will sheet over. Note Racing rule 53 " SKIN FRICTION A boat...