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-   -   Which way is the wind flowing??? (http://www.sailnet.com/forums/general-discussion-sailing-related/42050-way-wind-flowing.html)

CharlieCobra 04-07-2008 07:39 PM

Which way is the wind flowing???
 
Scenarios on a boat with hull speed of 8 knots.

Reaching at 10-15 knots TWS: Wind flow fore to aft.

Broad Reach 10-15 knots TWS: Winds flows aft forward?

Reaching at 30-35 knots TWS: Wind flows fore to aft, sorta.

Broad Reach at 30-35 TWS: Wind flow aft forward for sure.

Whaddya think? What's the flow looking like at the angles and wind speeds? Is the flow tearing away at high speed on the Reach or not? I don't have telltales on my sails and just sail by the cloth so I can't say for certain what the wind is really doing flow wise in these situations.

Classic30 04-07-2008 08:12 PM

CC, why don't you ask your wife for a short length of wool and tie about 1' of it on either side-stay about head height?

It's not expensive and would really help you work it out in real-time.

CharlieCobra 04-07-2008 08:16 PM

Yeah, I looked at telltales the last time I was in WM but didn't buy any. I use the Windex for direction usually and watch the Headsail luff and Mainsail shape. I guess I oughta get some during refit.

Classic30 04-07-2008 08:36 PM

Quote:

Originally Posted by CharlieCobra (Post 296702)
Yeah, I looked at telltales the last time I was in WM but didn't buy any. I use the Windex for direction usually and watch the Headsail luff and Mainsail shape. I guess I oughta get some during refit.

CC, you don't really need to buy telltales... You have a nice old boat and IMHO, unless you're seriously into racing, a couple of bits of wool would probably tell you all you need to know and look a lot more "in character" than a Windex and telltales on all your sails.

We've got a Windex but I hardly ever use it. Two reasons:
1. In steep chop and light airs, the bloody thing can spin though 360 degrees and I know the wind isn't doing that.
2. My neck gets sore staring up at the top of the mast! ;)

T34C 04-07-2008 08:40 PM

Refit???? You just need some yarn or a piece of casette tape tied to the shrouds. You can also buy a set of telltales that come with little stick on disks that allow you to retrofit them to your sails. Cheap and easy.

Alden68 04-07-2008 08:46 PM

I second the sticky disk ones. As you are apparently very interested in flow, I think you would benefit greatly from telltales, especially on the head sail.

Your sail may look full, but the tell tales do just that, tell you what part of the airfoil is stalling. If you enjoy screwing around with sail control lines, as I do, they give you lots of oportunity to play with trim, twist, etc to maximixe the amount of lift.

Plumper 04-07-2008 08:56 PM

On broad reaches tell tales don't do much anyway. Once the apparent wind is abaft the beam the sails aren't really giving much lift, they are pulling the boat. From a beam reach and higher the telltales tell all about sail shape.

Classic30 04-07-2008 08:56 PM

Quote:

Originally Posted by T34C (Post 296722)
Refit???? You just need some yarn or a piece of casette tape tied to the shrouds.

Oops, I just realised you lot call it "yarn" over there.. "wool" being the white stuff on the back of a sheep!

Hope I didn't cause any confusion. :o

Alden68 04-07-2008 09:04 PM

You put sheep on your sails??????????

;)

Faster 04-07-2008 09:05 PM

Charlie, for a cheap trial find some sticky tape and dig into your old cassette collections and rip out some magnetic tape.

Cut some 6-8 inch lengths and stick them onto your sails and shrouds and check it out.

Once you find the best location on your boat (for accuracy and visibility) then decide which permanent type you want - wool (yarn) or purchased ones. (they won't break the bank)


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