To Jib or not to Jib

Flying spinnaker downwind, is there a magic distance the foot/luff of the spin should be from the luff of the jib to avoid any drag or wind flow issues?

I know monhulls (even the big ULD sleds) drop their jib when flying the asymmetrics, but skiffs don't. Just interested in the thinking / theory behind when it's an advantage and when it's not.

Monodulls (my J22 included) run deeper angles and the jib gets in the way of the flow in the slot at those deeper angles. It also impedes the spin sheets (or the spin sheets distort the jib badly) at correct sailing angles - so we drop it to get it out of the way. On the multihulls, we leave the jibs up half out of convenience and half out of the fact that no rockstar has dropped or furled their jib and won a race yet.

So the telltales flowing correctly is misleading, and the airflow in the slot is actually disrupted? Hmmmm

Conversely, perhaps I could sail deeper if I dropped/furled it. Will have to do some VMG math on that one...

BTW it's my three-legger (PHRF 84 - slower than a H16). What's the J22 PHRF?

With the tri Ive found it that its best to drop it in sub-8 knots. Any other time it just easier to leave it up, especially sailing with only 2 on board.

we don't need no stanking math
sail it like you stole it !

Depends how hot you run your spin, my main sail telltale's streamed with the main nearly centre, so my jib must be working when set for a reach

After the last regatta, it is evident I'm running too hot on the spin angles.

So I tried to run deeper angles, which required less mainsheet/traveler to get the main telltales to stream correctly. So I'm about 12" down on the traveler (to get lower telltales streaming) and moderate easing on mainsheet (for the top)

They said I need to ease the spinnaker halyard about 12" too when running deeper (perhaps to reduce luff curl/collapse)? I thought you did that when you wanted to sail higher...

"VMG math". Seriously? Cite?

the low/slow vs. hot/high debate (which gets to C in the shortest time).

Now that most handheld GPS can estimate VMG, I guess it's more a question of the opportunity to test the sail setups and angles...

Never mind. There is this: http://www.c34.org/faq-pages/faq-polar-diagram.html

If I want to soak down wind or in really light air, I would ease the halyard a bit but probably 6 inches at the most, it let my pretty flat spin bag up a bit

You might be trading off a slightly fuller spinnaker for rotating the leading edge further to the side of the boat. If the luff rotates further to leeward, it gets even less air as you try to run deeper. We usually ease the tack a little (3-4 inches) when we're trying to run really high so we can rotate the sail around to leeward slightly.

To be honest I was always trying to make a silk purse out of a sows ear by running a flat F18 spin on the Nacra 5.8, it did go really well in good wind but the halyard had to be set within an inch of the correct spot depending on the angle I wanted and weight on the wire, my favourite angle with spin is two on the wire which is not good for VMG but great for the soul

That's what I thought, too, Jake. And as Timbo can attest, the spin I have is very full compared to what we're used to on F18 and N20 versions.. So I was having a hard time figuring out how going slack on the halyard would do any better at driving deep.

Timbo thought maybe it would keep the luff from curling as quickly as a tight halyard...