Bob,
The force by the mainsail driving the rig forwards is the cause of a pitch-pole. In addition, when the bows bury and stop the boat, the momentum of the rig adds to the forward-driving forces.
I am still in doubt:
If you want to depower the top section of the mainsail, the part that contributes the most moment (force*arm) to driving the rig forward, then would it not be most efficient to stall the sail?
When releasing the traveller (and mainsheet) you prevent stalling the sail when bearing away, don't you?
Your main advice bring crew-weight to the back of the boat, I assume we all agree on.
Thank you for a most constructive answer!
Stein
The problem with stalling the sails is it is very slow and you have an extremely narrow steering band. Lets say you keep the traveller centered and drive very deep effectively stalling the mainsail. You will be going slow and might feel somewhat under control. However if you were to steer up and unstall the sail, suddenly the mainsail will really load up and because the boatspeed is slow that creates the condition where the rig wants to go over the bows. Think twist and flow in the top of the mainsail. If you maintain that, you minimze the chances of pitchpoling. Always use twist to depower the top of the sail.
It's trickier flying a chute because you have so much more power in the entire sailplan and you have to keep some sheet tension to keep the mast in one piece. Dropping the traveller 4"-6" can make a huge difference from where you keep it sailing in moderate conditions. You can practice a lot of this in 10-15 knots air to see how the boat and sails respond.
Regarding blowing the jib to make the turn from upwind to downwind, I disagree if you have dropped the traveller and eased the mainsail in conditions over 16-18 knots. The crew will need to follow the turn with correct jib trim (avoid the stall) and that will keep things under control very nicely. Correct jib trim will pull the bows down. I use to sail Tornados and P-19's and the fine bows on those boats could be scary to turn down in big breeze.
Lots of pitchpoles occur due to incorrect weight placement and poor sail trim. The faster you go, the less loaded the rig is. Mainsail twist and boatspeed in heavy air are your friends. Stalled sails and going slow are the devil!
Bob Hodges