Sectorsteve said..
A few of the comments suggest here in 30knots and swell to be running just a small jib.
In my tophat returning north from Jervis Bay recently my sail plan started as a reefed main and my full hanked on reefable jib.
Seas = 2-3 m, wind 25- 30knots. Sailed due east form hole in the wall mooring and once near point perpendicular i stowed the main and decided to run with the jib only.
This was mostly fine, but around Crocodile head(outer JB) was a washing machine and around Gerringong was also large swell.
I think i would have had more stability with reefed main and a number 3 and sailing across the waves slightly. The boat was a bit hard to manage dead downwind in these conditions and for an auto pilot it would have been also because after this 6 hours of pretty fast sailing my arm was rooted.
I regretted this Sail plan later and it was really out of fear that i did it this way as i have the downhaul on the jib and can manage it from the cockpit.
I since heard somewhere that Tophats arent ideal dead downwind and im still yet to try this in a moderate/large seastate.
Reading Steve Dashews books confirms this, but he also says all boats are different.
I know this topic is about autohelm or not, and ive lately been a shocker for deviating off topic - im sorry, but im curious to hear what others think of sailing dead downwind in a large-ish sea with a certain sailplan. How do you do it to minimise stress on the rudder. Im looking forward to trying both sails next time in similar conditions because i have a feeling ill have more control and that therell be less pressure on the tiller/rudder.