For Lisa & Neil...congrats on the decision & I surely hope you''re pleased. If you would like to chat some more after your initial install, feel free to email me at firstname.lastname@example.org (24/7 on the boat, which we''re going back to in a few days). Note the comment below on ''settings''; it took me a while to zero in on what works best for us.
JNorth, a couple of thoughts about your unit: First, we did not wire it directly to the battery nor have I found it necessary. They''re justifiably concerned about all those stray voltage spikes and maybe even rf from a SSB ruining the unit performance; thus, their instructions. I do think it is important that you properly fuse/breaker the individual power line to the unit, beyond any group breaker at the panel.
You mention S turns & a ''low'' setting on the Rudder knob - I realize it''s somewhat counter-intuitive but that''s part of your problem. The unit adjusts the wheel in small/bigger increments depending on the rudder setting. You set it low, the boat heads off, it incrementally, slowly is turning the wheel to correct, but in the interim the sail trim has changed and the boat''s being driven even further off course. You can''t overcome that simply by turning te deadband way down, as the unit is still not ''authorized'' by you to make larger course corrections.
FWIW we''ve found - and heard the same thing from KOTCHKA, another bluewater CPT user - that both settings need to be kept as low as possible but with enough authority to control the boat. We have a skeg-hung rudder (not semi-balanced) and still we find the CPT does best when the deadband setting is 1.5-2 (motoring) or a bit more when sailing, and the rudder setting is 2-3 (tho'' more is needed under more strenuous conditions...usually). Turn on the unit in the slip with the dock lines a little loose and, while someone''s pulling on one bow line and then the other, see if you can''t adjust the settings so the unit is responding properly. (No distractions with this. Stick with it and ''play'' a while, until you get a feel for heading change vs. settings chosen). Almost all our CPT use has been at-sea and, with the settings I mention above, we find a course is maintained in the 5-10 degree range, tho'' occasionally above that - not too bad given that we''re being pushed around some by the seaway.
Hope this helps. Let me know if you have more questions.