Looks like we've got a bunch of us all figuring this out at the same time. I've only been out on my '05 260DA one afternoon, and I had the exact same experience. I had it trimmed "right" a couple of times (by accident), and the boat was handling fine. Dave (friend & co-owner) moved, or we changed direction and she would need some adjustment and I just couldn't retrim her back to where she needed to be.
This is clearly a case of us simply not having a feel for what changes what, and which trim to use when. I took flying lessons for a while. This played a part in the problems that I was having. A couple of folks on here pointed out that unlike ailerons, the right trim button works the let trim tab. Well blow me down. I was trying to correct a lean to starboard by hitting the bottom of the right trim button. That should have lowered the right tab a bit, lifting the starboard side level. In reality, I was actually lowering the left tab, which put me in the same situation that you encountered.
Since we have knowledgeable, experienced, drivers right here, and multiple people asking the same questions. I will ask a few related questions that I was going to ask in a new post.
I put my 260DA on a wash rack at the marina. I put the trim tabs all the way up. I then had Dave hit the top of both trim buttons for about 5 seconds. The back edges of the tabs had lowered about 3" or so. In an airplane that would be a very hard turn if not a full blown barrel roll, depending on how fast you were going. This HAS to be way too much tab for "normal" use on a boat, correct? My guess is that 1/2" of travel ought to be enough to correct for just about anything above 5 mph or so. At speed, even less would be required. This amounts to pressing a trim button for about 1/3 of a second. Is my logic correct, or is more tab required?
Both tabs should not be used at the same time, correct? If I correct for a port bow high list by hitting the top of the left trim button, the starboard tab will lower to correct the condition. If something changes and she develops a starboard list, I should first hit the bottom of the left trim tab retract the previously lowered starboard tab before even thinking about using the top of the right trim button to lower the bow on that side. Otherwise, I would end up lowering both tabs further and further as I kept correcting for each condition. The result is that the bow keeps getting planted further and further until I end up putting the boat in a condition that it wasn't designed to be driven in. Not to mention all of the drag associated with the tabs being deployed that far. In effect, the tabs would also be "fighting" each other. I am just along for the ride at that point, not really in control at all.
If I need to change speeds after being trimmed for a while, should I get in the habit of adjusting the throttle first and then hitting the bottoms of both trim tab buttons to retract both tabs before trying to retrim, or should I retract the tabs first and then adjust the throttle?
Why didn't Sea Rav put trim tab position indicators on the panel? This would help tremendously.
Regarding power trim, I was entering the marina for the first time the other day and was having a little difficulty controlling her at slower speeds. I had the outdrive pretty far up because I knew there were shallow spots close by, I was unfamiliar with the waters, I was nervous, and the depth alarm had gone off a couple of times. With the boat in the wash rack yesterday, I could see that there is very little, if any of the "fin" (rudder?) of the outdrive (the flat surface coming off of the bottom of the prop shaft housing tube) projecting below the bottom of the boat. My really stupid question is: is this the reason she was all "squirly" on me trolling into the marina? I need to keep the outdrive further down than that to have proper control, correct?
This all seemed related to captnjohn's original post. Captnjohn, please ask the mod to move this if you feel that it is a hijack of your thread.
Michael