Someone on the Rosborough list mentioned another kind of tabs, from Volvo. Here is a link to a dealer selling them. (I did not take the time to find the appropriate Volvo page because I know Joe will.
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This is what the Rosborough owner had to say:
Warren

This is what the Rosborough owner had to say:
Check out the Volvo BTS system. These are vertical interceptor blades, the kind developed for megayachts, rather than the conventional horizontal plates. I've used various tabs before and the performance from these is the best. After using these I wouldn't consider a conventional tab, especially for a trailerable boat as they fully retract so there's no plate sticking out the back. New units come with an optional GPS antenna. First trim the boat then push "A" and the boat trim is automatically remembered, even when powered off, to automatically compensate for changes of boat attitude caused by speed, wind or people moving about onboard. Very kool! You can reset a new position at any time or override the automatic mode. I installed a set of the original BTS system (GPS optional was introduced in '07) on a 22' walkaround cuddy, weight 4500lb. If anyone wants a pdf of the installation --there were errors in the instruction manual, which I'm sure have been fixed by now -- send me an email. We're purchased the 450 kit and the auto trim system for our Rossie. Just need the boat.
Warren