Dean,
Where the trim tas are positioned will have an effect on how the boat handles as well as fuel consumption. Trim tabs are one of those items that you do tend to "play with" as one position will not be optimal for all speeds or load distribution. I use the trim tabs to 1. level the boat side to side, while underway as the occupants move around. and 2. to minimize bow rise when coming up on plane in shallow water. Otherwise, mine are kept fully retracted as I don't have a planning problem.
If your trim tabs are hydraulic and manufactured by Boat Leveler, there are a couple of items that you can easily install which may be helpful. Bennett Trim Tabs has an auto trim tab control http://www.bennetttrimtabs.com/autotab.htm which allows you to adjust the trim tabs to where the boat's position in the water is optimal, save the position with a simple press of a button and then the auto trim tab control (atc) adjusts the trim tabs constantly to maintain that position. Bennett also has an auto trim tab retractor http://www.bennetttrimtabs.com/atr.htm which I have found to be more useful than the atc. The auto trim tab retractor fully retracts the trim tabs when the boat's engine is turned off. This is useful as it prevents a trim tab from getting tore up when left in the down position and loading the boat onto the trailer. A trim tab left down can come in contact with the trailer bunk or roller, damaging the trim tab, the cylinder or popping the hydraulic line off the cylinder or hydraulic pump unit. Both of these items install VERY easy on the Boat Leveler trim tabs.
Another tid-bit regarding trim tabs. If you have hydraulic trim tabs and you are loosing hydraulic oil but you don't know from where. The hydraulic system can be split in half real quick when troubleshooting the leak. When at the dock or on the trailer for a period of time, fully lower both trim tabs and leave them there for a period of time (ie: overnight). The trim tab which has the leak will retract slowly overtime and the trim tab that stays fully down is OK. You then can look for the leak at the trim cylinder, hose, hose connection or hydraulic valve in the pump on the side which has retracted. Wheather the trim tab retracted fully or partially over time is not an issue as it just reflects the severity of the leak and time. After fixing the leak, bleeding the trim tabs is as simple as running the tabs fully up and down a few times.
Phil Belcher
2003 266CCR
496 MAG, Bravo 3