|Get it Right!|
Part 3: Is there a downside to trim tabs?
By Capt. Bill Pike — June 2002
But they can do a heck of a lot more, too. Most vessels with a substantial deadrise tend to heel into crosswinds; some with substantial structure aloft--say, a tuna tower--lean away. In the first case, you can eliminate lowering the windward tab; in the second case, eliminate the leeward tab. You can even use trim tabs as a backup steering system. Lowering the starboard tab, for example, increases drag on the starboard side and steers the boat that way, and vice versa. This technique is ponderous, but it just might get you home if your steering pump kicks the bucket, although it will hardly return you to your slip or even your marina. Trim tabs, after all, are completely ineffective at docking or even displacement speeds.
Finally, there's choice. Imagine you need to transit a long channel to get into an anchorage, a channel where reduced speed is required. Without tabs, your options are limited--either you have to go too fast (at your lowest possible planing speed, which while it may reduce your wake may be unlawful and/or unsafe) or too slow (at your highest displacement speed, which will get you there...someday). Trim tabs to the rescue! Simply push the bow-down switches on your dashboard, and lower your tabs so they line up with your boat's running surface. (You can determine this quite simply. The next time you haul your boat, use a straight edge to align the tabs' surfaces with your boat's running surface, and mark the spot on your trim-tab gauges for future reference.) The extra lift and efficiency engendered by this technique, as well as the temporary extension of your boat's running surface, will broaden your throttle range, and instead of having to choose between speeds at extreme ends of the spectrum (like, say, 22 mph and 6 mph), you'll be able to split the difference.
Is there a downside to trim tabs? Nope, unless you count the fact that they can't do a darned thing about unscheduled boat rides.
This article originally appeared in the February 2003 issue of Power & Motoryacht magazine.