What happened to keel trim tabs?

[mattotoole]

What happened to keel trim tabs? Older Twelves, and a smattering of experimental sportboats used them, but I haven't seen them since. Why not? Do they not make sense technically, or were they legislated out of existence? It seems they'd be a simple way to generate more lift to windward.

[Raggi_Thor]

Some Minis (open 650) have them, for instance Dudley Dix' Didi Mini.
http://www.dixdesign.com/didimini.htm

I suppose the cost and hassle don't justify the extra lift.

One of Reichel-Pugh's latest designs uses a full length trim tab; another boat just featured in Seahorse rotates the entire keel fin.
In the future trimtab like foils will be used on canting keel boats to generate more righting moment when the keel is at max cant....

[tspeer]

AC boats generally have them, so there are probably about as many designs with them today as there were in the past.

If tabs are being used less, there may be several reasons for it. Tabs are less effective as turning devices on modern high aspect ratio keels because of the shorter chord compared to the twelves. And it may be that the modern ultralight displacement hulls with their dinghy-like round bilges and flatter sections are less sensitive to leeway, making it less important to use the tab to rotate the hull into the direction of travel.

[high on carbon]

Legislated out of existence for a long time in many classes, since the days of the Twelve Meters. Was thought by many to be too "high tech" Look at the standard set of meausrement rules from ISAF and there is typically a focus on one keel, one rudder, all on the centre line etc, BORING (I know Doug will agree with that for sure)

They are great though, my family owned a series of 8 meters, vintage and contemporary. The newest boat had a winged bulb keel with a trim tab and being able to come off the start line and drop the tab 4 degrees while putting the bow down to generate more velocity was a great feeling, point down, sail faster and higher.

We'd even use it downwind, sail a little higher to VMG on the run, then put the trim tab on backwards to pull you deeper towards the mark.

[jdv_nl]

Another development class having trim tabs, is the Int 5.5 m class. In the seventies, when a rubber fixed to the keel was abandoned in the rating rule, the trib tabs appeared. the latest designs by howlett/peterson and schmidt/wilke also do have them

[gybeset]

In Sydney and Hobart
Vanguard, Nicorette, most IRC one-offs lately