Profitseer,
this is an interesting approach, but even if you are right 50 % of the time about the global daily market direction, you will most probably ends up losing money with this method because, at some times, the trailing stop during market congestion period will forbid you to reach your profit target. You only considered the "good" impact of the trailing stop on potential losers, but didn't mention its potentially "bad" impact on your existing 50% winning trades...
Here is a clear example to illustrate that issue :
Lets say first that you initiate your trades at the day session open having as possible exits :
1) a profit target of 6 pt
2) an initial stop loss of 6 pt
and that your market direction assumption is right 50% of the time
We will then assume (for simplification purpose) that guessing right 50% of the time means :
1) you exit 50% of the time on your profit target
2) you hit 50 % of the time your stop loss
So we have defined a REFERENCE system which is a breakeven one (before commissions)
Starting from this situation, it is true to say that replacing the initial stop by a trailing stop will improve the profitability of the system, but ONLY IF there are no intraday retracements bigger than 6 points !!!
Indeed, as you mentioned, if a trade is going in your direction, but only by 2 point before going against you, a trailing stop will transform this - 6 pt loser into a - 4 pt loser.
a) The "gain" versus the reference system is 2 point
However, let's consider one of your previous winning trade (ie + 6 pt) but which had the following ongoing PL history : up first (+4) then retrace down til -3 before finishing at + 6. With the trailing stop in place, you would have exited the trade at -2 and not + 6
b) The "loss" versus the reference system is 8 pt
Even if a 6 pt + retracement against the daily direction (that you correctly guessed) should happen less frequently than a 6 pt - move (when your assumption was not correct), this is hurting more the stat of your system because of course, the minimum loss (vs reference system) in case b) is 6 point while what your maximum gain in case a) is by definition less than 6 points....
Conclusion : in the case of an equidistant trailing stop daytrading strategies, to make money, you should be correct more than 50 % of the time, AND, know that
=> for your 50% of winners, your target of 6 point will be reached with an "intra-trade" drawdown of less than 6 point.....
=> or the PL improvement induced by the trailing stop on your losers will be higher than the loss induced by you former winners transformed into losers (because they needed to go thru a 6 pt + retracement before reaching their target)...
Eddy