Joe,
Effectiveness and Hit Rates. No single definitive count of total skip-bombing missions exists in readily accessible unit histories or after-action reports available online
General improvement over high-altitude bombing
Fifth Air Force evaluations credit skip bombing with increasing ship-attack hit rates from approximately 1% with high-altitude bombing to more than 70% under proper skip-bombing conditions.
The bomb may hit the target and explode or sink and then explode doing more damage. Delay was 3-5 seconds.
Battle of the Bismarck Sea examples
During the Bismarck Sea action:
High-altitude and conventional attacks (105 sorties) dropped 387 bombs for about 7.5 % claimed hit ratio.
Skip/mast-height attacks (56 sorties; 137 bombs) claimed 48 hits — roughly 35 % hit probability per bomb.
Individual pilot-reported practice accuracy
Individual skip-bombing practice runs (e.g., Captain Kenneth McCullar) recorded hit rates up to 60% or higher in trials before combat.
Operational effectiveness
In the Bismarck Sea convoy engagement, Allied air forces sank all seven Japanese transports and four destroyers with relatively low bomber losses, a direct result of combined skip-bombing and strafing tactics.
More details: link
Air & Space magazine: link
Wolfhag
