For me, the crucial question of Sealion is not whether the Royal Navy could have defeated the Channel crossing (which I believe they comprehensively would have, purely on weight on numbers) but the logistics of the whole operation.
A German light infantry division consumed around 150-200 tonnes of supplies per day and around 400 tons while in heavy combat. A motorised/mechanised division consumed around 300 tons per day, a German armoured division consumed around 300 to 350 tons of supplies. An armoured division could consume up to 700 tons per day if it was in heavy combat.
For the Germans to supply the nine infantry and 2 airborne divisions put across in the first wave they have to land somewhere between 2200 tons per day (assuming 200 tons per day for light combat) and 4400 tons per day (assuming 400 tons per day for heavy combat).
In their anti-invasion preparations, the British thought that the Germans would have to bring across around 3300 tons per day, a round figure of 300 tons per division.
The port capacity in the Sealion invasion area was around 1400 tons per day, when at full capacity. The British plans were to wreck the port facilities in the event of a landing, which was expected to have the effect of cutting capacity to around 150 tons per week (one twentieth of estimated supply needed) in the first week, increasing to about 800 tons by the end of the second week.
Even if the German army achieves a coup de main and captures the port facilities intact (a highly unlikely scenario), it is still required to land somewhere close to 1900 tons (assuming the mean figure of 3300 tons per day) over open beaches without port facilities. Without the British Army, Royal Air Force or Royal Navy interfering. Or the weather.
To think Sealion has a reasonable chance of success, even with Fighter Command reduced to almost nothing, is wilfull denial of the evidence of the highest order.
