ADMIN NOTE: This thread was split from another discussion. You would more than likely rip the engines off their mounts or at least break some of the mounts and drive line gear. Unless they had some sort of "Drivesavers". And in that case they would sheer and you'd just stop dead in the water. Or, as has been mentioned by someone else, the electronic controls would not let the engines go from full forward speed into full reverse instantaneously. But I don't see how the transom would come apart in any case.