Following a drift in this thread (with apologies to Beau about that), I am now following CaptPKilbride suggestion to start a new specific thread on this subject. The debate was about how to avoid overloading mechanical engines, particularly in a boat where for some reason (like trimmable Arneson surface drives) it is relatively easy to run her above normal propeller demand load, also while cruising under the max rated RPM. I wouldn't focus on Arnesons though, because even if they surely are more prone to demand high engine loads compared to shafts, overload conditions can happen also with shafts, regardless of the reason (wrong or dirty props, fouled hull, excess weight onboard, whatever). CaptPKilbride explained me that his way to avoid such risk is, after fitting very accurate digital tachs, to shortly run the boat at WOT in the specific conditions (load, trim, etc) he wants to cruise in. If the boat can reach the rated max RPM, all is well and good. If she can't, he knows there's something to be adjusted. Now, I don't think there's anything wrong in his logic, and I have zero objections to it. But I believe that if the boat is fitted with EGT gauges, that is an equally effective way of spotting an excessive load as soon as it happens, with no need to run the boat at WOT. In fact, AFAIK, the very first consequence of overfueling the engines, at any RPM, is a noticeable and immediate EGT increase. And by immediate, I mean it - in a matter of a few seconds. In other words, as long as EGT remains close to its typical range (which can be easily recorder upon a seatrial in ideal conditions), by definition there is no engine overload to speak of. So, over to you guys, what do you think? Is one approach better than the other (and if so, which and why), or are both good enough? Besides, are you aware of any other tricks, maybe? Of course, I'm happy to be corrected by CaptPKilbride if in the above summary of his approach I misunderstood anything.