Its a bit counter intuitive but it shouldn't be to sailors who are well used to the difference in apparent wind speed when we turn into the wind and find it blowing a gale. But in practice we all put a bit more power on when pushing the tide out of [at least mild] frustration at the lack of progress, so all our experience is "going against the tide = the sound of more RPM". And then there's the usually true "fighting against something takes more effort".
The governor sets the desired revs. Sometimes the engine can't meet that target for one reason or another.
It would be easier to simply state that you do not know the answer either.Wow! Some real BS been spoken on this forum.
Good luck coming up with your crazy answers?
That sounds plausible but, at the speeds we're talking about, I wonder whether the difference between an 8 knot and a 2 knot headwind would be noticeable on the rev counter?
I doubt it; although the explanation is theoretically true on paper, if someone did the aerodynamics calculations the effects would be extremely tiny indeed.
Whether its noticeable would depend on the amount of RPM already running. Easier to picture if you think about how many RPM would the engine need to run to stop the boat being blown downwind when there is a 6 knot wind acting on it? Its obviously not no RPM. We've moved well away from the OP question though:
So service the engine & the RPM drop would possibly not happen because the governor will compensate & get it up to 3500 again
No good argument has ever ended with "End of (discussion)". In this case we know, from the OP's observation, that tide has an effect, so all that remains is to work out what the mechanism is.
As discussed previously in the thread, tide has no direct effect on the boat. In a classroom that's sufficient, but out in the real world you need to go further. I explained earlier how the bow wave would be affected, and others have explained how wind effect would be different in each direction. As such we can say with certainty that while tide might not have a direct effect on the boat, it most certainly does have an effect on the energy required for the boat to travel at a given speed through the water.
Maybe. Unless the governor includes an "integral" component - ie one which steady increases the fuel supply for a constant lack of revs - applying a load will always slow down the engine a bit, because if it hit target revs the controller would see no need to increase the fuel supply.
Does that apply even at full throttle as in the OP? Full throttle is wide open fuel supply isn't it? Unless the system is designed to hold back a bit so that there is some more to give even at full throttle
Which is what I said in post #3.....
It would not be wide open fuel supply. My digger recently went into a massive "race" mode & started to rev like h..ll. the driver shoved some rags into the air intake to stop it because the usual stop sequence did not work. The governor is definitely there to stop over revving & the engine will give more revs if allowed & not held back by load etc.
Unlikely until load starts to cause engine speed to fall off. The giverner will continue to open to maintain the pre-set RPM, but once it is fully open, the engine speed will start to drop as the load increases. As RPM falls off so the turbo boost will reduce, compounding the effect as the engine begins to labour.
If the propeller power curve is matched with engine power at max rpm = 3500, an increase in resistance would tilt upwards the propeller power curve which would then cross the engine power at a lower rpm; in other words the propeller would need more power at those given rpm which the engine is not able to provide --> lower rpm.