Loss of thrust, no loss of RPM, sudden

[smp]

Hi all. I've been motoring, motor sailing and sailing across Lake Ontario the past three days and all has been well with the A4. I had put a new coil, wires, plugs, distro cap, rotor, points and condenser, racor filter, polishing filter and all fuel lines .. all over the past year (not all at once). The motor has always run good and after the ignition system refresh which is what happened before this trip it's been running really well.

Today however ... motoring along at 5.5 knots which is my "good mileage" speed there was a stutter and it sounded liked the rpms dropped a bit. Upping the throttle resulted in higher revs but not a lot more thrust. I couldn't get it over 4 knots without really opening it up and I didn't want to do that not knowing what was wrong.

We nursed the boat to our destination, motorsailing in light air doing about 4 knots with the headsail out. When we got to the dock I banged it into reverse and gave it a nice jab of throttle and it suddenly felt like it really dug in as per usual. But now I'm tied up and it's been a long day of sailing and I wasn't leaving the dock again tonight.

What are the chances that this is just a fouled prop? Fishing net or something? This was my "it's usually a simple thing" hypothesis that I worked out before getting to the dock. Giving it that burst of high RPM reverse flung whatever was on there off maybe?

please oh please something simple.
I'm just hoping someone else has had this experience. Again, engine revs as usual, sounds as usual .. just no power.

Oh, to rule out a carb problem, which I'm skeptical on anyway because there is no change in RPM, no bogging, choking, hesitation etc I pulled out the choke slowly to see what would happen .. what I would expect happened, the exhaust smelled strongly of gasoline and the motor threatened to stall out. So, no carb problem likely?

[romantic comedy]

As I was reading, I thought the same thing. Fouled prop

Either that, or you hit some heavy water.

[Bingy]

If water is warm enough go for a swim to confirm prop is clear.:-)
:-

[Mo]

Sounds like you picked up something on the prop...if the engine is running smoothly as you describe that's likely the culprit...just some floating weeds is enough to make a difference.

[ndutton]

If a fouled prop was the case, reverse operation may have cleared it.

[Dave Neptune]

MASK wet not you

I agree, don't get wet! Stick the mask on and just dunk yer head in for a look if the water is clear. If you see anything on the prop get wet or call a diver.

I sail in an area of lots of kelp, so when running at night I don't always see a ball of kelp in the water. When I hit one it is just as you describe, however the first thing I do is slow and then go back and for the between forward and neutral applying a bit of throttle when in forward and reverse!!! Then I am on my way. Sometimes it takes a while to completely clear if it is a tougher variety of seaweed. If you got a net or something similar you may need to cut it loose.

Dave Neptune

[edwardc]

Another +1 on a fouled prop. The exact same thing happened to us last year in the middle of a 2-week trip. It was sea grass in our case. Backing cleared some of it, but I had to dive on the prop to get it all.

I agree, don't get wet! Stick the mask on and just dunk yer head in for a look if the water is clear. ...

That might work for you west coast guys, but here in the muddy Chesapeake, on a good day our visibility is only about 6 inches!

[smp]

Thanks all. That blast in reverse cleared it last night getting into that slip. I had the thought while nursing the boat along last night but have never dealt with a fouled prop and imagined a piece of rope or something just waiting to seize the shaft. No problem! Didn't even get wet enjoying a lovely anchorage in the Thousand Islands right now. Cheers