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Old 24-09-2018, 14:31   #16
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Re: Absolutely couldnít get out of the slip today

Lots of good scoops.

Kind of ran into a double problem, maybe a three bagger, backing out a slip, the vessel was Ericson/Olsen 34, narrow fairway, lots of boats in slips on both sides.

I tried to use backing and filling, and zip was happening, Could not maneuver , and the added attraction was as strong current and a wind acting on the bow to also keep it from turning to windward to depart.

The vessel was not answering to backing and filling, but I was able to back far enough astern, plus getting set down , that I put part of the stern into an empty slip. lucked out ! Ten added strong power with the helm hard over, and with the discharge current against the rudder, we swung her bow around enough to motor slowly out of the narrow fairway.


The vessel was a small private sort of a sailing club, and the owner was big into racing and had a folding prop....

I like the ideas put forth here, as well as a fouled prop fix it senario. Great ideas, in addition to the procedures that others have posted to fix the problem. Still learning everyday from the CF forum responses.
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Old 25-09-2018, 08:28   #17
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Re: Absolutely couldnít get out of the slip today

Diving on your boat to check everything might be a good idea. Here's why:

One day way back when I had a Cal29 with Atomic 4 we were approaching finish line of a race in about 2nd place when suddenly the rest of the fleet just sailed right by us. We just couldn't make the boat move. After we finally crossed the line in last place we motored home (about 3 miles) but couldn't do more than about 3 knots. Everything sounded and felt fine with motor, shaft and prop. MYSTERY!

After pulling into the slip and tying up, a HUGE piece of cardboard came floating up from under the bow just forward of the keel. It was smeared with a lot of our blue bottom paint.
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Old 25-09-2018, 12:05   #18
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Absolutely couldnít get out of the slip today

Quote:
Originally Posted by GordMay View Post
Indeed.
In reverse, the A4 tail shaft rotates opposite to the crankshaft, but at only 75% of engine RPM (1.33:1). The reverse speed of your prop is only 75% of the forward speed for the same engine rpm's, which is why you have to use a lot higher RPM's in reverse to accomplish a similar response from the prop, and why backing the boat is so much harder to accomplish for a given engine speed.


Add to that a prop is very inefficient when turned backwards, so itís likely that you get less than half the thrust in reverse
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Old 30-09-2018, 17:42   #19
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Re: Absolutely couldnít get out of the slip today

I had the same issue on an Islander 28 with a folding prop. Two issues: the prop I had didn't have much "bite" in reverse, and with time I learned how to adjust the clutches so the reverse clutch was actually grabbing in reverse. Unless they are adjusted properly they will slip, which makes it work terribly, in addition to the 75% ratio.

I would experience this when I'd be coming into the slip, I'd put it in reverse, and give it 90% throttle, then count to 5, and it would only slightly begin to slow. It made docking too stressful.

Here's a comparison. On my new boat, Hunter 420, almost three times the weight, with a Maxi-Prop, I put it in reverse, give it a bit of throttle (30%?) and it stops the boat quickly. When my wife is at the helm, if she leaves it in reverse too long (extra second or two), the boat will begin to back out of the slip!
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Old 30-09-2018, 22:19   #20
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Re: Absolutely couldnít get out of the slip today

3blade fixed prop normally pulls well in reverse. Anyway went back a couple of days later nothing on the prop and it worked as expected.

I think you were right that something was wrapped on the prop and if came off. Coupled with the wind from the right angle kept me pinned.
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Old 30-09-2018, 23:19   #21
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Re: Absolutely couldnít get out of the slip today

Our 1960s Atomic 4, 2-prop in reverse on a Columbia Defender (28.5-foot, 4-ton sloop) never had insufficient power.
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Old 01-10-2018, 04:38   #22
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Absolutely couldnít get out of the slip today

My boat actually goes FORWARD when in reverse if the prop gets fouled. I kid you not! Iíve had the boat pulling forwards against the springer while in reverse. It was very surprising.


Itís to do with the prop aperture at the back of the keel. Basically, once the prop fouls it produces more centrifugal displacement than forward displacement, and the prop aperture directs that centrifugal displacement aft resulting in forward thrust.

So check for fouling. It might explain a few things.
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