Ok, Here's my problem. My renault (not sure on the model) runs great, judging by the stuffing box, I can see that the engine and "transmission" are working. In forward everything spins one direction, including the prop. The best that I can tell. Sometimes it will go, most of the time it won't. Today I got under her and actually saw the prop turning, but she still wont go. I am totally stuck. Like i said I can she it goes into forward AND reverse, but she will not go..... ANYTHING, ANYONE.... HELP!!!
Propulsion
- Thread starter rickardcl
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Since you are not sure what model engine you have, I get the sense that you are new to this boat???? So my thought is, in addition to growth on the prop, maybe the PO put an undersized prop on it ???? But you know it doesn't take a lot of crud on the prop to debilitate its effectiveness. Is you engine rocking alot from the added stress of the growth at moderate RPMs.
Pull out the fuel cutoff (engine stop) button. Put the transmission in forward gear. Go under and see if the prop will turn or is loose .. It should be tight on the shaft and you should be able to turn it by hand in one direction and not the other.. again: BE SURE THE ENGINE STOP is engaged (Pull the decompression lever if that is available), since the engine could start if not, when you pull/push on the prop.. It could be that your prop is loose on the shaft and is not able to transmit power, even though it turns slowly.. If the prop is not loose, then ya may have a slipping transmission.. a reason to call in someone who knows this transmission.. could be as simple as a bad adjustment on the shift lever, or as complex as worn clutch cones.. Good Luck, Rick.
I would suggest that you put the engine in gear and see if you can rotate the prop on the shaft. If you can, then you key in the spline is probably rusted through or missing.
Some IFs and a suggestion.
If the nut holding the prop to the shaft was not tight
and
If there was no key fitted between prop and shaft
then
The result would be exactly as you describe
because
The small amount of friction between prop and shaft would cause it to begin to turn and in forward gear this would push the prop up the taper and it would drive the boat.
but
In reverse it would pull back from the shaft and loose all drive
and
Sometimes it would not drive in either direction.
This seems a long shot but it certainly fits the evidence you describe and would also give the lie to the boat having been maintained by persons who didn't know what they were doing so there could be problems elsewhere as well.
BTW you did not say if the shaft turned in both forward and reverse. If it doesn't then the problem would be in the gearbox, perhaps badly set up or worn cones.
Is the boat new to you? Is this a new problem?
If the nut holding the prop to the shaft was not tight
and
If there was no key fitted between prop and shaft
then
The result would be exactly as you describe
because
The small amount of friction between prop and shaft would cause it to begin to turn and in forward gear this would push the prop up the taper and it would drive the boat.
but
In reverse it would pull back from the shaft and loose all drive
and
Sometimes it would not drive in either direction.
This seems a long shot but it certainly fits the evidence you describe and would also give the lie to the boat having been maintained by persons who didn't know what they were doing so there could be problems elsewhere as well.
BTW you did not say if the shaft turned in both forward and reverse. If it doesn't then the problem would be in the gearbox, perhaps badly set up or worn cones.
Is the boat new to you? Is this a new problem?
I have now confirmed it is an RC8D. I have not yet gotten back in the water to check the keyway. This is a relatively new problem, that is progressively getting worse. This is a new boat to me (dec 09) but I have some limited experience with it, as the PO was my neighbor on the dock for a year. If not one of the keyways, then other than adjustment on the shift lever, my last option will be clutches (ugh). I just dont know the layout of the clutches in this engine, so it seems odd that forward and reverse would go out @ the same time, UNLESS they run off the same clutch. :cussing:
This may be a red herring (sorry Phil) but I once came across a boat which wouldn't do more than one knot in ahead or astern unless one constantly pressed hard on the gear lever.
Eventually I discovered that the Vire gearbox had a deliberate 1/8" fore and aft free movement of the output shaft and when it was put into gear the initial rotation caused by each cone clutch relied on the thrust from the prop to hold it in engagement. A very neat arrangement which works perfectly in ahead and astern because the harder it runs the better the clutch operation - until someone puts on a reverse handed prop!
I realised that the PO had reversed the engine control cables so everything looked normal.
I tried endlessly to explain this to the boat's (lady) owner but she refused to accept my explanation and simply sold the boat on very cheaply.
I often wonder how long it took for the new owner to figure it out.
Eventually I discovered that the Vire gearbox had a deliberate 1/8" fore and aft free movement of the output shaft and when it was put into gear the initial rotation caused by each cone clutch relied on the thrust from the prop to hold it in engagement. A very neat arrangement which works perfectly in ahead and astern because the harder it runs the better the clutch operation - until someone puts on a reverse handed prop!
I realised that the PO had reversed the engine control cables so everything looked normal.
I tried endlessly to explain this to the boat's (lady) owner but she refused to accept my explanation and simply sold the boat on very cheaply.
I often wonder how long it took for the new owner to figure it out.
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