R= Fx2

[Mandurah]

Please may I ask for any expert (or otherwise) guidance.

I have a 2 blade feathering propeller on my C & C 34

At 2200 rpm in forwards we struggle along at around 2.3kn/h.
At the same rpm in reverse we are sprinting along at over 4Kn/h
(At 3000 rpm in forward we get up just under 3kn/h.)

The problem started after the annual service earlier in the year.

I believe the problem is the prop is not opening fully when going from reverse (or neutral) into forward. I have tried increasing the revs more quickly to try to open the prop but is hasn't helped. I've even spent a very cold hour in the drink moving the propellor by hand from forwards to reverse to try freeing it up with not success.

We lifted the boat out again a couple of months ago, checked and adjusted everything, replaced the grease etc. it seemed better for a short while but is getting worse again.

If anybody can offer some other suggestions to try (before we end up having to lift her out again.)

Thanks



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[a64pilot]

Might help if you knew the brand / type of feathering prop.
I'm no expert, but we have members who are

[Mandurah]

Many thanks A64Pilot.

I'll have the info written down somewhere. I'll look it up today and post it ASAP.


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[FSMike]

Lol. Probably absurd, but my first thought was did someone take the props apart and put the blades in backwards?

[FamilyVan]

Originally Posted by FSMike

Lol. Probably absurd, but my first thought was did someone take the props apart and put the blades in backwards?

That's what I was going to suggest but you beat me to it.

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[Mandurah]

Thanks for all the replies.

When we took the boat out again to check and make the adjustments we looked to make sure if the blades were in right. It seemed from the set up that they only fit in one way so we took it to suggest this was correct.

The prop is an Autostream 2 blade. I don't the the model type in my file system here, that's written down and filed somewhere else (apparently!) I'll post this info ASAP.


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[Cheechako]

is this a new boat to you? People have been known to buy the wrong "hand" prop and have the shifter cable backwards.... so the transmission is in reverse when you push the shifter forward but the backwards prop rotation makes the boat go forward anyway.

[HankOnthewater]

Hi Mandurah
Indeed something is wrong now. What was the situation before, I mean did the boat do 5 knots? What kind of engine and gearbox? Engine is revving as you indicated, but is the propshaft? Can a hydraulic gearbox 'slip'? Or can the prop slip on the shaft?
If the prop is slipping (ie keyway missing) one can dive and check that (do I need to say with engine switched off?). A bit cool for diving in winter though.

Rather than getting the boat out of the water, or yourself into it, can you mount a go-pro (or similar) on a stick at a high frame rate and see what is happening? This time with engine running and in gear.

[Mandurah]

Hi Everyone,

Thanks so much for all the comments and suggestions.

I will work though all the suggestions over the next few weeks and see where we go.


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[a64pilot]

I'd try contacting the manufacturer of the prop, they may be better able to help

[Mandurah]

Hello

Just an update on the prop issues.

After much toing and froing, (the toing be a lot slower than the froing) we have finally made some progress.

I tracked down the Propeller Specialist, (that's his name and he is a throughly pleasant chap who also goes by the name of Steve.)

Anyway, Steve visited the sleepily seaside town of Mandurah on Tuesday morning when most civilised people are still tucked up in bed, rapidly assessed the situation, diagnosed a distinct lack of pitch as the issue and promptly made the required adjustments.

Aquila was back in the water after less than an hour in the sling and 2200 rpm now produces 4.5- 5 Kn/h which is fine.

So thanks everyone for all the suggestions and help. We did check the transmission and a bunch of other things from the suggestions, everyone's input was much appreciated. It's great that so many people took the time to respond.

Right, summer is coming. I'm going sailing!


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[Captain Bill]

As the owner of an autostream three bladed prop I can assure you that it is possible to assemble the props improperly and have them work in the manner you have decribed. By making a pitch adjustment one can regain some speed but it won't be as efficient and it will not feather. The fact that the pitch adjustment fixed the problem does not mean your prop is assembled properly. The problem is that the shape of the blades is a bit confusing. The blade has one edge that sticks out past the base perhaps a half inch while the other side is flush with the base. Logic would seem to dictate that the blade edge sticking out past the base should stream to the rear when the blade is feathered. This logical position is in fact 180 degrees wrong. The protruding edge faces forward and the flush edge faces aft.

[Mandurah]

Thanks Captain Bill.

We did check the installation before making the adjustment. The chap Steve is the local agent for Auto Stream props and he was happy it is installed correctly.

Hopefully It will now be ok.


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