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Old 04-01-2017, 10:04   #1
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Can a folding prop be re-pitched?

If I buy a used Martec or Gori folding prop and it doesnt turn out right, can they be re-pitched? I have a call into a prop shop but have not gotten a reply. There are so many variables involved in props that getting it right the first time is unlikely, so a re-pitch may be needed. Advice needed! Thanks, ____Grant.
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Old 05-01-2017, 04:56   #2
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Re: Can a folding prop be re-pitched?

With fixed pitch props, you can reduce the pitch a small amout by cropping the diameter (taking material off the tips). This sort of adjustment is fairly routine on larger high speed craft where it is very difficult to get the pitch exactly right by design. Its a professional job for a propeller shop and the whole thing needs to be re-balanced afterwards. It is probably only cost effective for large high speed craft where the props are manufactured to high accuracy and hence high cost.
In principle you could do the same for a folder, although you may well find it would be more expensive than just ordering replacement blades from the manufacturer. It could upset the unfolding in reverse of course, depending on how much material you remove
As for increasing pitch, the only thing I can think of is welding additional material on to increase diameter and re-fairing etc. Again, bespoke engineering like that would be expensive at yacht scale and probably not worth it.
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Old 05-01-2017, 04:58   #3
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Re: Can a folding prop be re-pitched?

Yes, can be repitched. By getting replacement blades with the appropriate pitch from the manufacturer and installing them in the hub.
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Old 05-01-2017, 05:28   #4
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Re: Can a folding prop be re-pitched?

If you havent bought it yet, perhaps consider a feathering variable pitch prop instead of a folding.

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Old 05-01-2017, 06:06   #5
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Re: Can a folding prop be re-pitched?

Consider a Maxi Prop, a feathering prop, if you can find a used on in the size you need. You can dial in whatever pitch you want when assembling. Won't have to buy new blades (expensive).
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Old 05-01-2017, 06:39   #6
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Re: Can a folding prop be re-pitched?

Re-pitching fixed blade propellers is very common, it's done all the time by propeller shops, but it does not involve removing material from the blade tips. Re-pitching the blades is done by clamping the prop to a table and twisting or pounding the blade to a different angle to the hub. The new pitch is confirmed with pitch blocks or measuring machines.

Removing diameter by trimming the blade tip is also done sometimes to match prop load to engine power, but in the case of displacement vessel speeds it is normally best to maintain as much diameter as possible.

Whether a folding prop can be re-pitched probably depends on the technical capabilities of the individual shop. Securing the entire prop or the individual blades might be difficult due to the small hub and lack of a secure attachment point.

As mentioned by others a better plan might be to check with the manufacturer for re-pitching or new blades.

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Old 05-01-2017, 07:43   #7
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Re: Can a folding prop be re-pitched?

I still havent heard back from the prop shop, but I may lean toward a MAX Prop or some other feathering prop. There are still a lot of things to decide on, so I am not in a hurry. Thanks Guys. ____Grant.
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Old 05-01-2017, 08:15   #8
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Re: Can a folding prop be re-pitched?

Huge price difference between repitching and a Max prop!! repitching (I just had my 17x9 repitched to 17x11) costs under $300 a Max prop...closer to $3k that's a lot of boat units!
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Old 05-01-2017, 09:45   #9
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Re: Can a folding prop be re-pitched?

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Originally Posted by gjordan View Post
I still havent heard back from the prop shop, ................. .
Call a different prop shop.
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Old 05-01-2017, 15:53   #10
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Re: Can a folding prop be re-pitched?

I just got in and found a message from the prop shop and he said that yes they can re-pitch a Gori or Martec, but not by large amounts. No mention of price or anything else, but at least I know it is doable. The shop is Bay Propeller which I think is in Alameda. Its good to know. _____Grant.
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Old 05-01-2017, 18:50   #11
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Re: Can a folding prop be re-pitched?

I purchased a three blade stainless steel feathering propeller from Autostream. All you need to adjust the pitch is a spanner, alan key and big lungs. The spanner and alan key are provided by Autostream.

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Old 05-01-2017, 19:36   #12
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Re: Can a folding prop be re-pitched?

Fore and aft, if you dont mind my asking, How much did you pay for your Autostream? Grant.
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Old 05-01-2017, 19:44   #13
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Re: Can a folding prop be re-pitched?

Bay Propeller is a great shop, they do good work.

Yes, you can have a Martec folding prop re-pitched within a relatively narrow band; you can send it to Martec in Long Beach and they can do the work for you.
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Old 05-01-2017, 22:52   #14
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Re: Can a folding prop be re-pitched?

It was around $3000 for a Autostream feathering propeller. Worth every cent I think. That was for a propeller to match a 20hp Yanmar.
I have adjusted the pitch a number of times and have almost got it right in the sweet spot.
We have twin rudders so at slow speeds Ninky can be hard to handle around the marina. This propeller is excellent in reverse, it is almost the same pitch in forward as in reverse and has really helped when berthing.

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Old 05-01-2017, 23:16   #15
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Re: Can a folding prop be re-pitched?

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It was around $3000 for a Autostream feathering propeller
I assume that's Aussie dollars, equal to around 22-2300 USD these days.

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