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Simon Currin
Administrator
Posts: 672


9/12/2017
Simon Currin
Administrator
Posts: 672
Dick,
I moved the thread as suggested. I doubt though that Janice and Andy will be able to reply for sometime as they are overwintering afloat near Maniitsoq, west Greenland. A place not known for internet connectivity.
Simon
Dick wrote:
Am I correct that this stream would be more easily found and make more sense under engines? Dick


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Simon Currin
S/V Shimshal simon@medex.org.uk
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Dick
Posts: 219


8/20/2017
Dick
Posts: 219
Am I correct that this stream would be more easily found and make more sense under engines? Dick

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Dick Stevenson, s/v Alchemy
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Dick
Posts: 219


8/20/2017
Dick
Posts: 219
Hi Janice,
We were sorry not to cross paths in Iceland as we heard you were about. Greenland introduced us to lots of ice, but (probably luckily) none found its way to the prop and we are now in Canada.
I suspect a fixed prop is wise, especially the NW passage as that is all/mostly motoring.
A couple of comments though:
For everyday life a Max prop is astoundingly robust. I caught a fish pot between blade and hull at cruising speed which stopped the prop cold and also stopped the engine. The blade was buried hard into the float and needed effort to extricate, but the prop looked fine as far as I could see underwater. I then worried that it would have been knocked out of balance. It was fine. I was surprised and impressed.
New style (years old now) Max props are easily pitch adjustable underwater.
As to the Max prop being damaged by cavitation because it is over-pitched, I am not so sure. I over pitch a bit more than slightly and have for years and have suffered no cavitation problems.. Could you, perhaps, have been motor-sailing? Cavitation can occur (I believe) when boat speed produced by the sails exceeds the speed generated by the prop. The prop then has no “grip” on the water and bad things unfold.
BTW, what type/model etc. prop puller did you use to get your prop off? This can be a difficult task on shore, let alone underwater: good on you.
My best, Dick Stevenson, s/v Alchemy

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Dick Stevenson, s/v Alchemy
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Janice FENNYMORE-WHITE
Posts: 5


7/31/2017
Well just to cufuffal you all, we have just gone back to a fixed prop on Destiny, the reason being that our Max Prop was slightly overpitched the last time we hauled out in Scotland in an effort to reduce fuel consumption, but whilst doing so we gained bad cavitation in a rough sea. We have not had the opportunity to reverse the procedure whilst in Iceland- the country has no travel lift and the cranes cost a fortune. Our solution has been to remove the prop by diving, something I had not wanted to do as I felt the risk of losing a part was too great (I would never consider even attempting to adjust the pitch underwater). But remove it I did with a large plastic box beneath it in very shallow water, I then fitted our new 23"x16 fixed prop from Clements Engineering. This is a relatively easy job underwater and for that reason I would recommend high lats or remote sailors to carry one.

We are now ready for meeting some ice this summer season in East Greenland and the North West Passage next year. The fixed prop is stronger than a Max Prop and about 1/5 of the price should we damage it.

Yes we have noticed that in light airs we are slower, but once over 5kts I think that we are doing the same speed, the spinning prop makes virtually no noise ( Our PRM greabox can trail in gear) and I think that handling under power is improved. We have far more thrust for the same rpm, we can stop the vessel far quicker and the prop walk is great for tight turns, admittedly useful only to Starboard.

The proof will be when we come to haul or in Alaska if we refit the Max Prop....
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Dick
Posts: 219


6/20/2017
Dick
Posts: 219
Hi Daria,
It is good to know that Max Prop was so actively concerned and helpful. That means a lot to me in a company. In 3 Max props over the decades, I have only dealt with their distributors, who have also been excellent.
Greasing underwater sounds like a silly thing to do, but I also needed to do so in the Bahamas one season, so it is good to spread around the word that this is possible.
My best, Dick Stevenson, s/v Alchemy

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Dick Stevenson, s/v Alchemy
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Daria Blackwell
Posts: 706


6/19/2017
Daria Blackwell
Posts: 706
As another follow-up note to our new propeller saga.... Alex had taken the throttle cable out and greased it. When he reinstalled it, he decided to start the engine and put it in gear to make sure it worked. The throttle worked but the prop wouldn't spin or feather. Alex contacted the manufacturer who said there wasn't enough grease in the prop. Meanwhile, the instructions to the yard delivered with the propeller were that it was ready to install, no additional grease needed. After several calls back and forth and learning the characteristics of grease required (broad temp range), Alex had to find suitable grease, dive on the prop, remove two tiny set screws underwater, fill with grease and reinsert screws. When he removed the screws, lots of air bubbles came out indicating it had not been sufficiently greased. It worked! Had he not serviced the throttle cable, we may not have known and it could have seized while underway.

Moral of the story, check grease while you can. BTW, the follow up by the MaxProp folks was impressive. They called multiple times to find out how successful we were at each stage, providing guidance all the way.

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Daria Blackwell - Rear Commodore, PR Officer, Editor OCC Digital Comms & Port Officer, West of Ireland s/v Aleria http://www.coastalboating.net
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Dick
Posts: 219


6/16/2017
Dick
Posts: 219
Hi James,
One of them pluses of the Forum is as an archive for information. It would be great if you can report your final decision, the research sources that were helpful and your thinking that lead to the decision you made.
Thanks, Dick Stevenson, s/v Alchemy

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Dick Stevenson, s/v Alchemy
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Threeships
Posts: 6


6/2/2017
Threeships
Posts: 6
Hi James
Chris and I have a 19" Three blade feathering prop on our Gitana 43 from hdraline based in Sydney Australia.
It gave us more speed in both forward and reverse gears, saved us almost 1/2 knot on drag over the old 19" fixed blade and has been trouble free for 5 years now.
Also worth noting is that as we have enough room for a shaft anode we put a plastic cutout between the prop and its shaped nose anode to prevent it working and still gain the benefit of a smooth nose.This was because the anodes were bespoke, expensive and wore quickly at the Alan key fixing bolts. We have had no adverse corrosion problems since doing this.
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Ginger
Posts: 12


5/29/2017
Ginger
Posts: 12
Hi Daria,
Nonplussed is such a great word. I look forward to hearing about your researches. Ours is 4 years old and I had not heard about any claim of “no prop walk” and it would not be a selling point for me. I over-pitch a little and will do a little more. I had not heard about it affecting prop walk, so that may contribute some to what I experience.
I would call Chris at Darglow. I would except I am no longer in the UK. I found him very knowledgeable about props and especially Max Props.
My best, Dick
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Daria Blackwell
Posts: 706


5/29/2017
Daria Blackwell
Posts: 706
Dick,
We are just as nonplussed as you. We had major prop walk on our old prop -- which was an older MaxProp design and much smaller blade area than the new one. We tried everything in testing this new one. No matter how hard or fast we pushed it in reverse, it did not swing the stern. I do not have the literature at home as it's on the boat, but it does say that the new design eliminates prop walk. In a few days, I'll post their notes here for reference.

There is a note on another Forum that people overpitch their MaxProp to create prop walk -- apparently the Dashews used that effectively instead of a bow thruster on one of their boats.

BTW, we also found that in order for it to feather after shutting the engine down, we had to keep the engine in forward gear at fairly high rpms or it didn't work.

Daria

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Daria Blackwell - Rear Commodore, PR Officer, Editor OCC Digital Comms & Port Officer, West of Ireland s/v Aleria http://www.coastalboating.net
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Ginger
Posts: 12


5/29/2017
Ginger
Posts: 12
Hi Daria and all,
I find your report somewhat curious. I am on my 4th Max-prop over 2 boats and a number of decades and I have found usable prop walk on all of them. I do admit, that it has been too long to remember whether my fixed prop had more prop walk, but I am clear that I have enough for reasonable maneuvering in marinas (without a bow thruster).
I will attest that the vastly increased power in reverse over fixed props (the blades feather so thrust in reverse equals thrust in forward) is a terrific benefit in maneuvering in tight spaces.
It may be that one needs to be more aggressive with the throttle (from a stand-still position or when going from reverse to forward or vice versa) to maximize prop walk in tight places.
Our latest MaxProp is a four bladed one of a larger diameter and quite a bit more blade acreage, bought so we have more thrust in adverse conditions. This is our third season with this prop and we are very happy.
BTW, the go-to book on props is, appropriately, called the Propeller Handbook (or something like that) by Dave Gerr. It is superb, and maybe a bit technical.
My best, Dick Stevenson, s/v Alchemy
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Ginger
Posts: 12


5/29/2017
Ginger
Posts: 12
DariaBlackwell wrote:
We just fitted a new feathering prop (MaxProp) and were amazed at how much better propulsion we have in forward gear and dismayed that we now have no prop walk in reverse. In reading the literature that came with the prop, we learned that the new props do not have significant prop walk, which we used very effectively to maneuver in tight spaces in marinas before. :(
edited by DariaBlackwell on 5/27/2017
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Daria Blackwell
Posts: 706


5/29/2017
Daria Blackwell
Posts: 706
Just found this article on prop comparisons. http://www.yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807 Perhaps that will give you some ideas.

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Daria Blackwell - Rear Commodore, PR Officer, Editor OCC Digital Comms & Port Officer, West of Ireland s/v Aleria http://www.coastalboating.net
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Daria Blackwell
Posts: 706


5/27/2017
Daria Blackwell
Posts: 706
We just fitted a new feathering prop (MaxProp) and were amazed at how much better propulsion we have in forward gear and dismayed that we now have no prop walk in reverse. In reading the literature that came with the prop, we learned that the new props do not have significant prop walk, which we used very effectively to maneuver in tight spaces in marinas before. :(
edited by DariaBlackwell on 5/27/2017

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Daria Blackwell - Rear Commodore, PR Officer, Editor OCC Digital Comms & Port Officer, West of Ireland s/v Aleria http://www.coastalboating.net
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Dick
Posts: 219


5/15/2017
Dick
Posts: 219
Hi James,

Complex question(s).

First you must answer for yourself some of the following in no particular order:

Weight of your boat?

Do you race?

Do you run your boat like a motor sailor (turn on your engine below 4-5 knots) or do you like to sail in light airs?

How much thrust do you want from your drive train?

There are fixed and folding, but some of the best props are feathering?

How much do you need reverse and prop walk for maneuvering around marinas?

Then you can go to a prop expert like Chris at Darglow (google Darglow in UK) who is very knowledgably and was very helpful when I addressed some of the same questions a few years ago.

My best, Dick Stevenson, s/v Alchemy
edited by 0 on 26/05/2017

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Dick Stevenson, s/v Alchemy
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archive
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5/14/2017
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hold that thought as they say!
i 'll head to good old Facebook and pop the question.
thanks and good luck with the migration to the new server and website.
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Simon Currin
Administrator
Posts: 672


5/14/2017
Simon Currin
Administrator
Posts: 672
James sorry can 't advise on props but I need to let you know that the Forum will be taken off line from tomorrow (Monday) whilst it is migrated to our new website. So folk won 't be able to respond from tomorrow.
Simon

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Simon Currin
S/V Shimshal simon@medex.org.uk
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archive
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5/14/2017
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Posts: 0
Hello all.
I recently bought a new Beta Marine 35 saildrive engine.
i am now in need of a new propeller.
I have a 43ft 'Gitana 43 ' sailboat.
There seem as many propellers as there are opinions on propellers.
However I am seeking your opinions now!
questions, 2 or 3 blade
fixed or folding (almost certainly folding)
supplier?
Type/pitch?
Thoughts on how to come up with the answers to the above questions also very welcome!
Many thanks in advance to you all.
Fair winds.
James
edited by 0 on 26/05/2017
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