Issues/problems with folding propellers

[slawosz]

Hi,
as I am considering 2 blade Gori for my Sadler 25, I am looking for as much info as I can gather. I know that after some time, there is a wear that might prevent propeller to open on low revs etc. I found some opinions that propeller might be prone to loosing even if properly attached, but I don't think its a case. What else should I know?

 

[Concerto]

I have a Gori 2 blade folding propeller on Concerto (Westerly Fulmar) and have had them on boats in the family going back to the 1970's. Never had a problem with any of them.

 

[slawosz]

I have a Gori 2 blade folding propeller on Concerto (Westerly Fulmar) and have had them on boats in the family going back to the 1970's. Never had a problem with any of them.

Only 2 blades? Which engine do you have and what speed can you reach?

 

[[70521]]

I have a Brunton's two blade folding prop no problems with >200 hours on the clock.

EDIT: As @slawosz is asking @Concerto engine size and boat speed. I'll add mine, VP2002 18hp and a boat speed of 5.5 knots. 10.10 mtr boat or 33 feet in old money.

 

[johnalison]

I have no experience with Gori props but I understand that they are on the expensive end of what is available. I wonder if a simpler 2-bladed prop such as the Volvo one might not serve as well. I have had one on my 34 for many years without trouble other than the bush failing, probably due to catching weed.

 

[Tranona]

I had a FlexoFold for 10 years without any problems. Modern folders, particularly 2 bladers are simple, trouble free and open and close readily. Nothing you should know except maybe FlexoFold are the best (Gori are also good)and don't buy one of the very cheap types!

This is worth reading - nothing more recent as it costs a lot to set up, but the results are still valid. yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807

 

[Concerto]

Only 2 blades? Which engine do you have and what speed can you reach?

Yes, only 2 blades. Concerto is fitted with a 28Hp Beta that has a 25Hp shaft rating. With a clean bottom in smooth water I can reach 7 knots. Generally when motoring I am doing about 5 to 5½ knots as this is the most economical fuel consumption. Please remember Concerto is 32ft, not 25ft like your Sadler so you may not achieve quite as much speed due to your shorter waterline length.

Lots of forumites seem to recommend Featherstream propellers, but I thought I should point out this thread from the Westerly Owners site about a big problem with one. It is also being published in the March 2023 issue of PBO.

- Andrew Carter

 

[Tranona]

Probably worth bringing in the 2 or 3 blade debate here because the tests linked to in the previous post give some empirical data to support the theory. 3 blades are better in reverse and better at ultimate bollard pull in forwards which helps maintain way in adverse conditions. This is true of both fixed and folding/feathering props as it essentially a function of blade area. The downside of 3 blades is extra drag when sailing if the blades are fixed but when feathered/folded the number of blades makes little difference. 3 blade are more commonly found on heavier boats as you get more thrust for given diameter but for many lighter displacement boats a 2 blade is fine. my Bavarias displaced 5.6 tonnes with a 30hp Volvo and both comfortably exceeded hull speed and stopped well in reverse. However the same engine fitted to the next size up Bavaria which displaced just over 7 tonnes normally had a 3 blade.

Of course each of those boats had more than enough power to achieve hull speed, but in your situation it is marginal with your 1GM and having a 3 blade (at substantially higher cost!) would offer little benefit over a 2 blade, which will already be a vast improvement over your current prop.

Suggest you talk to Darglow Engineering who sell FlexoFold here and have a vast amount of knowledge and will almost certainly have data on what is best for your boat.

 

[slawosz]

Probably worth bringing in the 2 or 3 blade debate here because the tests linked to in the previous post give some empirical data to support the theory. 3 blades are better in reverse and better at ultimate bollard pull in forwards which helps maintain way in adverse conditions. This is true of both fixed and folding/feathering props as it essentially a function of blade area. The downside of 3 blades is extra drag when sailing if the blades are fixed but when feathered/folded the number of blades makes little difference. 3 blade are more commonly found on heavier boats as you get more thrust for given diameter but for many lighter displacement boats a 2 blade is fine. my Bavarias displaced 5.6 tonnes with a 30hp Volvo and both comfortably exceeded hull speed and stopped well in reverse. However the same engine fitted to the next size up Bavaria which displaced just over 7 tonnes normally had a 3 blade.

Of course each of those boats had more than enough power to achieve hull speed, but in your situation it is marginal with your 1GM and having a 3 blade (at substantially higher cost!) would offer little benefit over a 2 blade, which will already be a vast improvement over your current prop.

Suggest you talk to Darglow Engineering who sell FlexoFold here and have a vast amount of knowledge and will almost certainly have data on what is best for your boat.

I started this topic, as the 2 vs 3 debate is pushing me slightly towards folding propeller - so I would love to learn more about some issues with those. I have quotes from 4 different suppliers mentioned here, FlexoFold is simply more expensive than Gori, and both has excellend reputation.

 

[Never Grumble]

Lots of forumites seem to recommend Featherstream propellers, but I thought I should point out this thread from the Westerly Owners site about a big problem with one. It is also being published in the March 2023 issue of PBO.

I dont have a Westerly so dont think I would be able to see the thread does it say much more than in the PBO article which I read but didn't give any clue on manufacturer

 

[Concerto]

I dont have a Westerly so dont think I would be able to see the thread does it say much more than in the PBO article which I read but didn't give any clue on manufacturer

The WOA forum is open to read. Give it a try. When published in a magazine, the publisher has to be aware of legal restraints. However in a forum, not part of a publisher group, people can talk more freely and ask questions. If you want to do this then it is free to register on the WOA forum and you do not need a Westerly.

 

[Tranona]

I started this topic, as the 2 vs 3 debate is pushing me slightly towards folding propeller - so I would love to learn more about some issues with those. I have quotes from 4 different suppliers mentioned here, FlexoFold is simply more expensive than Gori, and both has excellend reputation.

I should have added that there are no 3 bladed folders in 12" as there is little demand plus they are 3 times the price of 2 blade. So your choice is limited really to just the one size 2 blade. You can get a 3 blade Featherstream which is what Cornish Crabbers fit with a 1GM. That would be an excellent choice but twice the price of a folder and not sure really much advantage on your boat. (no room on a Crabber to fit a folder!)

 

[r_h]

I know that after some time, there is a wear that might prevent propeller to open on low revs etc.

Had to have pins replaced on a two-bladed folding Gori when it was 24 years old and the whole thing replaced after 30 years. As long as you have good anodes I reckon you don't have much to worry about for a long time.

 

[Poecheng]

I started this topic, as the 2 vs 3 debate is pushing me slightly towards folding propeller - so I would love to learn more about some issues with those. I have quotes from 4 different suppliers mentioned here, FlexoFold is simply more expensive than Gori, and both has excellend reputation.

The purpose of the Sadler 25 (I have had 2 x 26s and a 290) is to sail very well and IMHO the appropriate propellor is a folding propellor. There is nothing to be concerned about at all and everything to look forward to; it is a very nice feeling to get the sails trimmed, to turn the engine off, put the gearbox in reverse and to hear the clunk of the prop folding and know it is causing as little drag as possible.

 

[geem]

I started this topic, as the 2 vs 3 debate is pushing me slightly towards folding propeller - so I would love to learn more about some issues with those. I have quotes from 4 different suppliers mentioned here, FlexoFold is simply more expensive than Gori, and both has excellend reputation.

We have a 3 blade Brunton folder. It's 22" and has blades like Mickey Mouses ears. Lots of surface area. Pushes our 18/19t boat along very well. Super fuel efficient at 6 kts cruising speed. We can push in to 2 metre waves at 1500 rpm at 6 kts and 7 kts at 1700rpm. Can't fault tye Brunton prop. Very neat and hydrodynamic when folded done about 2000hrs in it so far.

 

[Never Grumble]

The WOA forum is open to read. Give it a try. When published in a magazine, the publisher has to be aware of legal restraints. However in a forum, not part of a publisher group, people can talk more freely and ask questions. If you want to do this then it is free to register on the WOA forum and you do not need a Westerly.

Many Thanks, I have had a look and been able to read part. The initial post required me to press a read more button but it wont let me see the bit under "the boat already had a rope cutter ... "