Flexofold 3 blade result, first time out today,some observations

[cliffdale]

Boat is a Dufour Classic 36.
We changed from a 2 blade fixed to a 3 blade folding.

First time out today this is what I noticed.

There is a huge difference in thrust going forward, the whoosh seen over the stern of the boat is significantly noticable. Revs were slightly lower for similar boat speed compared to last year.

There is a lot less power going astern. Revs were way up to get the boat moving, I expect this will affect the stopping performance.

The stern prop walk has mostly gone. This is good for me as prop walk mostly worked against what I wanted to do.

I did not notice a delay in the prop kicking in going forward to astern. There were no clunks as sometimes mentioned.

I think the main advantage for us is the blades will fold and the gear box will no longer rotate when sailing.

Also we chose the 3 blades for more thrust in a sea way. This has yet to be tested!

I just thought some of you might be interested as its a popular subject.

Cliff

 

[Stork_III]

You may need to put gear into reverse when sailing to fold the prop otherwise it may spin.

 

[Monique]

^ Ditto.

Nice looking kit too

 

[Tranona]

You may find reverse better, for example when backing out of a berth by putting it into reverse at tickover, then waiting a couple of seconds before revving. That gives the baldes time to open. As you know I have the 2 blade and that technique works for me.

 

[Slowtack]

Is that a small anode inserted at the forward end of the slot which the blade fits into?
Interested if this is the case as my old volvo folding 3-blade only has the main circular saildrive shaft anode and recently the blades are starting to show dezincification discoloration spots.

 

[snowleopard]

I think the main advantage for us is the blades will fold and the gear box will no longer rotate when sailing.

Is this your practical experience or are you assuming it will be the case?

I have 2-blade flex-o-folds and they do rotate while sailing unless I put them in gear. As we have bunks on top of the engines it is annoying to hear the gearbox constantly turning not to mention the wear.

 

[haydude]

Is that a small anode inserted at the forward end of the slot which the blade fits into?
Interested if this is the case as my old volvo folding 3-blade only has the main circular saildrive shaft anode and recently the blades are starting to show dezincification discoloration spots.

As discussed in another post, Volvo Penta propellers are Nichel Aluminium Copper Bronze alloy, therefore it is unlikely that they show dezincfication unless VP are fraudolent and deliver propellers in Zinc Copper Bronze alloy instead.

 

[kyleview]

You may need to put gear into reverse when sailing to fold the prop otherwise it may spin.

You WILL need to put gear into reverse when sailing to fold the prop otherwise it WILL spin - fact from experience.

 

[kyleview]

Is that a small anode inserted at the forward end of the slot which the blade fits into?
Interested if this is the case as my old volvo folding 3-blade only has the main circular saildrive shaft anode and recently the blades are starting to show dezincification discoloration spots.

No - they are nylon type "stops" to reduce the clunk/noise when the blades open. Pretty smart design idea, also have shown no wear after 600+ hours of usage.

I have found no problem in reverse, previous comment re letting open / spin for a few seconds in reverse before applying power is a good tip.

 

[Malo37]

We put a 3 blade Flexofold on our Regina38 to replace the fixed 3 blade this time last year. We have an extra one knot at cruising revs however stopping and manouvering astern requires some planning and stopping distance is at least doubled. When going from ahead to neutral when sailing, it is necessary to stop the shaft from rotating ie put it in reverse for a few seconds, in order to apply the hydrodynamic closing force to the prop. Once the prop has folded the engine can be put back into neutral ready for use.

 

[Boat44]

Interesting post; thanks.

We needed to replace our prop this winter; long story, and were considering the flexifold and varifold.

Ultimately went for the featherstream, as we charter I didn’t want the concerns over reversing as noted, although the forwards benefits would be nice to effectively increase range for same speed.

Cheers

 

[billmacfarlane]

That's good info. I was put back into the water Monday with the exact same new prop but I haven't tried it out yet. Hoping to do it next weekend.

 

[Quandary]

Is that a small anode inserted at the forward end of the slot which the blade fits into?
Interested if this is the case as my old volvo folding 3-blade only has the main circular saildrive shaft anode and recently the blades are starting to show dezincification discoloration spots.

Interesting, Are you sure it is a Volvo? I can not recall a VP three blade folder that did not have the three segment ring anode in a slot in the boss.

 

[snowleopard]

A couple of points worth noting for those considering a folding prop:

Tests in various magazines say the difference in push between 2 and 3 blade flex-o-folds is no more than 5%. The price difference is more like 50%

They do work in reverse, you just need to give it a bit more welly. During my sea trials I had the boat up to 10 knots then gave it full astern. The boat stopped in less than its own length. That was good enough for me

 

[cliffdale]

That's good info. I was put back into the water Monday with the exact same new prop but I haven't tried it out yet. Hoping to do it next weekend.

Let me know how you get on with your prop. Next time I'm out, Ill try the reverse tickover first before applying revs. I hope it makes a difference.

 

[cliffdale]

A couple of points worth noting for those considering a folding prop:

Tests in various magazines say the difference in push between 2 and 3 blade flex-o-folds is no more than 5%. The price difference is more like 50%

They do work in reverse, you just need to give it a bit more welly. During my sea trials I had the boat up to 10 knots then gave it full astern. The boat stopped in less than its own length. That was good enough for me

Yes, I found you need to give a lot more welly in reverse. I think the magazine tests are a bit artificial, a nice flat water marina on a calm day.

I'm hoping the extra expenditure will pay off when punching ahead in a sea way.

Cliff

 

[Slowtack]

Quandary - yes its a volvo product. Apparently the segmental anodes were omitted in earlier models. I looked at trying a system of low drag anodes using self tappers but not sure how to prevent them getting loose as they waste.

 

[Tranona]

Yes, I found you need to give a lot more welly in reverse. I think the magazine tests are a bit artificial, a nice flat water marina on a calm day.

I'm hoping the extra expenditure will pay off when punching ahead in a sea way.

Cliff

Yes, the tests used static thrust as that is the only way you can get consistent comparable results when you are testing a wide range of props. It is not always a good indicator of actual performance as technique has an influence. However, we carried out extensive tests of stopping power and maneouverability on my boat with a standard two blade fixed Volvo prop and a number of other props including the FlexoFold 2 blade and there was virtually no difference between the standard and the folder with the exception of the slight delay in reverse.