Radiche folding prop

[KAM]

Anyone out there have any experience with these. If so do you have any numbers such as cruising speed, revs, power boat size etc.

 

[HTS]

I have one fitted to a Hustler 30 long keel. It is driven by a Beta 20 (overpowered in my opinion) via a Sillette Sonic sail drive. It is a 2 bladed folding prop I think 15 x 9 but cannot be certain. It came with the boat.
I cannot achieve full revs at WOT. That said I have motored into horrendous seas for 24 hrs without any worries

Down side is that the prop is bronze and the sleeve which is bonded to the prop hub is Aluminium. The prop shaft is SS and the leg is Naval Bronze so the internal hub corrodes and I imagine I will have to replace the hub next year. There is an anode on the leg but it seems to protect the leg.

I reckon its a reasonable compromise but if I was starting from scratch I'd at least do a bit more research.

Bits are available and the dealer is Sillette in Cornwall who are excellent.

Hope this helps

 

[Dipper]

I have had one fitted to my Volvo 2001 (9HP) + 120S saildrive on my Seawolf 26 for around 23 years. It made a big difference to sailing performance - both speed and pointing ability. I get the impression it is not quite as 'grippy' as my fixed Volvo 2- bladed prop and it seems to struggle a bit more in rough seas under engine alone (but it's windy then isn't it so I could sail). I don't have a rev counter so can't comment on that.

The blades on the Radice saildrive version are very heavy so fling out nicely in reverse. In flat water, I've experimented with stopping distance. Coasting along at 4 knots in neutral then putting the engine into full reverse, I can stop in my own boatlength - 26ft. Ignore those that say reverse is a problem because in reverse the blades are forced open not closed. The only difficulty is if the boat is still going forward and the engine is in put into reverse in low revs, then the blades may struggle to open. A quick burst of power soon sorts that out.

Watch out for the grub screws with hexagonal inserts as the inserts can work loose leaving you with a grub screw that is difficult to remove. I changed mine to sawn off machine bolts with a slot cut in the top for a screwdriver.

All the above assumes that the design hasn't changed and that you are looking at the saildrive propeller.

 

[alahol2]

Ignore those that say reverse is a problem because in reverse the blades are forced open not closed.

You may want to think that one through. When the engine goes into reverse it is the blades of the prop that are trying to pull the boat through the water. The act of pulling has the effect of trying to close the blades. As you rightly say increased revs will counteract the 'closing' effect.
There's a video on youtube that shows the effect.

I sailed with a shaft mounted Radice folder for several years (28ft, 13HP) and found it perfectly adequate. Noticeable difference from a fixed prop when sailing.

 

[Concerto]

I have plenty of experience with Gori folding propellers and agree with alahol2's comments. I first used one in the early 1970's and never had a problem with a standard folding Gori. I fitted one to my Fulmar and the benefits of faster sailing and excellent performance under power. Speak to Glen at Sillette about the difference between the Radice and Gori, he sells both.

 

[KAM]

Here is my prop in forward and reverse. As you can see in reverse the prop adopts a cone angle reducing thrust. Never had a problem with reverse performance though but the forwards performance seems to be much poorer than one would expect when comparing with similar boats and prop sizes. I seem to need about 18Kw and 916 rpm at the prop to cruise at 5kts on a 10m fin keeler. It's a 16 x 13 prop. Several similar performance boats boats claim to be able to cruise a knot faster at 13kw with various different engine gearbox and prop combinations. Some with the same size prop.

Anyone got any real number for drag savings at certain speeds. I am skeptical about some of the numbers being quoted.

 

[Dipper]

You may want to think that one through. When the engine goes into reverse it is the blades of the prop that are trying to pull the boat through the water. The act of pulling has the effect of trying to close the blades. As you rightly say increased revs will counteract the 'closing' effect.
There's a video on youtube that shows the effect.

I have thought it through and you are right! My mistake and thanks for the correction. In my defence, if the engine is put in neutral whilst the boat is still moving astern the water flow will tend to keep the blades open.