Folding Prop

[oceandiamond]

Ocean Diamond has a standard fix three blader prop and was looking at the possibility of upgrading to a folding/feathering prop. We do quite a lot of motoring and was looking for an increase in power under motor.

Any comments/suggestions

[sitara]

It is important that the prop be matched to the engine power rating and the characteristics of the vessel. If the prop is too small the engine is underloaded and the boat is slow. If the prop is too big the engine is overloaded which is damaging to the engine.

The original factory fitted prop should be the optimum size for the factory fitted motor. A folding/feathering prop will reduce drag and improve sailing performance but will do nothing to increase performance under motor. If you do a lot of motoring then a correctly matched fixed prop is probably the best way to go in terms of extracting maximum power from the engine and in simplicity with no wearing/moving parts.

Hope this helps.

[hoppy]

I see from another thread you have a SO40. I fitted a Flexofold on my SO40.

I never used it with the standard fixed blade prop for comparison, but I am very happy with the speed and stopping power of the Flexofold

My engine is the 4JH3E

The prop specs were
18x13-3 R bladeset
ISO 30, 3-blade hub

As sitara has mentioned, it is very important that the prop is correctly matched. In addition to telling them which engine I had I also had to make sure of the gearbox ratio which in my case was 2.63 (Kanzaki gearbox)

[MartyB]

"SOME" "one" actually of the non fixed does have an od built into it, so one can motor at a igher speed and use less fuel, so I suppose you could consider this to be more power per say.

If you need "more" power, say due to going against currents, larger waves etc, getting a 4 blade prop of any sort would give you more bite into the water, so you would not lose as much speed in some of the conditions I mentioned at least from a forward perspective.

If you want more power in reverse, then some like the max prop, that prop gives you 100% power in reverse and forward, vs most fixed props only giving you 70-80% in reverse, and a bit of prop walk.......prop walk is varable as to if that is good or bad......I prefer none, but I can see where propwalk can be good if you are trying to back into a tight slip!

As noted, you do need to know the boat, gear ratio of trans, motor etc as to what will be the best size for you. Also some have reported going from one diam to the next larger, ie 16 to a 17" gives them better speed/power etc also. Similar to adding another blade to what you have. ie 3 to 4 in your case, myself from 2 to a 3 would be a good move where I sail........But fuel economy may go down as you are now turning more blade/wt, and moving parts like props, take more energy than up to 10 times the added wt of the prop in non moving wt.

Marty

[MalcolmP]

There is also a lot of views on this thread from last year:

jeanneau.proboards.com/index.cgi?action=display&board=eq&thread=1900&page=1

I do have to declare an interest but I have found the 3 blade autprop on my 39i with a 39hp Yanmar to be the perfect set up for our use - low drag, reduced fuel consumption or lower revs, great power ahead and reverse, less and more controllable propwalk and finally very efficient when motor sailing with low revs. It is also easy to service and has no complicated parts to replace

www.autoprop.info/

[oceandiamond]

thanks guys
really helpful and I'll chew on that for a while.
bye from OD in Malta

[so40gtb]

My SO40 has a Max-Prop, which works very well in both directions. There's a modest prop walk when first shifting into reverse, but it's gone as soon as the boat starts moving in the desired direction. I've used this quite effectively when maneuvering in tight spaces.

My prior boat, a SO34.2, had a Kiwi, which had a tad less power in reverse but was still far superior to a fixed prop. The Kiwi had near-zero prop walk, less than the Max Prop. And it costs less. No issues in the five years that we owned the boat.

[shiook]

With any of the non-fixed blade props, is there a delay in activation when you shift from forward to reverse and back again? My slip is very close to a bridge and there is 5 knot current at times. (2010 36i) Thanks!

[Don Reaves]

I've never noticed any with my Kiwiprop. Just keep it properly serviced.

Don

[Zanshin]

If you do a lot of motoring in calm waters, then the Gori prop, with the "overdrive" mode might be just right for you.

[dublin]

i have never been conscious of any delay with a kiwi. but then again i always pause in neutral (even when I had a fixed prop) asit is better for the gerbox.
The kiwi is less "mechanical" than other feathering props so there is likely to be less delay

I thought the "overdrive" on the gori was only of benefit when motorsailing (rather than motoring)

[Zanshin]

The "overdrive" I had on the 49DS was great, I would use it sometimes when motorsailing but it can also be used in calm waters. The danger is that due to the low revs and higher load is that the engine can overheat (which is why I wanted to put in an EGT gauge, but never did). Neither the Gori nor my current factory folding prop showed any problems or time delay between forward and reverse and vice-versa.

[j]

No delay with a Flexofold/36i

[DUET]

I have had a Gori, Martec, Maxprop and currently a Flex-a-Fold. The Flex-a-Fold is a superb unit. No drag sailing and certainly the fastest going forward in my opinion. The only drawback is that it is not particularly powerful in reverse as compared to the Max. There is no delay and doesn't fail to open. I specified the Flex-a-Fold when ordering my 50 DS, the first one installed by my Annapolis dealer. Its now standard equipment on the 57 which Zanshin can address.

[jimlowden]

I have used both folding and feathering props. There is a significant cost premium with the feathering and they require annual maintenance. However, they are usually adjustable and allow you to tweek the pitch to exactly match your hull and load. If that last 1/4 knot is important, particularly when dinghy towing, look at the feathering. Otherwise, save money and maintenance - less moving parts - and go for a three blade folding. My current boat has a flexofold 16x11 and performs well; the slightly greater drag over the feathering is not a big deal. In either case, a performance prop is the simplist most effective boost to sailing speed you can add to your boat.

[so40gtb]

No delay issues with the Kiwi.

The Maxprop flops over a tad late maybe once in 30 reversals. It seems to be a bit more vulnerable to fouling by sea vegetation. But it does bite somewhat better than the Kiwi.

[lois]

Hi
We've fitted a Darglow Featherstream (20"- 3 blade - £1500) to our SO40.3 (2005) and are very pleased with the performance - both under power and sail and particularly in reverse. We have a Maxprop on our boat in UK - again from Darglow - which is excellent. A bit more pricey but optimum for racing. I can recommend Darglow thoroughly.