any strong views on which 2 bladed folding prop to buy?

PaulR

PaulR

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current gori 2 blade folder sadly at end of it's life and according to experts not repairable so time to buy new one, question is which one?
our boat, a dehler 34 is used for family cruising - narrowed down choice to:-

another gori same as before,
a flex a fold (another danish manufacturer (ex gori people) and claims to be more effecient but is more expensive
a slipstream - made in stainless steel from down under

any views based on your own experience appreciated please- thanks
 
really pleased with my Brunton autoprop on a first 31.7 no quicker i do not think under sail than the original folder fitted but 2 knots quicker under motor, smoother and great control in reverse
 
IMHO beware of two bladed bronze folding props.
My VP prop ate anodes at the rate of a set every 6 weeks and showed worrying signs of electrolosis after one season.
Have now got a refund from VP and bought a Slipstream and I am hoping for better things.
My friend had a Gori which lasted three seasons before the teeth fell off. He has also now bought a Slipsteam.
Gori are now fitting anodes to there props but will they fair any better than VP?
Before anyone asks there was definitely no electrical problems in either case. The boats are both kept on swinging moorings with all electrics switched off when not in use.
As a point of interest VP and Gori props are both manufactured in the same town in Italy!
 
Don't bother with another Gori, they almost invariably lose their teeth. I think the same applies to most toothed folders. Successful with Kiwiprop since.
 
[ QUOTE ]
IMHO beware of two bladed bronze folding props.
My VP prop ate anodes at the rate of a set every 6 weeks and showed worrying signs of electrolosis after one season.....
Before anyone asks there was definitely no electrical problems .....

[/ QUOTE ]

I find the above incredible: it strongly suggests stray-current corrosion(unidentified).
By contrast, I fitted a Gori 2-blade in 1990, and it was replaced last year only because I installed a more powerful engine needing a bigger prop. The gearing and pins of the old one were worn after 16 years hard service so it clattered a bit, but there was no trace of corrosion.
Perhaps the difference is that I use a Vetus flexible coupling (hefty, solid rubber), a Cuttless bearing in the P-bracket, and the sterngland mounted in the sterntube by a rubberised hose: together they completely isolate the prop-shaft (electrically!)from the engine and any other metal. The electrolytic cell formed by prop-to-shaft contact is taken care of by fitting normal shaft anodes; they are usually about 30% corroded in a season. I fit a new one and leave the old one in place for a second season: No problems.
Needless to say, my new prop is also a Gori 2-blade folding, and I expect it to last at least ten years.
 
Re: \'they almost invariably lose their teeth\'

Not true. Mine is in its 8th year, after several thousand hours running, still on its original stops and the anodes easily last a year.
 
You may find it incredible my friend but it is nonetheless true. I did say that there were definitely no electrical problems in either case.
Furthermore the props in question were fitted to saildrive legs which apparently electrically isolate the prop from the engine.
Savageseadog has previously posted an interesting picture of a corroded Gori prop which proves a point. The Hallberg Rassey Web site has some interesting postings on the subject as has the Maxi owners Association web site.
The VP prop that I had on my previous boat did not suffer from the problem but since then VP have taken to fitting anodes to their props - one wonders why.
The best guess so far and a view held by several others is that they are now using a different metal which may not be up to the job.
I
 
''Furthermore the props in question were fitted to saildrive legs which apparently electrically isolate the prop from the engine''

Now it is credible! There have been previous postings about problems with propellers on saildrives. For some reason, beyond my ken, it does seem to be an unhappy combination.
But the root cause will still be electrolytic: dis-simliar metals in contact in seawater, whether or not it is compounded by stray currents.
So the answer for PaulR would seem to be: If you have a conventional installation with an isolated prop-shaft, by all means replace the Gori, but if you have a saildrive, think again!
 
i have a 2 blade MaxProp with no anodes at all. i have owned the boat for 8 yrs God knows how old the prop is as it was already fitted. there is some wear in the pivot points but a refill with grease sorts that.
as far as I'm concerned i would defiantly buy another /forums/images/graemlins/grin.gif
 
I agree, three boats ago, Gori prop, no problems. Last boat VP prop on saildrive/VP2002, current boat VP folder on VP2003 with saildrive, now about 14 years old. Only to be replaced by either a Bruton or Kiwi 'cos I want more power/lower revs when motoring.

Or have we just been lucky?
 
Why stick with a two blade folder? You are likely to get just as good sailing performance with a three blade feathering prop, and better motoring performance including much better drive in reverse. Not sure what a Gori costs, but I think the Kiwiprop is likely to be significantly cheaper.
 
Might want to have a look at the kiwi prop-got very good reviews. I believe its a feathering rather than folding design. Price £850(?) so may be a bit more expensive than a gori. Blades are some form of plastic so presumably less chance of corrossion.Very good service from distributors. Theres a D34 overseas thats raced thats got one I believe. A search on kiwi prop on these forums should turn up a lot of info.
 
I'm delighted with my Autoprop 3 blade. Despite it's high cost, it's extended my range significantly & pushes me along at 5.5 kts 500 rmp less than the fixed prop. Sailing performance is greatly improved & I don't get "prop walk" any more. Only drawback is min speed is 3 knots.
 
Any reason to get 2 blades?

I have mounted a 3 bladed kiwi last year. Very very pleased with it. Increased performance under sail and motor just as claimed by the manufacturers. Incredibly easy to service. Came up nice and clean (the hull was a mess!) after following a/f instructions from distributors. UK distributors are really fantastic: committed sailors who seem to do it mostly for the fun of it (their business is something else).
Price was VERY competitive last time I looked
 
Re: Any reason to get 2 blades?

Can't understand how it improves performance under power?

A Kiwi has flat blades that turn to give the best pitch for forwards & astern and least resistance (by turning end on to the water flow) when sailing.

A fixed prop has shaped blades that give 100% thrust forwards but are probably only 70% efficient (due to their shape to maximise forward thrust) going astern.

Therefore unless your boat was incorrectly proped in the 1st place a feathering prop should not improve it. I accept that you may choose to increase the forwards pitch to give a certain speed at lower revs and accept that being overpitched it will not reach full revs or max engine power.

Was your boat badly proped in the 1st place?

Sorry to querry your comments but I was recently asked my opinion of a Kiwi and all my knowledge is based on others experience that post on here and its great if you get a balanced post and a sound evaluation but without a better understanding its difficult to appreciate your evaluation.

Even a self pitching prop like the autoprop will only give better performance when motor sailing.

I accept the major benefit of a feathering prop in the power available astern.
 
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