MaxProp and Gori Propellers

[HarveyBigg]

I am planning a circumnavigation in a Hallberg-Rassy 46 and the boat is currently in build. The manufacturers have supplied both type of props as optional extras over the years and I like the prospect of less drag whilst sailing long passages.

The Maxprop is roughly twice the cost of the Gori, but requires less maintenance (no bearings to replace).

I would appreciated any views/opinions based on experience concerning the performance and reliability of either of these propellers......

I propose carrying the standard fixed prop as a spare.

Harvey Bigg

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[pandroid]

I have the Maxprop fitted to a HR36. Against the fixed prop it clearly is better - less prop walk in astern, about .5 to 1 knot extra sailing and a little extra motoring as the 17 inch Maxprop replaces a 16 inch fixed (Rassy deliberately underprop the stock boat slightly to reduce drag). I have had no problems with the prop, although of course it needs greasing once a year and the anode replacing. I'm afraid I cant compare it with the Gori, as I dont know anyone who has one. Volvo claim that their own 3 blade folder is better as it includes bushes to reduce the shock loads that the Maxprop puts on the gearbox when changing direction.

I dont know about the Gori, but you can fine tune the pitch of the Max-prop by simply adjusting it - this is useful as Maxprop dont always seem to get the settings dead on first time.

If you are thinking of having a rope stripper fitted, this is well worth doing when you buy the boat, as Rassy then use a different propshaft, and the latest boats use a cutlass bearing which make some strippers difficult to fit.

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[qsiv]

I wouldnt say the Maxprop requires that much less - we strip, regrease and fit a new anode every season.

It does work really well, mind you. I cant compare with the gori, having never had one.

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[gunnarsilins]

I agree with Pandroid.
Since 3 years I have a 3-blade MaxProp on my Moody 42 and she´s a new boat compared with the old fixed 3-blade!
I get 0,5 - 0,7 knots more speed under sail.
No need to apply the shaft brake.
Much better thrust in reverse.
A quite considerable propwalk is almost gone.
By fine-tuning the pitch I now get same cruising speed as before but at 250 rpm lower revs.

But the anode needs to be changed too often - when only 20-25% is wasted the whole anode will fall off because of bad engineering. And they are NOT cheap!

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[davidbains]

Harvey,
Have you considered a Autoprop by Brunton.
Recommended by Rod Heikell no less.
Must be cheaper too, and you get automatic pitch control which
is supposed to do wonders for motorsailing, whatever that is.

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[pandroid]

You strip the prop EVERY season? Really? We just pump it full of grease using the grease nipple. (Well, I get the yard to....)

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[qsiv]

Well, like you it's the engineers!

It doesnt seem to take long, and they like to get the hardened, sand laden grease out, and start with nice clean grease ... and increase their bill! The replacment of the anode is actually the really key element for us (ali boat and all that)

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[charles_reed]

They are not easily comparable - the Gori is the best folding prop you can get, whilst the Maxprop is one of a number of self-pitching props.

Whilst the Gori definitely reduces drag under sail, compared to a fixed prop, the 2-blade version does not give as much drive under power as a 2-blade fixed propellor and all folding propellors are very poor in reverse gear.

The Maxprop is probably the least drag of any prop under sail, but probably not as good as the Brunton Autoprop under power.

An exceptionally good alternative to any of the above is the Hundstedt propellor widely used by FV. With this you can alter pitch under way and I know of a number of trans-oceanic sailors who swear by them.

All the above need regular servicing, the Hundstedt probably least of all.

IMHO the best of them for general cruising is the Autoprop, it's better than the others in self-pitching for motor-sailing.

My boat has been fitted with Gori folding, fixed and the Autoprop in turn. I have sailed boats with Hundsted, Volvo 3-blade folding and the Maxprop.

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[HaraldS]

Don't have any of the props mentioned, but yet another 3-bladed folding prop.
Can absolutely NOT confirm bad performance in reverse.
I get a huge amount of power backwards, testing this at anchor I can easily stop the windlass which is supposed to pull in up to 1.2 tons.
It folds neatly when sailing and I doubt it has more drag than a feathering prop.
Can't see any down side with such a prop. Think the Gori is quite similar, just folds different (star shape vs triangle) and the hinges seem a bit thinner.
From what I know, large diameter feathering props don't work so well because they have a fixed pitch, which makes them cavitate at the perimeter.

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[charles_reed]

My comparison, on the same boat, was between 2-blade Gori and 2 blade fixed.

Certainly the fixed prop was much more effective in reverse than was the Gori and bit far better. I don't think there was any difference in ultimate still-water speeds and the fixed prop caused definite engine labouring when butting a head sea/wind in excess of about F6. On the other hand the Gori gave virtually no drive causing one or two moments of hysteria in windy conditions. Frankly I was relieved when it shed a blade and repair would have cost as much as a new fixed 2-blader.

However, the fixed prop had almost x2 the blade area of the Gori and was a slightly coarser pitch.

With regard to feathering props, your comment is true of the Maxprop, but the Autoprop is infinitely feathering and the Hundstedt can be adjusted from the engine room. Both these can be far more efficient than a fixed prop - the Autoprop does it automatically which is an advantage.

Effectively under sail and therefore reduced water-load the Autoprop coarsens its pitch and when you're butting into a head-sea it reduces, giving your engine a chance to reach maximum power, unlike the case with a fixed prop.

Mine is one of the early Autoprops and I've never regretted having it, however Brunton's spares prices maximise their profit from a captive market and the additional weight over either fixed or folding props does mean you need to change cutless bearings and shafts more frequently. Bite going astern takes some time to develop (rather like a folding prop) but when it does take it's better than any other prop. This leads to a very real embarrassment, until you allow for it - one goes into reverse to take way off, nothing appears to happen in the first second, so you increase revs, just as the pitch corrects, the resultant change in acceleration quite frequently has foredeck crew overboard.

Its greatest advantage is the ability to motor sail in light winds at just over a tickover and add 2-4 knots to waterspeed. The reduced drag over a folding prop makes only a marginal difference to water speed, but the effect on one's handicap is far more beneficial (if you race).
For me, especially for cruising against a schedule, there is no contest between folding and feathering props - the great difference is in purchase price. With no time constraints you, of course, can afford to be a purist and not use a motor at all.

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[charles_reed]

I\'d agree

I've never owned a Maxprop but I have had a Gori before the Autoprop, the Autoprop needs marginally more servicing than the Gori and its got water-lubricated bearings and no need to grease.

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[southchinasea]

Re: I\'d agree

I have a 3 bladed folding Gori on a 15.39m boat. See recent YM with some comments by James Jermain on Gori product during a boat test. Excellent general performance and an 'overdrive' function for motor sailing/calm water motoring whereby it remains in reverse pitch mode and produces very impressive boat speeds at lower revs. In regular mode works very well and reverse performance is also more than adequate. There is significant prop walk in reverse but I tend to try and use this to my advantage. The only maintenance I have done is to replace the large hub anode and small 'back end' anode a couple of times. Nice piece of engineering. All IMHO of course.

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