Maxi-Prop Feathering vs Volvo Penta Folding Prop

okolehao2

okolehao2

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Ok, so here it goes. I have a choice between a Maxi prop or a Volvo Penta 3 blade folding prop for my boat. I have a Benteau First 456 with a MD22. The Maxi-Prop runs about 1000 EUR more than the Volvo Penta Prop. The Maxi-Prop is of course a better fit and 20x13. Since volvo only makes a 19x16 and I really could use a 19x17. The old propellor was a 17 x 11, and perhaps explains why I only got 5.5 knots of motoring speed out of a 46 foot boat.

How does on make the call on this? Is this really worth the 1000 extra?

-Arthur
 
G'day okolehao2,

Another can of worms question. You need to ask yourself a few questions, what do you need when it comes to motoring, speed, economy, manuverabililty, reliability.

You choice will effect all of the above; The Auto prop will outperform and outlast a folding prop in most areas and operations but will cost a lot more as you have discovered.

Bottom line: If you can afford it get it, you will love the performance when motor sailing with an autoprop and it's always good to know you can stop the boat when entering a marina berth.

Avagoodweekend......
 
I think you've confused two quite different props. The Maxprop is an automatically feathering prop with fixed pitch (it can be adjusted with the boat out of the water). The Autoprop is a dynamically self-pitching prop with free-moving blades. What they do have in common is that they are both a lot more expensive than a folder.

I would first say that the choice need not be a 3-blade folder. I went for 2-blade folders which are much more efficient than you would imagine and vastly more so than a typical 2-blade fixed. Nor do you have to buy from Volvo just because you have a Volvo engine. Have a chat with CJR props about the Flex-o-Fold - they have a very large range of blades and should be able to come up with a good match. They do a 3-blade version if you're determines to have one. (no connection, just a satisfied customer)
 
Maxi props are definitly the business! When we bought our boat she had an old 2 bladed one and we upgraded it to a 3 bladed when it got to worn (fter arround 18 years) and the three bladed is fantastic - much better than a folder which we had on our previous boat.
 
Main advantage of a Maxprop over a folder is that efficiency is equal both in ahead and astern because the blades swing right round such that the are presenting the leading edge in both directions. A second advantage is the pitch can be fine tuned to the installation. You start by reading off pitch settings from a table relative to a fixed 3 balded prop. If you then find you are under or over-propped, you can change the setting next time the boat comes out of the water.

Although I have not experienced any problem, a feathering prop's blades are permanently extended and thus have a higher risk of picking up weed or abandoned warps while feathered than a folding prop would when folded. So, it is proabaly more important to have a rope cutter installation with a Maxprop. If you decide on a folding prop then I suggest you consider Gori, expensive but the best IMHO. Had a Gori 2 blade folder on my last boat and a Maxprop on the current one, both are excellent.
 
Can you use a feathering or folding prop with a long keeler? I changed my two blader for a three blader last year, and may have overdone the pitch, I was in a hurry to get it done before I went away and never did the calculations!! If I decide to rectify the situation this winter, it might be worth looking at folders and other options, and so am starting to research now !! I changed my 12:9 two blader for a 13:10 three blader. Main prob is that i cannot get the engine above 2800, and should be able to get at least 3200.
 
[ QUOTE ]
Main advantage of a Maxprop over a folder is that efficiency is equal both in ahead and astern because the blades swing right round such that the are presenting the leading edge in both directions.

[/ QUOTE ]
Not all folding props are equal.

My folding prop (a gori 3 blade) also works the correct way round in both forwards and reverse, and has better profiled blades than the Maxprop; so it will be more efficient than the Maxprop both in fwds and reverse.
 
I've had both Volvo and CJR 3 bladed folding props on various yachts over the years. They are nearly identical in design and both did everything I asked for them. I currently have a heavy displacement 37 footer with sail drive fitted with CHR 3 bladed flexofold and have no problems in going astern or stopping despite what others say about folding props. We get to cruising speed at 2200 rpm - 2500 rpm if we are really in a hurry or there's a strong headwind
These props are very simple in design, with few moving parts and almost nothing to go wrong. I cannot see the point on paying £1000 more - rather put the money towards some new sails
 
I had 3 number Volvo 2 bladed folding props fitted to a 36' charter yacht in 2 years before Volvo gave up replacing them under warantee and refunded my money. I don't know about the newer larger Volvo folding props but the smaller ones were insulated from the shaft and have their own 3 piece circular anode. The anodes corrode mostly around the centre screw position and then fly off due to centrifugal force. In the Hamble I would not expect the anodes to last longer than 3 months. Second problem was that the splines wore. Noticable play at about 300hrs and got so bad on one occassion that Volvo also replaced the saildrive shaft. In my opinion they are not robust enough for the hours a sailing school boat did in 12 months although to be fair to Volvo they did all the work FOC under warrantee. Apart from loss of Anodes I would expect the Volvo folding prop (as fitted to a 2030 engine) to be OK for say 3 to 6 years of ordinary usage. In my case though I did lose out on lost charter income and lift out costs. I later fitted a CJR flex o fold propellor to another boat with a 2040 engine. It doesn't need separate anodes and gave no problems.

On latest boat with fixed prop we have had 2 fishing nets in 2 weeks in sailing off French coast (Latest Yanmar gearbox states DO NOT sail with gearbox in astern) so intend to go the folding prop route to try to lessen the chance of picking up fishing nets!

I have a new CJR Variprop sized for a Volvo 2040 if anyone is interested. New boat came before I managed to fit it! PM me.
 
With most thrust being generated by the outer ends of the blades (due to the higher speed relative to the water) I would question if your Gori 3 blade is more efficient than the Maxprop, on blade area grounds, accepting the less than ideal "flat" profile of the Maxprop blades. As excellent as Gori props are, the blade profile is still a compromise in order to provide the mass to guarantee sufficient centripetal force to get the blades to unfold in a high speed water stream. Blade area on the Gori is also limited by the very clever folding design. The drag created by the lack of twist in Maxprop blades is offset by their thin aspect ratio relative to folding prop blades. As I have only used a 2 blade Gori, I can't comment further on its efficiency realive to a Maxprop but it would be interesting to hear a comparison from anyone who has used both on the same boat.
 
You should be able to fit a feathering prop, although a folding prop would probably need more space then your prop aperture will provide (although I'm not intimately acquainted with the Victoria 800's underwater geometry). You may find that the Autoprop is a non-starter as the blades physically reverse when astern is engaged and might re-arrange the shape of the aft end of your keel! Also, don't be tempted to fit the largest diameter you can squeeze in. You will need to allow a tip clearance of about 10% of prop diameter (I think - check!). Speak to Darglow Marine in Poole. Their website actually lists a few long keeled boats which a Max-Prop won't fit, but other feathering props will. Choose carefully and you won't be disappointed under power, and will be delighted under sail. Good luck - lovely pretty boat too!
 
In my case I couldn't fit the MaxProp so the Gori was the only realistic option.

The 3 bladed prop is a very different beast to the 2 bladed one you describe - and it doesn't rely on centripetal force to open the blades so it doesn't have the same thickening of the blades as the simpler folding props. It also has a similar DAR to a fixed prop so doesn't suffer any of the blade area limitations you suggest.
 
What I would like to see more than anything is the profile and info about your boat. Lot's good advice from our good friends but not much elsewhere?
regards.
Peter
 
You can get fixed blade props 're-pitched' . I got my 15x9 repitched to 15x8 and it increased the revs from 2800 to 3350 which I was satisfied with. Much cheaper than a new prop. Your prop supplier should be able to do it.
 
Thanks Dickh. Astonishing that one degree of pitch can make such a difference. Secretary of Vic association who has a Frances has changed to a three blader with a lesser pitch and says it seems to have transformed his motoring. He has a Yamnar as opposed to my Volvo, but I guess reducing the pitch is going to be one of my priorities for the winter.
 
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