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Post by NZL50505 on Jan 7, 2018 22:14:57 GMT
So still debating 3B Flexofold vs 3B Maxprop based on other user's experiences. I have the 3B Flexofold on my SO40 and are very happy with the reverse. At my marina when I return, I turn into the breakwater and chuck it into reverse to back up to my dock. She stops quickly and gets up to speed quickly so I can get steerage and keep away from the other yachts.
Are you shaft drive as well?
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Post by hoppy on Jan 7, 2018 23:30:33 GMT
Yes...
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Post by Spritz on Jan 8, 2018 0:27:32 GMT
I hav3 a 42DS built in 2011. No problem in reverse with the 3 blades given by jeanneau (fixed) and no problem with Autoprop.
i had a 43 DS and the 42 is more comfortable and faster under sail and under engine!
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Post by Syrah on Jan 10, 2018 7:21:19 GMT
We have a 2007 SO 42DS with a 3B Flexifold. It does prop walk to Port on initial motion in reverse, but I can comfortably back it all the way out of the marina once it’s moving (if required). It tends to be a bit light on in stopping power, and I have wondered about the merits of a feathering prop at times. You wouldn’t want to headed into a marina pen too fast and relying on the prop to pull up quickly.
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Post by NZL50505 on Jan 10, 2018 23:46:45 GMT
We have a 2007 SO 42DS with a 3B Flexifold. It does prop walk to Port on initial motion in reverse, but I can comfortably back it all the way out of the marina once it’s moving (if required). It tends to be a bit light on in stopping power, and I have wondered about the merits of a feathering prop at times. You wouldn’t want to headed into a marina pen too fast and relying on the prop to pull up quickly.
OK that's interesting.
If you are doing, say 1.5-2 kts (typical speed coming into a marina berth with a bit of a cross wind) how quickly can you stop?
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Post by Syrah on Jan 11, 2018 0:00:54 GMT
We have a 2007 SO 42DS with a 3B Slipstream. It does prop walk to Port on initial motion in reverse, but I can comfortably back it all the way out of the marina once it’s moving (if required). It tends to be a bit light on in stopping power, and I have wondered about the merits of a feathering prop at times. You wouldn’t want to headed into a marina pen too fast and relying on the prop to pull up quickly.
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Post by Syrah on Jan 11, 2018 0:04:30 GMT
I looked over my notes and it’s a slipstream. I had tried to edit, but it created a new post. At 1.5 it’s it pulls up pretty quickly, but at 3 plus it takes a long time to slow down.
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Post by Trevor on Jan 12, 2018 2:40:35 GMT
Hello nzl8970,
We have a 42DS with a Slipstream prop and reverse performance for us is not a problem at all. I don't mind prop walk and in fact sometimes I used to like it but this yacht doesn't have much prop walk with the slipstream prop.
Trevor
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Post by rene460 on Jan 12, 2018 4:30:09 GMT
We only have a SO30i, but many things are proportional. We have the Autostream feathering prop, with shaft drive and twin rudders. Nearly no prop walk, though a tendency to turn to port easier than starboard when we first start moving. Totally agree with 1.5 - 2 knots coming into the pen with a cross wind. Better 2 than below 1.5. We stop in about half a boat length with minimum revving in reverse, so I go neutral for a moment when the widest part of the hull is in the pen, then reverse to stop. We find it excellent. At double the speed, you have twice the momentum, so need either twice the thrust (plenty more revs), or twice the time to stop. Or some equivalent combination to give twice the rate of change of momentum.
Momentum = mass x velocity. Change of momentum = Force x time. Quite simple maths if you want to do it, so long as you use consistent units.
Your boat has more mass than ours, but you have a bigger prop which should produce proportionately more thrust. If your boat really has worse stopping performance than similar ones around you, it is possible that the aft direction rotation stop for the blade rotation on the propellor hub has not been correctly adjusted, and you have inadequate pitch in reverse. The prop has a different rotation stop for the forward direction, so this could be correct anyway. I think this is a long shot, but just another possibility to consider if the performance is really amiss, as the issue does seem to be specific to your boat.
rene460
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Post by elecco on Jan 26, 2018 23:39:55 GMT
Thanks. This is pre-purchase seatrial and boat has been recently antifouled so I don’t think prop would be dirty but I don’t know the boat or if the prop is malfunctioning. Either way sounds like it should be solvable either via a fix to current prop or replacement eg Brunton or Maxprop? Yes I’m in NZ (to answer someone’s Q). Thanks I have an SO 45 with a 3 blade Maxprop. I really like the prop and performance. Boat backs down well in reverse. She does have slight prop walk to Port, but I like that / use to my advantage at the dock. Prop easily feathers / unfeathers. ~Ed
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Post by zofiasailing on Feb 12, 2018 7:55:23 GMT
2006 SO42DS with standard 3blade prop. Yup, she walks to Port in reverse but we have learned to ‘use’ that characteristic where possible and, dare I admit, we have bow thrusters too🙀. Changing the prop has never been on our list of dreams.
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Post by NZL50505 on Feb 19, 2018 8:56:09 GMT
Those of you with Flexofold 3B or Maxprop 3B what forward speed performance do you get?
Last couple of weeks cruising have done my best to acclimatise to poor reversing performance inc visiting other marinas where you can’t control setup in advance. Managed ok so far but still in my mind to replace.
Despite the awful reversing I have to admit the forward drive is nuclear - at mid 2000s I’m doing 8kts and when I tested full speed for first time we nearly hit 9kts (SOG and waterspeed) whilst towing a dinghy. Without dinghy I’m sure we’d hit 9 kts.
So obviously I’d love to fix the reversing issues with the Volvo prop but don’t want to lose the amazing forward drive.
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Post by Tafika II on Feb 19, 2018 16:36:38 GMT
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Post by NZL50505 on Feb 20, 2018 6:10:09 GMT
Thanks Tafika that’s a really informative thread which I’ll bookmark. One thing I didn’t notice is what’s your maximum possible engine revs with Flexo 3B? Is it still 3,000rpm or close? I noticed our current Volvo prop allows us to rev to about 3,100 which is 100 above rated speed but seems useful to have for short bursts.
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Post by Tafika II on Feb 20, 2018 15:56:14 GMT
I think the max revs stayed the same, but I'll check it next time I'm on the boat & let you know.
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Post by NZL50505 on Mar 17, 2018 6:38:35 GMT
I think the max revs stayed the same, but I'll check it next time I'm on the boat & let you know. Still keen to hear what you discover!
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Post by Tafika II on Mar 19, 2018 15:26:56 GMT
Checked yesterday and MAX revs are around 3000RPM. I never go there so I'm not sure what meaning this has.
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Post by NZL50505 on Mar 19, 2018 22:17:19 GMT
Checked yesterday and MAX revs are around 3000RPM. I never go there so I'm not sure what meaning this has. The point of interest for me is that your 18x14 prop allows you to still reach max rated rpm (3,000) instead of reducing the max achievable revs. Because there has been some discussion in another thread about the right pitch and someone else (“rb”?) recently said that Flexofold had recommended he puts 20x13 on his boat despite having identical engine & gearbox to you (and me): jeanneau.proboards.com/thread/2501/2008-so42ds-flexofold-prop-specifications?page=2Hence I’ll be interested to see what his performance experience is with his 20x13 compared to your 18x14?
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Post by rc sail on Mar 20, 2018 18:10:22 GMT
You speed Sailors with fold props has got me interested in performance props so I requested quote from Flex-o-Fold. To add to your notes or your confusion, and For my 44 ds with 4jh5e, sail drive with 1:2.33, they have recommended 18x14 3L.
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Post by rene460 on Mar 21, 2018 11:51:48 GMT
Hi Trafika, that checking the revs at full throttle is just a quick and simple test to see how well the prop is matched to the engine, and should be done when hull and prop are freshly cleaned and antifouled. Then if later you do not achieve the same revs it most likely indicates prop fouling, though could be an engine problem.
Our Yanmar agent says the engine should reach a max about 10% higher than the maximum rpm specified by the manufacturer for the engine. If you do not reach this speed, the prop is considered oversized, while if it reaches it easily, and you are still not at full throttle, the prop is not supplying sufficient load.
The basic theory is that the engine is quite close to constant torque with revs near max revs, while the torque required by the prop varies with the speed cubed. The two can only match at one speed.
You will have noticed that some forum members prefer slightly over propped. This is because, like you most people never go at full throttle, though I suppose it is good to have the possibility for that rare extreme occasion. At lower revs, the prop is not fully loading the engine at that speed and you are missing some thrust. If you are only slightly over propped, then your propellor is matched for a slightly slower engine speed where you are more likely to use it.
I would love to have an authoritative article from some of the engine and prop manufacturers representatives. In the mean time, freshly cleaned we get about 3800 max compared with our engines max specified speed of 3600 rpm, and I have recorded the boat speed when I ease back to 3600 rpm, and can clearly see the reduction in this speed as the time for cleaning approaches.
As an aside, while most of us do not go near full revs very often, diesels definitely are more reliable if worked hard. Yanmar recommend in the manual supplied with our boat, that the engine be run for a short time at full revs every time. If this is not practical, they recommend racing (their term) the engine to full revs in neutral before shutting down.
I find that 2400 rpm takes me at the speed limit of 5 knots for the first mile from our marina, so once I am past the limit zone, I rev up to max revs for a brief period before cutting back and raising sail. So far it seems to be serving me well. Again, the revs required for 5 knots increases as cleaning time approaches.
Back on topic, there is probably not much difference between 20 x 13 and 18 x 14. One pushes a greater mass of water, the other pushes a smaller mass at higher velocity, both could give very similar thrust and engine load. The optimum may be inbetween, so might explain the different recommendations. Worth talking to the prop supplier about before ordering.
rene460
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Post by super g on Mar 22, 2018 7:47:41 GMT
I’ve had a 3blade fixed, feathering and folding on an S040ds and Sunfast and the feathering Maxprop was by far the best. The maxprop pitch can be easily changed and I had mine overpitched for lazy revs when motoring. In astern it could stop the Boat dead with minimal prop walk. The 3 blade folder I have now is okay but in astern but you have to rev the nuts off it, plus when transition from motoring to sailing I get a hell of clunk when putting her astern to lock the prop- cannot be good for the gearbox?
The fixed was the worst, loads of drag and took loads of revs, possibly undersized but was the standard jeanneau one.
I miss my maxprop.. I think my issue with folding props is the transition from ahead, I guess the forward movement and water flow is pushing the blades shut so loads of revs are needed to create enough centrepetal force to open them up.
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jmandeno
New Member
Posts: 3
Jeanneau Model: SO 519
Yacht Name: Five O’Clock
Home Port: Auckland
Country: New Zealand
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Post by jmandeno on Feb 12, 2019 2:56:25 GMT
We have a SO DS 42 here in Auckland. Swapped the Volvo folding prop (which worked perfectly on our Farr 1220) not long after commissioning Lush Life because of substantial prop walk in reverse, to a MaxProp 3 blade. Absolutely perfect - no issues at all.
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Post by NZL50505 on Feb 13, 2019 4:34:36 GMT
We have a SO DS 42 here in Auckland. Swapped the Volvo folding prop (which worked perfectly on our Farr 1220) not long after commissioning Lush Life because of substantial prop walk in reverse, to a MaxProp 3 blade. Absolutely perfect - no issues at all. Hi ‘Lush Life”. I know your boat - admired it at the viaduct fircmamy years before buying my own 42DS (Aleana). Given we’re identical how have you found forward performance with your Maxprop (max revs and boatsowed)? And can you remember the spec of your 3B? Thanks
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Post by zaphod on Feb 13, 2019 22:40:09 GMT
[\quote]Ahaaa a learning curve The new boats are caravans, big shiny and cheaply made -maximum lasting time in mind 5 years until the charter company sells the boats....sailing - who cares as long as there is a big bedroom down and shiny useless glass on one side of the sync - but looks nice .. no one actualli wants to sail - the boat is desined to use the maximum possible from the marina berth... that's why I'm with 1990 design.. been there done that with post 2005-2010 boats - returned to old desing as I want a boat not gin palace that do not leave the berth... [/quote] Wow! Now there are some generalizations! Why would you say such things in a forum where many of us own the very boats you show so much disdain for? Are you just trying to be obnoxious? I'm glad you are happy with your outdated old boat. To each his own. I happen to like the features and amenities that a modern boat has to offer. And as for the original topic of this thread, the reversing problems the OP describes have nothing to do with the design or age of the boat, and everything to do with the type of propeller the previous owner chose to equip the boat with. If you really want to discuss the merits of your 1990s boat vs modern boats, start a thread, and we will see you there!
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jmandeno
New Member
Posts: 3
Jeanneau Model: SO 519
Yacht Name: Five O’Clock
Home Port: Auckland
Country: New Zealand
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Post by jmandeno on Feb 13, 2019 22:57:26 GMT
Hi Aleana. Lush Life has a 20 inch Classic 3 blade MaxProp for a 30mm shaft. I can’t find details of the pitch it was set at, but I remember that the supplier, PYI Inc (USA) was able to tell me straight off what it should be as they had fitted a number of DS42’s with the prop. They have a very useful website. pyiinc.com
Cruise at 6.5 knots at 2,100 rpm. I think from memory that at 3,200 rpm we were around 8 knots.
We have just traded in Lush Life for a new SO 519 which arrives from France in early April.
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