Flexofold 2 or 3 blade folding on oversized 50hp FP Lavezzi

[CaptainRivet]

Originally Posted by Fbfisher

Talk to the very informed folks at Flex-o-Fold. They will collect all of the data about your boat and engines and tell you exactly which prop you need, they will also tell you the consequences of choosing two or three blades. As a result, your decision will be based on their expert knowledge.

I did this and am very happy with the result.

Well I asked them to share the prop calculation but they won’t.
Doesn‘t make decision easy as I think they would…not happy about that.
Having now a 17x15 fixed 3 blade from Volvo that fits quite well and they suggest a 18x13 3 blade and Tell me that’s ok as there blades are bigger and more effective then the Volvo.

[Tupaia]

Here's the thing prop manufacturers make propellers in set sizes. Their "calculations" involve fitting your boat to their props. Sometimes your boat matches their props better than others and you are very happy and rave about how good they are. Sometimes they don't and you complain how bad they are.


Custom propeller design is a combination of art and science. If you have a propeller "designed" for your boat it will cost a great deal of money and even then there will be no absolute guarantee. There are numerous custom designed propellers encapsulated in resin that are used as very expensive coffee tables.


The best option is to find a supplier that will stand by their product and offer to change it if it does not meet your expectations.



In the case of the OP with unusual engine / boat combination why not find a place with sufficient tides to dry out and try several props to establish the most appropriate.

[CaptainRivet]

Originally Posted by Tupaia

Here's the thing prop manufacturers make propellers in set sizes. Their "calculations" involve fitting your boat to their props. Sometimes your boat matches their props better than others and you are very happy and rave about how good they are. Sometimes they don't and you complain how bad they are.


Custom propeller design is a combination of art and science. If you have a propeller "designed" for your boat it will cost a great deal of money and even then there will be no absolute guarantee. There are numerous custom designed propellers encapsulated in resin that are used as very expensive coffee tables.


The best option is to find a supplier that will stand by their product and offer to change it if it does not meet your expectations.



In the case of the OP with unusual engine / boat combination why not find a place with sufficient tides to dry out and try several props to establish the most appropriate.

That would be awesome if there is a wholesaler who has different prop manufacturers and give me a set of each one to try.
Unfortunately i don't know such a wholesaler, if you or anyone know please share.
Otherwise i can just chose the one I think offers the best solution for the money and trust their suggestion/product and ask if they exchange if it doesn't fit.

[Peters Wet]

I have a 20x 14 RH flex o fold 3 blade for a 30.mm shaft 2000 Canadian dollars used one season excellent condition.

[malbert73]

Originally Posted by thegui

Hi

I have a FF 3 blade on my Hunter 37. Motoring in forward is no problem. However I have virtually NO Reverse. The blades do not open or open very slightly in reverse. If you do not plan to back up then you are fine, but I'd check out videos on line about the sketchy reverse or ask Flexofold. I'm thinking about switching to a feathering prop.

Not at all my experience with FoF. Though if you have a Yanmar they all seem to have a higher gear ratio in reverse so you have to really gun it.
I have great reverse with my Beta 50 and 3 blade flexofold. Also nice is when I repowered I was able to buy a new set of blades for 1/2 the cost of a new flexofold. Same hub

[CaptainRivet]

Originally Posted by Tupaia

Here's the thing prop manufacturers make propellers in set sizes. Their "calculations" involve fitting your boat to their props. Sometimes your boat matches their props better than others and you are very happy and rave about how good they are. Sometimes they don't and you complain how bad they are.


Custom propeller design is a combination of art and science. If you have a propeller "designed" for your boat it will cost a great deal of money and even then there will be no absolute guarantee. There are numerous custom designed propellers encapsulated in resin that are used as very expensive coffee tables.


The best option is to find a supplier that will stand by their product and offer to change it if it does not meet your expectations.



In the case of the OP with unusual engine / boat combination why not find a place with sufficient tides to dry out and try several props to establish the most appropriate.

I have exactly that problem with flexofold now:
decided for the 3-blade and the recommend the 18x13L
BUT i wanted Flexofold to confirm that i am not getting faster in idle in gear=ticktick then i am now with the 3-blade fixed 17x15.
this due to the cat is not maneuverable anymore when faster. if i am faster i cannot use this FOF prop and lost 4500Euro



in short they want me to order and risk all, they tell me since 4 month "believe our recomendation as this fits best your cat but don't want to make it part of the sales contract that the cat is not faster in idle then with the 17x15.
so basically its not worth anything if they don't stand behind their recommendation

after going forth and back with the sales team they finally involved the MD keld wrote the same bla bla then their sales team before.


Dear Christian

I´m really sorry if you don´t find our sales process professional.
In my opinion, it´s professional to openly say that besides the engine/propeller specifications, also many other factors will have an affect on specific speed/RPM mesurements under different circumstances (weight, wind, stream, accuracy of tachometer, use of one/two engines etc.).
Especially when very specific expectations and damands are expressed.
Propellers are sized to fit the engines max RPM, not boat speed by idle. Trust the Flexofold propellers will fulfil your expectations, but this just to explain how things works.
If the pitch is reduced 1“, speed will be reduced, but at same time, the max RPM will increase.
So, what´s your preference?

Based on our calculation, general experience etc., we trust that the propellers earlier offered are correct to fit the engine manufacture requirements.

As per earlier email from Marlene, we are - in principle – not going to issue any „carte blanche“ for someone to make whatever decisions/judgement for actions to be covered financially covered by Flexofold.
I trust the same for other propelller manufactures?



I understand that the intensive investigation, comparisons of different propeller types/sizes, different expectations and demands (some potentially contradictory) easily coursed doubts.
We trust our propeller recommendation will make you happy – like thousands of other sailboat owners worldwide.



Best regards,
Keld Willberg
Managing Director


sales process is not professional at all with flexofold as they don't listen what i want and need.



Tend to by kiwiprops now, if too fast i can adjust pitch...cheaper and sales process excelent.

[Jim Cate]

^^^^^

This seems a forthright and professional response to me, even if they don't give a specific response to your unusual query. Far better to say "we dunno" than blow smoke up your bum. As they point out, there are a lot of variables in determining boat speed at any RPM, and especially at very low speed where flow to the prop is unknown to their engineers.

And re comparing FOF to the Kiwi Prop: You are trading one of the most efficient propellor designs in the field for one with no-twist blades made of a somewhat fragile plastic. Basing the decision on speed at idle seems unwise to me... but your boat, your choice.

Jim

[fstbttms]

Originally Posted by CaptainRivet

I have exactly that problem with flexofold now:
decided for the 3-blade and the recommend the 18x13L
BUT i wanted Flexofold to confirm that i am not getting faster in idle in gear=ticktick then i am now with the 3-blade fixed 17x15.
this due to the cat is not maneuverable anymore when faster. if i am faster i cannot use this FOF prop and lost 4500Euro



in short they want me to order and risk all, they tell me since 4 month "believe our recomendation as this fits best your cat but don't want to make it part of the sales contract that the cat is not faster in idle then with the 17x15.
so basically its not worth anything if they don't stand behind their recommendation

after going forth and back with the sales team they finally involved the MD keld wrote the same bla bla then their sales team before.


Dear Christian

I´m really sorry if you don´t find our sales process professional.
In my opinion, it´s professional to openly say that besides the engine/propeller specifications, also many other factors will have an affect on specific speed/RPM mesurements under different circumstances (weight, wind, stream, accuracy of tachometer, use of one/two engines etc.).
Especially when very specific expectations and damands are expressed.
Propellers are sized to fit the engines max RPM, not boat speed by idle. Trust the Flexofold propellers will fulfil your expectations, but this just to explain how things works.
If the pitch is reduced 1“, speed will be reduced, but at same time, the max RPM will increase.
So, what´s your preference?

Based on our calculation, general experience etc., we trust that the propellers earlier offered are correct to fit the engine manufacture requirements.

As per earlier email from Marlene, we are - in principle – not going to issue any „carte blanche“ for someone to make whatever decisions/judgement for actions to be covered financially covered by Flexofold.
I trust the same for other propelller manufactures?



I understand that the intensive investigation, comparisons of different propeller types/sizes, different expectations and demands (some potentially contradictory) easily coursed doubts.
We trust our propeller recommendation will make you happy – like thousands of other sailboat owners worldwide.



Best regards,
Keld Willberg
Managing Director


sales process is not professional at all with flexofold as they don't listen what i want and need.



Tend to by kiwiprops now, if too fast i can adjust pitch...cheaper and sales process excelent.

You expect Flex-O-Fold to unconditionally back up their product based on the information you provided about a boat they’ve never seen? And when they refuse to put it in writing you go public with a claim that they are unprofessional?

Unbelievable

[skipmac]

When I purchased my FlexoFold there was a question about the size of the prop. I was told that if the one we mutually selected wasn't right I could return the blades within some reasonable time for exchange for a different size.

[malbert73]

Originally Posted by skipmac

When I purchased my FlexoFold there was a question about the size of the prop. I was told that if the one we mutually selected wasn't right I could return the blades within some reasonable time for exchange for a different size.

Exactly- same for me, and was specified that blades needed to be removed from service and out of water within days. Yes, the costs of the short haul and removal were on me, but still I think that’s above and beyond
I met Keld directly at the boat show and found him very easy to work with and very transparent. I exchanged blades when I repowered which is also a cost effective (1/2 of full prop) way to change up if you change engines or gear ratios.

I do think basing prop calculations on idle speed is really unusual and I can’t imagine anyone writing that into a contract. I haven’t read whole books on props but don’t think there’s any data driven way to ensure what the OP is trying to solve for. Lots of variables that are boat specific

[CaptainRivet]

Originally Posted by fstbttms

You expect Flex-O-Fold to unconditionally back up their product based on the information you provided about a boat they’ve never seen? And when they refuse to put it in writing you go public with a claim that they are unprofessional?

Unbelievable

Yes unbelievable that in 4 month a prop company with a reputation of good products screws up that badly and no one including MD Keld was giving me any substantial explanation, rough indication or anything that answers my request but just believe us and our recommendation.
I don‘t ask for an unconditional backup of their product, please read my post again.
The process in short was like this:
After sending a request for an offer over 2 month that went forth and back with FOF not responding to any of my requirements and just telling me how great their prop fits. As the offer expired during that time I made an order with reference to this offer incl. my 2 must requirements.
Instead of an answer to my request with 2 requirements I got an order form with credit card payment.
So I wrote them that I want my requests part of the order contract because they were ignored. This got then refused, again without any explanation.
So I asked again and then it got finally escalated to MD Keld which wrote the above email, again not trying to explain what their prop does in respect to my one unusual request and what a change from 17x15 to 18x13 means. Also I didn‘t get the offer that I can exchange blades if they don‘t fit.

Another user here finally got what I requested ( and this is what I expected from flexofold to answer), what I needed and what the change from 17x15 to 18x13 means in this 2 requirements:

https://www.cruisersforum.com/forums...ck-264257.html


And „Strangewise“ with the exact same data and requests I got the prop calc and both requirements confirmed by kiwiprop. So if Kiwiprop can do it, why the almighty flexofold cannot do it? They answered my requests, provided the calc and confirmed that I won‘t be faster in idle then now. The 2nd request I had with max rpm at WOT turned out to be a standard warranty requirement from all engine manufacturers when fitted to a engine under warranty. Again kiwiprop states this even in there FAQ and that all props calculated and delivered to fit exactly this requirement but flexofold MD Keld states all reason and excuses while they cannot do it….instead of trying to find a way to convince me.

[CaptainRivet]

Originally Posted by Jim Cate

^^^^^

This seems a forthright and professional response to me, even if they don't give a specific response to your unusual query. Far better to say "we dunno" than blow smoke up your bum. As they point out, there are a lot of variables in determining boat speed at any RPM, and especially at very low speed where flow to the prop is unknown to their engineers.

And re comparing FOF to the Kiwi Prop: You are trading one of the most efficient propellor designs in the field for one with no-twist blades made of a somewhat fragile plastic. Basing the decision on speed at idle seems unwise to me... but your boat, your choice.

Jim

Jim what is one of the most efficient propeller design worth when it’s so efficient that in idle it’s faster then my existing prop which then results that the cat is not maneuverable any more in tight harbours?
Nothing, you cannot use it
My requirement here is give me the best fitting prop but make sure it’s not faster as the current 17x15 fixed at idle speed or the cat gets unmaneuverable.
That’s an issue of the overpowered engines (which I bought like this and have a lot advantages too) fiitted. Have no choice then to take this into account when fitting a folding or feathering prop.

And yes you can give very clear answers which a user was able to give, not FoF:
FoF changes the pitch from 15 down to 13, so it’s slower at idle and it’s higher efficiency won‘t make up for 2‘ pitches down.
Going up in diameter by one from 17 to 18 won‘t add speed in idle.
So both facts ensure I won‘t be faster at idle then the 17x15 fixed.

[Phyrcooler]

Uh… what if going with less pitch results in slightly less resistance through the propulsion system… and your RPM’s jump up a few at idle… defeating your speed reduction plans, and only resulting with you receiving a net loss in performance (cruising and top end speed) and efficiency?

My own experience with boats idling faster than I need to maneuver (hello freaking DD!), is that I slip them into neutral… or… gasp… into reverse if I need to slow down. Giving up performance so you can idle slower is one of the most absurd things I’ve heard in a while. Unless you’re spending your days putting around marina’s, why would you do that? You paid for “overpowered” engines… and then take their traction away? But… I do respect one’s right to exercise their freedom to maneuver - at whatever speeds they are comfortable.

Ok… I’ve had a couple drinks with dinner… and I’m not supposed to drink and post. So… cheers y’all!

[George_SD]

After reading their response and your demands, I think it was professional and within reasonable expectations.

[alamoana]

I would choose a 3 blade prop to minimize vibration of a 2 bladed prop.
You do not need more speed under power, but would like better performance while sailing. Are you sure you could gain 2 kts with new props? Did you try sailing with and without props to confirm this? I believe 2 kts is a lot of speed to gain but I am usually wrong!
A feathering prop such as a Max Prop will give you a better hydrodynamic profile and allow you to change pitch if you do not get it right the first time.
I have studied and used Gerr’s Propeller Handbook extensively on my sailing Privilege cat and it is not easy to get it perfect the first or second time, so a feathering prop of the right diameter where you can dial in the pitch is a good idea.
Maybe new sails or less weight (Lithium batteries) or better rudders will get you a larger speed increase than folding props?
I would sail with and without props and confirm I can get close to 2 kts more speed.
Best of luck!