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Last Updated on June 3, 2020 by Amy

One of the first projects we tackled in the very early stages of outfitting our boat for cruising was to add folding propellors to our sailing catamaran. Now, after nearly 45,000 nm of total sailing – including a world circumnavigation – here’s our thoughts on folding propellers, and more specifically, our Flexofold propellers.

What are Folding Props and Why Install Them?

A fixed propeller on a motorboat is just fine – a boat on the move is always running their engines, so it’s not a big deal. However, a sailboat shuts off their engines while sailing. This means that the propellor is stationary and creating drag through the water as you sail.

Sail Magazine estimates that fixed propellers could reduce speed by up to 20%. On our 25 longest passages, we averaged 6.65 knots. Dropping by 20% would bring our speed down to 5.32 knots in the worst-case scenario.

A thousand-nuatical-mile passage at 6.65 knots is 150 hours long (6.25 days).

A thousand-nautical-mile passage at 5.32 knots is 188 hours long (7.8 days).

That’s a big difference for a boat that’s going to be sailing a lot of miles!

Additionally, folding props are much quieter under sail.

Drawbacks to Folding Props

Folding props are more expensive than fixed props and more complicated. Our fixed props are just a few parts, while our folding props have more than a dozen parts.

There has been a lot of talk about a descrease in manueverability with folding props, especially when in reverse. However, either because we have higher horsepower engines (55-hp) or the quality of our folding props is good, we have never had in issue with getting enough thrust in reverse. In fact, docking our boat is very easy and our maneuverability is excellent.

Why We Chose Flexofold

In an extensive test, Yachting Monthly reviews 15 feathering or folding propellers. Flexofold performed the best.

Additionally, Flexofolds can be installed easily and while the boat is still in the water. As you’ll see, we’ve tested this many times.

Our Flexofold Drama

We’ve been happy with the performance of our props and with the ease of install. Our folding props were first installed as part of our outfitting process in La Rochelle. Uchimata installed them for us.

HOWEVER, we have lost three propellers since 2014.

It is important to note that our boat has sail drives, whereas some boats have shaft drives. The locking mechanism to hold the propellers in place is different for each, so it seems that the issues are probably common to sail drives like ours.

Lost Prop #1

The first time we lost a prop we were just coming off a mooring ball in the USVI. We realized what had happened, and were able to get back on the mooring ball, call a diver, and locate the propeller on the seabed. We reinstalled the propeller and got back on track.

Lost Prop #2

The second propeller we lost was on passage between islands while sailing in the South Pacific in 2017. We didn’t notice exactly when we lost the prop. Regardless, the sea was miles deep, so we had lost the prop for good this time. We had taken the props off and reinstalled them while hauled out in Tonga a few months prior to this incident.

Once we arrived in Vanuatu, we installed our fixed prop as a back up to get us through till we could get a replacement folding propeller.

The fixed propeller is LOUD. It’s like a tornado under your bed!

When discussing the issue with Flexofold, they gave us some tips for install and said:

“Not even boat services are aware of this every time.”

To me, this indicates that Flexofold is not clearly explaining the installation instructions. And installing folding propellers is complicated.

When we got our folding props while sailing in New Caledonia, we very carefully installed them per specifications. We removed the props while we were at The Boat Works yard in Australia and again, we very carefully reinstalled them ourselves in April of 2018.

Lost Prop #3

Our third lost propeller was in the Mozambique Channel in November 2019. Again, we put our fixed prop back on, and this time we complained loudly to Flexofold. Our propellers had been on for nearly 18 months at this point.

In our discussions with Flexofold, in an attempt to get a replacement under warranty:

“Normally you can not loose a propeller, if all is mounted correctly. We have never experienced the loss of a propeller, if thread locker is fitted and not reused and tab washer is correctly locked and not reused, after taking off the propeller and installing again.”

This time, we KNOW we installed the propellers according to the instructions. And we are not the only ones who have experienced this problem (read forum discussions here, here, and here).

How can you prove an issue with the prop itself when the prop is gone?

We seriously considered changing to different propellers. There are other options out there: Gori, Max-Prop, and Sea Hawk, to name a few. Changing means not buying one prop but buying two props, doubling the cost of repairs.

When it came down to it though, we ordered another Flexofold prop. Will we regret it? Probably.

The prop arrived in Cape Town and we once again installed it ourselves. David took pictures of the entire process to prove that the install was done correctly should we have another situation. We paid extra special attention to the locking nut that you have to bend during the install.

Our plan is to reinstall again before we launch for the 2020-2021 season while we are out of the water and once again, document everything.

Do you have folding props? Have you lost any?

19 Comments

    1. Correction I have the Volvo folding props. They are different assembly. My saildrive and props are being painted today in St Lucia so doing some on the fly research to make sure the worker is following make-up instructions.

  1. As a casual observer with no experience with this prop specifically it would appear (and this is where there may have been a language difficulty) and in their instructions they fail to emphasise the difference sufficiently, there is a critical difference between locking the Main Prop nut by bending the locking tab forwards (towards the bow) and locking the shaft nut locking screw with the same tab by bending it backwards towards you (aft) which they suggest by using a flat head screwdriver. If this final step were to be missed or carelessly bent forward as well then the shaft nut locking screw is redundant and equally the tab on the main nut is achieving nothing and it is only the loctite on the thread which eventually give up and the nut unscrews. It just seems odd that this keeps happening and unless the shaft nut locking screw is the culprit due galvanic corrosion.

    1. Yes, and I think this was what happened in the earlier losses. The instructions were unclear and/or we incorrectly bent the tab. We will be interested to see if there’s a corrosion issue when we take it apart and inspect it every six months.

  2. Yes, we had flexofold props on our Helia (#183) and threw a prop in our second season. Not good, and not happy, they are expensive! Talked to a charter base operator in the Bahamas and he said folders come off all the time, a charter base operator in the VI’s said the opposite, fixed props come off all the time. In the forums, seems to be a recurring problem with both. Recently at Just Cats for extensive commissioning and Rafael convinced us to try Max Prop Easy’s 4 blade 18″, which are feathering not folding. Was told they are virtually guaranteed not to come off (perhaps because they have two shaft locking bolts on the shaft nut?). The performance is fantastic (they pull harder in reverse than fixed props),so time will tell as far as staying put.
    To feather you simply kill the engine while still in forward at about 2-3 knots.

  3. Hi – I tried to leave a reply, but guess my post was too long. We lost a Flexofold last week. The replacement should be delivered today. I am interested to hear if anyone has figured out why this is happening and has come up with a fix other than “following the instructions carefully”
    Neil
    SV Midnight Sun III

    1. Best of luck with your propellers! It is very frustrating, and I have not heard anything beyond that. We are documenting all installations and maintenance on the folding propellers now.

  4. Hey there – a friend of mine just told me about your folding prop experience. We have a 2019 Lagoon 40, which we took delivery of in La Rochelle (Dec 2018) and sailed it back to the USA. So the boat os now 18 months old and has sailed about 10,000 miles total. We were out on a 2-week long sail in the northern Gulf of Mexico and last week lost a Flexofold prop. We don’t know how or exactly when it happened. We motored out into the Gulf, sailed 50 miles and when we went head to wind to drop the sails – we had difficulty controlling the boat. When i got in the water – I was amazed to see a missing prop! The props have never been off the boat since new. We didn’t hit anything, or hear anything….no hull damage etc. I just ordered a new one from Flexofold and it should be here on Friday (amazed at 2-day shipping from Denmark)! I plan to take this up with my dealer and Lagoon as this seems like a bad installation. I plan to haul the boat to replace the prop so I can also thoroughly check the remaining one.

    I have included links not my blog etc. in case you wish to compare notes or try to collectively take this further. There is contact info on my blog.
    Cheers
    Neil
    SV Midnight Sun III
    https://midnightsunii.blogspot.com/
    https://www.youtube.com/channel/UCDCxZopebNN2u2MFDNf4eVA

  5. Howdy Amy & David,
    We do have flexofold props and have never lost anything from either of them. We purchased our 2015 boat in Summer 2018 and the boat came with flexofold props. We did have a haul out in winter of 2018 and had the props removed sandblasted, and reinstalled. These flexofold props don’t require any lubrication as they are lubricated by water…maintenance free . We did talk to the flexofold rep at the 2019 Annapolis boat show breifly and learned that we were not folding the props correctly while sailing or at anchor, you’re correct not much directions from Flexofold in the documentation or on web. The rep said we should always put both throttle levers in full reverse when not under engine power or else the props may not fully fold, which makes the engine spin backwards while sailing or at anchor if your in current.
    All the best,
    Kevin & Mary
    SV Pisces

    1. We have Yanmar engines and sail drives and have been told by Yanmar not to leave the saildrives in reverse. We have fly by wire throttles and were told to stop the engine, then select reverse for about 5 seconds, then shut the power off to the electronic controls… We usually run on one engine and can tell if a prop is not folded by the sound in the stern berths… Yanmar reasoned that there will always be some turning effect from a folded prop and that would exert stress on the gears if left in reverse.

      Other saildrive manufacturers may disagree.

      1. I missed a step…
        1) Engine off
        2) Select reverse for 5 seconds
        3) Throttle back to neutral
        4) Power to controls off

    2. Hey! You reminded me of an important distinction. Your boat has a shaft drive and ours has a sail drive. It’s a different locking mechanism on yours than on ours. I’m going to edit the post to reflect that.

      We put our engines in reverse when they are off, so we are doing that right!

  6. We have FlexoFold props. They are four years old, have had them off three times to replace shaft seals on SD60s… We’ve travelled from Malta to French Polynesia. Not lost one yet. Hopefully I’m not tempting fate…

    1. Hey Rick! Kevin reminded me that there is a different locking mechanism for sail drives verses shaft drives. Which do you have?

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