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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
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.”
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.