#1 2019-10-18 15:43:01

Philip_Rowcliffe
Member
Registered: 2014-10-10
Posts: 9

Darglow Feathering Prop

My V800 came with a Darglow prop when I bought her, but I'm just wondering whether the benefits really outweigh the disadvantages over a fixed prop, and would appreciate comments from other feathering prop users (or ex-users). As I see it, the disadvantages of the Darglow are a) annual maintenance required b) cost of anode replacement (at least once a year and expensive) c) mechanical, therefore more to go wrong d) more noisy than fixed prop (according to another posting on this forum). Alleged advantages are a) better performance in reverse b) better performance under sail. As far as performance in reverse, my boat still has a mind of her own and for performance under sail, I really don't know. Any thoughts / comments would be appreciated. I've looked at earlier postings on the site and, to be honest, I remain unconvinced of the benefits.
Thanks, Phil

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#2 2019-10-19 22:36:14

Don_Smith
Member
From: Chester
Registered: 2017-06-25
Posts: 29

Re: Darglow Feathering Prop

Phil,
My boat and I have an unwritten agreement; I decide where Triptych (V34) goes forward and she decides going astern. As time goes on I am getting more familiar with her quirks and therefore better at anticipating what she'll do.

Some tricks I use astern include:
1  Walking the boat off the finger to avoid prop walk, give a final shove and jump on
2  Minimal use of steering, it's a brake
3  Short bursts of astern, nothing too aggressive
4  Tow a bucket from the starboard quarter to counter the slither to port
5  Use a running spring from the starboard quarter to nudge the stern round or spring off generously if more appropriate
6  Read the wind to anticipate your bows blowing off
7  Read the water if there is tide under you
8  Read Duncan Wells 'Stressfree Sailing' and devise a few dodges of your own.

I put a Darglow prop on Triptych. I think she is better behaved astern than previously and I have no doubt drag has been reduced. The annual maintenance I think is worth it.

Hope that helps,
Don

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#3 2019-10-20 11:03:32

Jonathan_Hopper
Member
Registered: 2004-03-23
Posts: 93

Re: Darglow Feathering Prop

Maintenance - if you come out annually to antifoul, then adding greasing the prop to the list is not particularly onerous.   Anodes are expensive, but not annual in my experience.   I have had 2 anodes in about 7 years - though it is possible that using Velox prop antifoul has helped with this.   

Performance.   Under way it has more thrust in reverse but less thrust forward for the same prop size.   It is also quite noisy.   Under sail, particularly in light airs, performance is better.   If you are someone who say passagemakes and requires a speed of 4kn+ and so used the engine more, then perhaps there is less gain.   However, if your 'turning the engine on speed' is 2kn, then you will probably notice more of a benefit.

Depending on the shape of your rudder you may need to cut a little bit out to.

Overall, keeping the hull and propeller clean will probably have a bigger effect on boat speed than feathered prop.

Reversing ability - I find having a bit more thrust useful.   You can get to a speed where some helm will eventually respond much quicker, but also if you are using forward to steer you can use any space better knowing you can stop quicker.   If your rudder has a big cutout (I don't believe the 800s generally did) then it is worth filling this in.   However, don't think that more thrust by itself will change the lack of steering astern - that is all down to technique.   It might have less prop walk, but compared with some set ups I have never found prop walk to be particularly pronounced anyway.

All the options available are a compromise, and I think somewhat depends on what sort of sailing you do.

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#4 2019-10-20 15:04:24

John_Willis
Member
From: Guernsey
Registered: 2017-04-07
Posts: 34
Website

Re: Darglow Feathering Prop

Hello Phillip,

I have a 1997 Francis 34PH with Yanmar GM30F, fitted with a Darglow feathering prop.  Although I have only had her since 2017, together we have done well over 4,000 nms with plenty of motoring.

I agree with Jonathon on maintenance and anodes - its not a big deal. 

As to being more noisy, personally I don't think so, but then I do have tinnitus.

I have found both the Darglow and Kiwi prop to be very robust, happily surviving entanglements with wretched lobster pop tethers etc.  In 15 years of feathering props, I have never had a breakage.

I can't comment on reversing, as I don't know what she was like before, but she seems to have reasonable pull.  As to the propwalk, strong to port, if I can't get it to work to my advantage - i.e. having to reverse back and to starboard - I am lucky enough to have a bow thruster.

I can comment on motoring forwards.  Suspecting that she was a little on the slow side, I did a test on a calm day, when the tide was slack.  I recorded her speed in both directions, increasing the revs by 500rpm on each run until I got to to the maximum. It took a while, but seemed to prove that she was indeed around half a knot slower than Darglow predicted.  This might just be that she is a heavy old girl and/or that a feathering doesn't give as much shove going ahead.  They suggested I fit a cassette, which they would supply at a price, but I haven't got round to it so can't comment further.  In conclusion, IMHO, I think a fixed prop would give better shove motoring ahead.

HOWEVER, I do think that the sailing performance is noticeably better - true that is subjective, but I had another 34 footer where I had experienced both props and it was definitely the case.  Same with my Sadler 290 and Kiwi prop.  As I often do longer trips, that is important for me although I am no racer.  So, if sailing's the priority, a Darglow or similar might be worth it; if one motors a lot and sailing performance is not so important, perhaps not.

Finally, somewhere I have a copy of PBO (I think) with a very comprehensive comparison test of a variety of feathering and fixed props - that might be worth getting hold of.

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#5 2019-10-22 15:23:17

Philip_Rowcliffe
Member
Registered: 2014-10-10
Posts: 9

Re: Darglow Feathering Prop

Thanks very much for the comprehensive replies, much appreciated. I think I'll let sleeping dogs lie, and keep the Darglow. As always, there are still plenty of other boat projects to get on with.
All the best, Phil

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