Forums, Engine, Gearbox, Stern Gear, etc, Darglow propeller

Jerry at 13/02/2013 19:52:35
My Darglow prop was fitted, new, a year ago + a new anode. My boat lives in Portishead Marina. I took it out of water this week to find the anode had completely disappeared. The two retaining screws remained. Could that be 100% erosion or did it break off ?

George Isted at 14/02/2013 12:05:12
If the machine screws are still in place that means the anode has been doing its job. I normally get two years out of Darglow anode but it depends on where you berth, boats in marinas (especially if plugged into shore power and all skin fittings connected to a common earth) will eat an anode more quickly. Do you have a separate anode that the prop/engine are electrically bonded to, that will help.

moongirl at 14/02/2013 19:27:00
On Polar Star I found that there was either very little left of the anode or it had gone completely at the end of the Season. Polar Star was on a HISC mooring & thus not subjected to the electrical problems generated by shore power.

Silver Harmony at 26/02/2013 21:01:54
The first year I had Silver Harmony, the anode fell off the Darglow propeller, taking a chunk out of the rudder on it’s way past. I spoke to Darglow about it and they said that the screws can provide the lowest resistance electrical path from anode to propeller and therefore the anode disappears preferentially around the screws until it falls off, leaving the screws behind. The solution is to make sure the back of the propeller boss under the anode is really clean, to give good electrical contact, and to paint the back portion of the screws before installing them to insulate them electrically. This has worked fine for me for the last couple of years.

rocketman at 01/03/2013 00:01:46
I have had a Darglow prop for over 10 years and spent a fortune on prop anodes. I have always been concerned about the conductivity through the R&D coupling on my Yanmar engine. The electrical path through the R&D relies on a small piece of ‘metal loaded’ foam rubber. This time last year I fitted a Mcduff spring loaded carbon brush assembly onto the prop shaft and the prop anode is showing no sign of depletion after a season, however the main anode may have suffered a little.

Stuart.

GlennG at 10/03/2013 16:38:16
Are they worth it when compared with a £250 three bladed normal prop?

I appreciate there’s a tiny bit more drag, but lets face it, when there’s little wind you use the engine!

Alastair Pugh at 10/03/2013 17:08:37
Ooh, wash your mouth out! “A tiny bit more drag” is an anathema to any hard-racing-antifoul sailor who trimmed his 3" wide two-bladed prop down to 75mm.

Keny at 12/03/2013 09:54:49
One day when I had nothing to do I worked out what effect a standard 3 bladed fixed propeller would have on my boat speed. It worked out at approx. 0.8% at 5 knots. i.e. 1.5 minutes in a 3 hour race, or with my prop. 45 seconds. That could lose you a lot of places!!!
keny

George Isted at 13/03/2013 11:23:55
Ha! I’m with Alastair and Keny. No point in having a clean bottom and good sails if you are dragging around a three-blade sea anchor.

Then-again, if I was just cruising I may not care as much.

Reminds me – I need to check if I have a spare anode in the garage.