DuoProps - how long do yours last?

[klr650steve]

Hi
I am getting about 2 years use out of a set of props on a sealine S34 which is 5 years old with only 170 hours on it, I have just fitted the 3rd set of props so that equates to 85 hours use per set.
The props are genuine Volvo penta, the boat is fitted with a galvanic isolator and standard anodes plus an additional one fitted to each leg. The props appear to be damaged by cavitation and end up with holes in big enough to put your finger through.

I have taken the old ones to a prop repair company and the forward props were repairable, the aft props were beyond repair.

Any ideas?

regards
Steve

 

[ajay]

I used to get about 2 years (~200hours but time in water more important than hours really)
Same with you, forward was usually reusable or perfect, aft has pitting / some galvanic corrosion making it not sound to repair.

Check with a multimeter you have a low resistance path (ideally less than 1ohm) from your prop (scrape a pin hole down to the metal) to your nearest anode (collar usually)

Depending on your leg and manufacturer some combos never have proper protection. eg 290 volvo leg duoprop, aft prop has a rubber bush and no continuity through the hub.

Other thing to check is you dont have AF spray on the parts that make the electrical path to anode, such as the nut on the aft prop, the blunt end of the nose cone etc.

I found the aftermarket duo props better made than the volvo ones, they have thicker blades making repair easier. I think they were made by powertech and distributed by proprev (but I think this distro is no longer around as the web site is dead)

 

[MapisM]

You might be interested in my post #3 within this very old thread.
Obviously, not much has changed since then...

 

[[2068]]

Rears went a bit thin at 500hrs / 6 years.
Fronts are the originals.

 

[RIN]

We get around 4/5 years

Last ones put on were not Volvos and seem a little bit thicker. Still in good nick after 3 years

 

[CX54WEK]

Not long, as we are on the river we tend to bend them before they rot away

On a serious note, we have two sets which we swap around when one set is damaged. We are lucky if we get six months before they need swapping and repairing. No sign of rot/corrosion on them though when they do come off, just lumps missing or the ends bent over.

The set that are on now are damaged we found out when she was lifted for a quick repair on a leaking ram. We hadnt noticed (normally get a bad vibration) but it transpires that the rear blades are all bent in the same fashion. Doesnt seem to be making much difference to performance either as we got her top speed with them on a couple of weekends ago!!!

 

[KevB]

buy stainless?

 

[CX54WEK]

buy stainless?

What and send the shock through the gearbox instead of the props? No thanks.

The OH can repair them if they are not too bad and failing that they get repaired for £40 plus postage so not the end of the world.

 

[enterprise]

Stainless

Agree, get stainless, we are on our third season with C6's which are a replacement for the Alu A7's.

Not a mark on them, no corrosion or damage, no antifouling required, just a polish with a hard wax like Colonite lasts a whole season, wipe the surfaces of with a sponge when it's been standing for a while to remove the slime.

Not sure why your worried about shaft damage, the rubber bushing in the hub would save the drivetrain.

Only downside is price £1200 for two sets from EBY 3yrs ago so probably about the same now.

Protection is more critical with stainless props, the anodes were changed to Mil Spec Alu which last the whole season with approx 75% wasted when changed.

 

[Scubadoo]

I had the same problem as you when I first got my boat, the props lasted about two years before being pitted and beyond repair. However the boat has done about 700hrs and on it's 3rd set in 11years.

The key thing I discovered, the normal antifouling paint and the prop base coat paint just comes off after a while, once the bear Alu is in contact with the sea water they don't last long i.e. pitting.

So when I got my 2nd new set I rubbed them down to the bear Alu and then painted on 4 layers of epoxy, then two coats of antifouling paint. During the season the antifouling starts to flake off but the epoxy remains. The reason I ended up on a 3rd set recently was because of some damn fishing rope that damaged the prop hub.

 

[Scubadoo]

Not long, as we are on the river we tend to bend them before they rot away

On a serious note, we have two sets which we swap around when one set is damaged. We are lucky if we get six months before they need swapping and repairing. No sign of rot/corrosion on them though when they do come off, just lumps missing or the ends bent over.

Crikey you do go through your props only lasting 6months. How comes you ding your props so much?

 

[seawings222]

Try stainless, have mine on 6 years and no problems.

 

[PaulGooch]

Not long, as we are on the river we tend to bend them before they rot away

On a serious note, we have two sets which we swap around when one set is damaged. We are lucky if we get six months before they need swapping and repairing. No sign of rot/corrosion on them though when they do come off, just lumps missing or the ends bent over.

Crikey you do go through your props only lasting 6months. How comes you ding your props so much?

Women drivers

 

[CX54WEK]

"Crikey you do go through your props only lasting 6months. How comes you ding your props so much?"

The river we are on is only about 5ft deep at best (less in places), any obstructions that get thrown in or dropped in clip the props and bend them. We take her to some places she really isnt at home (The nottingham or selby canals spring to mind) and on top of that she does between 300 and 400 hours per year. So at 6 months they will have done between 150 and 200 hours. A few dings and lumps missing are to be expected.

The worse trip we had was going to York last year. We picked up a tree (not a branch a tree) on the tidal Ouse, between the props. It didnt stall the engine but ripped off 3 of the 7 blades. We limped into York and found a spare set at Linton Lock Marina. Had them changed the next day and a few hours later grounded her going up the River Ure bending the blades on the new set. We limped back to Lincoln on that set but it was painfully slow going.

 

[CX54WEK]

"Women drivers "

Cheeky git. I will have you know i have not been at the helm during any of the prop incidents

 

[Teddy]

Original Duo Props - 16yrs

My Duo Props fitted to my Sealine 330 are still original after 16 yrs.

First 5yrs in sea and remainder mainly on river (Thames). Every 2 yrs they are Tri-Luxed and have small ares of pitting, also a few small chips on blades.

4 yrs ago I stripped back to ally, etch primered, Primoconed, then Tri-Luxed. I'm sure they are good for a few more years yet.