Could the Brunton autoprop be what I need?

Nice prop for sail performance, tends to hum a little under engine ( Audible from everywhere on the boat ) Worth getting the anode hole machined out in the boss to fit a readily available anode though as the Brunton version is nearly 40 quid and a normal one is £8.50 !!
Your decision but if it is only to improve motoring performance stick with a fixed prop and save £££££££££s ...
 
From another angle, if you increase your speed in waves, the boat will become a U-boat and everyone will be misserable. If your prop is RH and your shaft 30mm you can experience increased sailing speed with a Kiwi prop I sale in For sale section with as little as 400GBP.
 
davidej said:
GrumpyOldGit said:
Worth getting the anode hole machined out in the boss to fit a readily available anode though as the Brunton version is nearly 40 quid and a normal one is £8.50 !!
QUOTE]

That sounds a really good idea - how do you do it?

What anode do you fit?
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Took the new prop to a bloke called 'Terry' in Brightlingsea with an anode from Heron Yacht Services ( Dauntless in Benfleet) that was a similar shape and size and said ' Can you make the boss accept this anode' ? he said Yep and job was a goodun. cost £20 to get it done and bolted straight on. Any decent engineer can do the job in half an hour. Just make sure the new anode is a standard size and not a one off !
Good luck and happy sailing:)
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I use an Autoprop H6-504 on Sun Odyssey 45 in the Med - certainly saves fuel, whether enough, can't say - it cost me €3,400 in 2007! But it gives me no problems and the grease change each year comes out as if hardly used - no water ingress or signs of wear.

I'd also like to know how to modify to take standard anodes....
 
I have one of the original Autoprops, 20 years old and about 8000 hrs.
It's just had the 2nd set of bearings fitted and needs bearing adjustment every 2nd year.
IMHO its greatest benefit is the improvement in motor-sailing, especially in the Med where its been for the last 6 years.
Reducing wastage of prop anodes is best served by fitting a shaft anode - the boss nodes last about 2 years.
Other props offer lower drag, but few such effective performance in adverse conditions and in reverse. Whether it's worth the premium is doubtful, unless you want the cruising benefits offered by the prop. Mine cost only £800 in the days when a comparable 3-blade fixed prop cost £100.
Ensuring it doesn't get too fouled is down to how effectively you burnish the propeller - I use a 3M polishing pad then several polishes using metal polish, followed by polishing with GRP polish, which does reduce the number of barnacles and tubulars that can gain a foothold.
For me, its probably been the best investment I've made on the boat, my hourly consumption averages about 1.3 litres/hour, but motor-sailing rpm are less than 2000 engine rpm.
The prop is slightly small for the current engine - which gives me 7.6 knots in still water at 3600 max rpm on a 29'10" LWL.
 
Last edited:
charles_reed said:
I have one of the original Autoprops, 20 years old and about 8000 hrs.
It's just had the 2nd set of bearings fitted and needs bearing adjustment every 2nd year.
IMHO its greatest benefit is the improvement in motor-sailing, especially in the Med where its been for the last 6 years.
Reducing wastage of prop anodes is best served by fitting a shaft anode - the boss nodes last about 2 years.
Other props offer lower drag, but few such effective performance in adverse conditions and in reverse. Whether it's worth the premium is doubtful, unless you want the cruising benefits offered by the prop. Mine cost only £800 in the days when a comparable 3-blade fixed prop cost £100.
Ensuring it doesn't get too fouled is down to how effectively you burnish the propeller - I use a 3M polishing pad then several polishes using metal polish, followed by polishing with GRP polish, which does reduce the number of barnacles and tubulars that can gain a foothold.
For me, its probably been the best investment I've made on the boat, my hourly consumption averages about 1.3 litres/hour, but motor-sailing rpm are less than 2000 engine rpm.
Click to expand...

Have found that a really good check of AutoProp performance is to keep record of speed at 2000 RPM - as soon as it is at all depleted - a quick dive and pan-scourer job on prop and shaft is all that is necessary to restore peak performance - max of twice per season in Med.
 
pmyatt said:
Have found that a really good check of AutoProp performance is to keep record of speed at 2000 RPM - as soon as it is at all depleted - a quick dive and pan-scourer job on prop and shaft is all that is necessary to restore peak performance - max of twice per season in Med.
Click to expand...

I'm sure you have the right approach. Our problem (I think) is that we believed the claims for the snake oil applied to the prop at the last lift-out :eek:
It didn't work. And we are trying to keep things going until we're out again, probably next year.
 
gnatsis said:
From another angle, if you increase your speed in waves, the boat will become a U-boat and everyone will be misserable. If your prop is RH and your shaft 30mm you can experience increased sailing speed with a Kiwi prop I sale in For sale section with as little as 400GBP.
Click to expand...

Reading through this long thread I'm seeing slightly conflicting stories on this point.

I am interested in changing from my old-fashioned 2 blade folding prop to something that will give me better bite in the water into waves and headwind.

I am very happy in flat water - can reach over 7.5kts but as soon as the chop builds it falls off fast and I want to at least maintain 6 kts without dialling up the revs to 3000+ (35ft boat, Yanmar 3GM).

If I also get better fuel consumption then that is a nice by-product but not the primary objective.

So clear question, will this Brunton thingy improve grip into a seaway and help me maintain decent boatspeed for the same revs?
 
Rob_Webb said:
...will this Brunton thingy improve grip into a seaway...
Click to expand...

Yes, assuming correct sizing etc. There should be much less cavitation than that produced by a fixed-pitch prop.


Rob_Webb said:
...and help me maintain decent boatspeed for the same revs?
Click to expand...

Same as what?

The primary ability of the Autoprop is its self-pitching facility. It's akin to an automatic gearbox of the CVT variety. For any given RPM the prop should adjust its pitch to give the maximum boat speed.

Flat water and little wind require a coarse pitch for best speed. The rougher the conditions, the finer the pitch needs to be for the prop to function correctly. I understand that a fixed-pitch prop is usually sized to give 'hull speed' at about 85% of maximum revs in moderate conditions.

Consequently an engine attached to a fixed-pitch prop needs to rev higher, to achieve boatspeed in quiet conditions, than one connected to an Autoprop. And in rough weather the Autoprop 'gears down' in much the same way that a vehicle autobox changes down when climbing a steep hill.

Highly reccommended.
 
Think you should look at whats recommended for your boat as first priority. Bav. have a set of tables with prop sizes for (in your case) the 2030. I have a 37 and spent a winter agonising over a similar issue. Priced around all the suppliers with huge differences in prop sizes and prices and eventually purchased the recommended 3 blade folder. About half the price of an Autoprop. Same boat speed for 500/600 RPM less and lovely balanced engine performance (sort of a "purr" now instead of "drum drum drum" sort of noise.
Anyway thats my experience if it's any help.
 
jackho said:
Think you should look at whats recommended for your boat as first priority. .
Click to expand...

Recommended by who? The factory (Beneteau in my case) was fitting as standard prop either a Radice K11 2-blade fixed 16X11 (which has proved to be the correct size) or a Radice E13 3-blade fixed 16X10. They don't make any recommendations for folding/feathering propellers (I believe, though to be honest I have never asked specifically for those).
 
I have a 3 blader Autoprop on my Westerly Sealord. Very pleased with it.
I notice when under sail it outpaces all the other boats of similar LOA in sight. It adds at least 1 1/2 knots with a clean bottom and a polished prop.

Some recommend that the gearbox be locked in reverse. I don't like this idea. I invested in a custom built locking mechanism manufactured in the USA by SHAFT LOK INC., which ensures the Bruntons does not continue to spin whwn sailing. This is a wise precaution to take as not all gearboxes are independently lubricated. Also it stops shaft noise. All you hear is water rushing past the hull. Bliss !.

The SHAFT LOK is a clamp arrangement that fits around the shaft in the engine room. Locking is controlled by a control wire with a pull button.
Unlocking is controlled by when starting the engine, giving the boat a very brief kick astern. This is sufficient to disengage the clamp. Brilliant !
 
cmedsailor said:
Recommended by who? The factory (Beneteau in my case) was fitting as standard prop either a Radice K11 2-blade fixed 16X11 (which has proved to be the correct size) or a Radice E13 3-blade fixed 16X10. They don't make any recommendations for folding/feathering propellers (I believe, though to be honest I have never asked specifically for those).
Click to expand...
Apologies , thought you had a Bav. however very similar disp. Anyway Volvo can advise as they will match the engine and gearbox ratio to their range of folding props for boat displacement. Also D B Marine Sales I found very helpful 01628 526032 who also have an excellent data base of boat specs.
 
charles_reed said:
I have one of the original Autoprops, 20 years old and about 8000 hrs.
It's just had the 2nd set of bearings fitted and needs bearing adjustment every 2nd year.
IMHO its greatest benefit is the improvement in motor-sailing, especially in the Med where its been for the last 6 years.
Reducing wastage of prop anodes is best served by fitting a shaft anode - the boss nodes last about 2 years.
Other props offer lower drag, but few such effective performance in adverse conditions and in reverse. Whether it's worth the premium is doubtful, unless you want the cruising benefits offered by the prop. Mine cost only £800 in the days when a comparable 3-blade fixed prop cost £100.
Ensuring it doesn't get too fouled is down to how effectively you burnish the propeller - I use a 3M polishing pad then several polishes using metal polish, followed by polishing with GRP polish, which does reduce the number of barnacles and tubulars that can gain a foothold.
For me, its probably been the best investment I've made on the boat, my hourly consumption averages about 1.3 litres/hour, but motor-sailing rpm are less than 2000 engine rpm.
The prop is slightly small for the current engine - which gives me 7.6 knots in still water at 3600 max rpm on a 29'10" LWL.
Click to expand...
Hi Charles, I'm considering to switch from fix-pitch to Bruntons. U say u burn 1.3 l/h when motorsailing, could u estimate (recall:)) your consumption with fixed blades? And what is your boat & the engine?
 
Skysail said:
+1, they are often recommended. But most people buy them to improve sailing performance, the motoring benefits are less obvious.
Click to expand...

I have one (I inherited it with the boat) and what an extraordinary piece of kit, I can get 7 knots at 2100rpm and I seem to be able to sail a little faster than faster boats (on paper) than mine even with crappy sails and as I am not a particularly talented sailor I put it down to the auto prop
 
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