Prop walk and folding props?

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mikehibb

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The old girl has always suffered from severe prop walk to port whilst going astern.
Now this could make me look like the worlds best skipper if the approach to our berth was just to slip backwards with a bit of port.

However we are on t'other side of the pontoon (need a bit of starbaord whilst going astern, med berth stern to etc) and we usually need a nudge from the marina pilot boat to get in first (or second attempt).

Anyway, mortgage will be paid off early 2011, so cash flow will improve and a spare bit will be available for one of these folding prop devices early 2011 season.

Was wondering what their performance is when going astern in general, I know that each individual boat will have its own characteristics, but looking for reports from others that have swapped from fixed 3 blade to a folding prop and any noticable changes.

FYI boat is 33 ft Dufour GibSea, the shallow fin keel version.

(Yes I have already considered asking for a berth on the other side of the pontoon, it would only make me look good when we return home, however we would still look like a vessel not under command when visiting any other places when going astern and slewing to port is undesireable)

Oh just to add, we did get the rudder checked for alignment too, spot on apparently.

As always, many thanks for all positive advice, and thanks to any humorous advice too.

Sorry but a bow thruster is not an option that I would want to look at. (well not yet)

Mike
 
Change of prop on its own unlikely to make any significant difference to prop walk as that is determined by the positioning of the prop relevant to the rudder and keel and the direction of rotation of the prop.

In general folding props are less effective in reverse than fixed, although it varies from design to design. Three bladed feathering props tend to give the best performance both ahead and astern.

Last year YM ran a test on a range of fancy props and discussed the pros and cons of each type. No clear recommendation for one type/design over another and you will find support from users of most of the popular types. Think you have to be clear about what you want to achieve by fitting one - and reduction in prop walk is not something that is easily achievable. The biggest advantage is reduction in drag which can lead to significant improvements in speed under sail - particularly in light airs. Some designs, Bruntons Autoprop for example give superior motorsailing or pure motoring performance in adverse conditions while having reduced drag when sailing.

Whether the benefits are worth the £1-2.5k they cost is for you to decide!
 
changed our 3 blade fixed for a 3 blade volvo folder a couple of years ago, has made no difference to performance under engine ahead or astern, she still goes astern sideways until we get some way on. Under sail is another matter, lots of improvement. However, as others have suggested, the bowthruster we had fitted last year has revolutionised steering astern.
 
Prop Walk

Ours always heads to port in reverse . But as Marsupial says a Bow Thruster makes it even easier in reverse :rolleyes: .. Well worth fitting . Revolutionised Marina berthing . Changed our fixed prop for a folding one . Still got prop walk and you go faster backwards ...... :eek:
 
prop walk is good. Come in at more angle and goose it reverse to walk the transom over. Converse if you are washing your rudder with the prop wash turn the boat hard port and goose the engine in fwd briefly it should throw your tail end back to stbd.
Hope I explained that right this isn't about a bow thruster learn how these pieces behave on your boat first
 
agree with the sentiments re using prop walk to your advantage, it can be very handy BUT when you have no room to get up speed "sideways" the bow thruster wins every time - I never thought I'd say that!
 
Volvo 4 blade folder

I have a Volvo 4 blade folding prop on my She 33 fin keel boat.
Good ahead and astern.
Definitely has prop walk, but I like it.
 
Concurr with sentiments re prop walk won't change with propeller and it's not a bad thing, just learn to use it. It tends to be most noticeable at low speed and medium revs, you'll never stop the stern kicking out when going astern but I find that a short burst at max rpm gives less transverse thrust than a longer burst at lower rpm and when going ahead, if your prop is ahead of your rudder, then make sure you have the rudder set to what you want and give it some welly, the initial steering effect is way more powerful than the transverse thrust.
I'd try to change berth so it was to your advantage rather than spending money on props, bow thrusts etc, nothing against bow thrusters really but they are a hassle, slow the boat down and need a bit of thought re batteries, cables etc. Another idea I liked but haven't tried is to keep a length of chain or similar on a bit of line and dangle it over the boats side or bow to offer resistance, it acts like an dragging anchor but shouldn't get caught on anything.
 
IAN13 said:
But as Marsupial says a Bow Thruster makes it even easier in reverse :rolleyes: .. Well worth fitting . Revolutionised Marina berthing .
Click to expand...

We watched a large modern yacht coming in to a berth in Titchmarsh this summer. There was quite a strong stern breeze straight down the alley.

All very cool on board, crew ready with warps etc. went past us at quite a brisk pace, and I wondered where he was intending to berth - there was an empty slot about opposite us.

Just past our berth he went hard astern and started to reverse into the opposite berth. I was very impressed - no way I would try that with a long keel.

At about 45 degrees and with the stern entering the berth it all went pear shaped. He went hard ahead but the wind took him sideways across the stern of the next boat downwind. Lots of shouting and rushing about.

He tried again with similar result, by now not looking cool at all but very red faced.

We then heard " B****y thruster wasn't switched on" :eek:

3rd time all went according to plan. Lots of bow thruster obviously needed to complete the planned manouvre.

Moral.

If you need some equipment for any planned evolution, make sure it is in place and working befoire you start. :D

I did wonder afterwards if he could have managed the whole thing more easily if he had come in bows first, but of course he could not then have stepped ashore from the built in passerelle. :rolleyes:
 
Rampage (Bavaria 38) has a Brunton Autprop fitted. There's little propwalk with this and its also lots more economical under motor than the standard Volvo 2 blade prop. It also gives us about 1/4 - 1/2 a knot more under sail in a reasonable wind. We had to refit the 2 balded prop this spring whilst waiting to get a new anode for the Autoprop and I couldn't wait to get rid of it. It required more revs to get the same speed under the motor and gave a nasty kick when trying to get into tight spaces.
Don't ask me why the Autoprop doesn't generate propwalk, but Brunton's claim it doesn't in their manual and I've found that to be so in practice.
 
I have a 3 blade folding Flexofold - http://www.flexofold.com/ - and find it very good. Boat does kick to port a bit, but prop bites quickly so with a bit of reverse steer you can reverse straight out. So far so good on a 42ft yacht with no bowtruster.
 
Prop walk is goooooood! I'd rather have a spot of prop walk and use it to my advantage when necesssary. Going for a bow thruster as soon as pennies allow.
 
duncan99210 said:
Rampage (Bavaria 38) has a Brunton Autprop fitted. There's little propwalk with this and its also lots more economical under motor than the standard Volvo 2 blade prop. It also gives us about 1/4 - 1/2 a knot more under sail in a reasonable wind. We had to refit the 2 balded prop this spring whilst waiting to get a new anode for the Autoprop and I couldn't wait to get rid of it. It required more revs to get the same speed under the motor and gave a nasty kick when trying to get into tight spaces.
Don't ask me why the Autoprop doesn't generate propwalk, but Brunton's claim it doesn't in their manual and I've found that to be so in practice.
Click to expand...
Not always true. Our boat has an Autoprop and a wicked kick to starboard in reverse!
 
mikehibb said:
The old girl has always suffered from severe prop walk to port whilst going astern.
Now this could make me look like the worlds best skipper if the approach to our berth was just to slip backwards with a bit of port.

However we are on t'other side of the pontoon (need a bit of starbaord whilst going astern, med berth stern to etc) and we usually need a nudge from the marina pilot boat to get in first (or second attempt).

Anyway, mortgage will be paid off early 2011, so cash flow will improve and a spare bit will be available for one of these folding prop devices early 2011 season.

Was wondering what their performance is when going astern in general, I know that each individual boat will have its own characteristics, but looking for reports from others that have swapped from fixed 3 blade to a folding prop and any noticable changes.

FYI boat is 33 ft Dufour GibSea, the shallow fin keel version.

(Yes I have already considered asking for a berth on the other side of the pontoon, it would only make me look good when we return home, however we would still look like a vessel not under command when visiting any other places when going astern and slewing to port is undesireable)

Oh just to add, we did get the rudder checked for alignment too, spot on apparently.

As always, many thanks for all positive advice, and thanks to any humorous advice too.

Sorry but a bow thruster is not an option that I would want to look at. (well not yet)

Mike
Click to expand...

Darglow's Featherstream prop is claimed to:

Greatly improved reverse thrust over a fixed propeller, it as powerfull in ahead as it is in astern giving less prop walk and outstanding close quarter's manoeuvrability."

I spoke to Bob Doyle and he has convinced me that a Featherstream is a better and cheaper (£1200) option to an Autoprop (£2k).

I
 
ianj99 said:
Darglow's Featherstream prop is claimed to:

Greatly improved reverse thrust over a fixed propeller, it as powerfull in ahead as it is in astern giving less prop walk and outstanding close quarter's manoeuvrability."

I spoke to Bob Doyle and he has convinced me that a Featherstream is a better and cheaper (£1200) option to an Autoprop (£2k).

I
Click to expand...

Different animals. The Featherstream has to have its pitch set, by trial and error, to find an optimum.
The Bruntons Autoprop automatically, (the clue is in the name), adjusts the pitch to suit the ambient conditions, which obviously vary from motoring in calm conditions, motoring against a rough sea, motor-sailing, towing etc.
A mere price comparison is meaningless.
 
Firstly many thanks to all that replied.

To address a couple of points:

Not looking at a bow thruster due to location of water tank.

Yes I know prop walk can be your friend, it was our friend on original berth, made me look like gods gift to close quater handling, we are now on a different berth with different approach. Might try and get swapped back.

Saw the link to those external mounted thruster pods, nice idea, but not sure if I want anything else strapped on below.

Looks like I will just have to perfect the manouvre with more practice. To be honest I think the problem is myself being over cautious with the approach speed. I need to give the old girl more welly astern to get some speed up in order to gain better steering control, on the old berth she would slip in on a little over tick over with the prop walk to our advantage.

Once again thanks all.

Mike.
 
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