How to reduce prop walk.

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cmedsailor

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When going astern (with a FIXED propeller) are there any techiques to reduce prop walk? I read somewhere to give initially short (2-3 seconds) bursts until the boat gets going and then leave the gear. I tried it lots of times but I didn't notice any difference. Any other ideas?
Thanks
 
What boat/keel type?

In general, and you will need some space, give it lotsa welly in reverse until the rudder takes charge - careful, you could break your wrist! Incidentally most peeps find it easier to face aft.
Reduce revs so that you're steadily going astern and steering wherever you want to go - figures of eight if you wish.

Warning: this topic comes up regularly and a certain SCOD owner reckons there's no solution!
 
36 feet, around 6 tonnes, fin keel.
If there is space there is of course no problem. Prop walk is sometimes useful. Also if I have space I first bring the boat at an angle that enentually will come to a straight line when start moving. But, sometimes things are not easy and you need to go as straight as possible.
 
Snick in and out of reverse with very short and gentle bursts to get her moving. Aim to get the water flowing over the rudder without the prop taking charge.

Remember propwalk is your friend, with practice you'll be able to berth your boat like a Jedi master.

"Feel the Force, Luke" /forums/images/graemlins/cool.gif
 
Imagine if the boat is going asterrn and the prop is "screwing" itself nicely through the water - no prop walk.

Now imagine the boats stationery and the prop thrashing the water like a paddle wheel steamer - that why it goes to one side when going astern - when the prop is thrashing. Rudder has no to little effect when there is small water flow over it.

So as others say - gentle power astern to get boat moving reduces prop walk, alternate between astern and neutral if necessary. Use prop walk as an assistant to a quick turn by applying too much power when necessary
 
I used to have a 40 footer that was a nighmare astern.
I tried everything, even a larger prop which did improve things a bit, but not that much.
Occasionally, everything worked perfectly and I could moor the bugger with just an inch either side, other times, most of the times it was a right cow.
There are so many variables, speed of boat, prop revs, cross wind.....the list is endless. I just leant to adapt to each different condition, but I must admit, I never mastered it.

My new boat, however is a completely different story. Big rudder, prop in a different position, relative to the keel, rudder etc and hull shape. This one's a honey to moor, even SWMBO has a go every now and then.
 
Lots of ideas on this one; not surprising given the variety of different designs.
Here are some notes I made years ago - may given you some ideas for your own experiments:
Single engine, RH prop, going astern.

1. Prop wash runs forward over the starboard side of the hull, (not over the rudder), and causes the stern to move to port.
2. There is some suction effect on the rudder but less effective than positive prop wash, so dominant force is the wash over the hull and tendency to turn to port.
3. Until the boat gathers way the rudder does NOTHING. Prop wash against hull is dominant.
4. Once there is way on the rudder will take effect. Turning to port will be relatively easy; turning to starboard may be impossible even with full revs!
5. When turning to port all four dominant forces are in your favour – prop walk, prop wash, suction on the rudder and rudder turned to port (left rudder).
6. When trying to turn to starboard the only effects in your favour are suction on the rudder and rudder turned to starboard and these forces are the less dominant ones. Putting on more speed will enhance these effects so they catch up with, and hopefully surpass the other effects.
7. Design of the boat determines how much right rudder is needed to keep the boat moving astern in a straight line.
8. If the boat gradually moves off to port even with a lot of right rudder on, then allow it to do so within the constraints of the channel. As you run out of space on the port side of the channel, give a big burst in forward to kick the stern to starboard and then go back into gentle reverse. You will proceed in a saw tooth shaped course down the channel – to applause from watching bystanders!
 
Direction of wind will make a huge difference to what happens when you start to reverse. Think about what will happen to your boat if you just stop, given the present wind direction & speed. Then, consider how she will react if you were to go astern with no wind. Now add the two together and that is what will happen. It may be that the two turning moments cancel each other out (prop walk pushes her stern to port, but wind on starboard tends to push bow off to port as well) or it may be that they aggravate each other. Set her up for the reverse manouver so that prop walk & wind effect help you get where you want to be. This is not simple, you need to practice both reversing AND let her find her natural stance in different wind conditions to know how she will behave.

Read Stuart Quarrie's book "Helming & Yacht Handling" if you want a better & more detailed explanation. And remember, plan what you want to do, do it & observe what actually happens, then review the differences between what you expected & the actual to understand the process better.

This "Plan_Do-Review" process is known as the "Kolb Learning Cycle" and is extremely useful - almost a philosophy for life as far as I am concerned.
 
Everytime you come into a marina/harbour instead of going straight to your berth have a play at manouvring your boat. Start with lots of room to mess about in and then reduce it each time. Try it with wind from different directions and different strengths of wind each time - make it hard for yourself and learn about your boats 'character' - sometimes it's good to know that it's just impossible to make your boat go in a direction that it was not designed to go in. Better to go in forward than to embaress yourself trying to do the impossible.
 
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36 feet, around 6 tonnes, fin keel.
If there is space there is of course no problem. Prop walk is sometimes useful. Also if I have space I first bring the boat at an angle that enentually will come to a straight line when start moving. But, sometimes things are not easy and you need to go as straight as possible.

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If its that tight use a warp as well, ther are more ways of controlling a boat than just the engine. (I do miss the sweeps my previous, wooden, boat carried)
 
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As you run out of space on the port side of the channel, give a big burst in forward to kick the stern to starboard and then go back into gentle reverse.

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That's what I said.

Make use of the fact that a burst ahead is instantly directional (because the water stream is directed straight past the rudder) and comes into play before the boat has actually gathered any forward way.

You can use the same effect to get out of a tight mooring by giving a forward burst on full rudder to swing the bow in and the stern out, then switch to slow astern and go out backwards.
 
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