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-   -   Prop walk combined with wind (http://www.sailnet.com/forums/general-discussion-sailing-related/97891-prop-walk-combined-wind.html)

LakePirate 03-26-2013 11:02 AM

Prop walk combined with wind
 
I moved to a new slip and started backing stern in. I haven't had to deal with heavy wind while doing it yet, but some high winds this past weekend got me thinking about the ramifications of it. My first question is if the prop walk is to port does that push the bow to starboard or just pull the stern to port? If it pushes the bow to starboard will a starboard wind help keep the boat movement straight? And would a port wind make the boat turn to port must easier? If these are true, then would it be easy to remember when backing down the alley I would always want the wind to starboard since I have prop walk to port?

MarkofSeaLife 03-26-2013 11:14 AM

Re: Prop walk combined with wind
 
Lol great question because it will depend on the turning moment of your boat.

The prop walk pulls your stern towards the port, but the bow will remain where it was.

On my boat I would prefer the prop walk, normally, into the wind so I can get off easier. But that's for fuel docks etc, I don't have a slip.

Can you go in bow first if necessary? Then, after you have worked it out you can go in bow or stern first depending on the conditions.

flandria 03-26-2013 11:24 AM

Re: Prop walk combined with wind
 
Good advice from MarkofSeaLife...

You will quickly know that, as you slow down into the slip, the power of the wind will be greater than propwalk or simple forward/backward momentum you still have. I have seen people do it in all sorts of conditions, most of which I would be unable to duplicate. It all comes down to a lot of experience, practice, getting to know your boat very well under ever more challenging conditions. But, as mentioned, when in doubt, go in bow first with the greatest possible amount of control.

jrd22 03-26-2013 12:13 PM

Re: Prop walk combined with wind
 
A lot depends on your boat; keel configuration, windage, etc. On my boat with a fixed three blade prop the stern moves quickly to port when in reverse at low rpm but tends to go straighter if I rev it up considerably. I also disagree that the bow stays put when the boat rotates to port at the stern, it turns on it's axis and the bow will hit the dock as I back out unless someone walks it out or I use a lot of throttle. Our boat with two furlers on the bow has quite a bit of windage forward of the mast so the wind moves the bow much faster than the stern so I need to take that into consideration (it actually helps to keep the boat backing straight if there is a wind from stb). Each boat is different and it's a matter of trial and error IMO.

SolSailor 03-26-2013 12:15 PM

Re: Prop walk combined with wind
 
Great advice above... and I agree that the wind will be a much bigger factor than the prop walk, so accounting for it's action on your bow will most likely override most everything else.

We also back stern into our slip at our Marina. Took some getting used to, but a few basic pointers helped me get the hang of it. I point this out not so much for you or many of the readers, but for other newbies like me that often forget about the basics...

1. In forward, you get steerage almost immediately because you are pushing water over your rudder (at least for my boat). In reverse, you will only get steerage once the boat starts moving a bit because you won't have any water going over the rudder until then. This means I keep my rudder almost centered until I can steer... and to take your wind action into account, I may have to put my bow a bit to windward to begin with so that it's not completely "out of whack" (very nautical term here) before I get steerage.

2. The prop walk for my boat does push the stern to port... but does nothing for the bow. I tend to line up in my alley pointed a bit to port before I start backing down, that way when I finally do get steerage my boat is lined up a bit better.

3. The prop walk for my boat tends to be less when short bursts of throttle (with a little ooomph) are applied, rather than a slow continuous throttle. This might be different for your prop... YMMV.

4. On a couple of occasions in heavier than usual wind, I just put the bow in first and worry about it later.

aa3jy 03-26-2013 12:33 PM

Re: Prop walk combined with wind
 
Lots of variables..

Free-board; Fin vs. Full Keel; barn door vs. spade rudder; left turning vs. right turning prop; wheel vs. tiller..I'm sure there are few more like Experience with the vessel

sailingfool 03-26-2013 12:37 PM

Re: Prop walk combined with wind
 
Any of the turning motions, such a prop walk, rotate a sailboat about its keel, more specifically I expect it is the CLR point, which we should appreciate from the weather helm/lee helm discussions.

If the stern is moving to port, the bow is moving to starboard. A bow thruster has the same affect...

jackdale 03-26-2013 12:45 PM

Re: Prop walk combined with wind
 
Quote:

Originally Posted by sailingfool (Post 1008102)
Any of the turning motions, such a prop walk, rotate a sailboat about its keel, more specifically I expect it is the CLR point, which we should appreciate from the weather helm/lee helm discussions.

If the stern is moving to port, the bow is moving to starboard. A bow thruster has the same affect...

Yep.

And that is why you can turn a boat in its own length by turning the wheel hard over and using prop walk to spin it on this keel. That works best with fin keel boats and no wind or current.

If you find you have too much prop walk, put the transmission in neutral. If you want more prop walk, throttle up.

Some saildrives have little or no prop walk. And some of those that do walk to starboard.

kellysails 03-26-2013 01:49 PM

Re: Prop walk combined with wind
 
My saildrive with MaxProp, zero prop walk. The boat backs up like a dream, never been on another boat like it.

BarryL 03-26-2013 02:05 PM

Re: Prop walk combined with wind
 
Hey,

My boat (O'day 35, shoal draft fin keel, fixed 3 blade prop) has moderate prop walk. On my boat (YMMV) the stern moves to port but the bow stays in place (assuming no wind).

When docking I use prop walk to my advantage in that I approach with dock lines and fenders on port. I motor to the dock at a 45 degree angle to the dock with the engine in forward and at idle speed. When I'm 50 feet or so away I place the transmission in neutral. When I'm 1 boat length from the dock I place the transmission in reverse. The boat slows, the stern swings towards the dock, the bow continues to get closer and when the boat is against the dock I place the engine in neutral, step off, and tie up.

I can turn the boat on her axis by placing the rudder hard over to starboard and alternating between reverse to forward.

Pulling into a slip stern first is not something I do very often and I'm not good at it. Add some side wind and I am not happy. I had to do that a few years ago when staying in block island and it took me about 15 minutes to get into the slip. I didn't damage anything and eventually my heart rate and blood pressure came back down.

Barry


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