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Old 08-23-2011, 09:55 AM   #1
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The boat that does not back up

Gentlemen:
I have an interesting case for your further appreciation, in fact, a mystery for me.
I friend of mine bought and used steel 48 fishing trawler. The boat is 18 years old and it has been trolling for shrimp. My friend turn it into a recreational boat, kept the tanks intact, changed the engine from a CAT to a Cummins, new furniture, same prop, nothing new or fancy that could eventually change the balance. As a matter of fact the boat sits leveled on the water with of a load. This past weekend, we took it for a first trial on sea. The boat went on the water last Wednesday afternoon and tied-up on a mooring until Saturday when we decided to sail with it. Here is the problem:
THE BOAT DOES NOT BACK UP IN A STRAIGHT LINE. She goes either side depending on wind or current. In a calm flat water day, which was Sunday, when in reverse, she went one side and then the other for no reason. The rudder is always at 0 degrees. I have never seen such thing! The boat was pulled out yesterday to a dry dock and nothing was detected. The rudder is perfectly aligned with the prop shat and the prop is the same as always has been. We dont know if this problem was already there on the previous 18 years as the boat was bought in a auction. The boat has no bow thruster; you can imagine the nightmare that will be to fit her in a pier slot.
Any ideas?
*
Thanks in advance
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Old 08-23-2011, 10:10 AM   #2
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The boat that does not back up

Virtually all single engine boats will not back straight because of prop-walk. Depending on the direction the prop turns in reverse (clockwise for a right-handed prop or counterclockwise for a left-handed prop), the stern will be moved sideways one way or the other by the prop walk. A right-hand prop will move the stern to starboard in reverse, a left-hand prop will move the stern to port in reverse. There is no cure--- it's the nature of the beast. Competent operators of single-engine boats quickly learn which direction the stern goes when the boat is reversed and they'll use this trait to their advantage while maneuvering or docking.

Other factors like current and wind can also affect the direction the stern swings when backing up.* They may reinforce the prop walk or they may counter or even overpower it.


-- Edited by Marin on Tuesday 23rd of August 2011 10:12:12 AM
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Old 08-23-2011, 10:24 AM   #3
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RE: The boat that does not back up

What you describe is a typical single engine trawler. The effects in reverse are prop walk. The tecnique used to back up in to your slip is called back and fill. How was it going forward at slow speed? Most people with single engines do not back into slips. Easy enough to do but takes to much time. Take the boat to a open spot and just play with it.
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Old 08-23-2011, 10:26 AM   #4
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RE: The boat that does not back up

Quote:
Vyndance wrote:
Most people with single engines do not back into slips.
*Wait... WHAT? :-D
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Old 08-23-2011, 10:36 AM   #5
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RE: The boat that does not back up

*Most people with single engines do not back into slips.

That simply is not true assuming you are not including sailboats. I can back single into a slip better than most twin engine guys. That's not brag, it's just the result of lots of practise. You just need to understand exactly what your particular boat does in reverse, then plan accordingly.

*
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Old 08-23-2011, 10:42 AM   #6
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RE: The boat that does not back up

If you figure out how to get a single screw boat to back up in reverse patent it ASAP b/c you will make a ton of $$$.
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Old 08-23-2011, 10:44 AM   #7
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RE: The boat that does not back up

I always backed in with no problems at all. It was hard to get off the tug bow in.
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Old 08-23-2011, 10:48 AM   #8
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RE: The boat that does not back up

No doubt a single screw can be backed into a slip but the question is can you get a single screw to go any distance in a straight line while reversing?
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Old 08-23-2011, 11:10 AM   #9
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The boat that does not back up

Quote:
Woodsong wrote:
If you figure out how to get a single screw boat to back up in reverse patent it ASAP b/c you will make a ton of $$$.
*It's dead simple.* You use the boat's intertia and transmission to keep the boat moving in a straight line.* I've backed 70-foot narrowboats in the UK--- and these are boats with shallow drafts, absolutely flat bottoms, and no keel or even keel strip to assist in tracking--- for hundreds of yards between rows of boats moored on either side of the canal with only a few feet of clearance to our boat using this technique.* Our boat maintained a steady speed of one or two miles an hour going backwards and tracked a dead straight course.* All it took was judgment of when to give it a brief shot of forward thrust against the rudder to counter the prop walk and keep the boat tracking straight.* The intertia of the boat kept it moving backwards and the brief shots of forward thrust against the rudder kept the stern from walking.

Granted this can become harder if there is a wind to deal with, but in terms of keeping the boat moving steadily backwards while tracking a straight line, intertia and the right timing of the use of forward and rudder is all it takes.


-- Edited by Marin on Tuesday 23rd of August 2011 11:11:33 AM
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Old 08-23-2011, 11:18 AM   #10
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The boat that does not back up

My Goodness, I didn't mean to upset anyone. The buzz word was time jleonard. Every cheap cell phone has video capabilities nowadays. Now remember when you mentioned your practice leading to "your" prowess? I offer this challange:

The boat in your avatar, single screw

Single hand, no help at all, no spring lines.

Beam even with ingress side of the slip

Backed in, one dockline around a cleat

Tide and wind condition of your choosing

60 seconds

$100


-- Edited by Vyndance on Tuesday 23rd of August 2011 11:20:31 AM
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Old 08-23-2011, 11:42 AM   #11
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RE: The boat that does not back up

Bob--- If you can find him you owe this guy $100.
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Old 08-23-2011, 11:53 AM   #12
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RE: The boat that does not back up

. Oh no I've seen that! Must be 30,000 lb aft cabin trawler in his avatar.
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Old 08-23-2011, 12:00 PM   #13
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RE: The boat that does not back up

How 'bout if Jay flies the skipper in the docking contest video up to back his boat in? Does that count? Bet it'll back into the slip in a straight line in less than 60 seconds then :-)
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Old 08-23-2011, 12:36 PM   #14
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RE: The boat that does not back up

Sure. He does it in the first shot for 100 bucks.
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Old 08-23-2011, 01:08 PM   #15
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RE: The boat that does not back up

No, no, you didn't specify in your initial list of conditions that the boat has to be backed into the slip in under 60 seconds the first time. So Jay (or whoever is driving his boat) should be allowed some practice shots.
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Old 08-23-2011, 01:56 PM   #16
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RE: The boat that does not back up

The original challange was to Jay and did not include the fisherman ringer from MD. Therefore if we fly in a ringer outside of the original challange the rules can change. Kind of like someone saying they can hit a Randy Johnson fast ball and bringing Arod to do it for them
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Old 08-23-2011, 05:15 PM   #17
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The boat that does not back up

I hate to take a mans hard earned*money but I'm damn sure I can do it, no practice shots. It's not rocket science just a little skill is all it takes. Now twin engine boat, I don't know. Larry


-- Edited by LarryW on Tuesday 23rd of August 2011 05:16:36 PM
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Old 08-23-2011, 05:25 PM   #18
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RE: The boat that does not back up

Quote:
LarryW wrote:
Now twin engine boat, I don't know. Larry


My dog can back our twin engine boat in a straight line.* Assuming counter-rotating props, a twin--- or at least our twin--- will back straight all day long wind and current notwithstanding.* In fact I will often flip our boat around in a marina fairway and back down*between a pair of*long finger docks with little clearance on either side to an open spot partway down rather than go down the slot*bow first. Going backwards the boat steers like a car with differential power (rudders remain centered all the time).
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Old 08-23-2011, 05:30 PM   #19
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RE: The boat that does not back up

I guess what I mean is I may need a little practice first on the twins. Larry
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Old 08-23-2011, 05:39 PM   #20
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RE: The boat that does not back up

Well, I never said I could do it in under 60 seconds. It's never a rush thing to get docked.

If it was my old Mainship 34 then maybe as that boat had enough power to do it.

The Albin with the deep keel takes a bit to get the stern to behave....but it does behave. Ther boat does only one thing in reverse...it crabs to port no matter where the rudder is. *So knowing that the rest is relatively easy.

*
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