Backing

markpierce wrote:rwidman wrote:
Nearly everyone at my marina backs into their slips. All the wet slip holders do. Once in a while a dry stack customer will take a slip for a weekend and a few of them pull in.

It's a pretty social place so there's a lot of getting on and off the boats, entertaining, etc. We couldn't do that bow in.

Click to expand...

*What do your marina mates think of*those (non-believers)*who dock bow-in?* With boats stern-to-stern, are there frequent and loud conversations between boats?**Are all/most the vessels*twin-engined motorboats with few or no sailboats?*

Most of us don't know the people who dock bow in and they are only in the water for a day or two.* They come to the marina, get in the boat and go.* Come back, get out of the boat and leave.* Dockhands will put the boat back in the drystack racks.

No frequent loud conversations between boats.* Actually, most of us put tables and chairs behind our boats when we are at the marina and we walk up and down the dock socializing and sharing food and drink.* A couple days ago, I was working on my boat and a friend from the other dock came over and invited me over for steamed oysters.

The marina's permit prohibits sailboats so there are no sailboats.* The vessels are single and twin engined motorboats.

BTW:* When the dockhands put a drystack boat in a slip for a customer, they dock it stern in.* Every time.

*

Backing in wouldn't be a problem, but we are bow in so that we can enjoy the scenery and the wildlife from our aft cockpit! *

I didn't buy a boat in order to socialize every minute of every day. I bought a boat to go out and enjoy the sights, read a book, even watch television, without interuption. So I pull bow in most of the time which fits the slip better, what with the triangle filler piece in most docks, and gives me the peace and quiet I went boating for. If you see me out puttering, then a friendly howdy or comment on my boat or the weather works well to start a conversation. Hey, it just dawned on me, maybe this is why my BBQ at home is on the back deck and not on the sidewalk out front.

If socializing is why you boat, then by all means back in along with a bunch of like minded folks and have a great time. That's not why everyone goes boating, and there's nothing wrong with either one of us.

Ken

Maybe I should have mentioned that stern in, it's just a matter of stepping off the dock onto the swim platform. Getting on and off the boat is much more complicated if it's docked bow in, especially when carrying food or supplies.

Mr Hawkins,

Beautiful picture of your boat! And I agree ...it's simpler. Any fool knows it's easier to run a boat in a straight line ahead than astern so it seems there are a lot of guys here bragg'in about their abilities to back their boat ......including me. But no mater how much I back my boat I'm never going to tell anyone that backing is as easy as going fwd. So it's amazing how many here on this thread choose the more difficult method to land their boat in their home slip. When I walk the docks (floats) I'm sure that over 80% of boats are bow in. And of the boats I see more of them are twin screw than on this forum but then this is coming from an old man without a thruster on either end and that probably is skewing my take on this. But if I had 15 thrusters I'm sure going bow into a slip would be easier. Going into a slip one can control the bow to a great extent w the stern but getting the stern between the float and the other boat (that one dos'nt want to touch) w little or no control (assuming no thruster) it's an accident waiting to happen. I'm assuming most all the backers here have at least one thruster. The more I think about it .. it really should'nt be much more difficult to back w no wind or current w a bow thruster. Perhaps I should get one but there are other things I want and if I had a thruster I think I'd want a stern thruster. Just say'in.

Eric

Someth'in I forgot to mention is that I think the vast majority of boat slips have a triangular wedge blocking the corner of of the slip so backing in anything but a double ender would only be practical if one had a slip about 3' longer than the boat. An exception to that would be an outboard as most all leave their OB leg in the up position in the slip. Wish they'd do that as that would get a lot of sharp SS props out of the fairway.


-- Edited by nomadwilly on Monday 16th of January 2012 11:45:36 AM

Several people talk of there boat backing to starboard. Most single screw back to port.

Curious as to how many people have left turn props.

SD

I have a left turning prop (in the prop shop when photo taken), so the Coot backs to starboard.

markpierce wrote:
I have a left turning prop (in the prop shop when photo taken), so the Coot backs to starboard.

Click to expand...

*Is there an advantage or disadvantage to having a right hand prop or left?

SD

skipperdude wrote:markpierce wrote:
I have a left turning prop (in the prop shop when photo taken), so the Coot backs to starboard.

Click to expand...

*Is there an advantage or disadvantage to having a right hand prop or left?

SD

Good question. I don't think there is, accept maybe as it relates to your actual dock arrangement in your home slip. In my case, I have a right hand rotation in forward, which is great when it comes to going forward into my starboard finger pier. However, the opposite would be beneficial when backing out.

Most importantly, the advantage comes in understanding your rotation and how it effects your backing. In my case, although the boat theoretically backs to port, it is not severe at all. I really don't notice the port tendency until I reach a couple knots in reverse.


-- Edited by Carey on Monday 16th of January 2012 12:44:24 PM

A twin walks to starboard in reverse both engines reverse, idle, rudder amidship?

SD


-- Edited by skipperdude on Monday 16th of January 2012 12:53:33 PM

skipperdude wrote:
A twin walks to starboard in reverse both engines reverse, idle, rudder amidship?

SD

Click to expand...

*No, because most twins have counter-rotating propellers.* So with both engines in reverse the propwalk of both props cancel each other out so the boat backs straight (assuming no wind, current, etc.)

This is one of the advantages of a twin.* If you put one transmission in forward and the other in reverse, both props will turn the same way and the propwalk force is, in effect, doubled.* So the stern will swing quite rapidly in the direction the combined propwalk is moving it.* Add rudder and this is why a twin can be pivoted in place.

Twins without counter-rotating props and both engines in reverse will swing their sterns in the direction the propwalk of both props is moving them.* But almost all modern (like 1960s and later) twins have counter-rotating props.

The PT boats of WWII had three engines and all three props rotated the same direction.* They were an absolute misery to maneuver at slow speeds according to PT vets I've interviewed.* And my wife and I have ridden on a restored one, and the effort it took to maneuver the thing back into a rather tricky slip was amazing.* Even though it was being driven by a fellow who had been a PT skipper during the war and knew how to do it.


-- Edited by Marin on Monday 16th of January 2012 01:23:07 PM

My Monk 36 single engine backs to stbd as did my previous boat a Camano 31, also a single.
Steve W

Never driven a twin. That was why I asked reguarding the begining of this tread as to who's boat backs to starboard. Several people said thay back to starboard so I was wondering if twins did so.

It appears only the Coot has a left*hand *prop.

So he will back to starboard. Right hand prop backs to port. Most boats have right hand props.

SD

According to the manuals, all Grand Banks single engine boats have left hand props.

If a signle-engine boat has a counterclockwise turning engine (viewed from the rear) like the Ford Lehman 120 and-- I think-- most other engines, and there is no counter-rotation gear in the transmission (as there is in the starboard transmission of most twins unless it has counter-rotating engines), this means the prop will turn the same way as the engine, so the prop has to be a left-hand prop.


-- Edited by Marin on Monday 16th of January 2012 01:30:46 PM

Marin wrote:
According to the manuals, all Grand Banks single engine boats have left hand props.

If a signle-engine boat has a counterclockwise turning engine (viewed from the rear) like the Ford Lehman 120 and-- I think-- most other engines, and there is no counter-rotation gear in the transmission (as there is in the starboard transmission of most twins unless it has counter-rotating engines), this means the prop will turn the same way as the engine, so the prop has to be a left-hand prop.



-- Edited by Marin on Monday 16th of January 2012 01:30:46 PM

Click to expand...

Most trawler style boats and cruisers have the steering on th starboard side as it makes it easier to watch the danger zone for crossing situations. *That puts the door on the starboard side also. *A left hand prop will back to starboard. *That makes it easier to bring along side the dock with a little burst of reverse to tuck the stern in.

Most of our trawlers have BW Velvet drive transmissions that have left hand rotation in fwd gear and prop walk to stbd in reverse.

Marin I do'nt think prop walk on a twin would be any more than a single as the props are usually smaller. Even when they are'nt (like a lot of trawlers on TF) the prop walk is proportional to the amount of power applied so prop walk should be the same (roughly) when backing.*

Eric

RE: Backing

I do'nt think prop walk on a twin would be any more than a single as the props are usually smaller. Even when they are'nt (like a lot of trawlers on TF) the prop walk is proportional to the amount of power applied so prop walk should be the same (roughly) when backing.*

______________________________________

With twins you have the same forces as a single plus a few more.*

The ability of the twin to rotate on its center point is the most obvious and the one we all focus on.* This is a result of applying forward and reverse thrust, running one*propeller in*forward and the other in reverse, as previously stated.**By applying*forward*propeller thrust on one side and reverse thrust on the other,*the boat will rotate on its center point.* The center point is not always constant and varies by boat design, thrust, momentum, wind, tide and other conditions.*

If you're really interested in the physics side of it, there are a number of subject papers online which go into great detail.

LB

nomadwilly wrote:
*

Marin I do'nt think prop walk on a twin would be any more than a single as the props are usually smaller. Even when they are'nt (like a lot of trawlers on TF) the prop walk is proportional to the amount of power applied so prop walk should be the same (roughly) when backing.*

*

Click to expand...

Speaking only for Grand Banks boats because they are the only ones I'm this familiar with, the prop used on a single engine GB is the same as the prop used on the port side of a twin-engine GB of the same size and using the same type of engine as the single.* In the case of FL120-powered GB36s, the diameter and pitch is 24 x 18 for their original, three-bladed props.

The only other evidence I have is that we chartered a single engine GB36 before we bought our own twin engine GB36.* To yaw the stern to starboard as a single left-hand prop will do in reverse, our twin with both props rotaing clockwise (port reverse, starboard forward) swings its stern to starboard much more responsively and faster than the single ever did. There are reasons for this other than just propwalk of course, but the combined propwalk of two props turning in the same direction instead of just one does play a signficant role.

One potential factor in our favor is that we have four-bladed props where I believe the single we chartered has a three-bladed prop (but I could be wrong about that).* And a four bladed prop develops more propwalk than a three-bladed prop of the same diameter, one reason why the prop shop folks say "A three backs better than a four."* By which they mean develops less propwalk.* It's also more efficient, but that's a different topic.


-- Edited by Marin on Monday 16th of January 2012 03:12:35 PM

Marin,

It's not NORMAL for a twin engine boat to have twice as much power as the single engines counterpart. And the 4 bladed prop will NORMALLY have less dia than it's 3 blade counterpart. And less dia means less walk. Also it would NORMALLY have less pitch because of more blade area and hence even less walk. In some ways Marin the GB boat is not normal and can't be correctly used as an example.

Eric

Edelweiss wrote:
The ability of the twin to rotate on its center point is the most obvious and the one we all focus on.*

Click to expand...

*The Coot's bow thruster has the same effect.

So you are saying most boats have left hand turning propellars.

contrary to what I have always thought.

I am pretty sure most outboard's are right hand.

'SD

markpierce wrote:Edelweiss wrote:
The ability of the twin to rotate on its center point is the most obvious and the one we all focus on.*

Click to expand...

*The Coot's bow thruster has the same effect.

*Rotate*the boat in a circle, now that it will do.***Right on!!

When "threading the needle" to get to available dockspace at one of our YC outstaions, I frequently do it in reverse, in order to get the favoured starboard landing. Steering is done by propwalk and forward power with rudder. In reverse, especially at low speeds, the rudders have no effect on direction. So if there is enough wind or current to present a predictable direction of drift, I set up to use the side that is in the direction of drift as the reversing engine, and the other side with the rudder kicked outboard to add a little bit of correcting force. Only if there isn't enough propwalk to counteract the wind/current, will I need to change the ruddder. If there is little or no current/wind, I alternate engines to keep centered between boats tied on either side of the passage.
My engines are counter-rotating, with starboard propwalk in reverse on port and port propwalk in reverse on starboard. My engines are identical, mated to BW Velvet drive trannies, one is 1.9:1 with no reversing of rotation in forward, the other is 2.0:1 reversing. I don't know why the gearing is different, as the props are very close to identical pitch.

I usually back my car or truck into a parking space or driveway as well.

Why, you might ask? Well, when I get ready to leave a few hours or days later, I can easily see what's in front of me. Traffic, pets, small children, etc.

Other than the social aspect and the fact that it's customary at my marina, backing into the slip is much the same. Leaving, you're going forward and have the best visibility and control.


-- Edited by rwidman on Monday 16th of January 2012 05:11:14 PM

nomadwilly wrote:
It's not NORMAL for a twin engine boat to have twice as much power as the single engines counterpart. And the 4 bladed prop will NORMALLY have less dia than it's 3 blade counterpart.

Click to expand...

I guess it depends on your definition of "normal."* The more modern production boats I'm familiar with that are offered in single and twin configurations--- and there are*not all that many of them besides GB although a number of the "Taiwan Trawlers" could be had either way--- all used the same engine in the twin as they did in the single.* I know you think that's wrong, but regardless, that's what they did.* Even into the 2000s with the GB36 before they discontinued it.

Second, according to the prop people we've talked to about our props--- at Kruger & Sons who I know you don't like despite virtually everyone we've talked to in this area telling us they are the best around, and a couple of others---* the answer we always got was that*for a given boat a three-bladed or four-bladed prop (or props if a twin)*should be the same diameter but the four bladed prop*would*normally be*pitched down one inch.

So our boat is very "normal" for what the production boat*companies have been doing since the mid-1960s.* Whether you think they should have been doing that, I suspect, was irrelevant as far as they were concerned


-- Edited by Marin on Monday 16th of January 2012 06:09:57 PM

*

Sidebar:**

If your marina allows transients, does your harbor master/marina jefe

tell them how to pull*in?***** KJ*

KJ wrote:
*

Sidebar:**

If your marina allows transients, does your harbor master/marina jefe

tell them how to pull*in?***** KJ*

Click to expand...

*Rarely unless it's up to a bulkhead and shallow water.

koliver wrote:
My engines are counter-rotating, with starboard propwalk in reverse on port and port propwalk in reverse on starboard. My engines are identical, mated to BW Velvet drive trannies, one is 1.9:1 with no reversing of rotation in forward, the other is 2.0:1 reversing. I don't know why the gearing is different, as the props are very close to identical pitch.

Click to expand...

*You sure you don't mean that your final ouput drives from the transmissions are counter-rotating with both engines turning the same way?

We have Velvet Drives in our GB with the similar ratios you describe-- 1.91 to 1 on the starboard side and 2.1 to 1 on the port side.* The reason they are different is that the starboard (1.91 : 1) has an extra gear in it to* reverse the rotation of the output shaft.* They could not fit this gear into the standard*transmission housing and keep the same drive ratio, hence the slight difference between the two.* But the engines--- in our case FL120s--- both turn the same way.* There are no counter-rotating FL120s.

GB accounted for the two different final drive ratios by pitching the port (slower) prop up an inch.* However the prop shops we talked to, including Kruger who we had rework our props completely, said they don't do this unless a customer asks as they don't feel it really makes any difference.* Our props are now*pitched the same and despite one turning a wee bit slower than the other at a given rpm,*whenthe helm is centered*the boat tracks straight.

KJ wrote:
*

Sidebar:**

If your marina allows transients, does your harbor master/marina jefe

tell them how to pull*in?***** KJ*

Not that I am aware of.* There's a more or less transient boat (supposed to be here for a month but it's been two so far) near mine.* It's stern in.

Here's a photo:

As you can see, the fairway is pretty narrow.* Add to that the tidal current and it's pretty important to have good control as you're leaving the slip.* Most boats can't just pull out of a slip, we have to pull out, back and straighten out, and then leave.* Usually crabbing yo compensate for the current.

Click to expand...

*

In the Pacific NW I think the norm is bow in. That certainly holds true for the majority of sailboat owners. For our 33' full keel sailboat, even when contending with tidal currents, we typically go bow in. Of course, being in the aft cockpit to back out means I'm right there and able to easily see into the fairway. Plus, as someone said, a single-screw full keel sailboat simply handles easier and is way more predictable going forward. However, if there is no wind and no current, and the slip next to me is open, and we want the vee-berth pointing away from a busy transient dock... It's a lot fun to back in! OK, so it might take two attempts sometimes, but it makes for good practice and helps keep me "one with the boat"...