Sterndrive maneuverability in reverse?

[nycdad]

Hello all. Question about my Cobalt 242, which I'm relatively new too (and loving every minute of it). Been working on docking and maneuvering in tight spaces, proper way to bump the drive in and out of gear and all the other basics I'm eager to learn. I know every boat handles differently and working on getting more intuitive with mine, especially in reverse. The boat steers fine in forward, but when reversing - at slow speeds but a bit extended backing out of my dock into the channel - I find the boat has a difficult time steering in reverse in one direction - specifically when I want the aft to go to port. It seems to naturally pull starboard. Even with the wheel turned all the way to the left, the boat then usually compensates for this pull by going back straight. I have a hard time getting the aft to go port. Sometimes from a stand still and with the right amount of bumping in reverse I can get the turning i need but it seems difficult. Is this normal? Been reading about prop torque, and wondering if this is what I'm experiencing? Thanks.

 

[Scott Danforth]

do you have a dual prop drive or a single prop drive. with a single prop, you get a bit of "prop walk" as the back end is pushed a bit to the side from the prop as your going in reverse at slow speeds

 

[oldjeep]

Are you trimmed all the way down, or trying to back uo with the drive trimmed way up? You can typically parallel park an i/o because they are so maneuverable.

 

[tpenfield]

Backing is not the same as going forward sorry to say. One aspect in addition to what has been mentioned is that some of the thrust from the prop is interrupted as it hits the transom and goes every which way

 

[alldodge]

The prop is designed to apply thrust forward, in reverse there is less force applied. Things that make it worst in reverse is if the prop is cupped. The prop has less bite and the rotation of the prop will also walk the boat sideways. Just something your going to have to practice to understand how your boat reacts.

 

[Oshkosh1]

Practice practice practice...

Boaters should practice landings like pilots. It's what takes skill. Anyone can push the throttle up and steer.

No two boats will handle the same. There are some general tendencies, however no one here can tell you for sure. Just go out on a weekday afternoon sometime when the docks are empty and just do some crash...er "touch" and go's. You'll learn very quickly how to handle it. Remember also(something I don't see much of) that your lines exist for two reasons; Holding to the dock and assisting in getting there. The stern is much easier to walk in if the bow is secured. You can simply tie off the bow, turn into the dock, back down and the stern will plant itself. Don't worry about the line parting...it'll take the strain. Especially helpful if on a river with any current.

 

[nycdad]

do you have a dual prop drive or a single prop drive. with a single prop, you get a bit of "prop walk" as the back end is pushed a bit to the side from the prop as your going in reverse at slow speeds

I have a dual prop. I guess I was also wondering if there could be something wrong with the boat/prop itself - like this situation is indicative of a "common" issue. Or is this just the quirkiness of the boat I need to learn.

 

[Oshkosh1]

I have a dual prop. I guess I was also wondering if there could be something wrong with the boat/prop itself - like this situation is indicative of a "common" issue. Or is this just the quirkiness of the boat I need to learn.

Nothing wrong with it. Although the counter rotation does offset some of the torque, you'll still see some of those issues. Just something you'll learn to compensate for over time. One of the reasons backing a boat into a slip can offer a challenge for even "seasoned" drivers who rarely perform it.

 

[KnotConnected]

Disclaimer: 4 years into ownership and I'm still a total noob when it comes to operating my single 454 with a Bravo-3, but I wouldn't really expect to back the boat up a lengthy distance in reverse. Especially if wind and current are factored in. Reverse with the single I/O is really used to reduce speed and manipulate direction (quick bumps into reverse when docking to push the stern or bow over).

I'm not sure what your environment looks like, but I'd probably get it away from the dock and spin around using bumps in F and R m then heading out through the channel going forward rather than trying to back all the way out.

 

[muskyfins]

I run a B3 and back into my slip which is in the main river channel. Current plays a big factor. In my case, if the Army corps is letting more water over the spillway=more current and bigger problems. Last night I was counting on current to pull me along and there was almost none.

 

[TyeeMan]

My old boat had a Volvo Duo Prop, DP drive, where the front prop is bigger in diameter, and the blades are bigger than the rear prop. Same deal, if I was backing away from the dock, you couldn't pay that boat to turn one direction, , could have been to port. Turn starboard on the other hand and it would turn on a dime.
Now my new to me boat has a Merc Alpha drive (single prop) and it's completely different, , much better. That said, it still turns harder one direction than the other, but waaaayyyy better than the Duo Prop.

 

[alldodge]

I have a dual prop. .

I take back most of what I said. The twin props offset each other and so long as there isn't wind or current you should be able to back right out without much issue. Your probably over steering, and probably to much speed. In gear and back out, small steps

 

[bruceb58]

Now my new to me boat has a Merc Alpha drive (single prop) and it's completely different, , much better. That said, it still turns harder one direction than the other, but waaaayyyy better than the Duo Prop.

You are the first person I have ever heard that from. My boat with a Duo-Prop is way better than any boat of any size that I have ever owned that has had a single prop. Also turns equally well in both directions

What sized boats were the two boats?

 

[frantically relaxing]

You can have this problem trying to turn either direction. Everyone has their own theory as to this problem, and here's mine, and I'll attempt an explanation

Prop wash...

Now, we all know boats pivot near their centerline. So, when you point the prop to port side to back up left, you want the stern to go left and the bow to go right. But the prop is pushing a ton of water under the starboard half of the boat. This water is essentially a big wave pushing against the the boat, and the keel just rides along side it. And the bow can't turn to the right because the prop wash pushes the bow left. So until the prop wash stops, the boat just kinda slides sideways while moving slightly left.

Same thing will happen trying to reverse right. Maybe not so much because of prop rotation, but I don't really know.

More throttle makes the situation worse, because it's more water fighting the boat.

Another reason for my theory, is my twin-engined flat-bottomed houseboat will reverse left or right on the same dime as it will in forward, since all the prop wash is well under the hull, and has nothing to push against.

If trimming up before reversing helps some of you, then that makes sense too, as the wash will be directed downward.

What works for me when I start sliding sideways is to throttle down to idle for a couple of seconds. The boat then starts to actually turn...

 

[Blind Date]

Now my new to me boat has a Merc Alpha drive (single prop) and it's completely different, , much better. That said, it still turns harder one direction than the other, but waaaayyyy better than the Duo Prop.

You are the first person I have ever heard that from. My boat with a Duo-Prop is way better than any boat of any size that I have ever owned that has had a single prop. Also turns equally well in both direction

+1 - Having owned 3 smaller boats w/Alpha's before my SeaRay w/B3 that has to be the craziest thing I've ever heard.

 

[nycdad]

My old boat had a Volvo Duo Prop, DP drive, where the front prop is bigger in diameter, and the blades are bigger than the rear prop. Same deal, if I was backing away from the dock, you couldn't pay that boat to turn one direction, , could have been to port. Turn starboard on the other hand and it would turn on a dime.
Now my new to me boat has a Merc Alpha drive (single prop) and it's completely different, , much better. That said, it still turns harder one direction than the other, but waaaayyyy better than the Duo Prop.

Thanks - yes I have a Volvo duo prop too. I can get it to turn both directions, but it definitely favors one side over another. I will be out with it Friday again, amusing all the neighbors as I try to do reverse circles, in both directions and get a better feel for the boat. It's not IMPOSSIBLE to turn one way over another but it definitely favors one way, and once it's turning in reverse that way, good luck getting it to change to the other way.... I actually think the swim platform has something to do with it. Just not very fluid dynamic in that direction!

Meanwhile thanks everyone for the spirited discussion on this, love to read it and at least i know that th boat/engine most likely aren't faulty.

 

[nycdad]

You can have this problem trying to turn either direction. Everyone has their own theory as to this problem, and here's mine, and I'll attempt an explanation

....

If trimming up before reversing helps some of you, then that makes sense too, as the wash will be directed downward.

.

Interesting - wouldn't being trimmed up move the water closer to the bottom of the hull, while being trimmed down directs the water under the hull?

 

[JASinIL2006]

No Title

With the outdrive trimmed down (or in) when in reverse, the axis of thrust is pointed directly at the hull (see illustration below). When the drive is trimmed up (out), the thrust is directed more downward, where it won't hit the hull/transom as much. Does that help?

 

[TyeeMan]

BruceB and Blind Date, I'd love to tell you otherwise but that's the way it was. The boat with Duo Prop was an 18' 3" Lund powered with a 4.3. I absolutely loved, loved, every aspect of the duo prop, EXCEPT turning in reverse. I could idle going straight in reverse into a 2.5' chop at 3 mph, gps. Try to back out of slip or away from a dock and turn to the right in with a light wind? Yeah, good luck with all that. I'll even go so far as to say going forward the boat turned harder (sharper) to the left than it did to the right. Add a bit of wind and you better have a real big right hand turning radius. All of this with the drive fully down.

New (to me) boat, 20 feet, wider, deeper, heavier, V-8, Alpha. All turning aspects at low speed are much better. That said I sure do miss that duo prop when your up on plane and cut a hard corner. Holy man did that thing dig in.

 

[bruceb58]

LOL....you are comparing a light 18' Lund with a 20' heavier boat in the wind?

A duoprop on an 18' Lund?