Boat Handling

B

BILL MORROCCO

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Jan 1, 2000
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3195
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72
I have always had a boat with twin inboards but am now looking at a boat with twin Alpha1 Gen2 outdrives. I was told the outdrive boat will handle different then twin inboards. Can anyone tell me if this is true.
 
Big difference. Not as easy to handle as twin inboards.
 
Agreed, much easier to handle my 34c than my FIL 33 Larson with duo props
 
Yes.
Last fall a new member and new boater at our club gave up the helm to me on haul out day because he was getting in over his head (really windy) when we backed out of his slip. The boat was a 30' Cruisers with twin I/O. It reacted really different than my boat. It seemed to take a lot more throttle to pivot and turn but I could have been the conditions. I managed not to hit anything but I didn't like how it handled at all. When I was away from the docks and other boats I played with it some in the river…still didn’t like it.

It was my first twin I/O boat that I had ever driven.

Good luck
Niles
 
The handling of a twin inboard is much more intuitive and simple. Mostly this is due to a) much wider separation of the props, and b) a nice big rudder.

I/Os are usually crammed as closely together as possible, and the skeg hardly qualifies as a rudder. To some extent, this is compensated by the use of "directed thrust".

There are other technical details that usually mean that reverse thrust in an inboard is generally more efficient than reverse from an I/O.

Net result: The handling is quite different. I personally find that inboards are MUCH easier than I/Os, and because of the requirement of using engine thrust to effect a direction change ( vs simple rudder action ), there is much more thrashing about with the engines when maneuvering an I/O.

That said, I would rate twin inboards only slightly more maneuverable than twin i/Os. YMMV.

--

Note: I have no experience w/ IPS and they likely handle differently than both of those mentioned above...
 
Very true.
With twin IO's you will be working the throttles, shifting and steering a lot.
Especially in close quarters.
Sometimes I will put one engine in neutral and just use the unit with power steering.
It takes some practice that's all.
Good luck.
 
I never use the steering when I was docking my twin I-O boat.

It will handle differently because of the pivot point. I-Os are behind the boat and inboards are under the boat

You can get I-Os to do exactly what inboards do.
 
Prop size also has a lot to do with it. The Alphas will only fit about a 15" diameter prop max. Bravo IIs will fit 20.5 inches or so. Inboards have much bigger props.
 
Big difference. The twin I/O's will be hard to get used to, but not impossible.
If they are counter rotating they won't be too bad. If they aren't, they will be real tough and you should consider swappping out the port drive to a counter rotating.
I did that last year and it was like I got a different boat around the dock.
 
I think most of you are missing the point that as you turn the wheel on the IO you are changing the direction of the prop greatly improving the effectiveness! While the two handle very differently after a short learn curve you will have no problems controlling the IOs.
 
No we're not missing the point. It does "greatly improve the effectiveness" but the problem is that when you have one engine going ahead and the other astern they tend to cancel each other out. With inboards, the ahead prop is working with a rudder while the astern prop is not, and the difference in side-thrust actually IMPROVES maneuverability.

I don't doubt one can learn twin outdrives, but they'll definitely be different.
 
Once you have twin screws , you won't be happy with outdrives. Not missing the boat. I've had both and learned to be proficient with outdrives, but the difference is like night and day.
 
I really dont see much of a difference. The only way to REALLY compare inboards to IO-s is to have the same boat with both set ups. You cant compare docking a 30ft express cruiser with inboards to docking a different 30ft boat with inboards. You have two completely different boats.

Every boat handles differently. If you can handle one, you can handle the other. Plain and simple
 
The big thing to remember is that the pivot point is behind the boat and not under it. What might be a slight movement in the stern is an exagerated movement in the bow.
This becomes more of a problem when backing up. The bow will swing a lot on you when you try to make a minor adjustment to get between the poles when backing in to a slip.
If both drives spin the same way the stern will swing hard to port when backing up because two props are pushing it that way. When the stern pushes to port, the bow can swing far to stbd if you don't watch out for it. When I had two spinning the same way I found it a little easier to back up with only one motor because it lessened the strong push to port just a little bit.
Now that I replaced the port drive with a counter rotating unit I use both motors to back in because the props offset each other and the boat now backs up in a straght line. Although this is better than before, I still need to remember that my pivot point is under the swin platform and I have to watch out for the big swing in the bow when I adjust the stern with the steering.
Overall it isn't bad at all, but nowhere near as easy to manuever around the dock as twin inboards.
Having the CR drive made a huge difference overall and was one of the greatest things I ever did to the boat.
The best is when you get someone who has a twin inboard boat and they start yelling directions in a tight situation beccause they see you have two motors. They are usually the indivviduals that have never had a twin I/O boat and therefore have no clue.
 
Also keep in mind inboard props are forward of the transom, I/O are aft, by a couple feet - makes a big difference in leverage and pivot point.
 
Also, inboard props are farther apart. I have piloted the same boat with both setups, Boatcrazy. I owned a Silverton 310 with twin outdrives and a friend had a Silverton 312 with twin inboards. They are identical hulls. Huge difference in handling, The inboard boat was much easier to maneuver around the dock.
Hey Boatcrazy-----WHITE!
 
Gregory im not understanding your WHITE comment. Care to explain?
 
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