Twins are NOT Identical

Pat is frustrated

Boaters who downsize their boat, experience more than just difference in size. Quite often, it involves a different drive system as well.

A common misconception is that twins are twins and they all handle the same way. So, if you go from a Twin Inboard to a Twin Sterndrive or vice-versa, the new boat will handle the same as the old one. Not so!

Twins are not identical. Pat discovered the hard way. Read her frustrating downsizing story.

Pat’s Story

Searay Sundancer

“We owned a 33’ Twin Inboard Sea Ray for years.” Pat told us as she explained her docking story. “Then, we downsized to a 28’ Twin Sterndrive Sport Cruiser. We thought we could bring our docking skills with us and continue to enjoy the boat. Out on the water wasn’t so bad, it was the docking that was the real problem. It just didn’t handle the same as our twin inboard.

Many times, we came close to hitting other boats when we tried to maneuver into our dock. Everybody told us to tie the bow line first, but that doesn’t work for us, because our side decks are too narrow. It is impossible to get to the bow.

narrow side decks

We are so stressed about docking, that we have only put 7 hours on the boat last year and considering getting out of boating all together.

In a last attempt to find a solution, I went searching on the internet to all the docking sites, docking aid sites and then found your website. I found so much information there and decided to order your Twin Sterndrive Lessons and Video, but wanted to talk to you first.

When I called and talked to you Doug, I learned more in that conversation than everything I had learned so far about docking a Twin I/O. I ordered the Twin I/O Introductory and Advanced Lessons and the Video.

I was so relieved to know that I didn’t have to tie the bow first. It just doesn’t work and I can’t understand why everybody keeps telling us to do it.

You told me your FLIPP Line procedure would eliminate the stress and fear of docking and that’s what we need. We are stressed enough at work and want to get away from stress—not add to it.

We even had a Mega Yacht Captain come aboard to teach us to dock our 28 and he couldn’t do it. He said the boat didn’t handle like he expected. He was absolutely no help to us at all. I was ready to buy a gadget to help get the line around the dock cleat or bollard and/or have a $10,000 bow thruster installed.

After my conversation with you, I realized that I didn’t need any of them. I could just follow your procedure and I would be able to dock effortlessly and stress free making boating the fun it’s supposed to be.

No one has been able to tell us how to dock a Twin I/O, except you and your method really, really works! Your FLIPP Line procedure works like magic”

Thanks Pat for your story

This problem is common among boaters who buy a boat with a drive system different than they are accustomed to.

The captain of the Mega Yacht, like so many boaters, assumed that his Twin Inboard method of docking would naturally work on Pat’s 28’ twin sterndrive; but, he obviously didn’t realize the big difference between inboards and sterndrives.

Like the saying “Just because a plumber has teeth, it doesn’t qualify him as a dentist.” Just because a Captain can dock a Twin Inboard, it doesn’t qualify him as a Sterndrive Docking Instructor”.

Moving from a twin inboard to a twin sterndrive requires learning all over again. Different docking and handling techniques are required. Here’s why…..

Twin Inboards


Twin Inboards have fixed shafts and propellers (non aimable) under the hull. The propellers are fitted to the shafts that extend on an angle through the bottom of the boat. The motors are fully inside the boat and are hence called inboards.

The rudders that are placed behind the propellers (also under the hull), deflect the propellers’ thrust for steering in forward. In reverse, the rudders rely on the water passing by them for steerage.

Twin Sterndrives


Twin Sterndrives or I/O’s are drive systems that are a combination of inboard engines connected through the transom to outdrives.

The package is known as a Sterndrive or an Inboard/Outboard or an I/O–Half in and half out. Sterndrives are not direct drives as some people call them.

The motor portion is totally inside the transom The outdrive portions are mounted outside the transom, positioning the propellers well aft of the transom of the boat. The drives turn to direct the propellers’ thrusts for steering.  In both forward and reverse, the drives and thereby the propellers, are aimed the direction you want the aft of the boat to be pushed or pulled.

Twin I/B vs Twin I/O

They are two totally different systems with propellers in totally different locations relative to the hull–totally under the hull versus totally behind the transom.  The propellers are fixed or non-aimable versus aimable. Therefore, it only stands to reason that they wouldn’t react the same way to the wheel, throttles and shifts.

Shorten Your Learning Curve

Jump the learning curve. Get the right Docking Lessons upfront, to avoid weekends of frustration experienced by Pat and so many others. Twins are NOT Identical.

4 thoughts on “Twins are NOT Identical”

  1. Dan Nottingham

    I went the opposite direction. For 7 years I had a 28′ Boston Whaler with twin 225hp outboards. I became fairly competent with this boat but sometime struggled in heavy wind as my bow would take off. With patience and practice (and more than one misstep) I learned how to dock the boat even on windy days.
    2 years ago we up-sized to a 42′ Egg Harbor with twin 500 hp inboards. I was terrified thinking of the damage I could cause while docking! To calm my nerves I bought your eBook on docking twin inboards. It made perfect sense! Once the concepts were in my head I felt confident that I could dock this thing. A few months later I got my chance. Our slip is complicated and I must pivot round 2 turns in the dock and then back into the slip. I followed your lessons – Jolly Green Giant facing forward, Jolly Green Giant facing backwards – and I docked like I knew what I was doing. Today, I get complements on my docking, and my wife on her first mate duties, almost every time we come in. It feels great. Thank you for teaching me.

    1. Dan,
      Great to get such positive feedback and the fact that other boaters are admiring your docking abilities is gratifying. That is exactly what we hope to accomplish with our lessons.
      Enjoy your Egg Harbor. We used to be Egg Harbor dealers a few decades ago and loved the quality and interior joinery.
      Doug Dawson

  2. Anthony Carbone Jr.

    Good morning,
    Twins are def not the same but your docking material has really helped me get accustomed to I/O’s. When growing up my dad had twin inboards, i learned quickly I/O twins are not the same. I wanted to know does any of your material address being in choppy waters or navigating through wakes and bigger wakes? I have a 2015 Sea Ray 31 Sundancer, great boat but they narrowed it up a little and i get nervous in some choppy water or when i am hit by wakes from the side. The boat has twin I/0 bravo three’s w 300hp each.
    Thank you again for your material. Anthony

    1. Anthony,
      Glad to hear our lessons are really helping you master different twins.
      With regard to your wakes question, we have a lesson for “Conquering Wakes” that you would probably find most helpful. What we talk about in this lesson applies to waves as well.
      See “Conquering Wakes” Lesson on our website
      It is only $12 and will make a lot of difference for you and your family.
      See also our free article Big Wakes Wreck Holidays under blogs on our website.
      Stay in touch with more questions.
      Happy boating.
      Doug Dawson

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