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What Is Boat Rigging?

Jun 24, 2020 ·

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Boat rigging — what is it, and how does it work?

Rigging is used on boats for a variety of purposes. Essentially, it’s the process of getting the boat ready for the customer’s intended use, whether it’s for something as specific as bass fishing or for general pleasure.

It’s important for marine technicians to have a broad knowledge of rigging, as a key part of their role is to install and configure all types of equipment and engines. Keep reading to learn all about boat rigging, including what it is, specific steps to follow and more.

What Is Rigging on a Boat?

Rigging involves configuring a boat in a way that best suits what the customer will be using the boat for and is in line with the manufacturer recommendations. As you can imagine, this process looks different for every type of boat. In this blog, we will break down outboard rigging and how it works.

How to Rig a Boat: Outboard Rigging

Installing an outboard, which is called “rigging,” involves much more than simply bolting the outboard to the transom. It includes connecting the steering system, throttle and shift controls, navigation and communication systems, engine control systems and more.

When it comes to rigging outboard engines, the process can be broken down into the following steps:

Step #1: Find the transom center

To rig an outboard engine, you must find the transom center using the arc method. To do so, select two identical locations as a reference point and use a straightedge to strike an arc near the top of the transom that crosses the centerline of the transom.

Using the same reference point on the opposite side of the transom, strike a second arc that crosses the centerline of the transom. Repeat these steps using the same reference points on the boat, but move in three or four inches on the straightedge to strike the second arc.

Reference marks for rigging a boat

Use a straightedge to draw a straight line through the intersecting points of the upper and lower arcs. This vertical line represents the transom centerline. Then, place the template on the transom aligning the center marks of the template with the vertical line.

Step #2: Engine spacing

Engine spacing is necessary for both single and dual engines, as it provides clearance so that there is no interference when the motors pivot on their steering axis or on their tilt axis.

On a single engine, remember to position them on the centerline of the transom. With a dual engine, offset each engine a minimum amount from the transom centerline to allow for full turning radius.

Step #3: Drilling the mounting holes

To drill the mounting holes, start by selecting the proper hole pattern based on the engine being mounted. Before starting to drill, check inside the transom area for anything that could be damaged during drilling.

Verify that all four holes are accessible from the inside, and make sure the top hole is at least the manufacturer’s recommended distance below the top of the transom. Keeping the drill bit at a 90 degree angle to the transom, drill holes while using the transom drilling fixture as a guide.

Step #4: Determining the transom height

To determine the transom height, measure from the top of the transom to the bottom of the boat at engine centerline. Select the correct engine shaft length and align the anti-ventilation plate so it’s level and at the recommended distance in relation to the bottom of the boat.

The benefits to raising the engine mounting height are decreased steering torque, increased boat stability, increased propeller ventilation during planing and increased maximum speed.

Step #5: Uncrating the engine

To uncrate the engine, start by taking pictures of the crate showing all corners to document any damage. Then, verify that there are no parts missing, as missing parts are the manufacturer’s responsibility.

Place the crate in the position indicated by the manufacturer’s crate markings and remove the cardboard, unpack all accessory items and set them aside. Refer to the manufacturer service manual for uncrating procedures.

Step #6: Mounting the engine

To ensure proper engine mounting, check that the top holes are not less than the manufacturer’s recommended distance from the transom top surface.

Install the steering cable to the motor prior to mounting the motor, and match the upper and lower mounting bolt positions. If the upper mounting bolts are installed in the top hole, the lower mounting bolts should be installed at the lower mounting slot. Then, insert the mounting bolt from inside of the transom.

When mounting the engine to the transom, remember the following:

  • Mounting bolts are metric thread — do not mix with SAE fasteners
  • Use underwater grade sealer on bolts to protect the transom
  • Use thread lubricant to avoid galling the mounting bolt threads
  • The bolt must extend completely through the washer and nut
  • Torque all mounting bolts to manufacturer specifications

Step #7: Installing dual engines

To install dual engines, mount the counter rotation engine on the port side when dual engines are used. Use dual cable steering for engines 150hp and above or with boats that are capable of attaining 50mph or more.

Refer to the boat manufacturer for information about dual installation. Engine wakes should meet at approximately 61’-78’ behind the boat.

Twin engine wake diagram

Measure from the centerline of the steering arms and the centerline of prop shafts. Install the tie bar between two motors, using the outer mounting hole in the steering arm. Adjust the toe-out; up to 1” toe-out is best. One nut on the tie bar enables the tilting of one motor without bending the rod. Ensure the props turn outward and that counter rotation is on the port side.

How Boat Rigging Applies to a Career in the Marine Industry

So why is boat rigging important, and how does it apply to a career in the marine industry?

Marine technicians spend their days working on a variety of different types of boats and engines, and a key component of their job is getting boats ready for the customer’s intended use. For this reason, knowing how to properly rig a boat is an essential skill to have.

In the Marine Technician Specialist Training Program offered at Marine Mechanics Institute (MMI), students learn everything from electrical diagnostics to the fundamentals of outboard rigging.1

This 51-week program7 includes a series of manufacturer-specific courses, where students have the opportunity to learn the design and operation unique to leading manufacturers, including:

Whether you dream of working on motorboats, sport fishing boats, sailboats or all of the above, MMI can provide you with a foundation of skills you can build on as you start your career in the marine industry. Classes begin every six weeks, so you may be able to start your training sooner than you think.

Curious about the types of careers you may be able to pursue in the marine industry? Check out our marine career guide.

Start Your Training at MMI

Marine Mechanics Institute has the instructors, facilities, and industry tools and technology to help you prepare for an exciting career.2

To learn more, head to our website and request information to get in touch with one of our Admissions Representatives today.

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1) MMI is an educational institution and cannot guarantee employment or salary.

2) For program outcome information and other disclosures, visit

7) Some programs may require longer than one year to complete.

Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.


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