Outboard Jack Plates, Everything You Need To Know!


There are many terms in the boating industry and some might not be so common. If you have heard the term “jack plate” you might be wondering what exactly is a jack plate.

Outboard Jack Plates, Everything You Need To Know! Outboard jack plates are a mechanism that goes in between the outboard engine of a boat and the transom of the boat’s hull. Their purpose is to give the operator or the installer the ability to raise and lower the height of the engine on the transom. Without changing the engine’s mounting height.

Jack plates come in all kinds of sizes and styles. Here is everything that you need to know about them and how they operate!

What Exactly Is An Outboard Engine Jack Plate?

A jack plate is a plate that you mount on the transom of the boat’s hull. You can then mount the outboard engine of your boat onto this plate.

Instead of directly onto the hull. This plate gives you the ability to raise the plate up or down. Which in turn allows you to change your engine’s height in the water.

You might be thinking to yourself “I can do that with the engines tilt and trim!” You are right there, and you can read more about trimming your engine. By reading our article on the engine’s tilt and trim system.

However, there is a couple key differences with jack plates. You can change the height of the engine without changing the angle of the propeller shaft. As well as lifting the engine completely out of the water!

How Jack Plates Operate

This allows for greater control of your engine. You can raise the height while keeping the boat trimmed down. You can even trim up while lowering the height of the engine.

These add many advantages and ease of maneuvering for the driver,

especially in shallow water!

As an added advantage, jack plates allow you to mount your engine much farther away from the transom. This adds weight at the back of the boat.

It also increases the overall length, which is useful if your boat is bow-heavy. And you want to raise your boat’s bow up in the water.

It also allows for that added bow raise during wide open throttle operation. Meaning that you can get more of the boat out of the water.

Which will gain top end speed of the boat by a couple of mph!

Jack Plates For Large Outboards & Tiller Motors

Jack plates are made for basically any type of outboard engine. Whether that is a 300 HP engine or a 5 HP tiller motor.

There are benefits to having a jack plate on either style.

Large Outboards

Larger outboards probably have more benefits to them over the tiller motors. That is because the larger engines get into performance, fuel economy, and many other benefits.

Tiller Motors

Where as the tiller motors are more of a mandatory thing. The jack plates are necessary to mount the tiller motor.

And the engines are more used to just move the boat around or for slow trolling. Moving a sailboat out into open water where the sails can be deployed and used.

The Different Types Of Jack Plates

There are three main different types of jack plates; fixed, manual and hydraulic.

Fixed Jack Plates

A fixed jack plates are usually the least expensive option when it comes to jack plates. As the name implies, you can lift your engine up and make it stay in a fixed position.

This would usually be the engine height at which your boat runs the most efficiently. Fixed jack plates have different holes where you can mount the engine.

You can choose which holes to mount the engine on depending on the height you want. Changing the engine height on a fixed jack plate is more difficult.

Because you cannot do it when you are on the water. This is because it will require a jack to hold the engine.

Or something to lift the engine as you un-mount it from one set of holes and remount it on another set.

Fixed jack plates present a relatively inexpensive solution to mount a long shaft outboard to a boat with a very short transom. Or if the mounting holes in the transom are too low or high.

You can also use these to add a little bit of setback to the boat so that it runs better in the water.

Manual Jack Plates

Manual jack plates, also known as mechanical jack plates, are more versatile. Unlike fixed jack plates that require you to remove the engine to change the height.

A manual jack plate has a continuous range of heights at which you can move the mounted engine. Manual jack plates are able to do this.

By using a slot inside the plate on which allows part of the plate to slide up or down.

When you find the perfect engine height for your boat and engine combination. You can tighten the plate with a wrench. And set the plate in position where you want it.

You can adjust the height of your engine on a manual jack plate. Without the use of special tools or jacks to hold the engine up.

You only need a wrench and some muscle for the job. Simply loosen up the bolt, raise, or lower your engine with a little bit of force, and tighten the bolt again.

This can be tricky to do on the water, and we recommend doing this on dry land only. But when push comes to shove, sometimes it can be done.

Without having to remove the engine, these are a step above the fixed jack plates. But still limit you from the ability to move the engine up or down while underway!

Hydraulic Jack Plates

Hydraulic Jack PlateHydraulic jack plates offer the most versatility, functionality, and convenience among all the other jack plates.

Like manual jack plates, these are capable of a continuous range of engine heights. Unlike manual jack plates though, they do not require any kind of wrench or socket to move them up or down.

Instead, these use hydraulic rams and pumps to push the plate up or down. Since these jack plates use hydraulic power to adjust the height, you have no need to physically exert yourself in the process!

Just pressing a button will do the trick, making it much more convenient than any other type of jack plate. These plates also offer more functionality over manual jack plates.

The use of hydraulic power enables the driver to adjust engine height while underway on the water. While the boat is running!

This can make the transition from deep to shallow water (or vice versa) seamless and without any hassles. That is not the only benefit that a jack plate has though.

What Are The Benefits Of A Jack Plate?

Better Efficiency

Many people who are contemplating buying jack plates have one question in common: will a jack plate increase speed? The short answer is yes.

Installing a jack plate on your boat for the outboard can allow your boat to go faster.

A jack plate will lift your engine up in the water and bring your propeller closer to the surface of the water. As a greater part of your engine is now out of the water.

There will be less drag force on the boat. This means that your boat is now capable of achieving greater efficiency.

The setback offered by the jack plate also means that the engine sits further away from the boat. The water here is less turbulent and disturbed. As compared to the water right behind the boat.

The propeller of your boat does not have to fight the turbulence as much and can get a better bite. As a result, it runs much more efficiently.

You can observe the increased efficiency in two ways:

  • Your boat will go faster
  • Your boat will get better gas mileage

Whether you choose the increased efficiency to go faster or get better gas mileage is up to you. What is certain is that your boat will cover more distance for the amount of work done by your engine.

Different boats have different profiles and a unique engine height at which they run the most efficient. You can find this out with just a little bit of trial and error.

A good way to start is to start from the lowest position or trimmed down position. Then work your way up, checking fuel efficiency at each point.

Be careful not to raise the engine out of the water too far though.

This can cause cavitation and damage the engine. If you are planning to install a jack plate on your boat. It might be a good idea to get a water pressure gauge installed at the same time.

If your current gauge doesn’t already show you this reading.

This will allow you to properly tune and find the best spot for your engine without the risk of cavitation. If your engine is taking in air. The gauge will inform you by showing a loss of water pressure.

This way you’ll know that it’s time to trim down a little bit!

Access to Shallow Waters

If your boat does not have a large deadrise, it is capable of going in much shallower waters. However, the outboard engine might hang so low in the water.

That the propeller or skeg might snag on stumps, rocks or the ground. Installing a jack plate can help to eliminate this problem entirely.

The jack plate can raise your engine enough so that the skeg does not hit the bottom. This allows you to go in shallower waters with ease.

Which is especially useful for people who like to troll for fish in rivers. But do not want to invest in another smaller boat.

Jack plates can also allow you to get on plane in shallower water too.

Ease of Planning

With a jack plate, you can get on plane in shallower water much quicker. Everyone who has tried to get their boat on plane in extremely shallow waters. At some point in time usually runs a ground.

With a jack plate, you can raise your engine up as high as you can in the water. Trim all the way down, and ease the throttle forward.

The boat will pop up on plane faster and more efficiently this way. Once the boat is on plane, you can recess the jack plate down and adjust the trim accordingly.

Just be sure not to raise the engine so much while planing that it begins to cavitate. This way of planing your boat is quicker and much safer.

It does not raise the bow too high to obstruct your field of vision and enables you to plane even in shallow waters.

Stability in Rough Water and In Tight Turns

One thing that most people often overlook is the capability of a jack plate in rough waters. In rough waters, your propeller might jump out of the water and start to cavitate.

A jack plate can offer more stability to your boat in such waters. Lowering your engine much further in the water allows the propeller to get more grip and navigate rough waters more easily.

Your boat responds very differently depending on the engine height. By tweaking the height just a little, you can get a lot better handling out of your boat.

If you have a few friends or cargo on your boat, it will give better handling when you lower the propeller. When the boat is not loaded.

You can also get good handling and better efficiency with the propeller slightly closer to the surface of the water. Then when pulling into a tight turn, you can get better stability if you lower your boat’s engine.

When it sits low in the water, the propeller can get the maximum amount of bite. Which will give you better control of your boat and prevent it from sliding out in tight turns.

This way, you can make turns that you simply cannot make on a boat without the jack plate!

Check Us Out!

Now that you know all about Jack Plates! Here are a couple of articles that you will also find very helpful!

What’s The Difference Between Boat Trim Tabs & Tilt & Trim?

How To Tie Up A Boat! Don’t Wake Up With it Underwater!

You can also find all kinds of awesome content on our YouTube Channel! We cover all kinds of How-To, DIY, and basically all things boating!

Aaron Hilligoss

Aaron has been working in the Marine Industry for over a decade and holds certifications for Yamaha and Mercury Marine. It is not uncommon for him to own and be working on at least three different boats at any given point in time!

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