What is boat draft and why it matters

If you’re looking to buy a boat, or want to take your boat into shallow waters, then you’ll need to know what boat draft is. More importantly, you’ll need to know what your boat’s draft is, so you don’t end up running aground.


Here’s what you need to know.


What is boat draft?

Boat draft is the distance between the deepest point on your boat and the waterline. It’s also the minimum water level required to float your boat, before it touches the bottom. Perhaps you’ve heard someone say a boat draws 30 inches?


Well, they’re simply saying that the boat’s draft is 30 inches.


How do you calculate boat draft?

Most boat specifications will include your boat’s draft. So be sure to consider this if you’re looking to buy. This is especially important if you’re going to be boating in shallower waters. If this is the case, you’ll want a smaller boat draft for greater access.


Boat draft is calculated differently, depending on the kind of boat you drive. For example, draft for boats with inboard pod drives or direct-drive inboard propulsion, is determined from the gear at the lowest point of the boat. This could be the rudder, propeller or any other gear below the boat.


If you’re operating an outboard, you’re likely to have two draft measurements. These specs will be shown as ‘drive down’ and ‘drive up’, as they indicate the boat’s draft distance when the drive is either lowered or raised up.


If the drive is up, the draft will be measured from the keel, or wherever the lowest point of the boat is now. When the drive is down, the lowest point of the boat is likely to be the skeg, which is located on the propellor’s front.


Boats with jet drive propulsion house their drive system within the boat. That means the boat’s draft is measured to the keel. If you’re unsure of what your boat draft is, take a look online at the specs of your particular model and make. You should get the information you need there.


Boat draft specs are approximate

Most draft measurements refer to boats that are running dry, which means the fuel tanks and water tanks are both on empty. They also don’t account for the weight of gear onboard, and of course the weight of passengers.


The weight distribution of passengers on smaller boats may also impact the boat’s draft. For example, whether the weight is distributed more towards the bow or the stern. The hull’s design can also effect how the draft responds to the boat’s load distribution.


As a general rule of thumb, the greater the weight onboard, the lower the boat will be on the water, and the more it will draw. If you need to know accurate draft measurements we recommend loading up the boat, as you normally would, then measuring the draft.

Why does boat draft matter?

If you’re heading out in shallow waters you’ll need to know your boat’s draft measurements. Anyone entering a harbour or dock, especially if the tide is low, should have a good idea of what their boat draws in order to stay off the bottom.


Anglers who enjoy fishing in the flats or shallows should also have a handle on their draft. If this kind of fishing is your preference, it’s probably wise to choose a boat with a low draft, so you can access those shallower spots without issue.


Need cover for your fishing boat?

When we’re not enjoying time out on the water, we tailor cover for boaties all over Australia. If you’d like your existing marine cover reviewed, or would like to cover your boat for the first time, please get in touch.


Our marine underwriters can put together a free quote for you (with no obligation) based on your boating needs. Talk to us to get started and stay safe out there!