Understanding Boat Trimmings

Posted on: 19 March 2020

Understanding boat trimming is important because of four key factors:

  • Comfortable Ride
  • Increased Speed
  • Engine Durability
  • Efficient Gas Mileage

Before getting into these factors, it is important to understand the meaning of boat trimming.

Boat trimming is simply the way your boat tilts forward or backward. You can tell by looking at your boat bow (nose of your boat) and stern (rear side of your boat).

If your boat is tilting forward (known as a negative trim), the bow appears to be digging or sinking deeper into the water (it can be referred to as bow down) and the stern rises slightly. If your boat is tilting backward (known as a positive trim), the stern appears to sink deeper in the water and the bow points upwards (bow up). Your boat can also be in a neutral trim; this is when it is parallel with the surface of the water.

Comfortable Ride

Before you take your boat out to deep waters and with the engine in neutral, it is recommended that you ensure your boat is in neutral trim. You can tell by looking at the tilt gauge or listening to changes in sounds from the tilt motor.

When your boat is moving, it gets pounded by waves. This can lead to an uncomfortable ride and that is why tilting is done. To make your boat ride more comfortable, you should tilt it backwards to reduce wave pounding.

Increased Speed

As water waves pound on your boat, speed is reduced because waves offer opposing resistance. Likewise, your boat's hull may experience drag (a kind of opposing forward movement or water pressure or force that acts on the surface of the hull). Tilting your boat backwards reduces waves pounding and drag, thus boat speed increases.

Engine Durability

Be careful not to tilt your boat backwards too much. Air can be sucked into the engine causing overheating, which is not a good thing; it leads to engine damage. What you want to be sucked into the lower unit of your outboard engine is water. You can tell that water is being sucked by quickly glancing behind and seeing a tell-tale stream. If you don't see it, you have tilted your boat too much.

Most boats also come with a tilt gauge to help you know when you tilt your boat too much. Experienced boat operators can also tell from the different sounds made by the engine.

Efficient Gas Mileage

If there is no resistance (either from waves or hull drag), you end up saving gas because your engine is not working harder. Tilting your boat backwards eliminates resistance, hence saves efficiency in gas mileage.