How do I Clean My Waterline?

Welcome to Shurhold’s Clean-N-Simple Tips. We are back at the site of our Wellcraft 340 Coastal project boat and today we are going to be talking about how to clean and maintain our waterlines on wet slipped boats.

Our boat is kept in a wet slip, and in order to do so we prepped the boat with a really high quality bottom paint.  Working with the great team over at SeaHawk Paints, we applied 2 primer barrier coats followed by 2 coats Biocop TF Anti-fouling paint with Bio Boost added since we are in a slime / algae prone area.  This SeaHawk paint is part of a newer breed of ablative paints.  The benefits to this type of paint are that as you use the boat it self polishes allowing fresh anti-fouling material to continually be exposed for maximum protection.

Now, when working on your waterline it is important to know what type of bottom paint you have.  While we want to clean the scum line we also want to take care not to remove or damage the anti-fouling paint.  Additionally, since the boat is in the water we do not want to work with any harsh chemicals that may hurt the environment.

If you are going to work from the boat or dock you will need:


Working from the dock or the boat we will want to clean a small section at a time.  Start by rinsing the area to soften and loosen the scum with the pressure from the hose.    Now, when we begin to scrub we want to start with our softest tool and only move up as needed.  Also, here you will find that our curved adapter will help you reach those odd angles from both the dock or the boat.

If you have a very soft ablative paint you will want to only use a soft brush and be careful not to smear it.  Only brush along the scum line above the paint from side to side or use one directional strokes down. Pulling up could bring soft paint onto the clean hull sides.

With our SeaHawk ablative paint this is not a worry as this newer breed of ablatives is hard enough to not smear. Personally, I find the best way to actually clean this area is from a small work raft, kayak or even standing near a sand bar and doing it up close and by hand.

In these situation you will need:

  • Spray bottle filled with properly mixed boat soap;
  • Soft Brush;
  • Light Duty Scrub Pad;
  • Magic Eraser Sponge; and
  • Suction Cleat


The suction cleat is key.  This will give you something on the hull to hold on to while you scrub so you do not keep pushing the boat away.  As before, we want to work a small section at a time and spray it with the boat soap.  Then work that area in a horizontal scrubbing motion to loosen and get rid of the scum.  Tougher areas that leave some staining are then easy to address with a Melamine sponge like the Magic Eraser.  Using this same motion with the sponge you will find that the staining and scum come right off.

If you have your boat in dry dock or up on a trailer there are many more options and chemicals we can use with out the issue of runoff.  So look for those tips on another episode.

Nothing looks worse than a boat cruising around with a dirty scum line.  Remember just hitting the waterline with nothing more than a soft brush once a week can keep the hull looking good with little to no effort.  If you let it go a bit longer like I did then a little elbow grease will do the trick.

Until next time keep your boat CLEAN-N-SIMPLE!