3 steps to a sparkling clean hull

rowing slow book,

Here’s a great question from one of my readers. She asked about how to keep her rowing shell hull sparkling clean:

We have a 1 year old Vespoli light 8, painted white. It’s shell was pristine until our last race, when the boats were parked on the trailer underneath an oak tree. It rained heavily all night and was over 90 degrees F the next day before the shell was taken off the trailer and re-rigged. The part of the shell that was under the tree now has dark blue/black spots on it, and you can clearly see where the straps were because that is the only part of the boat that is still white. We think the blackish residue, which would not come off unless we used our fingernails, is sap from the tree. We scrubbed the boat with soapy water for an hour without result. Have you heard of this before, and what cleaners or brushes should be use to take it off?

That’s a great question (and an unfortunate incident!). First things first…

The advantage of a clean hull

There are 3 reasons why a clean hull is important

  1. The boat will look better
  2. The boat will perform better
  3. The boat will last longer

There are numerous things that can attack a boat’s hull and age it prematurely. Keeping your hull clean can fend of many of those attackers and keep your hull younger, fitter, and faster.

A clean hull will have less friction on it, and that is a good thing. We like to go fast, and friction is not our friend.make it last forever, rowing boat maintenance guide

How to clean a rowing hull

There is a priority system I use when cleaning a rowing shell’s hull. It all depending on how dirty it is—and what the so called dirt actually is. It boils down to using one (or all) of these three choices:

  • soap and water
  • chemical solvent
  • abrasive compound

Step 1: Start simple — Use water and soap

If the hull is covered with slime from the water, or dust, mud or dirt, I use simple soap and water. I’ve had much success with a biodegradable laundry detergent, such as Arm and Hammer.

Make up a mixture of about 1 part soap to 10 parts water, get the hull wet with water, apply mixture, scrub with a sponge or soft pad, and that usually takes care of about 80% of the dirty hulls I see.

We make a habit of cleaning our hulls (inside and out) once a week, with soap and water.clean rowing shell hull

If your hull has more than just surface junk on it, you might want to try…

Step 2: Dissolve it — Use solvents

If the contaminates on the hull are things like tape residue, sap from trees, dried pollen, or other sticky stuff, I use a chemical solvent, such as mineral spirits (known in Europe as white spirits).

Mineral spirits are not very toxic, will dissolve many things, and then washes up with soap and water.

I only have coaches who know how to handle chemicals use mineral spirits. (Use as directed and only in well ventilated places.)

Friends at Pocock Racing Shells highly recommend Gel Gloss for everything. It is very easy to spray on and wipe off with a soft cloth. Although I have not tried it, they swear by it, which is a strong recommendations from a boat builder. They also use it on riggers to clean them.

For algae and water stains they recommend an algae cleaner, such as Star brite Instant Hull Cleaner.

If you still see crud that hasn’t come off, it might be time to try…

Step 3: Muscle time — Use rubbing compound

If the hull is covered with something that the first two steps won’t handle, I then revert to an abrasive solution, such as rubbing compound.

Rubbing compound is a common product found in many stores. It comes in a multitude of abrasiveness, called grits.

I’ve had luck using 3M Marine Rubbing Compound. However, there are much less abrasive grits, such as 4000 that will probably handle most situations you run into. I’ve found compounding to take care of most of the hull contamination that I’ve had, including paint splatters and very small scratches.

There are a few tricks to using rubbing compound:

  • Use only as directed
  • Do small areas at a time
  • Keep out of direct sunshine (if possible)
  • Apply with gentle motions to a wet surface
  • Use a clean cloth to apply
  • Wipe off when dry

A word of caution about rubbing compound: It is a form of liquid sandpaper, meaning that it will scratch the paint on a hull if you are not careful. So go slow, and carefully, using only the pressure and grit you need. Again, only a coach or experienced person should be doing this step.

These 3 simple steps to clean your rowing hull should be able to help you get your hull clean, and hopefully a little happier—and faster.


Mike Davenport writes the MaxRigging blog and is a regular contributor to Rowperfect – listen to him on RowingChat Podcast


2 thoughts on “3 steps to a sparkling clean hull

  1. Henry Law says:

    In respect of tree sap and other organic gunk, I think I’d try “Stihl Special Cleaner”, made by the garden-tools company of that name. Its description includes “Cleaner developed specially to remove organic substances like resin, oil and grass stains …”; I use it to clean garden tools (not just Stihl’s), and I think it would clean tree sap off a boat. It’s water-soluble too, which makes it much more convenient than white spirit or whatever.

  2. Albert Knop says:

    Sometimes a white boat will have a slightly yellow contamination that partly consists of lime. This occurs often when the shell is not washed with water or water and soap and only wiped drie with a towel. The best way to solve this is using a shower cleaner that is slightly acidic and dissolves the calcium. Spray is on, leave it for a while, go over it with a sponge soaked in the same shower cleaner and then rinse with water. The effect can be stunning.

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