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Keep Your Bimini Top Clean Without Using Bleach

Bimini tops draw mildew and get coated in bird feces as well. It’s bad, and it’s enough to make you want to get your hair pulled out. I’ve seen plenty of videos and tips on the Internet that advises you to use bleach from a Bimini top to clean mildew.

After you have read what I am going to tell you, don’t reach for the bleach. Bleach can do horrible harm to the canvas and the stitching in the wrong hands. Instead, use a pressure washer, flat on the ground, to clean your Bimini top.

Clean your boat Bimini top without using bleach

First, why do I hate bleach for Bimini cleaning so much? Simple; the bleaching chemicals in the canvas stitches can weaken the thread and can fade the Bimini over time as well.

Bleach can be fine for countertops, but on vinyl, fabric, and cloth fabrics, anything a Bimini top may have in it can be very damaging!

This is why you’re seeing so many pictures of seams in boat seats online that have begun to come apart. This is the harsh bleach that did this.

Tops from Bimini aren’t cheap. You can buy a patch, but you’ll save yourself some money if you can scrub the mold and mildew out of the canvas cover.

The Best Way to Clean Your Bimini Top

Now I have given you a great excuse not to use bleach. In my view, it’s time to give you the best way. And the great thing about it is that it’s easy, inexpensive, and effective.

1. Remove the canvas from the frame and boat

Take care to unclip the Bimini top and canvas and pull them away from the frame. On my pontoon boat, this is a relatively simple two bow frame set-up.

Don’t hurry this segment, as the canvas could tear and rip.

2. Lay the Bimini canvas top on a flat surface

On your driveway or patio, spread the Bimini top out so that it’s smooth.

To stop the canvas from lifting in the wind and getting dirtier, bring some weights down on the sides. I use a couple of rocks, but you can instead use some fitness weights.

3. Wash the mildew and dirt away with a pressure washer

Get one now if you don’t have a pressure washer. They are perfect for pontoon boat cleaning jobs of any sort, and I use mine on the deck and pontoons regularly.

I’ve got a Sun Joe. It’s inexpensive(ish) and does an excellent job.

You should be able to blow away all the mildew and mold in just a couple of minutes with a few up and down strokes.

Handy Hint: Don’t make use of the most efficient water setting. Start with low pressure, rising progressively until the mildew and mold are removed. If the pressure is set too high, you might tear the canvas, particularly if the jet hits a weak spot.

I know a local restaurateur from Bimini who uses this precise form. Interestingly, he did note that the water mix contains a very small amount of bleach.

However, most pressure washers claim to stay away from running bleach through them, so with my Sun Joe, it’s not something I’ve ever done.

4. Allow the canvas to dry out in the sun

Only let it dry out in the sun now, and you should make it look like it’s brand new again.

I generally manage to get 95 percent of all mildew and mold stains out by using this tool.

5. Apply Protectant to the canvas

When your Bimini is dry, add some protective marine grade 303 to it. I buy one that has a UV cover in it as well since it will help shield the canvas from the light. For obvious reasons, I did put extra on the seams.

To help avoid premature aging, cracking, and fading, products have a great product that contains strong UV blockers, I use marine grade 303 product.
303 Marine UV Protectant Spray on Amazon

My Results

This year, I didn’t clean my Bimini, but I managed to track down a Pinterest picture where a pontoon boat owner used the same strategy as me. The before and after cleaning pictures can be seen below.

How not to clean the Bimini Top mildew

A lot of people use bleach to get rid of mildew and stubborn stains in their homes. However, this is the exact strategy that I warn you not to do.

One recipe I’ve seen people use with disastrous results is:

  • 1 cup of bleach
  • 1 gallon of water
  • 1⁄4 cup of soft soap
  • Gentle bristle brush

Mistake #1

I’ve seen boaters use a bleach solution and a soft bristle brush to clean their Bimini top. Many times they allow the combination of bleach, soap, and water to soak into the canvas for 15 minutes. They then rinse all the soap, residue, and mildew or mold away.

Now, I’m not going to lie to you and tell you that the results you get don’t look fine. It will – At First.

But this isn’t the problem here, as it looks visually clean.

However, if this cleaning process is repeated frequently, what you can discover is that the threads will begin to pull apart over time. The canvas can also become faded and discolored.

Can a canvas boat cover or Bimini top be machine washed?

I didn’t do this myself, but on social media, I saw instances where pontoon boat owners threw the canvas top into a washer and got great results.

Here is the best article I’ve read online about cleaning methods for washing machines:

“In our washing machine, I wash my pontoon Bimini top canvas using Oxyclean. I then place it back on the Bimini frame until the cycle is done, so it can dry out in the light. I have a front loader as a caveat and the whole canvas fits in there. I have two Biminis on a 25-foot pontoon boat, and with their respective covers, I wash them one at a time. I took the boat cover to the coin laundry because it was too heavy! ”

Can a Bimini top be cleaned at the laundromat? 

Yes, they’re able to. Most laundromats have big enough drums, like a Bimini canvas, to clean oversized objects. You should be able to find a laundromat near a marina if you search locally-those guys would be used to this sort of order.

A friend of mine gets his Bimini washed like this once a year and each time it costs him only $35, which sure seems like affordable maintenance on a custom cover of $1500. Depending on boat length, they usually bill.

What about washing the canvas top in a swimming pool?

Yeah, you understood that correctly!

I’ve known some guys who put their own into a swimming pool overnight and then afterward rinse it off.

However, I’ve never done it. I used the spray down method detailed above with soap and brush.

What’s the best way to clean mildew off boat seats?

On vinyl boat seats, Mildew is a royal pain in the ass. But with a little planning and preparation, you can successfully drive it.

Read that for step-by-step directions, plus tips on all the equipment you need to do a great job.

The best way to clean boat canvas

But what about other boat canvas and covers?

When explaining how to clean a Bimini boat top, you can still use the pressure washer technique I mentioned above, but there is also another method I use that can work just as well.

  1. By laying it on the floor and using a boat vacuum to suck up all the crud, clean off any dust from the canvas cover.
  2. Using a broom to make it move and then vacuum again if there are still any larger dust patches left.
  3. Scrub the canvas cover of the boat with a clean hot water bucket and a very mild soap solution.
  4. If the dirt has been scrubbed away, spray down the boat canvas with a garden hose or pressure washer to clean the cleaning solution.
  5. Finally, by hanging back on your boat in the heat, or on a clothing line, you can dry out the canvas.

Can I stop seagulls pooping on my Bimini top?

Seagulls are your greatest enemy, aside from mildew and mold. Cleaning their poop off can be a task, but with the technique, I described above for cleaning your canvas Bimini cover, it is accomplished much faster.

If, however, you could stop the seagulls in their tracks before they had a chance to mess with your ships, in the long run, it would save you a lot of work.

I’ve been thinking about that already, and I’ve got some strategies to stop seagulls sitting on your ships. In this guide to deterring seagulls from creating a mess on your boat cover, canopy, and Bimini top, you can read how I did it.

My Recommendation

I highly recommend 303 Protective once you get it clean.
303 Marine UV Protectant Spray on Amazon

And one last thing, if you don’t like my approach, here’s a comment I saw from a very well-respected pontoon boat owner on Facebook about how he cleans his Bimini top pontoon… and yes, he uses bleach and says he never had any problems (I think it’s all down to personal choice):

With a soft Auto Pole Brush, I’ll wash both ends. In my street, using Awesome detergent and around 1⁄2 a cup of bleach to 2 gallons of water. I let it dry out well, then I use 3M 303 UV waterproofing to treat it. Only once a year do I do this.

John Allen

With more than a decade of experience cruising the lakes in my Crestliner Grand Cayman pontoon boat and my Boston Whaler, I now want to share everything I've learned with my community here at Boating Hub.