Bimini tops attract mildew and also get covered in bird poop. It’s horrible, and it’s enough to make you want to pull your hair out. I’ve seen plenty of videos and advice on the Internet which tells you to use bleach to clean mildew from a Bimini top.

Don’t reach for the bleach until you have read what I am going to tell you. Bleach in the wrong hands can do terrible damage to the canvas and stitching. Instead, clean your Bimini top with a pressure washer, laid flat on the ground. 

How to clean a boat Bimini top without bleach

First up, why do I hate bleach so much for Bimini cleaning. Simple; the bleaching chemicals can degrade the thread in the canvas stitches and can also fade the Bimini over time.

Bleach might be good for countertops, but it can be very destructive on vinyl, canvas, and cloth materials – everything a Bimini top might have in it!

This is why you see so many photos online of seams in boat seats that have started to come apart. It’s the harsh bleach that has done this.

Bimini tops aren’t cheap. You can buy a replacement (here are the ones I recommend), but if you can clean up the mold and mildew from the canvas cover, you save yourself some money.

How I clean Bimini tops instead (best way)

Now I’ve given you a great reason to not use bleach, it’s time to give you the best method in my opinion. And the great thing is, it’s simple, cheap, and effective.

1. Remove the Bimini canvas from the frame and boat

Take care to unclip and pull the Bimini top and canvas away from the frame. This is relatively simple on my pontoon boat two bow frame set-up.

Don’t rush this part, as you could tear and rip the canvas.

2. Lay the boat canvas down on a flat surface

Lay the Bimini top out on your driveway or patio so it’s flat.

Put some weights down on the edges to stop the canvas from lifting in the wind and getting dirtier. I use a few rocks, but you might use some fitness weights instead.

3. Use a pressure washer to clean the mildew and dirt away

If you don’t have a pressure washer, get one now. They are great for any type of pontoon boat cleaning jobs, and I regularly use mine on the deck and pontoons.

I have a Sun Joe. It’s cheap(ish) and does a great job. Read the reviews it has on Amazon.

With a few up and down strokes, you should be able to blast away all the mildew and mold in just a couple of minutes.

Handy Hint: Don’t use the most powerful setting. Start off with low pressure, gradually increasing until it removes the mildew and mold. If it’s set on too high a pressure, you might tear the canvas, especially if the jet hits a weak spot.

I know a local Bimini restorer who uses this exact method. Interestingly, he did mention that he does a very small amount of bleach into the water mix.

Most pressure washers say to stay away from running bleach through them though, so it’s not something I have ever done with my Sun Joe.

4. Let the boat Bimini top dry out in the sun

Now just leave it to dry out in the sun, and you should have it looking like brand new again.

Using this method, I usually manage to get 95% of all mildew and mold stains out.

5. Apply 303 protectant to the Bimini top

Once your Bimini is dry, apply some marine grade 303 protectant to it. I buy one which also has UV protection in it as it will help protect the canvas against the sun. I put extra on the seams for obvious reasons.

303 Products have a great product which contains powerful UV blockers to help stop premature aging, cracking, and fading. See which 303 I use on Amazon.

Before and after photos

I’ve not cleaned my Bimini this year but did manage to track down a photo on Pinterest where a pontoon boat owner had used the same method as me. Below you can see the before and after cleaning photos.

how to clean a canvas bimini top

The best way on how to clean Bimini top before and after photos (image credit unknown, found via Pinterest).

How not to clean mildew from Bimini top

In the video below you can see an example where a guy washes and cleans down the Bimini using bleach to get rid of mildew and stubborn stains.

This is the exact method I recommend you don’t do.

This is what he does if you don’t have time to watch the video in full.

What he uses:

  • 1 cup of bleach
  • 1 gallon of water
  • ¼ cup of mild soap
  • Soft bristle brush

How he cleans the Bimini:

He then cleans the Bimini top up with a soft bristle brush, allowing the mix of bleach, soap, and water to soak into the canvas for 15 minutes.

And finally, he rinses the Bimini with water until all the soap, residue, and mildew or mold is cleaned away, before letting the canvas dry out in the sun.

Now, I won’t lie to you and say that the results he gets looks good.

But that’s not really the problem here, as visually it looks clean.

However, if this cleaning process is repeated regularly what you’re going to find is that over time the threads will start to pull apart. The canvas can also become discolored and faded.

Watch the video now, but don’t do this!

Can you machine wash a canvas boat cover or Bimini?

I’ve not done this myself but have seen examples on social media where pontoon boat owners have thrown the canvas top into a washer and got great results.

Here is the best comment I read online regarding washing machine cleaning methods:

“I wash my pontoon Bimini top canvas in our washing machine using Oxyclean. Once the cycle has finished, I then put it back onto the Bimini frame so it can dry out in the sun. As a caveat, I have a front loader and the entire canvas fits in there. I have two Biminis on a 25-foor pontoon boat, and I wash them one at a time with their respective covers. The boat cover I took to a coin laundry as it was too big!” 

Can a laundromat clean a boat Bimini top? 

Yes, they can. Many laundromats have large enough drums to clean oversize items like a Bimini canvas. If you do a check locally, you should be able to find a laundromat that is near a marina – those guys will be used to this type of request.

A buddy of mine get his Bimini cleaned like this once a year and it costs him around $35 each time, which sure seems like cheap maintenance on a $1500 custom cover. They usually charge based on boat length.

Can you clean a Bimini canvas in a swimming pool?

Yes, you heard that right!

I’ve known some guys who throw theirs into a swimming pool overnight then rinse it off afterwards.

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

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

Mildew is a royal pain in the butt on vinyl boat seats. But you can shift it successfully with a little planning and preparation.

One of the most popular posts on Pontoonopedia which regularly gets shared on social media and web forums is my extensive guide on how to clean mildew off vinyl boat seats.

Read that for step by step instructions, plus advice on all the gear you need to do a great job.

What is the best way to clean boat canvas?

But what about other boat canvas and covers?

You can still use the pressure washer method I described above when detailing how to clean a boat Bimini top, but there’s also another process I use too which can work just as well.

  1. Clean off any dust from the canvas cover by laying it on the floor and using a boat vacuum (here are some great marine vacuum cleaners) to pull all the crud up.
  2. If there is still some larger dust patches remaining, use a broom to get it shifted, and then vacuum again.
  3. Scrub the boat canvas cover with clean bucket of warm water and a very mild soap solution.
  4. Once you have scrubbed the dirt away, spray the boat canvas down with garden hose or pressure washer to get the cleaning solution cleaned away.
  5. Finally, you can dry the canvas out by hanging back onto your boat in the sun, or over a clothes line.

How can I stop seagulls pooping on my Bimini top?

Aside from mildew and mold, seagulls are your worst enemy. Cleaning their poop off can be a mission, but is made much quicker with the method I outlined above for cleaning your canvas Bimini cover.

However, if you could stop the seagulls in their tracks before they had a chance to mess on your boat, it would save you a lot of work in the long run.

I’ve already thought of that, and have some methods for stopping seagulls sitting on your boat. You can read how I did it in this guide to deterring seagulls from making a mess on your boat cover, canopy and Bimini top.

The last word…

After you get it clean, I highly recommend 303 protectant.

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

“I will wash both sides with a soft auto pole brush. Using Awesome detergent and about ½ a cup of bleach to 2 gallons of water in my driveway. I let it dry out well, then treat it with 3M 303 UV waterproofing. I only do this once a year.”