Ok to pressure wash fiberglass?

[Max Simmons]

I'm cleaning up a fiberglass boat that's been sitting for a couple years accumulating various goop on the topsides. Was thinking of pressure washing first, but wondering about any potential damage. Can it harm gel-coat? Don't think it's cored so not worried about that aspect. Thoughts?

 

[Woodland Hills]

I hope not since the guy on the other side of the canal pressure washes his rental center consoles for 1/2 hour every day that we’ve been here. BTW, they still look like new.

 

[RCook]

My pressure washer includes different nozzles which make the spray more or less focused. For fiberglass I would not use the one or two most pinpoint focused.

 

[AmericanVagrant]

I have not had an issue pressure washing boats. Best practice would be to wax the surface afterwards to seal small pores, but not doing so isn't going to hurt anything, aside from no better resilience to getting dirty again.

 

[KnotYet]

My main concern would be avoiding any fasteners that are bedded to keep from
blowing away any of the compound. Go easy on any bare teak, too.

 

[rsn48]

On my Catalina boat, pressure washing did have consequences. The pressure washing took small, something like the size of a pea, chunks out of the fiberglass. Unless you have a nozzle that diffuses the spray, I would not do it.

 

[AZ2Loop]

Yes, you can pressure wash fiberglass hulls without damaging the gelcoat As others said above, depending on the power of your pressure washer, you probably should be careful what tip you are using. See rsn48's note above.

In a marina where I once worked, they had a 200 boat indoor rack storage barn. Nearly every boat that was fork lifted out of the water was pressure washed before going into the barn and on its assigned rack. No problems at all. The boats ranged from dinghies to 48 feet and some were over $1.5 million boats at the time, so we were not careless to say the least. The pressure washer never damaged them and did a great job keeping them clean. The right tip was no doubt important.
Also, every so often we would pull our rental and club boats out of the water and pressure wash them, too. It is very effective at taking the water line and various salt water growth/barnacles/etc. off the boats. Very efficient. I did not pay attention to what tip was on the pressure washer, as that was all it was used for and the right tip was always installed. I was careful around transducers, but we even cleaned them with the pressure washer on our rental and club boats.

 

[Pete Meisinger]

I have a gasoline powered pressure washer that probably generates 3500 lbs of pressure. It will literally take the bark off a tree. Don't use that!

Get a small electric one generating 1,000 maybe 1,500 lbs pressure. Still be very careful of any brightwork

pete

 

[tiltrider1]

I have a gasoline powered pressure washer that probably generates 3500 lbs of pressure. It will literally take the bark off a tree. Don't use that!

Get a small electric one generating 1,000 maybe 1,500 lbs pressure. Still be very careful of any brightwork

pete

I'm going to agree with Pete here. at 1200 psi you shouldn't have any issues. I use a 1200 psi machine to pressure wash the boat each spring. I also use it on all the canvas. I tried it on a life jacket once but it just shredded it so I don't recommend doing that. I also do not use it on vinyl cushions.

I would not recommend using anything greater than 1200 psi. The yards use 2400 psi machines to clean bottoms but in that case you want to blow off any poorly adhered bottom paint and sea creatures.

 

[rsn48]

Get a small electric one generating 1,000 maybe 1,500 lbs pressure. Still be very careful of any brightwork


I doubly agree with this. I bought a Ryobi gas power washer but I have to be careful what I use it on. I then went and purchased a cheapy - can't remember the brand - electric power washer, I use this one the most.

 

[Comodave]

As said above use a wider pattern spray so it isn’t as intense. Then move back from the glass and gradually move a bit closer. Don’t go any closer than necessary to get it clean. Then once it is clean, wax it.

 

[koliver]

I have this one:
https://www.kmstools.com/be-3-44-100-psi-pressure-washer-2-3-gpm-210cc-92528
I use it around the house, doing sundecks, concrete, etc and have taken it to clean docks. It is good, but the one at the YC lifter is WAY more powerful, which everyone uses to clean all of the growth off the bottoms of their boats, including me. I keep the spray focused about 4" away from the fibreglass, unless there is a barnacle or oyster shell too well attached, then I move right in. I used to be more reluctant to move in, but after using that amount of power on the boat bottom every year since 1987 (3 different boats) and never having any issues, I don't worry about this as a source of damage.

 

[Barking Sands]

I have a Frankenstein diesel pressure washer I built out of a single cylinder Yanmar clone. You could use to drill holes probably. Here is a video of me trying to use a surface cleaner. It just wanted to fly...lol.
https://youtu.be/J2rAvFkSkG8

Anyways as stated above...just be careful. Keep some distance from the surface and turn down the pressure to start. Most pressure washers actually do have adjustable pressure. Start low and work your way up to something comfortable and harmless. I would not get it near wood, caulking, anything bedded, windows, non skid etc.

 

[catalinajack]

No pressure washer anymore since we sold the dirt house but the gas-powered one I used to have was 4,000# max but had a pressure regulater. Plus, the output pressure could also be lowered by simply lowering the speed of the engine.

I have a gasoline powered pressure washer that probably generates 3500 lbs of pressure. It will literally take the bark off a tree. Don't use that!

Get a small electric one generating 1,000 maybe 1,500 lbs pressure. Still be very careful of any brightwork

pete

 

[moparharn]

What are you cleaning off? If it is organic (brown water stain, algae, mold) I would use a mix of 50/50 Hydrogen peroxide and Lysol Toilet bowl Cleaner. Mix in bug sprayer, shake it up, pressurize and spray on pre-wetted gelcoat. Let it set 30 seconds and rinse off with soft bristled brush. I am told this can stain a gelcoat, so use on remote test area first. I have used it on ten or so boats and never had an issue. It is a common internet recommendation and it works like nothing else I have ever used. Will make a brown stained hull look like new and does not effect shine. My sawzall ran out of battery power one day so I used my power washer to cut the board in half to fit it in dumpster. If a boat's gelcoat can have osmotic blistering, could it possibly allow water to be blasted through? My 2 cents.

 

[BandB]

Despite the arguments over the amount of pressure or type of pressure washer, I just don't see one as the appropriate way to wash a boat or a car.

 

[KnotYet]

Despite the arguments over the amount of pressure or type of pressure washer, I just don't see one as the appropriate way to wash a boat or a car.

In the marine environment, I've had a few occasions where I bought a small, cheap
power washer to clean boats.
The first time was to get about a year's worth of growth off the bottom a my tender.
It worked really well and saved me a bunch of time and work.

The second time was after a sea lion somehow got into the center cockpit(!) and left
a great quantity of digested sea food behind.

Then there was the time we 'allowed' a gull to nest on deck and fledge the hatchlings...

 

[rslifkin]

Pressure washers are good for bottom cleaning. I don't like using them on topsides, unless you have a large area to clean that has no deck fittings on it. Using them near any deck fitting is a good way to create a leak.

 

[Art]

In my masonry, concrete and tile construction business: I've been using pressure-washers for decades.

Have three washers currently. One is HD gas engine, one a medium duty gas engine and one is relatively gentle electric. Sometimes all three are going at once on my projects.

Be very careful testing the resilience of your boat's gel coat... by... utilizing different tips as well as holding the tip well away from the surface.

Practice makes perfect regarding the tip used and holding a distance to surface. Can really tear things up if too much pressure on too close a tolerance tip held too close to surface.

Important: Don't EVER get your finger or other skin portion close to the water ejection end... will cut you like a razor.

As others have said - be very gentle/careful using pressure washer on any wood.

 

[psneeld]

It's just a tool.


Whether a powerful or a weak one.


I have use very powerful commercial ones, even with hot water/steam or sand slurry on the bottoms of boats. Also on the topsides to clean dirt/slime/algae/mold etc. Even remove paint in some cases.


As long as there were not voids in the glass, never had one harm a boat bottom or topsides, even when taking off all the bottom paint down to the gel.


Sure, be careful of painted surfaces, decals, bedding around fittings, etc....depending on your washer....


But with the right tip and proper distance, pressure washers can be as gentle as a good garden nozzle or powerful.


Light electric ones will clean mold and dirt, bird droppings and other typical cleaning....but don't expect them to do the bottom of a fouled boat very well if at all.

 

[bill.kimbell]

You can DEFINITELY damage gelcoat w a pressure washer. Ask me how I know..

 

[CarlF]

I carry a small electric power washer to blast bird do out of the nonskid. Never caused any damage. I do make sure not to put the full force on any caulked seam. And I would be careful with the big boatyard gas ones. Although you don't see the boatyards every holding back.

Gelcoat is really tough stuff. Think of the water force on a high speed powerboat going into waves.

For stains that the pressure washer can't touch try acetone and then On&Off gel. Or just give it a sanding or heavy compounding - followed by polish and wax.

 

[ljk]

Be careful not to use the pressure washer on your vinyl seats! Don't ask me how I know!!!

 

[Northern Spy]

A lot of how effective (or how damaging) a high pressure washer is has to do with the angle of incidence of the water to the surface being washed and the spray pattern. Pressure is only one factor in using a high pressure washer.

There is a whole industry outside of what one casually sees in pressure washing.

Great reference is found here: https://www.spray.com/

 

[Art]

Flat-Deck broad-swipe pressure wash cleaner head.

Photos during portion of a projects for my construction company. I have three different pressure washers; many different tip fittings for different needs.

DeWalt fitting shown here is sold at HD. Can probably get it on the net too. Attaches to quick-clip pressure wash wand. Works well on fiberglass decks too... never took photos of that.

Always... test small portion before going nuts on any surface. This attachment makes quick work on cleaning decks! 3,100 psi, 2.8 gpm, 6.5 gasoline engine pressure washer powering it here.

PS: Redwood deck 5 years since last cleaning. Concrete many more years

 

[Eagle Pursuit]

Pressure washing will remove any dirt that is “proud” on the surface, like green mold/mildrew, mud, salt deposits, etc. but will not remove black streaks from water running off the deck or stains in the gel coat. A good cleaner/wax will be required to finish the job. In other words, pressure washing will not be a labor saving method to clean up a dirty boat. That will take some elbow grease and time. Use the right products and methods and you will end up with a clean shiny boat.

 

[Seevee]

I'm a huge fan of pressure washers. Very versatile, does a lot of cleaning and use them for many things including boats.


You don't have to use a #1 tip and try to cut a grove in the gel coat. Pick the tip appropriate for the job and wash at an appropriate distance. Yes, they can cause damage if you don't know what you're doing, but they save tons of hours if done correctly.



Have used them on boats for 40 years, no issues and did the job.