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How to Clean a dirty bottom

2525 Views 14 Replies 13 Participants Last post by  pdqaltair
My new boat was left to sit in a freshwater slip for who knows how long. There is a about an inch of of algae dried on the bottom and the boat is on a trailer.

I was told to use a caustic style bottom cleaner but read the label about proper disposal of the run off and chose to try a biodegradable cleaner first. I have made one attempt to clean the bottom and had to apply the cleaner and then scrape it off. It was tough slow work and with limited access because of the trailer.

I plan on putting the boat in a freshwater lake today and see if the algae softens up and will come off easier.

I am looking for any suggestions on how to get the bottom clean. This is my only day off this week and I plan on cruising this weekend, so I hope to get it clean today.
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12hp 3500psi pressure washer ... it will even take the bottom paint off
Power Sprayer

I'd rent or borrow a power sprayer if you can get any kind of access through the trailer, which sounds like the case. It'll make quick work of that stuff. You can get the spots that the trailer is sitting on by taking a quick swim with a brush once its in the water.

The caustic stuff (On&Off) works great both above and below waterline too but if you end up going that route, heed the warnings about eye/skin contact.
You can REALLy do a LOT of dammage with a powerwasher at should not be used cloesr than about 12" with a fan type nozzle

A 3500 psi unit can lift gelcoat doing untold dammage in the wrong hands :(
the title of this post was just to funny to pass up. the obvious answer is "toilet paper". a pressure washer could do some serious damage to your bottom. oh wait, you were talking about the bottom of you boat! never mine.
Get a pressure washer, use the 'fan' nozzle, and keep it 24" away until you get the 'feel' of it. Then get closer to get the really stuck on stuff off.
another option is a garden sprinkler, set to keep the hull wet for a day. if you cant use that much water mix up some soapy water in a garden sprayer and spray it hourly for a day. the soap will help the water "stick"
second wind just dont put them in the head when done with em
Yep I knew it would good advice......

the title of this post was just to funny to pass up. the obvious answer is "toilet paper". a pressure washer could do some serious damage to your bottom. oh wait, you were talking about the bottom of you boat! never mine.
as well as smart*ss comments. Mission accomplished. Looks like I inspired you to make your first post.

I will look into the pressure washer. I think they are available from Home Depot. My one problem is the boat is a West Wight Potter and and the trailer is so low to the ground and the trailer covers up a good portion of the boat. It will be hard to spray much of the boat without getting very close.
I have done two things with boats of that size.
1. get it under a large tree and use a chain hoist.
2. Tie the stern off to a large tree and pull the trailer out from under the boat. If blocked as it comes off it is not really that hard to winch the trailer back under the boat. Same as the ramp but reversed.
For the actual cleaning, I agree with a pressure washer but there will be left over stuff that will take elbow grease no matter what.
With that small a boat it should be easy to tip it over a ways to get at all of it. I once took an O'day 20 off a trailer in my parents backyard and using an old block and tackle ( steel blocks and 3/4" manila rope) and a small pickup with one block tied to a telephone pole we tipped the boat almost 90 degrees to paint the bottom and the centreboard before launch. When one side was done we righted the boat and winched it over the other way to do the other side. Afterwards we winched it back onto the trailer. And no spots were missed unlike a boat on jackstands. Even inside the centreboard trunk. And a West Wight Potter is a lighter boat. I'd also caution against the pressure washer.
Almost every fiberglass keelboat that comes out on a marina travel llift for maintenance or storage gets a once over with a pressure washer while it is still in the slings. If you use common sense, start slow/gentle and don't direct the stream at any hull-deck or centerboard trunk joints you're not going to have any problems with a pressure washer.
I've got a 1200 psi PW that would work on that one, as mentioned, use a wide spray head, stay away until you figure out how close you can get before damaging etc.

Along with putting it back in the water to soften it up should work too.
A 4" plastic disposable dry-wall knife works if it is wet, and is safe for the paint.

It is easier to hold on to if you mount it to a 2' length of broom stick.

I use this in the water, where a power washer won't go.
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