Power wash

[JonnyBoats]

A week from Monday my 38 ft Sloop is being hauled so I can put in my new engine. The yard where I am hauling does not have a power washer, but they will let me do my own work, so I plan on renting one.

I have heard that some are so powerful that they can put a hole through a clabboard! How powerful a unit should I rent for my boat, and do I need to be concerned about doing any damage?

[Figment]

They can put a hole through a clapboard if the operator WANTS to put a hole through a clapboard.

Start with a 20 degree nozzle (if the unit has interchangeable nozzles), and keep the spray head a few feet from the surface until you get the hang of it.

It's pressurized water. It behaves just like pressurized water from a garden hose, just at a different order of magnitude. It's completely intuitive.

[rshowarth]

A friend of mine rented a pressure washer to clean off the siding of his home. He etched a few cedar clapboards before he got the hang of it.

I have pressure washed my Mariner with a 2500 psi (?) pressure washer and the gel coat held up just fine. I was careful around the little mahogany I have.

[Tim]

Don't worry. A cedar clapboard is a lot softer and easier to damage than your fiberglass hull.

The unitiated do damage by failing to move the wand (thereby preventing heavy spray in only one small area), and by holding the tip too close to the surface.

Power washing is miserable, period, whenever and wherever it is done. The pressure makes holding the wand very tiring (that is, assuming the thing has any real pressyre, unlike the "homeowner" versions). It's wet and nasty.

Have fun.

[catamount]

Here's a pic to illustrate how it's done ;-)

[Quetzalsailor]

John,

I've got a Craftsman power washer which tops out at 2500psi and has an adjustable fan of output. At the widest, it's dandy for sidewalks. At the narrowest it'll cut your shoe in half (ask me how I know..).

I bought it to take the paint off the Terne metal roofs on our 1857 house. Using the narrowest setting, and fiddling with angle of attack, you can strip loose paint; you can't strip tight paint. And you can't hurt a tin roof.

Powerwashing wood clapboards or boat wood requires a delicate hand and a wider fan. The wood is much softer than any paint and you will dig holes in the wood and not necessarily dislodge visibly loose paint. You can clean weathered Teak or a wood deck but you have to balance degree of cleanliness with amount of wood removed and with the evenness of the appearance. This is a learnable skill.

I used the powerwasher to clean Osprey poop off the fiberglass deck of the Morgan 27. It works but the water removes all the loose gel from a sun-damaged surface leaving it beautifully clean but open to re-dirtying. Powerwashing a boat hull is a piece of cake and you'll be hard pressed to damage the fiberglass. I used to try to knock the loose bottom paint off, with some success.

Very carefully used, you can clean running rigging. You need to keep turning the line so that all of the surface is cleaned. It will saw up the dacron if you are too eager.

I've always wanted to use a powerwasher for cleaning the bilge but the overspray would soak everything and Sue vetoed the idea.

[Figment]

I used to try to knock the loose bottom paint off, with some success.

Powerwashers will strip ABLATIVE bottom paint with the greatest of ease. On one hand, it's so easy that you'll never want to use a sander again.
On the other hand, you can also wash away a full season's worth of antifouling in the blink of an eye. It's all a balance.

[Brad.Bates]

Hi John,

I hauled my boat a few weeks ago and used a smaller power washer than most are mentioning to clean the bottom -- 1500 PSI max. It worked great and the only paint that fell away was in a couple of spots that have some blister under it, and so those will be sanded and ground down anyway for repairs.

I found that mixing some of that industrial strength bleach that you can find in places like Lowes, Home Depot, etc. was useful if you have that type of sprayer available. I used about a 50% solution and I sprayed that over the hull first and let it set for fifteen minutes or so. After that I used the pressurized wash. The area that got the bleach treatment lost barnacles much easier than parts that did not get it. Also, the scraping seemed to go a bit faster on those areas. The more I did this the better it worked, and in the end I used two bleach applications one after the other, letting both set for fifteen minutes or so to loosen the barnacles.

And, if you have the time, do the shaded side of the hull and wait for time to pass to do the other side in the shade -- lets that solution soak in better.