Sharkhide - Marc Davis

Sharkhide - Marc Davis

I began using the product on drift boats that I refurbished and realized quickly how easy and simple it was to make boats that were decades old look new.

This hull had a sunbaked interior and a lot of discoloration on the exterior. Simply scrubbing the interior with Comet removed the oxidized paint. Sharkhide cleaner made the hull look like new and two coats of the finish will keep it looking that way for years.


This is the third in a series of articles concerning restoring and maintaining aluminum boats. The first was about restoring an almost fifty-year-old Valco sled and the second about applying Slip Plate #1 to drift boat bottoms. This article is about successfully “Sharkhiding” boats and actually making them look better than new.

One of the best things you can do is go to the website and do what they tell you. The amount of work you will want to do for a hull’s surface restoration will depend upon how you want the hull to look when it’s done. This article is meant to supplement the information on Sharkhide’s website, This address will give you Sharkhide’s available products and the best techniques to use them.



I’ll use as an example a runabout with a hull that is half painted and half bare aluminum down to the chines with an unfinished bottom. When I begin working on this boat I want to remove anything from the hull that would prevent the cleaner from coming into contact with the bare metal. Road tar, asphalt, grease, oil or any other material with an ability to coat the metal will affect a thorough cleaning of the hull. I also always check that the Sharkhide cleaner will not injure paint or vinyl that will remain on the boat. My favorite all-purpose pre-acid wash cleaner is Greased Lightning which is an excellent degreaser as well as cleaner. This product even gets off salmon egg “spooge” and the road deicers used in the Northwest. It sprays on as a foam out of the factory supplied bottle and just needs a little brush work to get down to bare metal. Spray on the Greased Lightning and use a soft cleaning brush followed by a good rinse.

The Sharkhide acid cleaner requires mixing with water. It is phosphoric acid that needs dilution. As with any acid follow the directions and use protectives like gloves and glasses. After dilution the acid is most easily applied with a 1-gallon plastic garden sprayer. Anything you do not want etched by the acid should be covered with a plastic sheet or not allowed to come in contact with the acid. Phosphoric acid does a great job cleaning galvanized trailers as well. If you don’t want the trailer etched keep the acid away from the zinc! Make sure to protect the painted surfaces and protect them with plastic sheeting and masking tape if you think they may be harmed.


Sharkhide applied to a new trailer keeps it looking new too.

If you are still a little undecided about doing this process spray several coats onto the bottom of the boat where it will not be seen (see picture of the bottom of my brand new Freedrifter). You can see the runs that show up on a brand new hull. This is after one light coat of acid wash. Do two more on the unseen bottom area and you should feel much more confident about how the job will look after etching on the visible part of the hull. Over time the cleaned bottom will return to its natural state with no harm done if you decide to leave it alone and not proceed.

Spray the diluted phosphoric acid onto the hull starting up high and let the acid run down the side of the hull keeping the aluminum wet with acid but not overdoing or wasting the spray. Within seconds you will see the acid begin working as it will generate white foam. For more deeply stained hulls the instructions suggest a stronger solution for the beginning coat. Remember that the acid only works while it is in contact with the hull. If it drips off or is washed off it is no longer working. The first time I sprayed it on and saw what it was doing I thought I had ruined my boat’s finish! It was all streaked and spotted but I did the second coat immediately and it looked better. With the third spraying (just a little up high on the hull) the metal looked like new. Stains, crud and oxides simply melt away with the acid wash! This all happens in seconds with no rubbing at all. If you are taking off vinyl decals or numbers you need to get off the adhesives to assure the acid contacts all the metal evenly. Lacquer thinner usually works very well for this process. Keep the can of lacquer thinner on the ground and away from anything it could possibly harm. Do not set it on the sides or deck of the boat! Again, follow the directions. The thinner is not good in any way for your body so use in a well ventilated area and keep it off your skin. By the way, the stuff is explosive so no smoking or sparks.


This is the bottom of a brand new boat after the drippings have run down the hull.  In a short period of time it will all look the same from oxidization. The unseen bottom is a great place to experiment to see what three shots of the cleaner will do.


If you used tape to cover hull decorations now is the time to remove it. Use a cloth wetted with acid and come right up to but do not touch the vinyl or paint. Now, thoroughly rinse the whole hull and let it dry. A caution: Water can dwell in seams like the chine and it does not mix well with Sharkhide. I always wait several hours before applying AND I always take the garden blower to any seam close to where the Sharkhide will be applied to blow away any residual moisture.

After the hull has been acid washed the dull gray metal will have turned almost white which is the color of freshly rolled aluminum. If you want a highly reflective finish now is the time to break out the buffer and polish or get ready with a lot of elbow grease if you choose to do it by hand. To see the possibilities look at FAQ’s on Sharkhide’s website for boat hulls that are polished or only acid washed. Polishing will eliminate most pitting and scratches.



As soon as the hull has been acid etched it is reoxidizing. The metal will gladly accept any stain so it’s a good idea to apply the Sharkhide soon. Every can I have ever opened always has a metal seal inside the threaded spout. As soon as that seal has been completely removed you will instantly tip over the can and slosh out thirty bucks worth of Sharkhide. I like to just make a small hole in the seal and then squeeze the liquid out onto the cotton diaper material for applying to the hull. A piece of the cloth cut to about 10” by 10” and then folded twice seems to be about perfect. Keep the folded cloth in your vinyl gloved hand and saturate with Sharkhide. The directions for application are very simple in that you do a small area and apply the Sharkhide only going in one direction. Put on enough to coat but not so much as to have any runs. The volatiles evaporate nearly instantly so you wipe it on and LEAVE IT ALONE! The job will turn out much better if you wait several days after the first coat to let it cure and then apply at least one more. I like three coats. A good place to begin is on the transom where mistakes made while learning show up less. On the transom you can always wipe it off with lacquer thinner and try again. One thing I like to do for my own edification is leave about a postage stamp sized area under the outboard without Sharkhide applied. In only a few launchings you will see what the boat would have looked like without applying the protectant.


Buffing the surface of an aluminum hull will give it a mirror like finish that's better than new before applying the Sharkhide that will keep it that way.


If the boat has some scratches and pits, polishing will reveal the hull beneath that can be made to look like Air Force One. I made the investment in having a crew come out and do mine in the driveway. Bob Graham at Easy Way Metal Polishing came to my home in the company van and dove into the six-year-old Weldcraft with a vengeance. All the hull paint was carefully masked. They then used lacquer thinner to remove the three coats that had been applied by me when the boat was new. That alone was more work than I wanted to do but I watched them carefully as they moved through the process. Using a commercially available metal polish and about a half dozen buffing pads they got out all the pits from rocks and a couple of scratches that I didn’t think had a chance of going away. They carefully went around decals and numbers. When the polishing was done and the boat cleaned they applied the first coat of Sharkhide. It was like watching an artist at work. From the picture of Bob shaving you can see how reflective the hull had become. The boat was left alone for two days and I applied the second and third coat on my own.



Mr. Graham can make an Airstream Travel Trailer look like new and boats look better than new. He also works on fiberglass boats to bring back that show room sparkle. It’s a lot cheaper to do it yourself but Bob is an expert and the beautiful finish will show for years if you keep up the Sharkhide.

I began using the product on drift boats that I refurbished and realized quickly how easy and simple it was to make boats that were decades old look new. I did it by following the directions and watching Youtube. You can do this on your own but if you want it done professionally or desire the aircraft like finish contact Bob's son Bailey at




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