Cleaning Boat Bottoms?

[MikeeH]

Great advise and a couple of issues I hadn't considered (like intakes for aux machinery and the causes for the trim of a "static" vessel changing). Thanks and keep additional comments/suggestions coming!

 

[veggiedog]

I cleaned my sailboat in the slip while diving and I got green stuff (copper oxide) in all my gear (bladder cover, gloves, wetsuit). Nasty job and I won't subject my gear to that anymore: cleaned out relatively easily with elbow grease though.

I prefer to just clean mine staying out of the water while it is in the slip (3 sides enclosed) using a long handle with a stiff brush like they use to wash fleet vehicles. My boat is in freshwater though. It is very handy to be able to inspect the bottom though.

 

[TallahasseeRick]

I’ve done this for years. As mentioned before, a “hookah” rig is much easier than full scuba but scuba works, too.

It’s your boat, you can decide where to clean it. Get out of the marina. Take it out and anchor in some calm water. Calm water! Don’t try it in waves or the boat will bash you in the head every 10 seconds.

Forget the cheapo suction cup do-dads at the boat store. Get a real one. Get the suction cups that mirror and glass workers use to carry glass. Even the cheapest version of those is much, MUCH better.

A powerboat, right? (so I’m assuming you use hard bottom paint instead of ablative.) You’ll need a drywall taping knife, maybe about an 8” wide one. Get one with the thinnest, most flexible stainless blade they have. You’ll also need 2 plastic scrubby pads mounted on a plastic handle, they are in the barbecue grill cleaning supplies. (Don’t use either of these on ablative. Use a soft, natural bristle scrub brush.)

Go under the boat and get neutral to a bit positive. Suction cup yourself to the bottom of the boat. Hold on with one hand and with the other hand scrape the big stuff off with the taping knife. Big, long, continuous strokes. Then clean the slime off that section with the barbecue cleaner (the hard part.) Move to the next spot. Repeat. An hour later you’re done. Scrape and scrub the prop with the same tools. Change your zincs while you’re down there. Swim around and scrub the waterline especially well. That’s it.

39 feet? Just over one tank and an hour and a half for a really thorough job, half a tank and 30 minutes for just a scrape.

If you do it for any boats other than your own, charge them a freakin’ fortune for it. There are lots more fun things to do with scuba equipment than this job, believe me.

 

[crazyitalian]

I also have a question about this since it's been brought up. I've considered doing this for extra money but a friend cautioned me that if I used a hookah rig (which is what I was going to do), then the 1st stage would need to deliver air at a higher pressure than normal because of the force that would be necessary to deliver the air through a much longer hose. If one were working with a 20-30' hose, how much of a greater pressure would be necessary so breathing wouldn't be too arduous? For those of you that are good with physics, is there some kind of equation to use or a rule of thumb that may be employed when dealing with much longer hoses? Thanks.

P.S.- Is there decent money to be made doing this? I know the work wouldn't be too fun, but I can't imagine that there's a glut of bottom cleaners. How much do people that do this type of work generally charge? Is it by the foot or does it very depending on where you are?

 

[james croft]

I also have a question about this since it's been brought up. I've considered doing this for extra money but a friend cautioned me that if I used a hookah rig (which is what I was going to do), then the 1st stage would need to deliver air at a higher pressure than normal because of the force that would be necessary to deliver the air through a much longer hose. If one were working with a 20-30' hose, how much of a greater pressure would be necessary so breathing wouldn't be too arduous? For those of you that are good with physics, is there some kind of equation to use or a rule of thumb that may be employed when dealing with much longer hoses? Thanks.

The main consideration is not the length of the hose but the depth of water the second stage is at. Every 33 fsw is another 14.7 psi. Most smaller vessels don't have enough draft that you will have to worry about changing the intermediate pressure unless you get much deeper. Properly equipped umbilicals are tended and have an airhose as well as a pneumofathometer hose that allows a tender to see the divers depth as well as making adjustments if needed in the intermediate pressure on the dive console. They normally have hardwire comm with a full face mask or dive hat as well. Marinas are dangerous for all the reasons listed above. I would not consider diving around marinas due to the danger of electrocution. A simple thing such as a malfunctioning battery charger or other improperly wired electronics can result in ac current going through the propeller shaft or outdrive grounding to the bottom of the harbor in a cone shape pattern that will cause a diver in this area to become electrocuted.

 

[jamiep3]

I had a boat on the bay(Worton Creek, 25' sailboat), I sometimes cleaned it with only a snorkel. I used a stiff brush and putty knife. I always got out of the harbor to a cove I knew where the vis was 1'3', not the 1" in marina. A friend of mine does this as a sidelne, he has a good suction cup handle.

Hope this helps.

 

[MikeeH]

Jamie, we're just north of Worton Creek on the Sassafras.

All this input deserves some more details about my situation.
The boat is a Silverton 351 (a sedan) and I only use an ablative paint... don't need all that hard paint build-up and loss of biocides during the 4 months of lay-up on the hard. We are in fresh water so there aren't many hard thingies growing on her. Draft is 3' so we're not deep. There are plenty of quiet coves where we can drop the hook and "git r done!"

All this great input! I'm looking forward to making my dockmates jealous!

 

[serambin]

Bottom paint has worst than copper oxide in it so don't get it in your mouth (or eyes or . . .). Most contain a variety of heavy metals and assorted poisons. As to time, my boat was 40 feet and on dry dock it took a couple of hours. Under water, my guess is closer to 3-4 hours.

Remember, the remaining paint will lose a lot of its effectiveness after the first scrub-off. so even though the bottom is clean, the hull will foul again in about 1/2 the time.

I used to see boats careened around Soldier Key south of Key Biscayne in the spring and fall when tides are greatest there. The owners drove them in shallow and let them lay over on sandy bottom with the falling tide, then with the rising tide they wenched them off on the anchor windless. The big difference is that they painted anti-fouling paint back onto most of the hull after cleaning.

Stan

 

[pipedope]

I also have a question about this since it's been brought up. I've considered doing this for extra money but a friend cautioned me that if I used a hookah rig (which is what I was going to do), then the 1st stage would need to deliver air at a higher pressure than normal because of the force that would be necessary to deliver the air through a much longer hose. If one were working with a 20-30' hose, how much of a greater pressure would be necessary so breathing wouldn't be too arduous? For those of you that are good with physics, is there some kind of equation to use or a rule of thumb that may be employed when dealing with much longer hoses? Thanks.

P.S.- Is there decent money to be made doing this? I know the work wouldn't be too fun, but I can't imagine that there's a glut of bottom cleaners. How much do people that do this type of work generally charge? Is it by the foot or does it very depending on where you are?

In theory there is no difference between theory and practice. In practice, there is.
Your friend is right in theory at least. In practice it doesn't matter much for normal depths and operations.
Most purpose built hooka rigs work at about 40 psi for an intermediate pressure (IP) and work fine down to 60 or 80 feet.
Lots of bottom cleaning divers us a standard scuba tank and regulator with a 100' (give or take) hose between the 1st and 2nd stage. This way the diver is not encumbered by the tank. Usually they wear a wet suit but little or no wieght so they are positive and can crawl along the bottom of the boat as they work.

The first choice of tool is cloth or a bit of carpet. This will remove new growth without removing much paint. If harder things are to be removed a wooden board
is good. If you make one end square and the other tapered it is more versitile, a handle is a nice addition.
Metal scrapers should be a last resort and if possible only used on props and other metal.

If there is a current, start downcurrent and work up. The current will help carry away the crud so you can see more as you work.

It is better to wipe with a carpet often enough that the slime doesn't get really going and no hard stuff gets a foothold.

As far as making money, it depends on your market and skills. If you offer some sort of unique service that you can charge more for then you can do well, otherwise you have to get really fast.

Want to have fun?
Try doing the first bottom cleaning in over a year on a cruising sailboat of 40', on breath hold.