Water logged (description and found to not be) This is a Good Post!

If you have the time, one trick that will work like a charm is to bag the boat. You can use heavy plastic wrap or whatever and _carefully_ seal every seam with high-quality duct-tape. Then hook up a good vacuum pump and let it run. If you seal things well, you can get way down into the sub-500-micron vacuum level and water will evaporate and be pulled out by the pump. But it will take some time. That’s really the only sure-fire way I know to remove water. I have tried forcing heated air through the inside of the boat but never had a lot of luck with moisture that gets trapped in foam where the air never reaches. But if water can bleed in, a vacuum will bleed it back out. You can tell when it is dry because until it is, the vacuum will never reach that -25″ + level as the water will boil off and prevent the vacuum from getting that hard. Be aware that you will also boil off the fuel so make sure the cap is on tight, and that any vents are sealed.

I know people that have tried a hundred pounds of silica gel in small cloth bags scattered throughout the interior of a boat, or putting it in an enclosed garage and sitting a heavy-duty dehumidifier in the floor of the boat, but have not seen one of those make a difference. A few years ago A friend bought a boat cheaply and discovered it was about 250 pounds overweight. The vacuum pump did the trick although he did burn up a $100 pump before getting something a bit better. You might even be able to rent a really heavy-duty pump at a rental center. 5cfm is the minimum and in this application, bigger is better.

There may be other good ideas floating around, but I do know this one works although it takes some time and some effort as it is too easy to get sloppy with the tape and leave leaks. So far as I know, this is an original idea. I got it from a combination of having worked on a few A/C systems in the past, (cars and home) and from building model airplanes where many use vacuum-bagging to tightly press a balsa skin onto a foam wing core, with fiberglass cloth/resin on top.

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2008 Pantera Classic
2014 Mercury Pro XS 200

The boat my friend bought appeared (according to his calculations) to be about 250 pounds overweight. I thought, OK, 250 pounds divided by 8 pounds per gallon (actually a bit more but I rounded) was about 31 gallons of water. No way that much water can be distributed throughout that boat (It was a 19′ boat). But I did a little math that I do not remember now, and calculated how many cubic feet of water vapor that was, and figured that we needed a week to cause it to “boil away” at low vacuum. It seems to me (this was maybe 10 years or a little more ago) that we actually decreased the weight by just over 200 pounds. I don’t know how much wood and foam there was in that boat, but apparently enough to soak up over 20 gallons of water.

And, of course, with the old days of wood in the transom and stringers/etc, after it is dried out, one still has to question the remaining strength left since plywood will delaminate when soaked long enough, marine or not. More recent boats, particularly basscat boats don’t have that wood issue so if you extract the moisture you should be good to go. Just don’t forget the tank. First day he went out to check on it after about 4 hours and the outside storage shed he had it in smelled like a gas refinery.

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2008 Pantera Classic
2014 Mercury Pro XS 200

I would agree. I think that one issue we saw is that many manufacturers seem to give a hull weight that is on the low side. I noticed that when BWB did their various tests over the years, it was not uncommon to see a 100 pound range for hull weights. And that makes perfect sense to me for any process that has human hands involved. The idea scenario would be as BCB suggests, except that when you pick up the boat new, you fill it up, leave all the crap out (tackle, etc) and get a weight and save it. 10 years later if you think it is getting a bit heavy, you can weight it again.

The problem with the “vacuum” approach is that it is not particularly fast. Of course, running this for an extended period is not going to hurt anything but the vacuum pump itself, but it is not easy to know when you are “done” since truck scales are not very good at weighing 10 pounds or so to see if you have removed another gallon of water or not.

One thing I failed to mention, when you start the process, within an hour the vacuum ought to be at least -15″ or so depending on outside temp, if you don’t get down to that point you most likely have a leak in the bag and you can suck until the cows come home with no effect. Care to guess how I know that?

But note you need to let the pump run an hour before you start watching the vacuum guage. At 5cfm or so (unless you have a big industrial vacuum pump hidden away) it will take quite a while just to get the air out of the boat when you think about the bilge, back end, storage compartments, etc. 5cfm is at sea level pressure, as the vacuum drops so does the volume. Be patient. I suppose you could run the pump output through a dehumidifier and collect the water to see what you are getting, if you are curious, but you have to make sure that outside air is not going thru the thing as well.

All that said, I would not even think about starting the process until you are sure you are overweight and not just either down on power, overloaded with tackle and people, or have a prop that has lost some pitch due to age or abuse. The “faster days” are ahead of us, when we get to the 50 degree dry air (and below).

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2008 Pantera Classic
2014 Mercury Pro XS 200

There’s only one problem. The only reasonable way to “read a plug” is to get the motor warmed up, run it at WOT down the river for a minute or so, then cut it off with the emergency cutoff switch. Use the TM to get over to the dock, then pull the plugs. If you are worried about dropping something, put the boat on the trailer and get it into the parking lot. But do _not_ crank the motor. Now you can look for the nice tanned tip color. If you idle for even a few seconds the plugs will soot/carbon up and you can’t tell squat about how it is running at WOT.

Be _very_ careful about stepping down in jet sizes. The difference between too fat and just right is important. But the difference between too fat or just right and too lean will be _very_ expensive. Too lean leads to pre-ignition or overly-hot burn rate, which will melt the top of one or more pistons and create a major repair job. Factory jets are overly “fat” for that very reason, to prevent a powerhead melt-down when you get fuel that is a little down on octane. Unless you run a DFI motor, the fuel has more than one purpose. As it blows thru the crankcase it cools the motor. Extra fuel dampens the speed at which the combustion flame front propagates, which is easier on the motor and doesn’t produce as much heat on top of the piston. So make sure you read ’em the right way to avoid a gross problem.

BTW making the “bag” takes a little thought. You can’t just stretch the plastic over the top of the boat and tape everything up. With a hard vacuum, that plastic will be subjected to 14.7psi and it will cave in, rip or tear, or stretch, or cut itself on an unseen sharp edge, etc. I bought the plastic in a big roll at Lowe’s. Still have most of it in the box downstairs, 10+ years later, as I have yet to find something else to use it for. Haven’t had a storm rip my roof off or anything as this would be a good temp cover.

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2008 Pantera Classic
2014 Mercury Pro XS 200