Removal of Flex Seal coating from hull?

[Broken-Mold]

I am going tomorrow to look at a 14' Alumacraft boat which I will likely purchase. The current owner sprayed the whole exterior of the aluminum hull with Flex Seal. I plan to row this boat more than motor power it and would prefer the hull be as smooth and friction free as possible. Does anyone know how or even if that much Flex Seal can be removed from a hull?

 

[jbcurt00]

Get most caustic aircraft paint stripper you can find, apply liberally, cover w plastic for up to 24hrs,
Scrape away loose material until you have a god awful mess to mop up and put in a trash bag.
then use a 3500psi rotating head pressure washer using HOT water, then repeat and repeat and repeat.
And repeat....

And even then you might need to mechanically remove quite a bit w a stainless steel wire cup &/or wheel on a grinder.

Sucks, ask me how I know..... mine was the inside of the hull w diy truck bed liner...

Do your best to minimize stripper & pressure washer around the seams.

FYI, this stuff was likely applied in a poor attempt to fix/minimize leaks, so there will be work to be done post removal.

 

[dingbat]

. I plan to row this boat more than motor power it and would prefer the hull be as smooth and friction free as possible.

In that case, you want a rough surface. The smoother the hull the more friction it generates

 

[Broken-Mold]

In that case, you want a rough surface. The smoother the hull the more friction it generates

So hydrodynamics is the opposite of aerodynamics? Interesting.
Please explain.

 

[Broken-Mold]

Get most caustic aircraft paint stripper you can find, apply liberally, cover w plastic for up to 24hrs,
Scrape away loose material until you have a god awful mess to mop up and put in a trash bag.
then use a 3500psi rotating head pressure washer using HOT water, then repeat and repeat and repeat.
And repeat....

And even then you might need to mechanically remove quite a bit w a stainless steel wire cup &/or wheel on a grinder.

Sucks, ask me how I know..... mine was the inside of the hull w diy truck bed liner...

Do your best to minimize stripper & pressure washer around the seams.

FYI, this stuff was likely applied in a poor attempt to fix/minimize leaks, so there will be work to be done post removal.

I'm hoping it is coated thinly and very little surface prep was done prior to application so it's not adhered very well.
Since that crap is rubber I assumed that the same solvents and strippers that remove paint may have little effect. I hope I'm wrong.

 

[Dubed]

I'm hoping it is coated thinly and very little surface prep was done prior to application so it's not adhered very well.
Since that crap is rubber I assumed that the same solvents and strippers that remove paint may have little effect. I hope I'm wrong.

Maybe try peeling it off while applying a "little" heat with a heat gun. Worth a shot before chemicals

 

[briangcc]

So hydrodynamics is the opposite of aerodynamics? Interesting.
Please explain.

If'n I recall my HS science classes after all these years....

The not so smooth surface generates bubbles as the craft goes through the water so it has less drag. So you're in essence riding on a slight cushion of air.

 

[jbcurt00]

same reason golf balls are dimpled

on a 14ft aluminum boat, the added drag of an uneven surface (doubt the FlexSeal was applied evenly) and weight would be a concern, again, why was it coated. Likely to cover something up or stop a leak.

Good luck

 

[dingbat]

So hydrodynamics is the opposite of aerodynamics? Interesting.
Please explain.

Pretty good article explaining the physics

A smooth bottom is a fast bottom - International GP14 Class Association

A smooth bottom is a fast bottom. Is the bottom of your boat smooth enough? You can’t be a sailor and not be a scientist. Every time you leave the dock, you become part aerodynamicist, part hydrodynamicist — even part cosmologist (when you get that urge to bang the left corner!). Sometimes it’s...

www.gp14.org

 

[silverbul]

Why on earth would anyone want to row a boat in 2024? if you want to work out, buy a peloton. boating is supposed to be fun. get a small 2 stroke or a trolling motor. ENJOY. i would be willing to bet you would only row that boat ONCE. jmo

 

[Broken-Mold]

Why on earth would anyone want to row a boat in 2024? if you want to work out, buy a peloton. boating is supposed to be fun. get a small 2 stroke or a trolling motor. ENJOY. i would be willing to bet you would only row that boat ONCE. jmo

If I were a betting man (which I am not) I'd take you up on that bet.
I've rowed an A model 14' Alumacraft quite a bit. I don't do it for exercise or speed. I do it because it's quiet and relaxing after a stressful day. I'm currently looking for a B model which Alumacraft advertised as made for rowing.
I also have a 15' Grumman canoe with one of the seats removed so I can use a seat set directly on the floor. I built a crude rowing rig for it that's 48" between the oarlocks. I row it with 7 1/2' spoon blade spruce oars. It moves through the water effortlessly and almost silent. I've made miles and miles of late afternoon laps at sunset around and around my pond just fast enough to barely hear the water parting for me to pass. I refer to the Grumman as my "Silver Valium."
I row the Alumacraft so my little wifey can enjoy it with me. The Alumacraft doesn't row anywhere close to how well the Grumman rows but it's much more stable and less tippy. Neither of us are swimmers so we don't like getting wet.
If all you know is boating with heavy, stinky, noisy motors you should buy some oarlock bushings for your boat and a set of spoon blade oars and give rowing a try late one evening when the sun is just setting and the water is glassy smooth.

PS I have a 5hp Tohatsu motor that moves my Alumacraft along quite well but I much prefer oar power.

 

[matt167]

Why on earth would anyone want to row a boat in 2024? if you want to work out, buy a peloton. boating is supposed to be fun. get a small 2 stroke or a trolling motor. ENJOY. i would be willing to bet you would only row that boat ONCE. jmo

There are zero power reservoirs where you can only row. Ones here in NY the boats even need to be registered with the DEP watershed and left at designated spots on the shoreline…. As for why someone would bother. The fishing is usually really good

 

[Scott Danforth]

So hydrodynamics is the opposite of aerodynamics? Interesting.
Please explain.

No, they are similar. Has to do with a boundary layer. Ask yourself why a golfball has 320 dimples. Or why a baseball has 108 stitches ( and why a batch of rough stitches 10 years ago made pitches faster)

Same reason a row boat will want a rough surface

 

[Dubed]

No, they are similar. Has to do with a boundary layer. Ask yourself why a golfball has 320 dimples. Or why a baseball has 108 stitches ( and why a batch of rough stitches 10 years ago made pitches faster)

Same reason a row boat will want a rough surface

Interesting.... very counter intuitive

 

[dubs283]

Why on earth would anyone want to row a boat in 2024? if you want to work out, buy a peloton. boating is supposed to be fun.

Different strokes, fella

I find it odd that in a free world someone would impugn another's idea of fun. Fun is discretionary to an individual's taste and is part of the beauty that makes all of us human beings.

I find the idea of using a stationary piece of equipment for exercise to be quite boring, jmo

 

[garbageguy]

The discussions regarding hydraulics and flow of fluids against solids are always interesting. Fluids can be liquids or gases. The variables in the governing equations are the same - fluid densities, velocities, roughness coefficients, and your objectives are important when looking to apply these principles.
In your situation, velocities are so low that the roughness coefficient differences are almost negligible. In the goofball situation, the fluid density is that of air, the velocities are high, and the objective is to have the ball go far and straight.
In your case, I would remove as much of that coating mechanically until you're sick of that, bring a flexible/cut milk jug for bailing, test it close to shore, and go rowing on small non-moving waterways

 

[Chris1956]

Do you think the flex seal was put on to seal rivets? There are a lot of aluminum boats out there. Why take on such a headache?

 

[Broken-Mold]

Do you think the flex seal was put on to seal rivets? There are a lot of aluminum boats out there. Why take on such a headache?

It was a very rough boat. Someone had fiberglassed part of the exterior hull before the Flex Seal was applied. A lot of it was peeling off. It had been used as a creek boat too many times. It even had what appeared to be a 3 or 4" tear in one side repaired on the inside with automotive Bondo (!). He came down to $200 for the boat and old trailer but I left it. I'm still tempted to go back and get it for a "later" project.
I came back home and within a couple of hours stumbled upon a 1954 12' Alumacraft model E, trailer, and 1957 18hp Johnson Sea Horse which I went and looked at last night. The owner's widow gave me a good deal on it so I bought it. Dang. I'm such a sucker for old, broken stuff that needs a home. Just ask my wife.

 

[Chris1956]

Gee, a few more like that and I predict you will be the one looking for a home. (smile)