Why have a vinyl pin-stripe at the waterline?

[Jerry Woodward]

Why do so many boats have a pin-stripe at the waterline or 1 inch above the waterline? After spending two days trying to get the 20 year old vinyl stripe off my boat, I don't think I want to put one back on. It seems to me that it creates too many problems cleaning the hull at the waterline. It creates a hard-to-clean space between the top of the bottom paint and the pin stripe. Any scraping there risks scratching/tearing the vinyl. That is why it is so hard to get my old vinyl stripe off. It is scratched in so many places that I can't remove it in one continuous piece using a heat gun. Yes, I've read all the threads on removing vinyl and nothing works very well other than careful and painstaking scraping with a heat gun on low.

Anyway, almost all the boats in my boatyard have such a stripe and the only reason I can see for doing it is aesthetics. But I don't think that is a good enough reason given the difficulties it creates.

[hellosailor]

Actually, Jerry, that stripe is required under federal safety regulations dating back to WW2. The stripes are required because they serve to confuse enemy submariners who surface close by, and try to aim their torpedos based on the apparent waterline of the target vessel. Putting the stripe precisely one inch above the waterline apparently causes the torpedo to be set deep enough to miss the vessel, so this is a major safety concern. Or at least was, when it was made into law back then.

I don't think they'll ticket you for removing the stripe, but you would have to ask your local USCG if they are still enforcing it.

[CaptTom]

Good answer!

One other, much less interesting, answer might be that many of the stripes are a dark color, and many hulls are a light color, so the stripe might hide the scum line that can develop from various sources.

[SailingFan]

I imagine it could also serve as a handy means to check your list and loading distribution, for those times when you want to make sure you are evenly loaded prior to departure (for your own use, I doubt anyone else will care!).

[KJB]

One could always paint the bootstripe on. I did on a small sailboat I recently sold. They just look better, with a stripe on. Also, you may not get sunk when in enemy waters.

[SV DestinyAscen]

Originally Posted by hellosailor

Actually, Jerry, that stripe is required under federal safety regulations dating back to WW2. The stripes are required because they serve to confuse enemy submariners who surface close by, and try to aim their torpedos based on the apparent waterline of the target vessel. Putting the stripe precisely one inch above the waterline apparently causes the torpedo to be set deep enough to miss the vessel, so this is a major safety concern. Or at least was, when it was made into law back then.

I don't think they'll ticket you for removing the stripe, but you would have to ask your local USCG if they are still enforcing it.

The Kriegsmarine had very advanced magnetic fuses fairly early on in the war, and it allowed their torpedos to utilize smaller warheads for the same effectiveness (benefit of longer range/better speed/without lengthening launch tube/further challenging torpedo storage).

The torpedos would be programmed depending on the known draft of the ship being targeted, and basically detonate once it is below the ship's keel. The change in pressure basically used the ship's weight against itself and broke the ship's keel against the ship's weight. Also allowed single smaller torpedoes to sink a well constructed large ship with good spaced bulkheads/even armor belts.

[Jerry Woodward]

Originally Posted by hellosailor

Actually, Jerry, that stripe is required under federal safety regulations dating back to WW2. The stripes are required because they serve to confuse enemy submariners who surface close by, and try to aim their torpedos based on the apparent waterline of the target vessel. Putting the stripe precisely one inch above the waterline apparently causes the torpedo to be set deep enough to miss the vessel, so this is a major safety concern. Or at least was, when it was made into law back then.

I don't think they'll ticket you for removing the stripe, but you would have to ask your local USCG if they are still enforcing it.

I called the USCG and they said the stripe is ABSOLUTELY required and moreover, that new regulations state that it must be made out of highly reflective material so the subs can see the stripe at night. So I will be complying with that reg and the rest of you are in violation!

[UNCIVILIZED]

One way to replicate such a stripe while easing cleaning chores, is to paint the stripe on using bottom paint. Often in a color matching your primary bottom paint color. And then in the gap between the stripe & the bottom paint, use a contrasting bottom paint color like white. That way you then have an extra 2" of antifouling above the WL. For scum, marine growth retardance, or just in case you wind up loading the boat a bit heavily.


For the OP, have you tried some of the adhesive removers that are out there? And yes, I know what a pain vinyl can be to remove. Something seemingly lost on those pushing to have vinyl wrapping replace paint on one's topsides.

[john61ct]

3M makes an 'eraser wheel' does the job

[deblen]

https://www.youtube.com/watch?v=HHKN5_UfDik

[Suijin]

Mine is painted on and is easy to clean. However, when I painted the topsides I should have raised the waterline about 1-2" which would have made the bootstripe even easier to clean, as it would not get as dirty.

As for getting vinyl off, make a scraper out of a scrap of acrylic, sharpening one end like a chisel. You'll still need the heat gun, but you can go to town the with scraper without fear of damaging the gelcoat if you round off the outside edges. Keep the leading edge sharp by pressing a against a sander now and then



Yards often have sheets of this left over from replacing hatch glazing. Cut whatever shape you want and sharpen one end on a belt sander. I made a dozen or so from a sheet from a discarded lobster tank.

[Dsanduril]

Well, if you are going to put it back, you might as well do it right:

On steel, iron or plastic vessels the boot-topping area shall be defined as follows: the bottom edge of the boot-topping shall coincide with the normal light operating waterline of the vessel. For vessels 150 ft. and over in length the top edge of boot-topping shall, at amidships, be above the normal full load waterline a distance equal to 1/8 the freeboard measured to the full load waterline.

For vessels less than 150 ft. in length this distance shall equal 1/6 the freeboard measured to the full load waterline. At the bow the distance from the upper edge of the boot-topping to the full load waterline shall be 1.33 times the distance amidships above the full load waterline, and at the stern the distance from the upper edge to the full load waterline shall be 0.66 times the amidships distance.

On wooden vessels the bottom edge of the boot-topping shall coincide with the full load waterline of the vessel. The upper edge of the boot-topping shall be identical with that described above for steel, iron and plastic vessels. Where metal sheathing is installed in way of the boot-topping area the instruction for steel vessels shall be followed.

[Jerry Woodward]

Wow, that eraser wheel looks like it might do the trick. I've tried all sorts of solvents, including acetone. It seems like the vinyl itself has gotten weaker, but the adhesive has gotten stronger.

Dsandural, what are you quoting? It sounds like some sort of regulation.

[Dsanduril]

That's the (very old) USCG specifications for painting their own cutters (so not a regulation, just the specification document sent to the boat builder/painter). The intent of the boot topping as described is really related to merchant vessels, the boot topping would be dry when the vessel is not loaded and would be completely underwater when fully laden. Since merchant vessels go back and forth in load frequently this is the highest wear area for paint (sometimes underwater, sometimes above water, tugs push in this area, can rub against wharfs, etc.). Boot topping paint used to be a special, high adhesion, fast drying, wear resistant coating - as opposed to most bottom paints, that if put on in this area would quickly wear away). Really has no meaning with current paint technologies and in yachting where we don't tend to go back and forth between light and heavy load levels. For us, it's mostly aesthetics.

[StuM]

I removed mine once using WD40 to soften the residue with no apparent ill effects. (but I washed it off quickly with soapy water).