Wet surface area for 28ft boat

[pjbori]

Hi there! Is there anyone here with a LOA 7.39 ft / 8.35 m boat (LWL 23.62 ft / 7.20 m) with a 8.53 ft / 2.60 m and 4.43 ft / 1.35 m draft that knows the wet surface area of their boat (i.e. the area to be painted)? I'm just trying to figure out the amount of paint to buy and would really appreciate the input. Thank!

[Pete7]

International paints do a website that will work it out for you. There is no need to go into exact details, not least is the paint is in 2 or 2.5L tins.

https://www.international-yachtpaint...b/paint-guides

Pete

[Chotu]

https://www.calculatoratoz.com/en/we...tor/Calc-27319

[Pete7]

I guess the other way is to buy a tin of this and if there is any left over put the extra on the waterline, bows and rudder, job done.

https://www.international-yachtpaint...ing/micron-350

[SVTatia]

LWL x beam at waterline (approximate) x .85.
Some formulas and calculators don't account for full or fin keel and nothing will be exact but you will have an idea of the coverage before you buy. And always buy a bit more.

[bil56]

@pjbori :
what is your boat?

[Spot]

Originally Posted by bil56

@pjbori :
what is your boat?

Guessing it is a Tur 84, pic and text from sailboatdata.com.

[Kelkara]

My boat is a teeny bit smaller than yours ... and 1.5 gallons of ablative paint did 2 coats with almost nothing to spare.

[grantmc]

Originally Posted by Kelkara

My boat is a teeny bit smaller than yours ... and 1.5 gallons of ablative paint did 2 coats with almost nothing to spare.

I have the same, a 26 footer, but here we use the true system of measurement. So a 4 litre can will do 2 coats (3 around the top 30 cm or so).

[Stu Jackson]

Gee, wouldn't the amount be determined by both the area and the number of coats you plan to use?


FYI, in general, there have been countless millions of boats that have been painted, and unless there is an unusual hull form, in general the number of gallons (or litres) is pretty much based on the boat length. Therefore, since your detailed measurements are appreciated for your attention to detail, it pretty much doesn't matter in this case. Good info to have, no doubt.

[Boatwright]

Originally Posted by Chotu

https://www.calculatoratoz.com/en/we...tor/Calc-27319

This formula while interesting doesn't yield plausible results. #1 problem is you are only allowed to enter displacement in volume. I tried using the pint is a pound and got a 1,700 sq ft answer for a 30' WL, full keel boat, which is about 4 x the right approximation.

Having painted many boats over the years I have used the following formula for bottom paint:

At widest beam place tape measure at the keel bottom, measure up to waterline. This measure x WL x 2 = Approx surface area of a full keel hull.

This ignores the curves in the actual shape of the hull and will usually leave paint left over. Leftover bottom paint fills the shelves of thousands of garages -- one of those costs of our other sins. Do I smell the approaching spring in this question?