|
From the Boatshop |
|
|
by Ron Magen (along the shores of the ever improving Delaware) Philladelphia, Pennsylvania - USA
Painting Primer
|
 |
Title is a bad pun, but I couldn't resist . . . like fishing with a hand grenade.
I'll try to answer all the questions without being pedantic.
Eric - '. . . don't want to buy 2 quarts @$26/qt for a cup of paint' . . .
‘Penny wise & Pound foolish' to quote old Ben Franklin. NOBODY, and I MEAN NOBODY is cheaper than me !! On a P19 the 'wetted surface' (from the Loaded Water Line to the bottom of the extended keel) is only about 100 sq.ft. This should take about a FULL QUART of paint per coat. If you're doing it with a 'cup' (which is 1/4 of a quart) the paint is 'stretched' to almost uselessness. The reason for AT LEAST TWO COATS is to insure COMPLETE coverage and no missed spots or 'holidays'. I prefer the first coat to be a 'flag' coat because it tells me where and when I have to repaint.
If you think $26.oo a quart is steep . . . price AWLGRIP or one of the Linear Polyurethane systems if you want to go into real shock !!
MICRON CSC is a 'Name Brand' (Interlux) and you will ALWAYS pay more for it. I have found that the West Marine 'house brand' (CPP) is actually better . . . 55% Cu vs 39%, 1/4 the re-coat time, etc., and cheaper. IN ADDITION - wait for a SALE and buy it by the GALLON !!. You're going to use it anyway (it's ABLATIVE, remember) and if you store it properly it will last FOR YEARS.
Whichever paint you choose; go to Home Depot or a local paint store, if you're not going to use the bottom paint NOW get 4 EMPTY quart cans & lids otherwise only 2 or 3. Ask them to shake the paint . . . ask nicely and they will - although they'll probably want to open the can first, cause it's a HELL of a lot heavier than they're used to dealing with. When you get home, make aluminum foil 'collars' for the sealing rims of the quart cans. (This is so you don't 'slobber' into the sealing joint and glue them shut).Stir & decant the gallon of bottom paint into the smaller cans . . . FILL THEM to about a1/2 to 1/4 inch of the rim. Remove the foil and gently place the lids on the cans and use a rubber mallet, or put a block of wood across them and use a regular hammer, to tap the lids flush to the rim. Label them with contents, color, and date. No air = no dried film. I even store mine upside down.
USING a FOAM roller is a good idea for EPOXY or a THIN FILM finish . . .
The idea with ablative, or sloughing, paint is to lay down MATERIAL. You want an applicator with some 'carrying capacity' and that will not 'pick-up' the finish. That is also why the paint instructions usually say to 'roll in one direction only'. What I do is select an area about two feet 'wide' and from chine to keel. (I'll get back to this in a minute). Make a big 'W' with the roller, then use single strokes, with a slight overlap in the fore & aft direction to 'fill in' the area. One coat in the morning, one in the afternoon, and done. Or just the one coat if you don't see your 'flag'. If you do, it may only be in certain areas . . . like the leading edge of the keel, the cutwater, or the chines.
We usually do the 'outside' and the waterline first. My wife will carefully mask over the bootstripe and then either of us will paint the first couple of inches below with a disposable chip brush & 3 inch roller. Typically we have done all this work while the boat was ON THE TRAILER. The keel was done in 'two parts'; all I could reach while lowered to a block of wood - then raised and the rest done CAREFULLY inside the boat. This time I had the boat on stands at the yard, but still had to do the keel in sections; the top 16 inches was inside the trunk.
WHILE I do agree that a 'BABY BOTTOM SMOOTH' job is a thing of pride to the craftsman, in this case, "Size (& SPEED) DOES Matter". 'Hull Speed' is a factor of Water Line Length . . .for DISPLACEMENT boats. Look at the America's Cup boats and the stringent formula's they are built & INSPECTED to. Every little nuance is used to gain 10ths of knots of speed including NO bottom paint, 'wet sanding/polishing' the hull after every race, and such tricks as 'soaping' the hull to reduce surface tension during the start maneuvers. Now look at a P19 from the front while it's on it's trailer, with your eyes at about the waterline. Looks like a 'PT Boat' doesn't it? And except for that rocker aft (which helps her not 'squat' under power, reduces wetted surface when 'on her feet', and increases
waterline at heel) she's a 'semi-planing hull'. That's the design, in this case a compromise of several issues with plywood construction in the original formulation, and it is the greatest factor effecting speed. In addition, energy and resistance through a fluid is on a geometric, rather than arithmetic, basis. The faster something goes, the more energy it takes, AND the more resistance it must overcome, AND the lesser the rate of (velocity) increase. Then we get into such esoterica as Laminar Flow, Surface Barrier Effect, etc. Generally speaking, Resistance increases as the Square of the Speed - 2x Speed = 4x Resistance. At the velocities of Potters, the shape of the keel, which is NOT a true FOIL, gives more lift or induced drag that the smoothed over irregularities of the bottom paint.
The TECHNIQUE KNOWN AS "TIPPING OFF" . . .
(“SolorFry” was close) is used with epoxy or similar smooth, or relatively thin coatings. It is definitely used to get those glass-smooth varnish finishes. A FINE almost dry brush, or section of foam roller in the case of epoxy, is ever so lightly passed over the finish to remove, break, or smooth bubbles or imperfections. Long, light, smooth, continuous strokes are used . . . it's almost sensuous. It is very much a 'hands on' and delicate technique; some people never master it.
Bottom Painting Your Rudder - RE: Chris, Bill C., Judy, Mark C. . . .
I don't know if I'm a 'throw back', 'throw up', or just pain in the butt, BUT I LIKE WOOD.
However, I'm neither as old, or opinionated as one renowned naval architect who called fiberglass construction, 'frozen snot'; I do own a 'plastic' Potter. However, the few touches of 'properly varnished' brightwork, and oiled Teak, Bronze fittings, and 'fancy & functional' ropework do give a warm & classic feel. That goes for the rudder & tiller, too.
The 'trick' is to combine the 'look' of the wood with the protection of epoxy, plus something to repel the 'critters'. Judy was 60% right, and Mark C. inadvertently had the other 40%. (NOTE: my 1989 rudder has White Gelcoat covered Fiberglass 'panels' that hold the blade to the upper stock, and allow the rotation for 'beaching'. I have also modified it to a true 'kick-up')
First, clean the rudder throughly. Then sand it well and do any repairs of dings or holes or soft spots. (This means dig them out to solid wood, if you have to Then fill / repair with a 'filler' of epoxy & wood flour.} A couple of coats of epoxy resin, maybe with a bit of MILLED FIBERGLASS added for extra protection. Embed some pieces of glass cloth at 'wear' spots like the bottom of the blade, or cover the entire blade if you wish. REMEMBER to keep the leading edge well rounded and maintain the foil profile. Let the epoxy cure WELL. Wash with water and a bit of liquid soap to remove any blush that may remain. Lightly sand and give it SEVERAL COATS of a good HARD, UV resistant Varnish. This will protect the epoxy from UV degradation and give a glass-smooth finish. NOW for the 'Critters' - WAX the RUDDER BLADE. There are a couple of Bottom Wax's on the market - not exactly cheap, have Teflon as an ingredient, and stated to, ". . . last an entire season". As I said before, 'I'm CHEAP". I already have a tin of West Marine 'house brand' Boat Wax with Teflon so I used that. Couple of coats, well buffed. The problem on the Delaware River is slime, not barnacles. There are also a few 'biocide additives' that can be added to paints. You might want to look at them, to see if they are 'clear' and can be added to your wax. Or, to use a part of what someone has already suggested, which is what I do, occasionally take your rudder off and scrub it with your deck brush. A few minutes, a splash of water, and done. Could even take another 5 minutes and apply more wax.
21st Century ? - Ken F. . . .
I was looking for a simple wheel with an attached drum for a simple cable & pulley steering set-up for a small boat I built. Used to see it in the 'boat stores' in Atlantic City, made by PERKO . Found out from EDSON that was, "years ago" !! My first boat was a 14 ft. garvey; 3/4 inch pine sides, 3/4 inch pine cross-planked bottom. 'Industrial' grey paint, and Red Bottom Paint an eighth inch thick on her bottom. EPA? Colors? Epoxy? Teflon?
Try to find 'Red Lead' today. I think there is only about one or two brands of the old 'thick stuff' left. BUT, there's a new 'miracle juice' out every year.
I'll shut up now, and let you get back to your 'regularly scheduled programming'.
Regards,
Ron Magen
Backyard Boatshop
click here for a list of Columns by Ron Magen
|
