How Much Bottom Paint?

[sbsbw]

Ok, Painting my 26 footer, fin keel, How much bottom paint should I buy?

Also recomdations for bottom paint?

Thanks,

SBSBW

I know that this must have been asked before, but i figure this is much easier then searching for such a thread.

[Wild Wassa]

Calculate the area to be painted in sq m and multiply by the number of coats to be applied. Use 10 sq m per litre per coat as a guide (when you can't check the coverage in the tech notes or on the can). In most cases this will allow for minor errors in calculation.

For the bottom - take maximum beam, plus draught and multiply by the length at waterline.

If you can buy Norglass Topflight Anti-Fouling in the US, a premium long life copper coating, this is a good paint. It is for vessels that exceed 10 knots, it can be repeatedly scrubbed and wet sanded for a racing finish if needed.

Warren.

[ 06-14-2005, 09:39 PM: Message edited by: Wild Wassa ]

[RiverRat]

There once was a guy here named "Bottom Paint" that knew this question inside and out. I guess the yahoos from the bilge (Memphis Mike) got him banned. Too bad. Doesn't look like anyone knows the answer. Maybe one of those bilge yahoos (like the expert in everything Joe), will be an expert and let you know.

[Mrleft8]

I can't tell you how much you'll need, but I can anti-recomend the Boat U.S. (made by Interlux, theoretically the same stuff but different label and half the price) Ablative anti-fouling bottom paint. I followed the directions on the can to a "T". The stuff sloughed off in all the most critical areas in just over a month. I'm going with a hard shell finish this year.

[Matt J.]

Our marina swears by Petit. I've been told to expect ~300 SF/gallon... so you can do the math.

[WoodenBNut]

It depends!! What water the boat is in (salt or fresh). Hull material. Use of boat (always in water or stored on trailer), etc, etc. Best place to start might be the information on bottom paints at http://www.yachtpaint.com/ , or www.pettitpaint.com (http://www.pettitpaint.com) . Go to their bottom paint sections and tech info sections. They have excellent sections on estimating paint needed. Also, what might be an appropriate bottom paint to use.
The only thing I gotta say is "bottom prep and painting is a very nasty job". Try to get some bottom paint that is very effective at preventing marine fouling, will last a long time and maybe requires to sanding of the existing bottom coat. Bottom sanding is a really nasty job too.
Sorry I can't be of more help. But the references that I gave are really good.

[Wild Wassa]

Originally posted by RiverRat:
"Doesn't look like anyone knows the answer."

Is my formula wrong for calculating the amount used?

Told by someone who is guessing.

Warren.

[ 06-16-2005, 11:12 AM: Message edited by: Wild Wassa ]

[Gary E]

Formulas might be right, and lets spose that it turns out to say 3 quarts, or a few ounces shy...

BUY a GALLON.... paint it....

Next year... BUY a GALLON.... using last yrs leftover.....

Next yr.... BUY a GALLON....use the leftover...

Next yr..... One of these years ya not gona havta buy a new gallon...

[ 06-16-2005, 11:02 AM: Message edited by: Gary E ]

[Wild Wassa]

Originally posted by Gary E:
"Formulas might be right ..."

It isn't a matter of 'might be'.

Was I suppose to convert metric to US imperial for the slow learners on this site ... or draw them a little picture?

Warren.

[ 06-16-2005, 11:23 AM: Message edited by: Wild Wassa ]

[Gary E]

Warren,
My use of the word "formula" was re the guys that say the paint covers so many square ft, meter's, or whatevers etc... they are estimates at best, close but not ZACTLY on the money. That's why I buy more than I need. Who is to blame or better yet who is gona complain if the calculations are wrong and the guy needs more paint than estimated? THE GUY IN THE MIRROR....BUY EXTRA...

[Matt J.]

Ah, Gary...

I posted 300SF/gallon... say I'm off by half, or twice... if you don't guesstimate how many gallons to buy in the first place, how many should he buy? What if a gallon covered only 100SF, or went to 500? Where do you start? Point is that to get a ballpark guesstimated WAG in the first place I offered, as did Warren, a place to start. If I come up with exactly 300 SF, I'd buy a gallon and a quart or a half...

Geez. Lighten up, doood. smile.gif

[Gary E]

Same to you Matt

[Skiff Junkie]

I can't tell you how much you'll need, but I can anti-recomend the Boat U.S. (made by Interlux, theoretically the same stuff but different label and half the price) Ablative anti-fouling bottom paint. I followed the directions on the can to a "T". The stuff sloughed off in all the most critical areas in just over a month. The same goes for the West Marine brand.

[Ian McColgin]

I always liked ablative paints on my boats, large full keel displacement sail boats. I get two to three years out of the cheapest copper stuff with a pound of ceyanne per gallon. No bull.

With that sort of bottom paint I just roll on with a fine nap roller and launch in an hour or so.

I go with one coat per painting, except the 6" below the waterline. The water's motion allows for air induced electrolysis there. With most bottom paints and especially with ablatives, you'll want the extra layer to prevent deterioration just there.

Since you've a fin keeled boat and might well be in fresh water, you might want a hard bottom paint. Especially if you race. The hard paints can take a nicer smoother working out.

Still one coat except at the waterline.

Were I you I'd try to estimate the surface area correctly and believe the coverage claims on the can. Bottom paint is expensive enough that you'll not want a gallon if two quarts would do.

My own estimating approach when I'm to paint a strange boat is: (1/2b)(lwl) + (d)(lwl). Close enough for a normal profile sail boat. Too little if she has a really super long keel and a bit too much if it's a narrow fin keel. That's what fudge factor is for.

G'luck

[Noah]

Hey sbsbw,

Where is the boat, and what is the bottom made out of? Most of the sailboat guys use VC-17, or some other hard bottom paint here on the lake if they have a fiberglass boat. On my wooden hulled Hinckley I use "Petit Un-epoxy" only because the Shelburne Shipyard has it for $12 a quart, and I only need 3 quarts to do the bottom.

Noah

[Venchka]

Funny thing about paint pricing. Like George Kirby told me, "3 quarts equals a gallon." So, Gary's "buy a gallon, save the leftovers" scheme makes sense unless you know you can cover the boat with two quarts.

Someone said "go by the estimate on the can" for coverage? That would be 100 sq. ft./quart or 400 sq. ft./gallon. That would make Matt's estimate a bit conservative but ok for guesstimating purposes.

Piece of cake!

ARRRRRRRRRRRRHHHHHHHHHHH! Noah blew my "buy a gallon instead of 3 quarts" theory.

Wayne
In the Swamp. :D

[ 06-16-2005, 03:52 PM: Message edited by: Venchka ]

[Noah]

I change my bottom color from last year, and I really didn't want a quart of nasty bottom paint kicking around in my basement for a year.

Plus they only sell it in quarts...

I got 2 gallons of topsides paint from George, does that help?

[Venchka]

smile.gif Ayup!

Wayne
In the Swamp. :D

[Bayboat]

How much bottom paint?
There are many things in boat construction and maintenance that are hard to estimate closely.
This is one of them. Just get enough so that when you finish painting the bottom is all the same color.

[Gary E]

Just get enough so that when you finish painting the bottom is all the same color. That takes all the fun outa it...LOL

Back in the 60's I saw 2 guys in the marina painting the bottom of a 30 ft'r, one side RED other side Blue... He used WHAT HE HAD... are the fish gona care?

[Stiletto]

I've been using black since I've had my boat, but got given about a quart of red leftover by a mate who sold his boat. I mixed it into the new 4litre pail and the leftover 1 litre from last time to end up with a unique purply/brown colour. As Gary says, I'm sure the fish wont mind but I hope the weed does and stays away from it.

Since I even bought a new paint mixer I was thinking of adding chili powder, maybe cayenne is better.

[Gary E]

Ian McColgin
I always liked ablative paints on my boats, large full keel displacement sail boats. I get two to three years out of the cheapest copper stuff with a pound of ceyanne per gallon. No bull.
Ian's got it right, it just works...
I used that on my sportfish, but I put on 2 coats each time and 2 yrs between paint jobs.

[paladin]

Take the note from Ian...it's an old California fishermans trick with the cayenne pepper...been doing it fer 30 years and depending on how much you use the boat...3 years will be about right..

[chergui]

I talked to a guy who swears by "Jotun" antifouling paint. Made in Norway. http://www.jotun.com/

They claim it's good up to 60 months and it seems to be what a lot of large freighters use. The guy I talked to re-does his every 2 years. I would very much like to hear if anyone has used it. I don't know if it's hard or ablative thought. Not sure what they do on those big ships.

[Stiletto]

It is Jotun that I've been using. I like it and it is somewhat cheaper than the 'racing' brands.
I would rate it moderate to hard.

I'm going to buy some cayenne this weekend.

[Andrew S/Y Rocquette]

another useful trick is doing the first one or two layers in a colour different from the final - helps know when it's time to redo as it shows through...

[RiverRat]

Here's the "straight dope" on bottom paint,

If the hull is new and unpainted, then it'll need to be prepped differently. If epoxied (fiberglass), then it'll need sanding with 80 grit, wiped down with Interlux 202 (dewaxer) primed with Pettit "No sand" primer (etching primer) and then painted. Roll on with a 3/8 nap and tip off smooth. Do 2 foot squares.

For wood, it depends upon wiether its ply or plank.

If previously painted, you cannot mix ablatives and modified epoxies. High quality ablative can cover modifieds but the solvents in the modifieds will melt the holding power of previous applied ablatives thus,

Ablative over other ablatives, modified epoxies or new hulls. Modified epoxies over themselves or new hull only.

Buy a paint that is suitable for the WATER and TYPE of boat. Modified epoxies for fast speed boats or racing sailboats and ablatives for everything else.

Hard finishes can be "burnished", sanded with 320 or finer grit. 600 grit preferable.

With the fierce competition from the last 3 paint manufactureres (US owned) in the US, with all the $ spent on research and developement, do you really think they would ignore ceyene pepper if it really worked? If adding 50 cents worth inproved the paint more than millions $ spent developing "biolox", pepper would have been an ingrediant 50 years ago. Anyone that adds it to thier paint, deserves to be the one sanding the bottom when it becomes overgrown.

There are many fiberglass and racing sailboat sites where this has been posted and it is more commanly known.

If the boat is hualed out for the winter, the pesticide properties are affected. If its kept in for the winter, the waterline should recieve another coat to help protect against removal by chafting ice.

Tributyl tin, illegal to sell bottom paint containing it, is available. For those whom preffer to "mix thier own".

Buy a gallon. Do not let the left over paint freeze in the winter, it will seperate out and will not remix propperly. Read and adhere to all manufacturers reccommendations.

Bottom paint is a "Toxic Pesticide" ONLY and needs to be treated with respect.

[ 06-24-2005, 12:27 PM: Message edited by: RiverRat ]

[Seth Wood]

Where might one find a POUND of cayenne pepper?

Remind me not to come to any chili cookoffs with you all.

[Donn]

MotherNature.com (http://www.mothernature.com/shop/detail.cfm/Sku/34108) sells a pound of ground Cayenne for $5.79.