Need Some Guidance on Finishing My First Boat

[AndrewT]

My kids and I are in the process of building a Macomber 15 (seen in the last issue of Small Boats, and online in WB's plans section). It's my first build, and we're really enjoying it.

I'm starting to think about finishes. What I'd like is to paint the hull sides and bottom, and finish the mahogany transom and other trim "bright." Unfortunately, wood finishing is not one of my strengths. I think I understand the concept behind painting the hull - sand, fiberglass, sand, prime, paint. But I have no idea how to go about finishing the brightwork.

The boat will be garage-kept, not stored in the water. It'll get used a few times a month between about March and October, and for no more than about 8 hours at a time in the water. (The closest water to us is about 30-40 minutes away.) So we'll trailer to and from and store the boat dry.

I've ordered a copy of "Fine Yacht Finishes" but I would be grateful if some of you experienced builders could give me a heads up on what to expect. Thanks in advance.

[Mrleft8]

Ah....
I don't suppose that the transom and other brightwork bits are not yet installed..... That would make life easier...
Essentially you're looking for as flat, and/or smooth a surface as possible. On the transom I'd sand with a block of wood wrapped in sand paper, starting with 100 grit and working down through the grits to 180-220. Then I'd brush on a coat of shellac thinned 60-75% with alcohol. Then sand to 320 with the block and paper. Then I'd brush on a coat of Benjamin Moore 440 Spar varnish thinned 50% with turpentine (Not paint thinner).Use a paint strainer funnel every time you pour varnish and or turpentine from one container to another to strain out lumps, bumps, bugs, and hair. After that was dry (a week), I'd get the whole surface wet, and rub it down with a wet rag wrapped around a block of wood and charged liberally with pumice. Then I'd let that dry (A few hours) and wipe it down with turpentine, let that dry, and brush on another coat of varnish thinned out 25%. Then I'd repeat the rub down with a rag and pumice again in a few days. Then I'd brush on another coat thinned down 10% and repeat. Then I'd brush on another coat, full strength, and let it dry 1 week. I'd wrap a damp rag around a block of wood, and charge it with rottenstone and rub the finish out until you get no shiny spots.... Wipe it down with turpentine and let it dry.... Finally put on the last coat being very careful to not leave any drips, lap marks, or blips. It's important not to have dust, or other things (like mosquitoes) land in this last coat, so move slowly, wear clean dust free (As possible) clothes and a hat or shower cap. (Have someone take a picture for later ) And make sure windows, doors etc are closed. A small tent made out of poly can help if you're in a garage situation.
If all goes well, you'll have a mirror like finish, that in your case should last 5+ years without any special attention.
You can do the same thing with rails and thwarts. The rails you won't be using a block of wood on, but the results will still be outstanding. Use a good brush. Cheap brushes will just frustrate you, and $18 isn't much when you look at the big picture.

[AndrewT]

Holy crap. Is there nothing that can be applied with a spray can in a couple of hours?

I'm kidding. I knew it would be a real project. On the plus side, I haven't installed much beyond the transom. The remaining mahogany I'll try to finish before installing (although this looks like about a three-week project).

One question - when you say "charged liberally with pumice," I think I understand what that means, but could you elaborate? The only pumice I have is a scrubbing block I use to clean rust of off old stuff. Can you get it in powder form somewhere? (Same question re: rottenstone.)

[Gerarddm]

A bit much, I think. This boat is not a Riva.

Sand down to 180. Clean the surface thoroughly and tack it. Mask off the area. Choose your varnish. Brush on a first split coat of 50/50 varnish and thinner. Let dry 24 hours,sand lightly with 220, clean, tack. Apply second split coat, now 75 percent varnish. Let dry, lightly 220 sand, clean, tack. Now apply 6 coats or so of full strength varnish, lightly sanding and tacking in between each. Last coat be anal about dust in the air,etc. and do not sand it. Done.

[AndrewT]

Well, that seems a lot more reasonable. This boat is mainly for my kids, who are currently 7 and 9, so I'm not expecting it to be treated real well.

What's the thinking on epoxy? I am fiberglassing the bottom of the boat and probably up the sides to the first plank lap (not planning to try to 'glass the lapstrake sides), mainly for waterproofing the cross-planked bottom and the chine joint, and a little added abrasion protection. I am planning to coat the remaining (non-fiberglassed and non-varnished) wood in epoxy before painting, unless someone can explain to me why I shouldn't or don't need to. A related question - what kind of paint should I use on the hull sides? I've read that porch & deck enamel works well ILO expensive marine paints, but I don't want to be repainting this thing every other year. Somebody guide me.

[Canoeyawl]

A cross planked bottom and fiberglass?

Hmmm... I wouldn't do that

[AndrewT]

A cross planked bottom and fiberglass? Hmmm... I wouldn't do that

Well, speak up, man. What's the issue? The wood moving? If so, I thought the whole point of encapsulating the wood with glass/epoxy was to stabilize and prevent wood movement? I could be wrong (in fact, there's a strong chance I'm wrong, since I've never built a boat before), but it just seemed to me that covering the bottom in glass/epoxy was going to be less maintenance, long-term, than what the plans called for (namely, cross-planking with caulk between the planks). Since this thing isn't going to live in the water, I envisioned the planks shrinking over the off-season, pulling apart, needing to be recaulked every year, then swelling tight and/or splitting the first time it gets dropped in the water in the spring.

Plus, I'm using Cypress for my planking, which looks great but has a tendency to absorb water like a sponge.

Or is it the fiberglass, instead of using some other cloth? Or something else? New guy here, open to suggestions, don't want to spend 100's of hours of labor only to screw it up.

[Mrleft8]

Ah.... First..... Yes both rottenstone and pumice are available in powder form. I get them at the hardware store. I get "Rainbow Sundry Products" brand.
And also, yes perhaps this is overkill for your particular boat...
And third.... By "charged liberally" I mean that I take a damp rag and dip it in the pumice or rottenstone and whatever falls off falls off. That which sticks, is the charge..... It's a sort of "see as you go" kinda thing....

[Brian Palmer]

You do not want to fiberglass the bottom of a solid wood boat, only a plywood boat. The wood will move anyway and split your fiberglass.

Treat the inside bottom of the boat with a mix of linseed oil and turpentine. You can paint the rest of the insides. After you treat the inside of the bottom, you can keep the planking swollen and tight if you spread some salt on the inside of the bottom and lay down some soggy carpeting inside if it seems to get too dry. Take the carpeting out when you use the boat. The salt will make the bottom hygroscopic and it will pull moisture from the air (unless you live in a desert). I did this with a cross planked boat I had and the planking stayed tight. Do not try filling the boat with a hose to make the planks swell. You could damage it from the weight of the water.

Follow the instructions on the can of spar varnish and you will probably be fine. This is a boat, not a piano. Make sure it is spar varnish because it is designed for exposure to the sun.

For the sides and bottom outside, get some oil based primer and paint and follow the directions on the can. Use some Penetrol or thinner if it seems like the paint is too thick and stiff and hard to brush. You do not need any special boat bottom paint for a boat that is not going to stay in the water.

Sand everything down to about 150 grit before you start painting or varnishing. Sand with 220 grit between coats of varnish, maybe 180 grit between coats of paint.

Good luck,

Brian

[AndrewT]

Okay, we need to talk about this whole cross-planked bottom mess. I know myself, and I know my kids, and there is no way we are going to "spread some salt...and lay down some soggy carpeting..." Not a chance. On a good day, the boat will get hosed down when we get home from the lake to remove road grime. Most days it will get backed into the barn and forgotten about until we need it again. It sounds like we need a new plan for the bottom.

The skiff is flat-bottomed with little rocker. Any reason, other than aesthetics, I can't replace the cross-planked 1"-thick bottom with a plywood bottom covered in glass/epoxy?

[Mrleft8]

Okay, we need to talk about this whole cross-planked bottom mess. I know myself, and I know my kids, and there is no way we are going to "spread some salt...and lay down some soggy carpeting..." Not a chance. On a good day, the boat will get hosed down when we get home from the lake to remove road grime. Most days it will get backed into the barn and forgotten about until we need it again. It sounds like we need a new plan for the bottom.

The skiff is flat-bottomed with little rocker. Any reason, other than aesthetics, I can't replace the cross-planked 1"-thick bottom with a plywood bottom covered in glass/epoxy?

Probably not. Look for 3/4" MDO 2 side (Paper faced on both sides) AKA "Sign Board" It's what the DOT uses to make those big green road signs that help you get lost on the interstates.

[Brian Palmer]

You only need to do the salt once every few years, not every time you use it. What is your "barn" like? If the boat is stored in an unheated barn with a dirt floor, it may stay tight between uses with no further treatment.

If you haven't put the bottom on yet, plywood is certainly the way to go. If it is already on, give it a try as is before you pull it off and replace it with plywood.

Brian

[AndrewT]

Bottom isn't in place yet. I think I'll go with the MDO suggestion.

[Jefe]

Hey Andrew,

I had the same kind of varnish dilemma as you on my first build. I'd go with what Gerard said or what I did, which was:

I used coats as follows 75% thinner, 25% thinner, 15% thinner, then 2 unthinned coats. Finely sanded and wiped with a tack cloth in between.

http://forum.woodenboat.com/showthre...ish-over-epoxy

Here's how it came out. The seat slats are mahogany, the rest is framing lumber. All was stained with water based aniline stain (bought as a powder from WD Lockwood).



The boat is stored uncovered - outside all year long and it has held up very well for the last 3 years with no additional coats.