Boat building method questions

Discussion in 'Boatbuilding' started by The Rooster, Nov 21, 2013.

  1. The Rooster
    Joined: Nov 2013
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    The Rooster Junior Member

    I'm building my first wooden boat. It will be very simply made, nothing fancy at all, modeled after a Jon boat in style. Most might even say it's redneck as can be, but it's what I want. An example can be seen in the following thread link, posted by another member here, GaryBriggs, it's the second picture posted in that thread. I like it for its simple, clean look, and ease of build. He built that one, and it seems it would suit my needs also, though I will make mine a bit larger.

    http://www.boatdesign.net/forums/boat-design/small-boat-creek-fishing-wanted-48958.html

    Joints will be fitted in a way where they can be simply cut and screwed together. Most parts will simply butt joint together at 90 degree angles, with a couple of joints that may be at different angles. The hull will be 3/8 plywood with some 1x wood in the boat for framing and making bench seats.

    I have a few basic questions before I start on it.

    First, can I simply use deck screws to assemble it? I plan to use various sizes of scorpion screws. These are ceramic coated and made for treated lumber deck building. I will not be using treated lumber. The heads of these screws are made to be countersunk, which all of them will be.

    Second, as I'm assembling the parts, should I use any form of sealant between them? If not, then I will at least use Titebond 3 wood glue. It is supposed to be water proof. I feel that this will improve the overall strength of the boat by bonding the parts together with adhesive in addition to fasteners. It might also serve to form a physical barrier for leaks between joints.

    Third, once the boat is assembled, what will I use as an overall sealer to protect the wood surfaces? I'd like to find something off the shelf at Lowe's or Home Depot that is relatively inexpensive. Today at Lowe's I saw an Olympic branded wood sealer that says it can last up to 10 years on fences, and about 6-8 years on decks. I believe this is due to horizontal exposure to the sun vs. a fence being vertical. Cost was about $36 per gallon. Will this work?

    Fourth, I'm also thinking of painting the boat to make it a color, or maybe just staining it. Stain would look nicer I think. I know if I stain it then a top coat water sealant is also needed, as mentioned above. If I paint it, will the paint serve as both the sealer and finish, or is a clear sealer still needed? Also, if I paint it, I read online somewhere that porch paint will work. Is this correct?

    Sorry for so many obviously newbie questions. My goal here is to make an inexpensive fishing boat for creeks. I'd like it to last a while and not look too shabby, maybe even appealingly nice when seen by those who don't have one. But the main goal is to save money, fish, have it last a good while when completed, and not sink or get me wet from leaks. This boat will spend more time out of the water than in, and will likely be covered under a tarp in the back yard, elevated off the ground of course. I will use a standard trolling motor to run it. Hope this is enough information to give you an idea of what I'm doing. I've been told I should just forget it and buy a good aluminum Jon boat. Somehow, this seems much more fun.
     
  2. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Screws: Somebody had to try those ceramic coated screws eventually. I don't know except to say any break n the coating is enough to create problems. However, a simple boat might be built cheaper using them. I suggest screwing some into similar wood and then submerge the wood in a saline water filled bucket for a couple of months and see what happens.
    Adhesive: Wood not totally sealed with epoxy will swell and move around so hard-setting glues like Titebond 3 aren't as good as a more flexible sealant if fasteners are being used anyway. 3m 5200 would be my choice for a caulk-gun adhesive.
    I suggest paint over a home sealant on internal surfaces. It will not discolor or require recoating as soon.
    Stain is a waste of time----- even on houses as far as I'm concerned. It takes a lot of product to do a decent job and doesn't hold up very well compared to paint. Prime and paint is far better protection. Porch and deck enamels over alkyd primer would be my choice.
     
  3. The Rooster
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    The Rooster Junior Member

    I'm somewhat confused about the paint over a home sealant part. Sealant goes on first, then paint?
     
  4. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Just paint---- the type sealant you mention isn't going to be effective on a boat to the degree you want it to be. A proper boat sealant would be epoxy, which is applied over all surfaces in several coats and effectively allows the interior of the wood part to remain dry.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    TiteBond III will work, but only on very tight fitting (perfect) joints and only if the boat is kept dry, when not in use. If standing water is left on a TiteBond III joint, it will loosen, creep and release if under much tension or shear.

    Sealants fall into two basic categories - one is semi rigid, like 3M-5200 and acts like an adhesive as seam sealant, while other types are surface coatings. It would be a wise thing, considering how you plan to build, to have a bead of 3M-5200 under the chine logs and in every seam. As to a surface sealant, I wouldn't bother on a trailer boat like this, but epoxy is the hands down way to go. Varnish and paint don't seal crap, neither do things like Thompson's or other topical products (like Olympic brand, which is actually a rebadged PPG product and mostly dissolved wax). If the boat is well cared for, kept dry, well ventilated and covered, it'll be fine for decade, without supper goo in a can.

    There are lots of paint choices, but you get what you pay for. Porch and Deck enamel works, but isn't very durable, but it is cheap enough to touch up when it needs it. Higher quality paints usually reflect this in the price. The last paint I bought (last month) was over $400 a gallon, so pick your poison wisely. Paint and clear coatings are pretty much the same thing, in the various resin categories they come in. You don't need a clear protective coating over paint, nor varnish or polyurethane, unless working with a 2 component water borne or solvent based LPU (the $400 and up per gallon stuff). This is what they use on cars, aircraft and other high end products. Don't even think about an LPU paint job without a lot of research.

    The coated screws you're referring to are typically intended for use with alkaline copper quaternary (ACQ) or copper azole (CA) mixtures, used in pressure treated wood. These wouldn't serve any useful purpose on a boat build without PT. In most cases these types of screws are low quality and tend to break easily in shear. In fact, it's common to break off a head, just driving them in. Use stainless or if you must go low ball on the very things that hold the boat together, then hot dipped galvanized. They do sell zinc coated, a plating process that often has the word galvanized in the product title, but these are usually crap.

    The reason the marine industry uses some of the products, materials and techniques we do is, we've all tried the slap it together with duct tape routine and seen the results. The industry is constantly trying new stuff, but a Liquid Nails and Lowe's/Depot material boat is usually very short lived, unless stored inside and not used much.
     
  6. The Rooster
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    The Rooster Junior Member

    EUREKA!!!

    What about spray on or roll on truck bed liner? Or rubberized undercoating, as used on automobiles, for a hull sealant? Would this work to seal the hull? I'm thinking it would make a pretty rugged surface to resist scratching when the boat is beached, and a pretty good waterproofing material for the hours at a time that the boat will see water.

    Will it be pretty? No, but it won't look bad either. I could probably even paint it and enjoy the look of it for as long as it lasts, and then repaint as needed.
     
  7. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    Hey I been thinking a utility boat for my mangrove creeks for crabbing, netting and a bit of bait soaking. Something cheap and nasty that can be dragged out and left upside down

    Something like a flat bottomed barge types. Each side made from two lengths of 8x1 fitted to make 16x1 and bottom from a sheet and half of 9mm ply. I think 11 to 12 feet is good length for a short boat. Tried 8' and didnt work very well

    Cut the sides so its a nice curve up to the bow and she wouldnt look too bad. Get a bunch of screws and glue and screw the bottom play into shape

    I think Purbond would be suitable here as the glue. There is a product called Penetrol which touts to be a marine grade sealer for woods and metals. I think after sanding the whole lot paint with that to prime and then mix some in marine enamal paint and paint the lot. That should seal it good for cheap utility craft

    No reason why you cant get that looking sleek and sexy like this with careful thot

    [​IMG]
     
  8. PAR
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    PAR Yacht Designer/Builder

    There are a few different types of truck bed liner. Polyurea, polyurethane, LPU and others. The latest stuff is LPU and it's fairly costly, but very durable. It's about $150 a gallon for black, but you can buy a neutral base and tint, so many colors are available. It's a typical catalyst LPU, can be hand applied, dries quickly and the texture can be control to a degree, but the best part is it doesn't have particulates in the resin to make it tough.

    The most common truck bed liner is polyurea and this stuff can be sprayed or hand applied. It most often has some sort of particulate in it (rubber, polyurethane beads, Kevlar, etc.) which form the texture. I've tried getting it without the particulates, for testing, but it's like pulling teeth in a mirror. This isn't quite as tough as the LPU's, but significantly cheaper, with some only $60 a gallon. You'll need about a gallon to fully coat your boat, with a 30 mil film. The polyurethanes are similar to the polyureas, unless it's intended for spraying.

    Most truck bed liner do allow a good bit of moisture vapor through the coating (9% - 10%), so the wood would need to be encapsulated. If the wood was encapsulated, it makes a fine and quite tough coating. For your boat, you should consider one of the truck bed liners, as it will not see much in water time, comparatively, so the risk is minimal and we can get some free "in service" testing. I think a lot of folks would be interested in the results.
     
  9. The Rooster
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    The Rooster Junior Member

    Ok, I understand encapsulated to mean being completely surrounded, as in both inside and outside. I was thinking of applying it to the outside hull only. Am I unclear on what you meant exactly?

    Also, if it lets as much as 9 - 10 percent moisture by it, well then as a woodworker, to me this means a decent amount of expansion and then contraction as it dries out again later. Would a coating of this type survive that much movement without cracking?
     
  10. PAR
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    PAR Yacht Designer/Builder

    Yes, the coating will survive, if the substrate (the plywood) is encapsulated, which is exactly as the word sounds, all the wooden elements are entombed in epoxy. This said, I think the elongation properties of some of these products can tolerate wet/dry cycling (dimensional changes) without an epoxy coating.

    I've been doing some industry testing of truck bed liner products for a few years and they show promise. If you contact me privately (click on my icon), I can avoid breaking my NDA and "suggest" the better products from the rebadged and crappy stuff.
     
  11. The Rooster
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    The Rooster Junior Member

  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The Bondo product you've listed is about the worst thing you can attempt to "coat" a wooden boat with. It's polyester resin and absolutely notorious for not sticking (to wood) and causing rot.

    Instead of trying to come up with new ways to build on the cheap, with new techniques and questionable materials, maybe building a down and dirty plank on frame thing, would be better. You wouldn't need goo, just screws or ring nails and you can use 1x stock for most of the build. 1x12 sides, maybe a plywood bottom with a butt block or two, some simple 1x4 frames and ta-da a boat. Squirt some 3M-5200 in the seams, as you assemble it and learn the same things the rest of us cheapskate builders have learned (the hard way) over the generations.

    Reinventing the wheel isn't as fruitful as might appear on paper.
     
  13. The Rooster
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    The Rooster Junior Member

    I've been looking for a really cheap way to make a fishable boat to justify doing it. I could just buy a 12 foot aluminum jon boat from Bass Pro Shops for about $700. Add a battery and trolling motor for another $200 and that's $900 plus tax. I'd like to do it for half that price with wood. If it's going to be near to the price of just buying it then I may as well not. That's why I've been trying to cheap out on things. It seems I will have to compromise on one of three things, weight, cost, and durability. Durability is a must so it seems one of the other two will have to go. If cost is the one that has to go then I'll probably just have to go with a prefabbed aluminum boat.
     
  14. PAR
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    PAR Yacht Designer/Builder

    Durability with cheap materials and cobbled together techniques is an oxymoron, so . . .
     

  15. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    Always more expensive to build . Production boats are stamped out cheap.

    If i had a 1000 dollar budget i would purchase a 5000 dollar boat used ...for one thousand dollars.

    Millions of boats for sale
     
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