adopting a plywood boat to strip plank...

Hey all -

I've been considering starting a build of a wooden runabout/ski boat - something like one of the 14-16' glen-l outboards, and I've been trying to figure out how the build would go before going any farther. Anyway, I've got a few unique 'problems' to work around which I'd like your advice on:

1. I'm not going to use epoxy. I'm building the boat for fun and at home - I just don't want the stuff in my house and I don't enjoy being suited up with all the protected garb, and would rather not run the risk of sensitization. The same goes for trying to minimize the use of any other toxic materials.

2. I live inland in the south east of the US. I'm looking to source most of the materials locally, or at least that I can go pick up. While I don't mind ordering stuff online, for this project I'd like to avoid it. I've ordered several large batches of wood before and had them shipped, and that's fine but for this project I'd like to see what I can do locally, since I would rather buy materials as needed (excuses to go to the lumberyard!). Unfortunately, this rules out good, reasonably priced marine plywood, and I would go for good exterior plywood but to be honest, I wouldn't use the stuff sold in yards here for a dog house, let alone a boat - it's nasty stuff. This is leading me to think about strip planking, as I can get a decent selection of wood for framing (SYP, white oak) and planking (WRC, atlantic cedar, etc).

BTW, I've been working wood for a while, so I'm not afraid of a little more joinery work. In fact, I'd like that. So, a few questions:

1. All of the glen-l designs are ply on frame. Can these be redesigned for strip planking without epoxy/fiberglass encapsulation? It seems like there are two distinct planking methods, one in which the planks provide the structure and one in which the glass does. How would I go about finding the information to recalculating the framing and planking scantlings for a boat like that?

2. What types of glues would be locally available for use?

3. What would a finishing schedule look like for a non-fiberglass/epoxy boat? I've read of some of the northern Europeans using oil for complete impregnation and finishing with paint/varnish. Are there other methods. Unfortunately, I'm having a hard time finding info on these since it seems like everyone just coats everything in epoxy, but there have to be other methods of preserving a wooden boat.

4. Are there other designs already that are available for strip planking. I couldn't find any that were outboard runabout/ski boats of that size, but maybe I'm not looking in the right place.

Thanks all - I'm thinking that this could be a fun winter project, so I have time to weight my options. I appreciate any help I can get!

 

These are ply, but u can have a look at this site:

http://www.bateau.com/proddetail.php?prod=PH16

 

That Bateau design is precisely what Lake Cat is trying to avoid Knut. In fact, I'm fairly sure that Bateau offers taped seam as it's sole wooden construction method on all designs.

A plywood design, could be converted to strip planking, but it's not well suited for this conversion. The reason is the large, unsupported areas the plywood covers are "developed". The plywood is dimensional stable and self supporting enough to span these areas with little additional support. Strip plank would be at a disadvantage in this regard, likely requiring stringers and frames to make up the difference. You'd also be building a slab sided boat with a method ideally suited for round bilge construction.

Batten seam may be a better choice, certainly less tedious then strip planking. This method has be all but replaced with plywood, but still has merit.

Epoxy isn't nearly as bad as many make it out to be. You don't need a full up suit and respirator. You just need to work neat and not try to wear, eat or smear it all over you. A dust mask when sanding it is a wise precaution, as it is when mixing in some of the filler types (like silica or milled fibers). Gloves of course and cloths you wouldn't mind if you got a drip or two on. Chemically, it's fairly inert so long as you aren't using your bald spot as a squeegee on over head work, you'll be fine. Only prolonged, repeated exposure will cause sensitization, though some people are more inclined to this then others. Those that are sensitive to other quite alkaline materials should be careful around the stuff, but general protection (gloves, working neat and a dust mask) is all that's needed.

Epoxy is so much superior to other adhesives/coatings that it's very difficult to replace it, without dramatic compromises in the build type being necessary.

If you want to build in strip plank, find a strip planked design, though many of these also require a fair amount of epoxy effort.

The only other option is a traditional type of build, which usually needs much more in structure and materials to complete, but is free of epoxy. Carvel, lapstrake, batten seam, double planking, traditional strip plank are a few of these methods. The boat will be heavier and you'll battle leaks, caulking and fastener retention the life of the boat.

 

Careful out there; The unhardened epoxy resins and hardeners are toxic, irritating, and allergen at least. The fumes from the process are not that dangerous but I'd take care of air circulation.

I would emphasize on PAR's suggestions that skin contact with unhardened epoxy parts or mixture is best to be avoided. Use latex gloves or such which provide protection for chemicals and ensure that they tolerate also the solvents if you use any for cleaning. Eg. aceton is quite nasty on skin and dissolves also many usual plastic gloves. Aceton is really good for cleaning up epoxies though, if not too good.

Safety goggles are also a wise precaution.

 

PAR got me to think of the Handy Billy, batten seam planking, materials available at most shops. But then again; thats not something to pull a skier behind...

 

Okay, it seems like converting plywood to planking might not be a great idea. Is this true with the ply on frame boats as well, or just stitch and glue? The ones I'm looking at seem to have frames about 2-3 feet apart, as well as chine, sheer and keel logs.

What would it take to work out a new design to accommodate strip planking without epoxy? I'm sure this is a dumb question, but are there architects that would draw up plans for a small boat like this?

I understand the benefits of epoxy very well. I just don't want it around my house, and if friends come over to help, I don't want to worry about them. If I had somewhere else to build, this wouldn't bother me. Plus, since this is to be a winter project, that sort of kills the use of epoxy anyway unless I resort to some type of heating contraption for all the joints (or a tent).

Thanks for your advice so far - I know this seems like a bit of a silly exercise but I'd like to explore all my options and plan for the best (for my needs) and most fun build from the start.

 

Wood dust is a health hazard too. Some species, like cedar can cause severe allergic reactions. Epoxy is FDA approved for food contact.

 

Considering the designs you've been looking at, a custom would likely be out of your price range.

I have a few non-epoxy designs that may be suitable, drop me a line by email (click on my name) and we'll talk about it.

Iiki, we have to assume folks will not try to drink glasses of uncured resin. Cured epoxy is quite inert, in fact used to seal electrical leads on implants, such as a pace maker.

 

liki,

Don't use aceton to clean epoxy off your skin. It will drive the chemicals in deeper. Use white vinigar. The acidity breaks up the epoxy. Wash the remander off with a good soap and water.

Ray

 

I sympathize with your views on epoxy, since you have nowhere else to build but inside the house. That makes it impossible to get away from the stuff, although it’s not all that bad. I myself use a construction method that eliminates most but not all of the epoxy, but it is suited only for very small narrow boats like canoes and I would not recommend it for a power boat.

The glue used between the strips needn’t be epoxy, at least for the cedar strip construction used on kayaks that I am familiar with, but this method of construction usually has glass/epoxy applied to both sides to provide the cross-grain strength that ply has and wood strip lacks. Traditional construction used steamed oak or ash ribs riveted to the strips for the same effect, and is rather tedious.

However, designs intended for ply construction are best built in ply. I don’t see that changing from ply to wood strip gains you much, without epoxy you will still have to attach it to a frame using fasteners. The extra thickness of the solid wood may make seam sealing easier but there will be a lot more of them, so the logical choice for you is probably ply-on-frame.

Perhaps the best approach would be to use fasteners in combination with a polyurethane marine adhesive sealant like 3M’s 5200. It should do as good a job of keeping the water out as epoxy, but I don’t have any experience with it: perhaps the other members would advise if it will work. You would need to ensure the frame longitudinal members are substantial enough to retain the fasteners, and if adapting a stitch/glue or taped seam design I imagine you would need more frames to provide the stiffness that otherwise would be provided by the glued and taped seams.

 

Terry - thanks for the advice. I definitely am considering that route as there are at least some designs that I could get plans for that would suit ply on frame. The reason I wanted to convert to strip planking was because I can't find any good marine (or even good exterior) plywood locally, and I wanted to do this project piece by piece and avoid doing large shipments. But, after having talked with a few people, it seems that some of the lumberyards can special order some better plywood so that opens up the door for a ply boat again.

So, my current plan is the glen-l zip using southern yellow pine for the frame and exterior grade (best I can find) for the ply. Hot dipped galvanized screws/nails for the fasteners and a good waterproof PU glue for assembly (5200 or PL Premium). The hull will be painted and the deck will be varnished (I'll probably veneer a solid wood to the deck and trim over the plywood). I'm thinking that I can get most of the materials locally (except for hardware, but maybe even that) and I will have avoided epoxy in the build. Since this will be a trailer boat only in fresh water, I'm thinking this plan should be more than adequate. What do you all think?

 

keep power tools away from these people if they cant be trusted with epoxy.

Epoxy in the garage is not a problem. I built a foam core boat in my garage that used about 50 gallons; wife complained about many things, but epoxy was not one of them. Unless you have a large lamination kicking off, there is basically no odor. Of course, your work space should be reasonably vented.

Your making a huge compromise in excluding epoxy and for a benefit that is not logical. Are you going to paint this boat? If so, your paint is likely to be much more dangerous than epoxy.

We have middle school kids who build boats from epoxy IN THEIR CLASSROOM, its not hazardous unless you drink it or somehow spray it.

I also do not understand the other self imposed restriction of buying locally, your going to pay much more than you have to for a smaller selection.

Why not start out with "this is what I want" and then go to "Whats the best way of accomplishing this"

 

Joel,

I couldn't agree more!!

 

Me too

I'm respectful of epoxy, but not overly concerned about it. I too want to strip plank a ply design (A Welsford Navigator). I have not seen the plans yet to judge how hard it would be. The navigator is a glued lapstrake ply boat with longdituninal chine logs wupporting the edges of the planks. I plan to either follow the original chines or "round off" the station frames somehow (if Mr Welsford does not shoot me for doing so). Undoubtedly the boat will not look so good without the lapping strakes.

The reason I want to do this is because I like the look of the nagigator (especially in Luke Fosters's video: http://lukefoster.com/dauntless/wp-c...-pirate-12.wmv) and I want to test to see how long it takes to strip plank a boat in my own wierd way before I comit to doing a larger project and to see how well "tight knot" slash sawn western red cedar transforms into strip planks.

My plan would be to coat planks of plain sawn lumber with epoxy, let it dry and then cut it into battens. I would nail the battens to the frames using raptor plastic nails and perhaps glue it to the frames using Gorilla glue. The epoxy on 2-sides of the battens (top and bottom rather than inside and out) would ensure that these sides are coated effectively.

I would leave a small gap (1/16" or so) between the battens. Oce the hull is completely "planked" I would glass the inside of the hull and when that is hard, would force thickened expoxy between the battens from the outside and sand it all fair. Finally glass over outside of the hull.

I'm hoping that I can reduce the amount of time from erecting the frames to having a hull that I can float on a mooring or store at the local "toy storage". Even at the expense of spending more time setting up the project.

I think with a little calculation I could match the glass + strip-plank cross grain strength and stiffness to the 1/4" ply that the design calls for.

I keep thinking to myself, "what would George Buehler do ?"

 

Strip planking a Navigator would require moving a fair amount of displacement around to accommodate rounding over the strakes. If you have these skills then why fool with one of Welsford's designs and just pen up your own.

In short, you'll have to make the navigator a round bilge, okay maybe a "soft faceted" bilge boat. This means "stealing from Paul to pay Peter" in the body plan, which will alter hull volume. If you can handle this level of volumetric adjustment, then you don't need Welsford's plans.

I'm not sure why you don't want the glued lap version of the Navigator. Your suggested scantlings will be heavier then Welsford's and his aren't light by any stretch of the imagination.

I'm also not sure why you'd want to invent yet another strip planking method (I can think of at least a dozen different strip methods), when there has to be one well suited to your skills, desires and material choices.

George Buehler would build a traditional lapstrake version of the Navigator and skip the goo aspect of the build. He would likely use solid lumber for the planking and it would be God awful heavy and unable to get out of it's own way, in anything less then force 7 winds.