Ask twice, cut once: Instant Boat for first timer

[qwaszx86]

Hey everybody! About six months ago I posted about my interest in building an instant boat, and with your help I settled on the Gypsy. Well it's been a while, but I finally purchased plywood and I'm ready to get down to business (after I get answers to about 5000 questions).

So I laid down 1' measurements to begin forming the shapes of the sides and bottom, and I've run into my first "Whoa I better ask somebody first" question:

The instructions say to measure in from the edges of my ply at each 1' interval and drive a nail in, then wrap a batten around the nails to form the curves of the sides. I'm wondering if I'm supposed to leave some "wiggle room" for sanding or planing down later, and how much.

If I'm not supposed to leave wiggle room, isn't having nails driven into the exact edge of the sides already going to throw off my curves by a very slight amount?

From reading about other plywood boats and instant boats I gather that you are supposed to leave a 1/4" or so around the sides and plane it down, but I can't find any specific reference to that, so maybe I'm making it up? Basically I'm feeling some hesitation about just how to lay these measurements down, so any help would be appreciated.

One last thing: any recommendations for what to use as a batten? I need something I can purchase, ideally, because I don't have a table saw to rip a thin strip of wood I could use.

Thanks!

[tazmann]

I work with metal myself but it's pretty much the same. Lay it out and mark it as they say in the plans then cut just to the outside edge of the mark. Then you just lightly hit it with the sander to get any high spots and saw marks off and it should be right on the money. A straight peice of 1x1 from the lumber yard works pretty good for a batton or even a 3/4 x 3/4 aluminum angle iron, what ever you use there just make sure it's a nice fair curve when marking.
Tom

[alan white]

This is basic carpentry. I assume you mean you drive a brad (small nail) at a distance from the plywood's edge, and the distance is given to you in an inch increment plus a fraction. You would already have drawn accurate lines along which to measure, possibly every foot along the plywood.
First of all, you are essentially lofting curves and some correction will be required. The designer wants you to come as close to averaging the lines from the given measurements as possible.
That means you begin by coming as close as possible to the intended line. As you do so, attempt at all times to anticipate the finished piece being what the designer intended, meaning set your brads or small finish nails (4d is good) to one side of that anticipated perfect line so that the finished panel's edge is ON a thin pencil line.
Of course, I wouldn't know how close to the pencil line you can hold your saw blade. You obviously need to remain a small distance from the line at a minimum. You need to avoid running into the line with your saw. Period.
Finish by using whatever tool you can work accurately with to come up to the pencil line, maybe cutting the line in half.
Belt sander, plane, whatever works.
Here's a tip. When you set your brads, do not attempt to run your fairing batten against every nail but instead sight down the curve and attempt to make the curve as close to the intended one but without any humps or clumsy curves. The reason is that no set of measurements are ever 100% accurate. They can't be because we work in sixteenths and sometimes thirty-seconds, and even then the eye can see that, for example, the line needs to be some small distance from the given mark. This is art and not science.
Do your best to come close as possible. It will be fine. There is no more accurate way to do it.

[Tug]

http://www.boatdesign.net/gallery/sh...6/ppuser/22042

Hope this helps...
Cheers
Tug

[qwaszx86]

thanks for the tips. It's particularly good to know not to rely too much on the location of the nails.

Tug, I remember seeing that clip at some point in the past. It was very useful before I put together my Gypsy model. Going to go watch it a hundred more times now!

[marshmat]

Phil Bolger's tack-and-tape plans fit together well enough that you shouldn't have much, if any, trimming and filling to do as you assemble the panels. If you put the nails exactly where marked on the plans, put the batten to the outside of the true edge, and trace the face of the batten that contacts the nails, you'll be darned close. These were hand-drawn plans- no computerized unfolding, although some corrections were made to the as-drawn shape of the bilge panels after the first boat was built- it's remarkable how well they fit together.

In any case, the epoxy fillets and glass tape will compensate quite well for errors as big as a quarter of an inch over small sections.

[qwaszx86]

Hey everyone, I've gotten the bottom, one side and one bilge panel laid out. Things are moving pretty slowly, as I can only work on the weekends, but I have to say it was supremely satisfying to see those shapes come together.

Now it's time to cut those shapes out and trace their mirror images for the other sides, but before I do that I need to either butt strap the pieces together or make a glass butt joint.

If anybody has strong feelings about the pros and cons of either method I would love to hear them. I'm leaning toward the glass joint for strength and looks but if it's really not going to be a huge difference then I'm not too picky.

If I do butt strap them, however, I have a question. The instructions call for the butt straps to be two pieces of 1/4" ply, nailed through the hull with a 1" copper nail, which will poke through. I'm supposed to bend the points over and then trace the mirror image for the other side. My question is what happens to those ugly nail points sticking out of my boat? Are they small enough that they will eventually be covered by the fiberglass and paint? I assume they won't be noticeable, but before I commit I want to make sure.

As always, I'm grateful for all the help.

[marshmat]

Glass butt joints work well if you can apply enough pressure to keep them flat while the epoxy cures. This can be pretty hard to do with 1/4" panels.

Butt blocks are plenty strong enough, and much easier than scarphing or glass butts. If you decide to do this with copper nails, it'll be easy to bend them over far enough that they aren't a problem. 3/4" screws also work. Don't forget to epoxy the joining face of the butt block.

[messabout]

You are going to like the Gypsy. It is a sweet little boat despite its simplicity. The rig is very modest but it will make the boat go quite nicely and the rig is very simple. The only down side to the rig is that the clew end is way up high. That is good in terms of not having it bash your head when tacking. The high clew puts a considerable downward sheet pressure on the end of the boom. You may wish to use an adjustable topping lift to avoid stretching the leech too much. Aside from that, the rig is a joy to use.

Keep on buildin'