57 replies to this topic

[AndrewB]

First frame is outlined. I need the stringers/gunwales cut before I continue, since I don't know the exact size they will be. 1" board = 3/4". Plans call for 5/8". Will the piece I get have 1 nice side, then plane the other side down 1/8"? Can I plane it just 1/16"? I also have to locate a plane. Time to try and find a decent cedar board in Kalamazoo MI. I have a neighbor several doors down that runs an amateur saw mill. Perhaps I can get some boards from him? And/or borrow some tools.

[woodman]

8' long 2x4's or 2x6's from home depot work just fine..rip it down on a table saw with a thin kerf (1/16'') blade will minimize waste. Searching through the 8' 2x4's down here is easy to find boards with no knots some times...

[AndrewB]

We have Home Depot, Lowes and Menards for big box stores, as well as several lumber yards. I rather support the local lumber yards if they are anywhere close on price.

Do you flip the board vertical and rip it down for the 5/8" thickness (1.5" / 2 - 1/16 = 11/16, with 1/16 to spare for sanding?)

[Hirilonde]

Do you flip the board vertical and rip it down for the 5/8" thickness (1.5" / 2 - 1/16 = 11/16, with 1/16 to spare for sanding?)

If using 2x stock is the route you are going I would rip the whole thing to the width of the stringers and/or gunwales first, then rip to thickness. I bought 5/4" stock, which is dressed to 1" and just ripped to thickness. The board foot price was a little higher, but the only waste I had was sawdust so I know I came out ahead of culling through knotty material. It all comes down to what you can get a hold of readily and for a reasonable price. Junk isn't worth any price, and that is often what the big box stores sell.

[AndrewB]

I have been calling around trying to find some marine grade plywood. The only place I have found so far wants $100 for a 4'x8'x.5". Is the exterior stuff that much worse?

[AndrewB]

Found a place that has Baltic Birch 1/2" 4'x8' exterior grade glue, no voids for 59 and 1"x4"x16' clear WRC for 1.92 Board/Ft, for $120 total. It will be in tomorrow morning. I know I could get the WRC from a big box, but then I would have to scarf at least 1 join, if not more in the case of knots. Oh, and they will rip it for me.

[Kudzu]

Exterior pine plywood we get is horrible! I will not build prototypes from it. You saw the photo in the book didn't you? Quality will very from mill to mill but our is not worth using for a boat. Barely worth using on a house.

 101_0921.JPG   54.65K   5 downloads

Yes marine grade is expensive but what is that boat worth to you? You will still only have $400 +/- in the boat, that is a dirt cheap for a quality boat. If you build it right and take care if this is not a throw away boat, it will last for years and years. So spending $100 on plywood is not as outrageous as it first sounds.

BTW Real Baltic birch does not come in 4x8 sheets. It only comes in 5' x 5' and it is imported from Russia. Not saying that is not a good plywood to use, but it is not Baltic birch. Just make sure it is suitable.

[Hirilonde]

BTW Real Baltic birch does not come in 4x8 sheets. It only comes in 5' x 5' and it is imported from Russia. Not saying that is not a good plywood to use, but it is not Baltic birch. Just make sure it is suitable.

Yup. There are a lot of birch ply products out there and include lumber core birch veneer ply, birch veneer cabinet grade and others. They all have different characteristics and are intended for different uses. None of them are as good as Baltic Birch for structural integrity, and BS 1088 marine is the best you can get (assuming it is actually made to the standard). It never ceases to amaze me how misleading some lumber yards can be. The misuse of the word Mahogany is one of the most deceptive of them all. If you doubt our word on this then do some homework. Knowledge is the best protection from deceptive representation of wood products.

Your boat deserves the best.

[AndrewB]

I saw that picture, but couldn't tell what was going on in the black and white version in the ebook.

I was poking around to see if I could find some weight/strength measurements for the birch plywood. Seems these guys are producing baltic birch in 4'x8' http://www.boulterpl...erPlywood_4.htm (Also they use the exterior glue on only the 4'x8', which is what the supplier told me as well). I will take some pictures when I get it home tonight.

I was hoping to do all the lofting on the table before glueing down the paper to the plywood. But in order to do the curves where the water pressure pushes in the skin without the glue/nails/thin wood or plastic, I either need to use a large compass + http://www.1728.org/circsect.htm (Chord + Segment height calculator, set compass to radius) or freehand it. Any other methods? Or am I overthinking it?

[Hirilonde]

Hmmm, maybe that is Baltic Birch in 4x8 sheets. But at $96 vs $135 for BS 1088 Okoume why try it out? Or just go with the 5x5 which is enough for 2 Curlews if carefully layed out.

I think you are overthinking the curves. I did mine with a string compass and various sizes of plates and bowls from the kitchen. There was nothing scientific about the choice for any given raidius other than it looked like it would work and looked good to my eye.

[Kudzu]

Got to say Boulter has a good reputation as a supplier and that just might be made from Baltic Birch then. Could be someone is importing the wood and a making the plywood here in th US? That is news to me.

[AndrewB]

Faintly stamped on edge is "Made in China", sigh.

They assured me it was exterior grade glue. And looking at the edge, I don't see any voids.


The WRC was gorgeous, no hint of a knot anywhere along the 16'. It has been so long since I worked with wood that picking up the wood and ripping it, a wave of nostalgia waved over me from the scent and gorgeous coloring to the wood. Used my camera phone to snap a few more photos of the wood, which can be seen in this album:
Curlew Build Album

I have finished 3 of the frames. Waiting to glue it up before doing the curves. I need to figure out a better desk situation. Standing over the ping-pong table for a couple hours has made my back SORE today. But is an ideal place to clamp a scrap piece of wood as a stop for the large square I am using for measurements.

I assume on the 4'4.5" frame the 3rd offset is for where the Fanny beam is suggested to go since it didn't add any noticeable curve?

[Gzwilling]

To see a good way to draw the curves, got yostworks.com. This is another person who designs fuselage frame kayaks. In his "woodframe manuel" got to "cross sections" then scroll to the 4th page. You will see how to draw the curves.
George

[P Douglass (WA)]

That's a good site. It's yostwErks.com.

[AndrewB]

I am now done drawing 7 of the 8 frames. Tonight I hope to finish the last frame, bow/stern assemblies and coaming drawn out. Then this weekend I will glue all the paper down to the plywood and cut out everything from the good plywood. The coaming and brackets I need to get some cheaper plywood to make the mold/brackets with.

[AndrewB]

Is there a reason for going with circle cutouts on the bow/stern plates instead of doing it similar to the frames (1" border)?

[Hirilonde]

It doesn't matter much the exact shape of the cut outs except that there is wood where the stringers and gunwales land and that they are strong enough to withstand collision. I don't think a 1" perimimeter with the landing areas added would be quite strong enough to withstand possible collisions. By the time you take these 2 parameters into consideration you can't really remove much more material than the circles anyway. Think of these pieces as a truss, where the wood between the circles is like a web. This strengthens the whole thing considerably.

[AndrewB]

Thanks. I guess I will leave the interior alone till I am ready to tie down the stringers/gunwales.

Jeff - It appears there is a missing offset in the Nook version for the Bow plate. Looking at the other builds and the outline shape, it appears there is a 1" step at X = 3. I have one offset at X=3 with Y=3/16. My guess there is a missing offset of X=3, Y=1 3/16? (This would give a minor angle going up 3/16", from the X=0, Y=1 start).

[Kudzu]

I have been really hesitant to thin up the bow and stern as you decribe. It would probably work but if you drop the boat off the roof of your car (I have) or you ram hard into something on the water (I have) or you swing it around inside the shop and hit the wall hard (I have done that too) I know the more solid piece will take that impact. I figure the bow and stern will get the hardest impart most of the time.

If you thin it up you weaken it. Too much? I don't know. The weight savings just never seems worth it to me. I have drawn almost every boat I have designed with thinner sections and then I go back and change to it lighteng holes.

Aethery, if I am understanding your question, no. The 3 x 3/16 is right and the next offset is 6 x 6/16.

[AndrewB]

The green is adding a 1 inch bump at the 3" mark. Red is following the offsets.

Book
Red
0 1
3 3/16
6 6/16


My Version
Green
0 1
3 1 3/16
3 3/16
6 6/16
Compared to the image, I am suppose to have a bump somewhere around there: