BYYB Forums

This thread is the second part of what started here: http://byyb.org/forum/index.php?topic=2466.0
Due to some technical problems I am continuing the story in this new thread.

I will copy page 12 from "Schooner build 1" as a start for this second thread


Posted by: warren percell
Reefing points are for smart sailors!!! dumb sailors get wet. Beautiful pics. Keep sending them.


Posted by: Dave Blake
Nice photos, Timo.  What species is the wood?  Looks like spruce.
Dave


Posted by: Timo Knuuttila
It is pine (Pinus Sylvestris), the one we have a lot here in Finland and the one we use for almost everything. We call it just pine because it is the only species of the family that grows in Finland. All the other species are more or less garden trees here with their specific names.

I still doubt that I will ever need to reef more than striking the topsails. I mean never on my lakes. When I will eventually venture to the Baltic Sea I will definitely have reefing points.


Posted by: Paul Riccelli PE,NA
We'd call that stuff Scot's pine or eastern white pine over here. Finish fir, Finish redwood and Polish redwood are popular names in Timo's area.

It looks a lot like Douglas fir, with dark amber grain lines, separated by yellow. It weighs about the same and has other similar attributes as well. It grows world wide, but north eastern and western Europe seem to enjoy most of it, though I suspect a lot could be found in Siberia and some is known in parts of Canada and upper new England. It doesn't seem to check like Douglas fir.


Posted by: Dave Blake
Scotch pine...many a Christmas tree at our house.  Not native but common in North America.
Dave


Posted by: Timo Knuuttila
The name Sylvestris suggests Christmas tree, but we never use it as a Christmas tree. Even the finnish word for Christmas tree is actually "Christmas spruce" and that is the only proper Christmas tree in Finland   ;D


Posted by: Paul Riccelli PE,NA
In this country and I suspect Canada as well, Scots pine grows in fairly even terrain, while in Timo's area and along the ridge of mountains that cut Europe in half, these same pines are on uneven soil. Growing on inclined soil means they are tightly packed together and harvested less often. This makes for wholesome and useful stock for building materials. On flat ground, the trees tend to be spaced farther apart. This difference in spacing means limbs are more frequent on even soil forests, which produces mature trees with lots of little knots when harvested. This are great for Christmas trees, but not so good when you want a 12' knot free 2x8. On inclined soil, they all fight for soil and sun light which forces them to grow tall and straight before branching out, above their neighboring brothers. This makes nice building stock, but louse Christmas trees, as one side may be well branched, but the side facing the mountain is branchless.

Sometimes this inclined forest floor rule can be cheated. On my land I have a hundreds of southern yellow pines. Most are about 110 years old, the last time my land was harvested. Because the land is fertile, receives a tremendous amount of sunlight annually and hasn't been disturbed with fires or selective cutting, the SYP is about 60 to 80 feet tall and they are very tightly packed. Most haven't any branches for the first 30' while a substantial amount haven't any for the first 50'. That's right, 50' lengths of perfectly clear, straight grained SYP.

I also have oaks of every color and many of these also have very straight, "lean" trunks. I cut two a couple of years ago for a project I was working on and the first had a 30' trunk with no branches, while the second had about 25' until the crotch. Both, where 18" white oaks. All because of the very tight grouping and unmolested growing area. In our current economic environment (last 50 years), unmolested tree stands are typically cut and replanted with fast growing (quickly harvested) pines. This is a economic choice made by the land owner, but some first and second growth still remain. I still have several acres of second growth. Mountainous terrain is difficult to harvest, so it's more prevalent, for building material stock, I just got lucky with my flat land stuff.

Posted by: Timo Knuuttila
The (lower) branches are also actively trimmed off the standing trees while they are young to produce knotless timber.
This is young trees where you might pick the best ones to trim them and let them grow old. Most of the trees are harvested earlier for pulping, but the selected ones are allowed to grow old and they are sold as logs to sawmills.

Posted by: Timo Knuuttila
This is how I made the scarfs into the staves for masts.  The plywood guide was attached just slightly higher than the thickness of the staves so I could put the sticks under it.


After using the skilsaw I had five staves ready.


Here is the jig to glue the pieces together. There is a stripe of packaging tape to prevent the epoxy from sticking into the jig.



I glued the blank for main boom from two pieces yesterday. And again, it is not possible to have too many clamps. My inventory is on the heavy side, which was good for the boom but I will need to get a lot more and a lot lighter clamps for planking.

Posted by: Paul Riccelli PE,NA
It's pretty important to proportion scarf's properly. I'll assume your stave stock is about 18 - 19 mm, which means the scarf should be 152 mm if scarfing the thickness (typical). It's very unusual to have a stave scarfed across it's width, which not only would make a much longer joint, it's also in line with torsional loads. Generally, you want scarfs to oppose loads, so the joint is perpendicular to the load path. On most spars this means the scarf is angled from outside to inside of the finished piece. This leaves only the single horizontal seam exposed, which is less objectionable looking to most eyes. Ideally the slope of the scarf should have the inboard (inside the mast) seam facing up, so if a splash hit the mast and the joint let moisture in, it would naturally drain out of, not into the mast.

On a lightly loaded rig like this one, the standing rigging bears most of the load, so you'll probably be fine.

OK, now we are back in business!

And I can answer Paul´s comments about my scarfing policy   I was expecting those comments as well as the other one, which I haven´t seen yet. You guys should check the pictures of the scarf method to find a goof that shows that the pics are not real but faked afterwards. When actually doing the job I forgot my camera at home  ;D

But the scarfs ...  My scarfs are a lot shorter than standard, but because the mast is made up of eight staves and the adjacent scarfs will be scattered 40 cm I am quite confident that I am safe. Also, the scarfs will be at least a meter from the partners or the place where the gaff or boom jaws will load the mast.

The glue lines as such are not an issue since the masts will be painted.

And isn´t the epoxy joint supposed to be stronger than the wood it is joining? Actually I have tested that and all my sticks have broken at other places than the glue line.

Okay, now back to where we where. This is the image that apparently screwed up the previous thread.



The lowest board in this image shows how it appears you've cut your scarfs, which is very unusual. This type of scarf will be visible, will also present the most seam line to moisture ingress and lastly offers the potential of point loading on the adjacent mast stave.

Also note that there is considerably less surface area for the adhesive to live. This shouldn't be an issue with epoxy, but would be with other glues.

The other draw back to these short scarfs is flex. A short scarf will cause a localized stiffness in the area. This shouldn't be a problem on the masts, but will be on the other spars. The gaffs, topsail yards and booms and to a lesser extent the sprit, will need to flex uniformly, so long, width or thickness derived scarfs are preferred.

In short the first and second scarf examples in the above sketch are the best suited for spars. The lowest one is commonly found in low strain members like stringers or other lightly stressed, long pieces.

Paul is absolutely right in everything he is saying above. (As usual.  )
I wouldn´t dream of doing this kind of joint if the joined piece would be the whole member. Now every scarf will only be one quarter of the mast and those joints are scattered so the effective length of the joint between upper and lower part of the mast is 20x the diameter.

All the other spars are without any scarfs, only the masts are too long (6meters) to be found in one piece.

Some progress with the spars: I have been gluing the staves and I finished the ones for the main mast. Some headscratching was caused by the length of the staves, which is too much to run them through the table saw in the workshop. Finally I came up with a solution like this.


The box fence will keep the stave at the right place and I can push the skilsaw through the stave making a 45 degree cut.


After two passes each I have eight birds mouth staves ready to be tapered to the measures of the main mast.


I have two more staves to scarf for the fore mast.

The lamination for the main boom shows some twist but fortunately there is enough timber to plane and make it straight.

Clever problem solving Timo. Boat building is all about problem solving. When I lived in St. Pete, I had a garage with my tools in it. I was building a 40' Spray replica and milling long stock. When I got to ripping spar stock, I came across a similar problem and ran out of garage for the length I needed to mill. I cut a hole in the end wall of the garage and put a horizontal roller there, which acted like a support.

Don't worry so much about twist in the stave stock Timo. Most of the time it can be untwisted as it's put into the assembly.

I am not worried about the staves twisting. I was referring to the blank that is supposed to be the main boom.

That hole is a clever solution, but wouldn´t work with me. As some of you remember, my workshop is in an air raid shelter which is in the basement (under ground) of a condo block and has walls made of concrete about 30cm (one foot) thick. No widening of the door as an option.

That is the reason why I have to be VERY careful not to assemble anything too big to negotiate out of the door and up the staircase  ;D