07 August 2011

Tail Block Takes Shape

Dang! I don't mind making mistakes once, but after I've learned a lesson -- and even blogged about learning it -- it's quite annoying to make it again.

You will note that I very carefully marked the center of the sheave axle on my design. You can't see it in the the photo below, but I had also marked the location of the axle on one of the cheeks. But, while playing with the pieces, and noticing that I could make the block a good 1/4" smaller by pushing the spacers closer together, I moved the location of the sheave just a bit. So my carefully preserved mark was no longer useful. 

Even worse, by moving the spacers together, the sheave needed to be placed just so. There wasn't enough room left inside the block for any error. 

I said last time that I noticed this error right away, but now that I'm looking at the photos below, I can see that I gave myself too much credit. Clearly I was far too focused on carving my beautiful new block into shape to notice that I'd forgotten to drill the hole for the axle. Ignorance is bliss, so I will carry on  in the same spirit for a bit longer...

After giving the epoxy a good 24 hours to dry, I trimmed up the new block on my trusty (and rusty) bandsaw. I was immensely pleased to compare it with my Mark I block. Clearly, progress had been made.

Rough trimming on Bandsaw
The only shaping I planned to do was to round the corners off, all around. This block would live under my boom, so I didn't want any sharp corners that could dent my skull. Again, there might be a better way to do this, but my new sanding board made quick and easy work of the job.

There must be a more scientific way to do this, right???
In the process of doing all this sanding, with many different grades of sand paper, I ended up with a pile of full sheets, half-sheets, and slightly used sheets of sand paper. Sorting through the pile to find the right size and grade needed quickly got old, but suddenly all those years of working in an office came in handy.

I found an old accordion file, made up a few labels with '60', 80', '100'... all the way up to ''400', and, voila, created a very convenient sandpaper file system. You have no idea how happy this little 'invention' made me. Quite embarrassing.

A brilliant idea, if I do say so myself!
Right around that happy moment, I must have discovered my missing axle hole. It is not recorded what I said, but I'm pretty sure it was something salty.

At any rate, there was nothing for it but to eyeball the location, and try my luck with my drill press. I must have been due a bit of luck, because, as you can see from the photo below, I was dead on.

Final check for fit before assembly
Then it was time for the fun bit -- finishing. I had been using the procedure much loved on the Wooden Boat Forum, which is to plunge the block into a linseed oil bath and leave it there for a few days. But I'd been reading an excellent basic woodworking book, Anthony Guidice's The Seven Essentials of Woodworking, which recommended a different procedure that made a lot of sense to me.

In short, you essentially paint the piece with three coats of linseed oil. For the first coat, you thin the linseed oil with mineral spirits. The second and third coats are applied full strength. Let dry for 24 hours between coats.

Since I hadn't seen any evidence that linseed oil 'penetrates' the wood if left in a bath for several days, I reasoned that the oil bath was equivalent to one coat. Three coats sounded better, so I figured it was worth a try. I'll try to remember to blog about the results in the fall.

At any rate, there is nothing more fun that applying that first coat of linseed oil, and seeing the color spring out. I also love the smell of linseed oil. Odd, I know!

The first of 3 coats of linseed oil... what a color!
After three days, it was time to turn to rope work. I wanted this block for a kind of tail block, under my boom. It would be an important part of my outhaul/reefing tackle, as illustrated in Tom Cunliffe's book.

For the block end, I just spliced in an eye and secured the block in the eye with tarred nylon. Easy peasy.

For the hook end, I had to learn a new splice -- the shackle splice -- but the only tricky bit was the crown knot that starts the splice off. I used the description in Brian Toss's The Complete Rigger's Apprentice: Tools and Techniques for Modern and Traditional Rigging, page 82.

The result looked pretty rugged to me. The little tufts are just the ends of the splice. I now prefer to leave the ends just cut off, rather than melting them, as some people do. I don't like the feel of the hard little ends, and don't see how they make a splice any stronger.

Assembled block with tail.
Here's a close-up shot of the block. Notice how the sheave is recessed into the bottom spacer. The opening is plenty big enough for 3/8" line, and would handle 1/2" line in a pinch.

These are, by far, the best glue joints I've ever made, and the sheave fits perfectly into the slot. Practice makes perfect?

Finally, some joinery I can be proud of.
 Perfect glue joints, perfect fit.
A final comparison with the Mark I block... No comparison!

Size comparison -- a big improvement!
And here's the tackle installed under the Blue Moon's boom. The Blue Moon's main is small enough so I only need a 2:1 tackle, instead of the 3:1 shown in Tom's book.

With 2 oak cheek blocks on either side of the boom for the reefing tackle, and the new outhaul tackle, all run with 3/8" line, I now have total confidence in my sail controls. Unfortunately, it's August on Long Island Sound, and the wind is on summer vacation. I went out in the biggest wind we've had for awhile, but it was only 20 knots... not much of a test. Will have to wait for October or November to do a real test. Stay tuned...

Installed on the boom as part of the outhaul tackle.
I must remember to untie my reef points after lowering sail... I always forget.
If you remember the oak boom cleat I made a while back, here it is, an important part of the system.

Tied off to oak boom cleat...
And that's it! My next project on the Blue Moon is to repaint the deck. Painting isn't very exciting, but you never know when you're going to learn something new...

>>> Next Episode: Painting Stem-to-Stern


  1. I love your blog. I end up here because I was googling what "chine log" means???

    I am trying to make super cheap yacht from a scratch. I will use it at the lake so I am not trying to make something ocean worthy. Hope your blog will demystify some things for me.

  2. If I've learned one lesson its: have as small a boat as possible! With hurricane Irene bearing down on us, I was wishing I had an 18 footer I could haul out on a trailer and take home with me.

    Go small, go now, as they say.

  3. Builder Mosman
    Brilliant post mate, keep up the good work

  4. I love your blog, found it when I was looking up how to build a wooden boat (I know, your's is a "how not to"). Only thing is, I noticed that you said that you leave the end of the splice hanging out, if you cut them not quite flush, and then take some sail twine, or small stuff (anything like you used for seizing, sorry for the lingo, I'm enlisted USN), and wrap it around, half an inch above and below where the ends come out, it gives it a smooth look, but doesn't leave it hard like melting does (used that trick when remaking life lines for the frigate I was on)

    1. Sounds interesting. I'd love to see a photo of your technique.


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