Another Layer of Veneer and Shaping the Outer Stem

March saw the end of applying the first layer of Mahogany veneer, as seen above, and the beginning of the second layer.

This second layer is applied at about a 90 degree angle to the first.

Of course, the scribing as described in the previous post continues. Note some of the fancy scribing up near the keel in the picture above.

The hull looks different, a little more streamline, with the strips running from the top of the bow and angled toward the lower stern. Both directions can be seen from the bow.

Here are some "action shots" of the second layer being applied...

The hull is wetted with the epoxy.

Note all those plastic staples holding the veneer on...

The underside of the next strip is wetted with epoxy, and Richard mixes more epoxy with wood flour to the consistency of frosting.

The thickened epoxy is applied over the previously wetted area to fill voids and give a base for the strip to smoosh into...

Absolutely no voids are wanted in the hull. Richard is basically creating plywood in the shape of a boat by gluing up these thin layers.

The pre-scribed strip with the wetted back is set into position as marked.

Once the marks line up, a couple of staples hold it in position so that it can be smoothed down evenly.

Of course, if only one or two staples hold the upper end down, then as you work to the lower end the upper end will pop up...

Working it back down, from one end to the other. It seems to have a mind of its own.

Applying lots and lots of nails seems the only way to tame it.

All the way around every curve.

Pow, pow, pow...

Richard is starting to get very tired of this phase. It will be about 200 hrs into this phase when both layers of veneering are complete on both sides of the hull. He is ready for something new.

During some down time while waiting for the last of the plastic nails and more epoxy to arrive, Richard started to lay-up the outer stem. He used the extra mahogany veneer.

The outer stem needs to be shaped exactly the same as the inner stem. The stem is the front edge of the boat, as seen above. A piece of the veneer was screwed directly to the existing inner stem, and left to hang over on the right and left, to create a jig for the gluing and clamping. A layer of tape was applied to the veneer jig to prevent any excess epoxy from sticking to the jig. This would allow the thick built-up outer stem to be removed and give access for the jig to be unscrewed from the inner stem when complete.

Layer upon layer of veneer were epoxied together and clamped to the jig.

All the clamps that were needed to maintain the tight curve makes it look like a porcupine.

The outer stem is made long to run all the way up to accommodate the bow sprit (toward the floor at this point).

By the keel, it also runs long, and will be shaped into the deadwood.

The outer stem that has been being layed-up over days is then unclamped from its base form. The jig was then unscrewed from the inner stem.

The resulting thick stem is a perfect fit.

It will need to be shaped, tapered and cut to the correct width when it is ready to be permanently attached.

Read More..

Getting a Consistent Taper when Shaping Spars

Mike has attached a comment to my last posting, which I will answer very briefly. He is Mikes comment: -

Thanks for sharing these insights into boat building Ross.

Something Im having trouble with is getting a consistent taper on a small diameter spar perhaps you could share some gems with us.

Cheers
Mike

Now, I could write a very long answer to this, as it goes right back to the marking and cutting process if making a hollow spar, or to the lamination and marking process if building a solid stick. That is something for a proper book, so for the moment, Ill give just a quick run-down on my normal method - this applies to all sorts of spars, and to oars and paddles.

Here is a hollow mast glued-up. Despite the apparent disarray, the mast has been very carefully straightened and chocked on the bench so that the blank will be straight when the glue cures

Rough planing of the mast is done with the longest plane I have on hand. This one is a Record No.5 Jack Plane - If I had a longer one Id use it. It is important to support the spar well, and to use little pressure, otherwise the spar will bow while the plane passes.

Marking a square-sectioned, tapered blank for 8-siding using a home-made spar guage (the previous photos were of a Birds Mouth spar which comes out octagonal anyway - although you do have to plane off a few spurs)

Once the spar has been brought to an octagonal shape I mark it as shown using a dark pencil, scribbling into a wide, visible line. This is not my original idea - it has been use for years and years by knowledgable builders. I place the pencil marks about one cubit apart i.e. the length of my forearm!

The purpose of the series of pencil marks is so that one can visualise the widths of the facets when planing to sixteen sides. This is very difficult to judge without a visual guide, and I actually monitor my progress by measuring the pencil marked portions and the planed gaps with vernier calipers. You wont get it perfect, but aiming for perfection will give a better job overall.

After planing to sixteen sides, I re-draw the pencil marks to make an unbroken ring once again, and then plane to produce a 32-sided spar - still working with the No.5 Jack Plane, although if the timber is soft and well-behaved, I sometimes move to a low-angle block plane for its better feel

From there on, I use a flexible long-board. I havent got any photos of doing this on a spar, but this gives you the idea. Sometimes I make a concave long-board using a heavy cardboard (or PVC) with the paper glued in with spray adhesive. On my normal flat long-boards, I wrap the paper up around each end of the board as seen in this picture, and glue the ends down with hot-melt glue.

I know that some people use the inside-out sanding belt driven by a drill to attempt to get a nicely rounded spar with minimal effort. Well, I did it once, and will NEVER do it again. Because of human frailty, and the varying hardness of the timber as you move from areas of vertical grain to flat grain, it is virtually impossible to get a fair and even taper, and the spar will end up out-of-round (unless, possibly, it is a very carefully made stave mast with the grain of each stave aligned) - for my money, it is a good way to ruin a spar.

If you plane carefully to the 32-sided stage, the long-board (flat and/or concave) with give you a beautifully rounded spar in a very short time. Better still, you could leave it octagonal (with edges rounded a bit) - far less labor, and the mast ends up significantly stronger, as the eight corners of the octagon are at the greatest possible distance from the neutral axis of the mast - very efficient, and it looks ok as well!

Despite what I said in the last paragraph about leaving spars octagonal, you can see from this photo that I dont often follow my own advice! I made all of these by hand using just planes and sandpaper. The boat is an Aber I built for Dr. Paul Truscott

Read More..