More Keel Work

Well, the holidays have come and gone. The past busy month and a half have left me with less time for boaty things. For the most time I've dealt with that by neglecting the internet portions of my boating hobby, though the building part has slowed a bit, too.

I'd been going back and forth about how to finish the keel. For better or worse, I'm going to go with the center layer of the keel running vertically. With that in mind, I've fit most of the wood needed, and I've started working out a method to drill for the keel bolts. I've discussed the issues involved at length in previous posts, so I'll mostly just show some pictures of how things are going.

I've left a recess for the lead ballast. The first layer will need to be cut away, too, but I'll leave it in as long as I can to add some strength to what would otherwise be a weak section in the middle. I've been doing my epoxy work in the basement for the last month or two, which involves moving the keel quite a bit. Here's another view.

I still have some things to work out at the stern. Namely how the outer stern post will fit against the deadwood. The pencil line in this view is a rough approximation of the final shape. If you look closely, you can see where I've drawn a grid on the deadwood. The squares are 3" on each side, which corresponds to 1/4" on the plans. I drew the corresponding grid on the plans, and marked on the deadwood where the curve should intersect the grid lines - well roughly, anyway. It needs to be tweaked a little bit, but it gives a good impression what the finished product will look like.

Here's a view from a different angle.

It's starting to come together. The next jobs are to figure out the keel/stern post interface, and glue the first two layers together. After that, I think the third layer should go very quickly, with relatively few pieces whose shapes can be found by tracing the already glued-up layers.

Working on the Keel. Decisions, Decisions.

With the stem epoxied in place, I began to work on the keel. I wasn't quite sure how to go about this, and as I was feeling my way through, I didn't take pictures for the most part. I began by crawling under the hull and marking the locations of the floors. (In a house, these would be called "joists", and the floor would be laid on the joists. In a boat, the "sole" is laid on the "floors." Just one of those nautical things.) Their locations are found relative to the "stations" which are the locations of the molds which give the hull it's shape as the planks are hung.

This may seem like a bit of procrastination, but in fact it was not. The keel bolts go through the keel and keelson, and are bolted through the floors. After marking their locations, I drilled a pilot hole vertically through the keelson with a long 1/8" bit. The keel bolts will be 1/2" and 3/8", but I wanted to drill through to find their location on the outside of the hull. That also showed me the location of each station. They are each separated by 29" horizontally, but the curvature of the hull makes it difficult to measure with any reliability on the outside of the hull.

Next, at each station, I cut the end of a 2x4 so that it would stand vertically when set on the hull. I measured the depth of the keel from the planking at each station, and cut the 2x4's to these lengths. Setting them on the hull shows where the bottom of the keel ought to be. The keel runs in a straight from the 3rd station to the 8th, I was a little bit surprised that they seemed to line up exactly as they ought to.

As I said, I didn't take many photos as I was working along, but this shot from later in the process shows the 2x4's at the 7th and 8th station.

I had a nice straight clear piece of sassafras, about 5 inches wide, that I was able to clamp to the 2x4's. With the edge of the board aligned with the tops of the 2x4's, this put the board in just the right position. For most of the length of the keel, it doesn't protrude much more than this from the bottom of the planking. I was able to fill the gap between the hull and the bottom of this board with a two offcuts from the stem, scribed to fit into place. You can see them in this picture, taken after they were epoxied in place.

At this point, I was a little unsure how best to proceed. The keel is to be three layers of (roughly) 3/4" stock. Is it best to fit one layer, and then add to that, or work "from the front to the back." I'm still not entirely sure, maybe I'll have it figured out by the time I finish with it. In any case, I kind of did both. I was able to scribe three more boards to fill in the deadwood near the stern.

At the same time, I began work on the second layer. Probably. I say that because I have some doubts about how I will do that. Some builders of this design have let the grain in the center layer run vertically, perpendicular to the grain of the outer layers. There are a couple advantages to this, but normally this kind of cross-grain construction is not desirable. Wood expands and contracts as it's moisture content varies. As it gains moisture, it doesn't expand uniformly, though. It expands more across the grain than along the grain. Plywood is made of thin sheets of wood, glued with the grain alternating in direction. This makes plywood "dimensionally stable." It's dimensions don't change much with changes in humidity. Construction the keel in this way would make it very stable, and also less likely to warp. Certain aspects of the construction are also simplified with this approach.

On the other hand, what will happen when the keel absorbs water, as it inevitably will, or dries out over the winter? The builders who have used this method have not had any complaints, but... Well, I don't know.

To the right, you can see the start of work on the center, vertical, layer. It's quite easy to cut these pieces to the correct shape. There are a lot of them, though, so it doesn't seem to be a time saver, though that was not the purpose. In any case, I'm a little undecided about whether to continue in this way or not. I think now that it may be just as easy to do three layers, all running fore and aft. I'll try to make some progress in other areas while I mull this over...

Here's another view of the situation.

Preparing for the Keel

I've ordered 4oz fiberglass cloth, which I will use to sheath the hull. This is meant primarily for surface protection, especially for the edges of the plywood. I will most likely cover each plank separately, which means the cloth will not really add any strength to the hull, but that is not needed in any case. The cloth, and some additional epoxy, should be arriving soon, but as the temperature today is topping out at 13F (that's -10C) I don't know that I'll be doing much epoxy work any time soon. The System Three fast hardener will cure as low as 35F, but I ordered the medium hardener, as I probably will be doing most of this work when it is a bit warmer.

In the mean time, I'm starting to get the hull ready to accept the outer stem and stern posts and the keel. Where the planking meets the keelson I've left the overlaps rough. Before attaching the keel I'll have to smooth this out using the power plane. Over to the right you can see the view along the keelson. There are screw holes along the edge of the planking, those will have to be filled in with epoxy - which will also have to wait until the temperature warms up a bit.

Here you can see the view down from above the stern. Here also, the plank ends are uneven, and will need to be planed down to make a smooth surface for the outer stern post. The view at the stem is similar.

Keeping in mind what I've learned about using the power plane, I'm trying to take things nice and easy. I'm trying to go slowly, removing about 1/32 inch at each pass, and checking frequently with a level to make sure the surface is even. At first, I'm just taking off enough to make a level reference surface for the bed of the plane. After that, I'll go back and plane down until the width of the flat surface is equal to that of the keel. This will require a bit of thinking. As designed, the keel is 2.5" thick, with a bulge in the center section to accommodate a 4" wide lead ballast keel. I'll want to figure out just how I'll do this before I try to go too far. I'll need to see what kind of timber I can get for the keel before I can be sure how I'll get that done.

Where the centerline of the boat curves toward the stem and stern, the level becomes useless, and I use the face of the inner stem and stern posts as a guide. I've planed things down so the edges of the planks protrude just a millimeter or so in front of the inner posts. I don't want to plane past this reference surface until I must. Ideally, I wouldn't remove any of the stem and stern posts, just plane the planking down to it.

There is one area that is going to cause some problems. For some reason, which is lost to me now, I didn't recess the plank lands on the garboard at the stern. At the time, I filled in the gap with epoxy mixed with some sort of plastic filler, but making a fair surface for the keel to land on may be a bit of a challenge. Well, that's what makes life interesting, isn't it?

Until things warm up a bit, I'll have to look for ways to keep the project moving forward. I can make patterns for the outer stem and stern posts, lay out the pieces and glue them in the basement. I haven't decided whether these will be laminated, or sawn from glued up pieces, but I'm leaning toward the latter. That's what I did for the inner posts. I can also work on sanding the hull, in preparation for fairing and fiberglass. Most likely, it won't be too long before the temperature comes back up. In the meantime, well, it's ski season! Generally, the colder and snowier it gets, the happier I am.