Life around the boat
Most of the posts so far have been aimed at catching up on some of the big projects. There are lots of smaller projects that are going on as well on a daily basis around the boat. Here’s a sample.
Evie and Ginger have been prepping the deck for caulking.
What they’re doing is called “reefing out the seams.”
Reefing is the process of cleaning out of the seam in preparation for new caulking. In this case, they’re using reefing hooks
and mallets to pull out the old oakum and seam compound.
In case you’re not familiar with how caulking is set up, here’s a diagram. The decking meets wood-to-wood along the bottom third of it’s edge. Above that, the seam is bevelled out slightly to form the caulking bevel. This bevel creates the seam into which the caulking will be driven. It looks like this in cross section:
Cotten is first driven into the bottom of the caulking seam (blue in the diagram), followed by oakum (red), and finally a flexible seam compound (black) covers it all. The seam is open at the bottom in this diagram, but in real life, the two planks should meet tightly along the inner face.
You’ll see the same arrangement if you look at a planking seam. Here’s what it looks like in real life.
In this photo, you’re looking down onto the top edge of a plank. The plank above it has been removed to reveal the caulking seam. The cotton is light colored, and the oakum is brown.
Oakum is hemp fiber that’s been treated with pine tar to make it waterproof and a little sticky.
This is the same method for sealing seams that was used when the Morgan was built, and it’s the same method that continues to be used on wooden boats today. Smaller boats will only use cotton caulking, but otherwise, identical.
The frames (called “futtocks” when they’re in sections) butt up to each other as they go up the sides of the hull. These butts should be staggered along their length to make the hull strong. If they’re lined up, the series of joints could open up if stressed, like a zipper, along the length of the hull. We found some frame butts from a previous restoration had not been properly staggered. I’ve marked these butts with red lines.
If every other frame’s butts were well above or below this line, the zipper effect would be eliminated. I’ve illustrated this with the green lines.
So, the planking crew has switched over to zipper frame remediation lately. That’s slowed down planking progress, but they’re getting close to done.
Once a new futtock has been installed, it’s side-trunneled to its neighbor to help lock it into place.
Bob and the young fellas have wrapped the bottom of the boat with a plastic skirt and installed fans and misters to create a very moist environment.
This will help reduce any plank shrinking. As wood dries, it shrinks along its width, and this causes all those nicely caulked seams to open up. We really don’t want that.
The seams are grey because we paint the caulking after driving it in. The paint helps to further seal the joint by locking the caulking to the wood and soaking into the caulking a bit.
A few words on internal tension in wood.
Sometimes the way that a tree has grown will create compression and tension areas inside the wood. Improper drying can also lead to similar internal stresses in wood. Unless a board is warping or splitting like crazy, it’s almost impossible to predict where and how these tensions will show up. However, when you rip a board, those tensions become quickly visible. Take this board, for instance
The curved board on the left was just cut from the board on the right. The seam in between them was originally a straight cut. As the saw neared the end of the cut, the two boards sprung away from each other with a great deal of force. Here’s another view of the same board.
This kind of thing can drive furniture makers crazy if they’re wanting to get straight parts from a board. Luckily for us, we can often make a curve work in our favor since most planks have some shape to them. As long as we shape the mating edges to form a fair line, we can get them to butt up to one another sweetly.
If you’re interested in how wood moves and behaves, there’s probably no better book to reference than Bruce Hoadley’s Understanding Wood. It’s the bible for woodworkers.