I saw an article in Woodenboat magazine (WB #237, March-April 2014) about a year ago describing a simple but elegant mast hinge. I figured that a hinged mast would be easier to manage and set up than standing on a boat on a trailer and manhandling a free-footed 15' spar with all the lines and rigging doodads. So I copied the article and put it on my desk for future reference. This past weekend, I made the mast and hinge.
For two reasons, I decided to forgo JW's hollow mast design and try out the birds-mouth method. First, I thought having a lighter mast would be good for boat-handling (less weight aloft), and for ease of rigging-from-the-trailer. Second, I wanted to gain woodworking experience by using the birds mouth technique.
I bought a nice piece of 16' sitka spruce, and managed to completely destroy it. I had purchased a birds mouth router bit from one of the woodworking mags, but I don't have a router table. So I improvised one. The bit sort of worked...but my table didn't help, and I managed to mangle all my staves beyond usefulness. Not wanting to shell out another $200 for a plank of sitka, I figured I could use prime clear pine. I bought some 8' lengths from Home Depot, and used a rented contractor table saw to make the 45-degree angle cuts after scarfing them together to make 16' lengths. The table saw did a much better job.
(Note: I keep thinking that a router has the potential to be such an amazing tool. But that thing scares the be-jeezus out of me. The bits are wicked sharp—I sliced my hand wide open and deep just grazing one of them while reaching for another tool! And much as I try, I find that the router has an amazing ability to instantly destroy a perfectly good piece of wood if you're not extremely careful. So for the moment, I use it only when absolutely necessary.
Anyway. If you want to try making a birds mouth mast, there are some great calculators from Duckworks that can give you all the dimensions you'll possibly need. Here are some pix from my efforts:
|Gluing up the stub-mast. This I'm starting square. I'll shape it to an octagon at the deck-level, and then round it where the hinge parts meet.|
|Here's the bottom of the stub-mast. The square bit will fit into the mast-step installed in the boat a few months ago.|
|Here's a dry-fit of the hinge assembly. The entire hinge is 18" long. The bolts are 1/2" stainless, counter sunk into the mast, except for the "lock" pin for ease of access. The stub-mast has not been shaped yet.|
|different view of the hinge|