Monday, April 27, 2015

A hinged main mast

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:

Upper mast all glued up. I used cheap hose clamps about 1 per foot of mast length to hold it all together.  The very top and very bottom of the mast have an octagonal solid ash plug. The lower one to hold the hinge parts, the upper one for a solid place to attach the peak halyard block. There's also a solid plug about 18" down from the top where the hounds will be. 

End view of the birds mouth mast. I'm pleased that my math and geometry (never my best subjects!) worked out right and that my cuts were sufficiently accurate to give a nice fit. My dad was kind enough to let me know that a good carpenter would never leave his plane edge down on his bench. Point taken.
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. 

Making the mast round. Not the plane on it's side ;P    Nothing more gratifying or better smelling than a nice pile of wood-shavings. I took somebody's advice and made sure all the staves grain was going in the same direction, which made the planing a joy. No tear-outs. In this photo, you can see the two stainless hinge "cheeks" with a hardwood spacer between them.

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

Flipped and 'Glassed...

Amazingly, I was able to get her flipped over by myself and using the leverage of a couple of my little "Burro Brand" knock-down sawhorses, was able to position her bottom up for some detailing on the outside. Once you've spent months looking at a boat from a certain angle (on the jig), it's very strange to turn her over. She looks very different and it takes some getting used to.

As I search through the photos, I realize I didn't take any pictures of the fiberglass operation. At any rate. It proceeded quickly and without fuss. I enjoy fiberglassing. There is something very satisfying about smoothing all the fabric and wetting it out and squeegeeing the resin to all the right places. I did a pretty clean job of it, and then proceeded to putting the skeg together. 

I laminated the skeg from various pieces of white oak and mahogany I had laying around.

Here's my improvised jig for compressing the sternmost laminations. It's useful to have a collection of bar clamps. The plastic sheeting covers it so that the compression blocks don't get glued to the skeg. 

After the glue sets up, you can see the various laminations. In this photo, you can also see the difference in color between the naked plywood planks and the area that's been fiberglassed. 

Here's some detail of the centerboard trunk bits. I tried to give them a graceful curve both going in and exiting the trunk. The screw holes will be filled later. 

View of the shaped skeg toward the stern

At this point of the build I went into a sort of depression. There were several things happening. One, I was berating myself about the quality of my workmanship, which I consider to be substandard. Friends look at what I've done and are all suitably impressed. But I look around at what other builders have done, and I'm blown away by their skill and accuracy. So there was that whole thing happening in my head. 

The other thing was the false stem. Early on, I had read where somebody recommended tracing the stem frame onto a piece of ply so that you could bend the false stem to that curve later. I did that. And I laminated up a beautiful white oak false stem. It bent to the curve very nicely. But when I went to put it onto the boat, the curve was wrong and there was a yawning gap between the forefoot of the boat and the inner edge of my false stem. To beat all, the oak laminations and epoxy were SO hard, I couldn't get the darn thing to flex one little bit. So I had to scrap it.

What followed was about 2 months of trying and trying to laminate directly onto my hull. It turned out I was making my laminations too thick and they were snapping right at the tightest curve. I tried different methods, of making a go of it, but every time, right when I would get to the critical moment, the lams would snap.

Finally, I planed down several more staves of white oak to about 3 or 4mm thickness and managed to glue them up in place using nails and sacrificial ply to hold it all to the hull. Sheesh. My least favorite part of the build so far. 

Finished Planking!

I just realized that I hadn't posted in a while. I figured it had been a month or two...but SIX MONTHS?? You'll probably think I have completely abandoned the project, but you would be wrong. We had a cold Wisconsin winter that seems to be dragging on as even in late April, it's unseasonably cold and windy. I worked in the garage as much as work, family, illness, and other commitments would allow. So let me give you an update. I'll do this as a series of small posts so that in the future, it will be easier to reference the various stages of the build.

First off, I finished the planking in the beginning of December 2014. I took the hull off the building jig and cut the various boards down to size to build a little cradle on casters, so I can move it around the garage, and out the door to work on it during nice days. Also, as I begin to move into the finishing stages, it will be better to do all that nasty sanding outside where the dust can blow away and not coat every tool and clog up every corner.

View on the cradle from the port stern quarter. She looks good from far, but far from good! 
At first glance, the sheer looks pretty nice. as you get closer you can see that some of my mis-measurements and bad cuts make her a little less attractive. Lesson learned: Fair your planks before you attach them to the boat. I thought I could use an edge planer to smooth down those little humps and valleys once I had the plank attached. It's not as easy to do as one might think.

View from the port bow quarter. I tried some of the phenolic micro-balloons in an epoxy mixture to make a fairing compound. You can see the brownish purplish smudge on the bow in an attempt to make my first gain-cut look a little better. The top plank where the edge meets the stem didn't turn out as nice as I'd like. But once the false stem is attached and the bowsprit is in place, I don't think anybody will ever notice.

Nice sun-flare of my phone-camera. View from the starboard stern quarter. 

View from dead astern. Pretty symmetrical. 

'Mid-ships view. Love those Welsford lines, and the nice little bulge in the belly. Just like the builder!

Then the snows came and she never saw the light of day for another 4 months! Before moving her back inside, I muscled her off the cradle into the grass and rolled her around a bit. I wanted to get a feel for how solid and strong the hull was at this point. One of my friends asked where I planned to sail her. I told him Lake Michigan and maybe Superior. He balked at that and said he wouldn't be caught dead in my little pile of matchsticks on those bodies. But I have to say, as I man-handled her around, she didn't squeak, crack, or groan. She felt very solid indeed. Once we get all the 'glass and 'poxy and decks and such in place, I imagine she'll be a right solid little boat.