Thursday, January 21, 2010

The Big Flip - January '10

After a few weeks off for winter break, the boatshop is humming once again. Unfortunately the once plentiful red cedar planking stock has run out, so there are still a few more planks to hang. But with more red cedar on the way, there's plenty of other work to be done.

In the picture below you can see the sheer clamp almost fully installed. The sheer clamp is a structural piece of the boat that will strengthen the hull and help to define the shape of the hull at the sheer. On the catboat the sheer clamp is yellow cedar, an excellent choice because of it's clear, even grain. The sheer clamp helps define the shape of the hull, so while you want a strong wood, you also want a wood that will bend easily and evenly to create a nice fair sheer.

You might also notice in the picture a large box-like structure balanced on the keel. We'll see more of that later when we get ready to flip the hull.



Here's a good shot of the sheer clamp looking forward.



The sheer clamps meet at the stem where they are fastened to the cheek blocks. Getting the clamps to bend in to meet the stem can be a bit difficult. Steaming the clamp would do the trick, but the aft end of the clamp is already fastened, so removing them and putting them in the steam box would be time consuming.



A quicker solution is to "steam" the clamps in place. By wrapping the pieces in rags and dousing them in hot water you can achieve much the same result as putting them in a steam box. This is a good solution when putting a piece in the steam box just isn't an option.

You can see here that we've wrapped the clamps at the point where we need a little extra bend.



Before dousing the wood in hot water, you want to be ready to bend it. We're in a bit of an awkward spot here, so we've decided to use a Spanish windlass to draw the two clamps in. We'll see how it works in a minute, but start by tying a loop around the two pieces you want to draw together. The tighter the better.



Now, just add hot water.



After letting the wood soak, we're ready to bend the pieces into place. By inserting a piece of wood in the loop we created and twisting, we can draw our pieces together. There are a few varieties of the Spanish windlass and most work well, just make sure you're using a strong enough rope.



Once the pieces are bent, we can trim them a little and tighten the windlass. We'll do the final fitting of the clamps to the cheek blocks before fastening them in place.



Not a bad fit so far.



Since we're going to be flipping the hull over, the last thing we want is for our rope to break and the clamps to come springing out, so we're doubling up our windlass with a second line. I think this is a custom knot Tim's working on, so sorry folks, you won't find this one in your knot books.



With the clamps bent and secured we can move on to the real business of the day: flipping the boat. The box-like structure that we saw earlier is going to be a cradle for the hull to sit in once it's flipped.



You could just flip the boat and block it up on the floor, but by building a cradle that fits the hull as it is on the building jig, you can minimize the amount of distortion you get in your hull shape. We are after all trying to reproduce that same shape we lofted all those months ago.



Before we flip the boat, we've also got to free up the building jig. We'll be flipping the boat in place, so we've got to make sure that once it's flipped we've got someplace to put it down again, that means moving the building jig out of the way. For the most part it's an easy job, but these blocks we glue to the floor with 5200 are pretty tenacious.



With the new cradle complete and the hull ready to be flipped, we're ready to move the hoist into position. We'll use a sling between two winches to take the weight of the hull, then with many hands to assist, we'll flip her over.



Here's a little time-lapse of all the last minute preparations: loosening the hull from the building jig, moving the hoist into position, etc.



And now, the big flip. Insert drum roll here.



In case to missed anything, here's the operation. Step one, the hull is lifted off the building jig using the two winches in unison, and a lot of people to help stabilize. Two, the building jig is slid out from under the boat. Three, the hull is lowered to the floor. Four, straps are repositioned for the flip. We have two winches so when we're flipping the boat one will be raising and the other lowering to create the rolling action. Five, hull is raised just high enough to facilitate flipping. Six, winches begin rolling action. Seven, rolling is completed by hand, sliding the hull in the straps. Eight, hull (now right-side up) is lowered to the floor. Nine, straps are repositioned again to raised the hull high enough to slide the cradle underneath. Ten, hull is raised, cradle is positioned underneath, and hull is lowered into position.

It's as easy as that.



With the hull now right-side up, it's quite a different view. And it's the first time we've gotten this view of the stem since we were assembling the backbone. Impressive.



And she certainly has grown since then. Wow.



With a successful flip behind us, the boatshop was full of smiles and congratulations. And a few sighs of relief too.



Right-side up it's almost as if you're seeing the hull for the first time. The plank lines we spent so much time on look great, and the planking job Jonas and Matt have done is topnotch. Great job guys!



Speaking of the builders, here's one for the catboat family album.



The building jig is looking a little empty now...



With all the attention on the new cradle.



The guys did a great job fitting it to the shape of the hull.



And these stout legs make it a sturdy work platform.



Yes, I did say work platform. There is a little more of that to go. Flipping the hull is a great way to end the week, but it's back to work on Monday. There are bent frames to install, the final planks to hang, deck beams to fit...and the list goes on.

But that can wait till Monday. For now there's just the wind in our hair and the sound of lapping water against the hull...