Building the Pirate Ship Tree House

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When Vanessa mentioned that they’d like a tree house in their yard I jumped at the idea. I don’t recall whose idea it was to make a pirate ship, but they’ve always loved the pirate theme and the decision was a natural. I looked on the web to see tree houses, pirate ships, and pirate ship tree houses. The site for ours was constrained by the relatively small size of the two redwood trees and the proximity to the fence lines in the corner of the lot. So it would have to be a smallish tree house, kept way from the fences as much as possible. I drew up a rough design in Sketchup and got approval of Paul & Vanessa.

On the web there is info about how to hang weight in a tree while doing the minimum of damage. The best notion was that of floating brackets hanging on large lag screws. A few large holes seems to cause less damage than many small holes. And the floating brackets prevent the structure from being pinned to the tree which would promote rot and put stresses on the structure when the trees move and grow. To avoid this they sell some very pricey screws called Garnier Limbs. These are large lag screws and their advantage is that they have a collar of large diameter where the weight of the structure bears on the tree, thereby spreading the downward force over a larger area. I decided to use this approach but to make my own from 1 inch lag screws, 2 ½ inch diameter washers, and pipe for spacers. I copied the floating brackets I saw and welded these from ¼ inch steel plate and rectangular tube.

The tree house was to be basically a deck suspended freestanding in the trees with boat frames as the deck rails. At this point I wasn’t sure how or if I would plank (cover) the boat frames. The whole thing was to be built around two main joists which rest on four flat brackets. I hung false “beams” under the key joists using galvanized brackets and put the other deck joists on top of these. The deck would be mostly on the side of the trees away from the fence and would be supported also by two diagonals, mounted on diagonal brackets. To allow a boat shape, the deck had to project out quite a distance past natural support of the brackets. This made it necessary to have a cable supporting the bow (front) of the deck. I used a standard large lag screw mounted high and 3/16 plastic coated aircraft cable for this support. The cable became the ship’s “forestay” (the trees are the ship’s masts). The wood structure at this point was new pressure-treated fir – typical for decks.

Paul & Vanessa had replaced a large section of old fence and Paul saved the old fence boards. Some were rotten to the point of being unusable, but I was able to clean up most of them and had enough for all the decking (floor). I also cut some into narrower pieces for use inside the tree house.

For the ship’s keel (bottom) I used a redwood 2x6 mounted more on the diagonals more or less at the center line of the deck. To this I would attach frames for the ship hull. I wanted exaggerated curves for the ship based on examples I saw on the web. I drew a bunch of curves (Bezier curves) using Sketchup and found I could get pretty curvy using 2x6s. My original thought was to design each frame and give the ship curves not only up and down, but also front and back. This turned out to be way too complicated. So all frames were basically the same except for at the front of the boat. And I got very lucky in that when I cut out the hull frame, the drop (the wood that falls away) was quite suitable for the above deck rail. So very little wood was wasted. I used cheap Home Depot fir for the frames.

Then the question was how to plank the hull. My initial thought was some kind of thin bendable plastic strips. But I settled on redwood bender board, used for garden paths etc. It’s 4” wide and ¼” thick and I bought 12 foot lengths – lots and lots of them. I attached them to the frames with my pneumatic staple gun using longish staples. Trimming the projecting pieces required the oscillating saw (Fein saw) since any other kind of saw would shake everything loose. It was a bit challenging getting the bendy part at the bow to all hold together.

I wanted the topside higher at the stern (back) to simulate a galleon poop deck. I simulated this with an iron railing (bed footboard no longer in use) mounted on top of the stern frames. Tilting it backward enhanced the curvy look. We had to have cannon ports of course. My original attempt was to have boxes on both sides of the planking. It turned out the outside boxes looked too clunky so I settled on inside boxes only. The boxes were necessary to attach the planking around where I cut holes.

The entry for the tree house rather designed itself. I left a non-planked portion on the fence side between the two trees. Here I hung a “rope ladder” made of 2x4s hanging on rope and secured at the bottom. The ladder discourages all but determined adults, but kids seem to do well with it. I welded up grab bars at the top of the ladder out of ¾” steel tube. The inward portion of the grab bars also serve to hang a self-closing gate/door.

I stretched some synthetic manila rope for safety across the portion of the topsides which was cut down amidships and under the rail. I built a little decorative railing to connect the iron stern railing to continue the curve of the cut down portion. On the entry side (the back) I gave the door a similar shape with the idea of continuing the curve here too. It sorta works if you look at the right angle.

Solar powered lanterns hanging at the stern (Martha found these at the thrift store), stern windows of salvaged Plexiglas, cannons made from bed footboard feet, a garden post for bowsprit, and a prow with fiberglass mermaid figurehead (EBay), and a mainsail and a spritsail all complete the picture.

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