Fire Raft 2010

As usual, we spent our Fourth of July down in Burien on the waterfront at our friends Ed and Terry's house. Also as usual, the centerpiece of the affair was the floating fire raft, a raft piled high with wood, fireworks, and various other incendiary devices, set on fire from ashore by various means and left to burn throughout the evening.

That was where all the common threads of 4th of July fire rafts ended, though, because this year our friend Maxx is back in town, and he seized the raft by the horns and built, from scratch, a completely new platform and frame, a high-tech, storeable, re-usable, NASA-approved fire raft. I'm including some pictures of the assembly and deployment here; you can find more in our Flickr stream.

It started with two circular sheets of OSB sandwiched together to form a two-ply base for the platform. Beneath, the lids of twenty-five five gallon buckets were glued and screwed to the base, to which the buckets themselves would later be attached for flotation. Above, a lip of 2x4s were screwed down to allow us to pile stuff inside, namely sand, which was hoped to provide sufficient insulation for the wood below to keep the platform from being incinerated as occurs in typical years.


Another innovation was the use of two eye-bolts, on opposite sides of the raft, for both anchoring and control. The far eye-bolt would have a line tied to it, looped through the anchor shackle off-shore, and then back to shore... pulling on the shore-end of this line would pull the raft out into place over the anchor site. To the other eye-bolt another line was attached and led back directly to shore. Used in opposition to the anchor-side line, this allowed us to orient the raft with one side constantly facing shore regardless of wind or current. This feature made our standard ignition system much less fraught, as the line leading to it had less risk of becoming fouled as the raft spun around through the day. It also allowed us to position fireworks that might otherwise prove a danger to those ashore safely on the seaward side of the raft, and to construct a flammable 'basket' of sorts for aiming bottle rockets or roman candles at to set the thing off.

The basket was formed by a seven-foot tall lightweight, pyramidal frame that set within the lip of the platform. The frame stabilized the wood stacked up on the raft, provided a place to hang our accelerants, and gave the whole thing a touch of class, rather than simply being a whomping pile of stuff.

The frame and base were built off-site, then assembled on the bulkhead on the morning of the event. Another change from years past were the tides; there wasn't really a low tide at any sane hour on the 4th this year, so there was water all the way up to the seawall beneath the house and no beach area in which to assemble the raft. This proved most difficult with respect to installing the buckets. They were easy enough to put in place while the raft was upside down on the seawall, but when it had to be turned over and passed down to the water, they tended to bang into things and get knocked off or loose. This was exacerbated by both the increasing weight of the raft, and by the bricks we put in some of the center buckets for ballast. Jim and I argued for additional sealant to be used on the buckets to secure them to the lids screwed to the raft, but we were over-ruled... with disastrous consequences!

We eventually got all the buckets attached, and with some additional manpower provided by Ed, Maxx's friend Sean, and Ed's cousins Bruce and Justin we lifted the raft down onto some rocks, and then into the water.

This is where the high water complicated matters further: we needed sand to layer the platform with, but had only rock available. All the sand was under two or three feet of water, and we didn't have a dredge handy.

So, the raft got towed down past the seawall to a small, rocky beach, where we managed to scrape together enough sand to put about an inch over the platform inside the lip. As Maxx objected vociferously throughout the remainder of the day, this was outside of spec, but as later events would show, fire proved among the least of our worries.

We brought the raft back below the house and as everyone else started stacking it with wood (including the traditional dried Christmas trees, three this year!) I set to work on the secret ingredient: white gas. In years past, attempts had been made to just set the wood on fire directly with roman candles, or to pre-soak the pile in an accelerant, or to position balloons full of gas around the framework and to try to hit and ignite those (you would be amazed how fire-resistant your average party balloon can be). A slow evolution led to open containers, usually bags, filled with gas and positioned around the structure, into which a lucky shot could fall, igniting the whole contraption. Last year, however, I hit on the ne plus ultra of fire raft remote ignition systems: a plastic juice or milk container, half-filled with white gas, suspended from the highest point on the raft near its pivot point, with a line led down from the top to the base of the raft and then to shore. Holes are poked in the top of the container, causing it to form a sort of sprinkler when upended, as will occur when the line led to shore is pulled. This arrangement prevents the gas from spilling and evaporating due to wave action, and allows the pile to be doused with it just before the audience starts firing roman candles and bottle rockets at the thing.

I used a plastic nut container this year, with a small water bottle as backup, and after all the wood and fireworks were positioned aboard, Maxx hung them from the frame. Although the raft has a considerable amount of flotation, it still wasn't enough to allow us to put as much wood on it as was available, or as we had hoped. Still, there was a fair amount and the platform was just above the surface of the water when we pulled it out into position.

As the day drew on, however, the platform began to list. One of the buckets, apparently, had developed a leak. At first this was not significant, and one out of twenty-five wasn't a cause for serious concern. The wind shifted, however, and the waves started hitting the raft on the side it was already listing, causing the platform to take on water and some of the lumber to start to float off. It got worse more dramatically just as dark began to fall, so we decided to go ahead and light it off a little early. Here are the results:



It gets a little shaky after the raft ignites because I was beneath the deck where everyone was shooting from, and a rain of fiery debris started coming down on me. As you can see, though, once again the method has proven quite effective.

The raft burned well into the evening, until we finally put it out from shore with hoses... there was some concern that the hot coals were going to burn through the platform. It was impossible to see through the ash and in the darkness whether or not this was the case, and since we left town the next day I have not yet received a formal report on the post-fire inspection, but it seemed prudent. Also, with the bulk of its cargo burnt off, the listing became less of an issue with the remaining buckets retaining more than sufficient buoyancy to compensate for the leaky one. In fact, I don't even know for sure where the leaks were; we had one bucket that flat out ruptured when we were installing them, it's possible that happened with one or more of the others as well and wasn't caught at launch.

All in all it was a successful effort, but the real test will be if the setup retains its utility to be used again next year as more than just scrap for the 2011 raft!