August 7, 2021
This is 9 of 11 log posts covering The Glaciers of Kenai Fjords expedition.
Southwestern Inlet – down NW Fjord, Harris Pt – Surok Pt – Cloudy Cape – through McArthur Pass – Moonlight Bay – Midnight Cove
Clark-Johnson and Bella, exploring. (Photo: Shawn Dilles)
It was a long haul down the fjord and then along the exposed southeastern side of Harris Peninsula. The wind and the seas had picked up, both from 90 degrees off our port side. The nearest land in that direction was the central Oregon coast about 1,200 miles away. The swells were not huge but they were just the right amplitude and frequency to get us rolling too much for comfort. Our guests weren’t complaining, yet, but when Patsy puts the coffee pot in the sink it’s time to deploy the paravanes. Paravanes are the devices we use to stabilize the Endeavour and reduce the nausea-inducing side-to-side motion in heavy seas.
Sailboats don’t need stabilizers because the wind against their sails and the water against their keel reduces rolling while driving the sailboat forward. Ocean-going power-driven vessels without sails – especially those with efficient round hulls rather than hard-chine hulls (built from plates of metal or plywood), all need stabilizing in some conditions. Stabilizers don’t stop the roll, but they dampen it, breaking up the oscillation. Imagine a truck with springs but no shock absorbers. Stabilizers are the shock absorbers.
Larger modern boats often have active fin stabilizers, which are fins that stick out of the hull under the water, one on each side, constantly being angled up or down by a motorized system to counteract each roll. When one side of the boat starts to go up, the fin on that side points down. Active fin systems work well when the boat is moving fast enough, but the gear is expensive, it takes up a lot of room below, and none of it is any good unless the boat is moving. Also, these systems are complex enough that if they break far from port it’s unlikely you’ll be able to make repairs at sea and you’re going to have an uncomfortable ride home. Also, the fins are always sticking out there, creating fuel-robbing drag, vulnerable to damage, whether you need them or not.
Some smaller high-tech boats have giant round gyroscopes bolted to the inside of the hull. They work spookily well, but they’re noisy, and heavy, and on bigger boats they have to be too large to be practical. On the Endeavour I would need two giant gyroscopes, each bigger than our engine. They would take up the entire companionway below and sound like brobdingnagian beehives.
The simplest stabilizers are rolling chocks. These are long thin boards attached lengthwise down the hull on each side, about half the length of the boat, extending maybe a foot out from the hull. When the boat rolls, the extra keels bite into the water, slowing the roll. I once had a 50-foot troller-style boat with rolling chocks and they worked. It was hard to tell how well they worked because they were always there. Being always there means, too, that they were always creating some drag, whether I needed them or not. But again, I don’t know how much drag. Rolling chocks are very common on round-hulled workboats.
Paravanes, like those on the Endeavour, are two heavy triangular fins (called “fish”) that are suspended from long poles ten or twelve feet long on each side of the boat, hanging about eight feet down into the water on steel cables. The Endeavour is 72 feet long and weighs about 82 tons, but the fish are only 600 square inches each, about the surface area of a king-sized pizza. Underway, the slight downward angle of the fish in the water creates a surprising amount of pull which, that far off the centerline of the boat, suppresses the roll. The fish are ballasted with two half-spheres of lead on the top and bottom of its leading point and weigh about 65 pounds, but it isn’t the weight that does the work, it’s the water pressure against the deltoid fin. When you don’t need them, you pull in the poles and pull up the fish and store the fish on deck, saving drag and fuel. Salmon trollers, who already have tall poles that fold down on each side, use paravanes. They are effective, cheap, and easy to fix. I keep spare fish and cable down in the engine room.
We usually only deploy the paravanes when we’re in the open ocean, and then only when we need them, which depends on the size of the seas and our heading. Within 45 degrees into or away from a swell (that’s 180 degrees or half of the compass) we don’t bother. Even large beam swells can be fine, if they are spaced far enough apart or close enough together that they don’t reinforce the boat’s moment of roll. But when they’re abeam and the wrong frequency, they are essential. We love our paravanes.
The downside of paravanes is that someone (like me) has to go up onto the top deck in bouncy weather to deploy them. If I’m running the boat by myself, I throttle back to idle forward, use the trolling gear to slow our speed further – down to one knot or so, just enough for steerage – and point the bow into the swell, then engage the autopilot. Then I climb up the aft ladder to the top deck. If the autopilot has kept our bow into the waves, the rolling won’t be bad, but the pitching – the rocking horse motion – can be. And it’s likely to be windy and raining or snowing. Up near the smokestack, I release a pole on one side, lowering it by lines and blocks (pullies) to a 45-degree angle off that side, then I pick up the heavy triangular fish (attached to the end of the pole with the cable) and drop it overboard, checking to make sure the fish is flying through the water as it should. Then I go over to the other side and do the same. Back down on the lower deck I set the shorter strut poles on each side. They keep the long poles in place in heavy seas.
Bringing the fish up is almost the reverse. We’ll be in calm water, which is nice, and I’ll bring the boat to a dead stop, not slow forward. No autopilot needed. Then I’ll go up top, put on gloves, pull a pole in upright with the lines, and then pull the heavy fish up by hand, running the cable over a roller. The boat really has to have no forward motion. Any water pressure makes it impossible to get the fish to the surface. Even so, this is hard work. I’ve decided that I’ll be officially old when I can no longer do it by myself. That day isn’t so far off. I’ll have to figure out a smarter way to pull them up. I have in mind a motorized pinch-wheel device, something like crabbers use to pull their pots.
Just before Ragged Island we bent our course slightly more west and entered McArthur Pass. In the swell shadow of the island the water became flat calm. We motored through the narrow, shallow passage, paravanes still down, and emerged on the other side in McCarty Fjord. We turned north, and three and a half miles under low clouds, we turned east into Moonlight Bay, and from Moonlight Bay we turned north into tiny, high-walled Midnight Cove. Another cirque. It was deep, well over 120 feet deep in the middle, so we anchored at the far end in 60 feet of water, not far off a waterfall cascading in from the forest above.
It was only 1530 and there were five hours of daylight left, but the clouds were too heavy and low. It would have been pointless to make the run up to McCarty Glacier at the end of the fjord today, and this was the last good anchorage in that direction. We were in for the night.
- William Urschel