Open Water Basics (Saltwater)

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Shaggy
Posts: 172
Joined: Thu Aug 23, 2007 10:51 am

Open Water Basics (Saltwater)

Post by Shaggy » Thu Jul 22, 2010 10:28 am

OPEN WATER BASICS: BAY & HEADLAND CROSSING

This post is still under construction. I just did a trip with Hig involving a number of bay & headland crossings, and decided to summarize the basics I learned. Hig, who has MUCH more experience on this, has agreed to provide editorial & color commentary, and hopeful some cool pix.

What is it? Bay crossing, as I'm using it, is paddling across large saltwater bays (up to several miles). Headland crossing is paddling around exposed saltwater headlands. Traversing large lakes is similar but generally easier, so I'm focusing on the saltwater end.

What's it good for? Open water crossings let you do some otherwise arduous or impossible trips with relative ease. For instance, check out our blog post on the recent Kamishak Bay Trip.

Recommended Tools of the Trade:
  • Reliable Packraft. There's really nothing to puncture you out in a big bay, but you definitely want a raft that won't spontaneously come apart under use.
    Paddle.
    PFD. I HIGHLY recommend this.
    Paddle Lanyard. Again, highly recommended. [See lanyard building post: viewtopic.php?f=28&t=1057]
    Optional: Compass, Map (topographic is best). [need varies by situation]
    Optional: GPS w/ map software.
Hazards & Risk Management:
Your main hazard is exposure: you're in a relatively slow, wind-sensitive craft a long way from shore. You'll need to allow plenty of time to cross, factoring in tidal currents or wind drift, and err on the side of caution where winds are subject to rapid change or exposure is high.

Bay crossing requires awareness. Perhaps the most dangerous thing to do is just "put your head down and paddle." You want to notice if you're drifting in a current, so you can compensate for it, or see an incoming storm or fog bank far enough a way to tuck in towards shore.

The most acute risk is losing your boat or paddle. For that reason, we prefer to do crossings with a boat-to-paddle lanyard, about 4 ft. long. How it works: if you fall out, HOLD ONTO YOUR PADDLE. Your paddle connects you to your boat. The lanyard prevents winds or waves from moving your boat away from you. Climb back into the boat, keeping a secure connection to the paddle or lanyard at all times. This can be enhanced by having a wrist loop. NOTE: THIS IS A GREAT SAFETY TOOL IN OPEN WATER, BUT COULD BE VERY DANGEROUS ON RIVERS. Personally, I always do open water with a lanyard, and never do swift water / rivers with lanyard.

NAVIGATION

Paddling + Currents + Wind Push = Actual Route

That's your basic equation. Keeping track of your actual direction of travel (vs. the direction of paddling) will tell you your combined wind push + currents. Note that both wind and currents will frequently change over the course of a long crossing.

LOW-TECH NAV

Parallax Bearing: Line up two objects, one near and one far away, at your destination (straight ahead) or straight behind you. (example: a distinctive tree on shore, and a distant mountain peak). If you drift off-line, they will move apart with respect to each other.

Parallax Speed: Using the same principle, you can sometimes judge your forward speed. If you look directly perpendicular to you line-of-travel and can see both shore and a distant feature (usually mountains) that is MUCH further away than shore, the rate at which the shoreline and the distant landscape move past each other is your approximate rate of travel.

Paddle Sighting: Hig can do this, I'm pretty bad at it still. It takes practice: Line you paddle up lengthwise with your destination, sighting along it. Holding the paddle motionless, look back along it quickly. The offset of where it's pointing behind you from you launch point (or another known point you've paddled straight out from, on your given leg) is your current+wind offset.

Compass Bearing: If you might lose visibility (fog, night), having a relatively current compass bearing to shore (factoring in wind + current offset) is valuable. The most realistic way to do this is very roughly: choose a bearing with lots of "wiggle room" (i.e., site on the middle of mile-long shore).

HIGH TECH NAV
GPS navigation is very helpful, but two key things to remember: One, not all maps in a GPS are up-to-date in remote areas. Two, a GPS can run out of batteries, fry out, or fall in the bay at an unfortunate moment.

TIDAL RIPS & CURRENTS: Tidal currents can be powerful, but are predictable. Before attempting long crossings, familiarize yourself with the local tidal regime. Expect high and low tides to be roughly 1 day + 1 hour aftfer the last major high or low. Long, narrow bays are likely to produce the most pronounced tidal currents. Tidal "rips" occur where changing water velocities can cause waves to stack in height, forming areas of taller waves in otherwise lower conditions. This rips are dangerous because they can surf or flip you. Fortunately, they don't jump up suddenly out of nowhere: keep a weather eye out, and you should be able to spot them.

Rips (and large eddies) often form around constricting terrain, like islands and narrow bay or river mouths.

WIND WAVES & FETCH: Wind waves are your typical "waves on the ocean." Your big concern on a crossing is if they get so big and steep they capsize you. Big waves are more time-and-energy consuming to paddle through, but not inherently dangerous. Breaking waves are the big concern.

"Fetch" is the distance-over-water wind has to build up the waves. Longer fetch @ a given windspeed = bigger waves.

NO-GO CRITERIA
Things that should really raise red flags:
  • High-speed marine traffic, especially if driven by drunk people. Packrafts can't dodge well.
    BIG ships. Large vessels are unlikely to see you, and can generate substantial wake.
    Large current-to-shoreline-length ratios. I.E., a 1 mile lake crossing to a half-mile target shore isn't a big deal. A 1 mile saltwater crossing to a half-mile target shore in a narrow bay with a 4-knot tidal current could be really tough.
    Major exposure. Examples: Exposure to substantial fetch (miles) w/ unstable or windy weather; a large bay open to the ocean with downvalley/offshore breezes.
    Long crossings: Just plain long... this should be pretty intuitive.
    Ice Floes: dicey, dicey, dicey. Know what you're doing before attempting anything like this - and reading Erin McKittrick's Icy Bay chapter in A Long Trek Home is recommended. It came close to a "death scenario."
Cool Friends: Seals and sea otters are pretty likely to check you out. Hig & Erin once were bluff charged by sea lions. We have yet to encounter a whale.
All posts are personal opinions only.

"Boldness has a genius, power, and magic." -Goethe

RomanDial
Posts: 428
Joined: Mon Oct 01, 2007 11:13 am

Re: Open Water Basics (Saltwater)

Post by RomanDial » Fri Jul 23, 2010 9:42 am

This is super. Thanks for posting it. It'll be interesting to see packrafters rediscover sea-kayak skills as we have whitewater ones.

Shaggy
Posts: 172
Joined: Thu Aug 23, 2007 10:51 am

Re: Open Water Basics (Saltwater)

Post by Shaggy » Fri Jul 23, 2010 12:40 pm

Thanks Roman. I'd be keen to hear your comments on open water crossings, too.
All posts are personal opinions only.

"Boldness has a genius, power, and magic." -Goethe

Hig
Posts: 105
Joined: Wed Sep 24, 2008 9:31 pm

Re: Open Water Basics (Saltwater)

Post by Hig » Thu Jul 29, 2010 10:03 am

Nice post Andrew. A few thoughts:

The paddle + current + wind equation is an important way to think about open water travel. Also, there's a big difference in the way wind and current affect your raft. One way of thinking about it is that current affects your velocity (speed and direction) while wind affects the force driving your boat:
Current is directly additive to your normal paddling speed. So if you have a 2 mph current going west and you're paddling at 2 mph north, then your speed will be a bit over 3 mph to the northwest. Despite packraft's relatively high "windage" (wind resistance) they're still water boats and are driven by the water more than the wind.
Wind and paddling force add together to give the direction the boat is being driven relative to the water. If you paddle straight into moderate wind (15-20 mph?) you can completely overcome its force and even nearly match still-air speeds. For example, lets assume that if you paddle at a comfortable pace in still air/water you can go 2.5 mph. If you push hard and double your paddling force, you can go 3.5 mph. The reason that you only speed up 1 mph after working so hard is that the friction with the water goes up quickly above 2.5 mph. Now say you encounter a head-wind strong enough that it stops you if you paddle normally. If at that point you paddle at the harder rate you'll hit 2.5 mph against the wind, gaining much more (2.5 mph instead of 1) for your extra effort. It is of course possible to have a wind strong enough that it can't be paddled against. Also, I find that paddling into wind is very frustrating regardless of whether you're making progress... I'll avoid it if possible. A GPS helps since it tells you how much headway you're making even if it feels like none.

And speaking of GPS... they can be extremely useful in this setting. I find a compass very hard to use since you're often detecting angles that are small enough you have to be careful, and if it's anything difficult you'll need your hands on your paddle anyway. Even without installed maps a GPS tells you what your true velocity is, which is often the thing you most want to know on the water.

In general, there are many cases where navigating wind and currents can be really complex and interesting. Even after getting pretty comfortable with this in the Inside Passage we'd still encounter situations we just could not make sense of (why is the current going up this bay when the tide is going out???) There's a lot to think about, but one thing I'll throw out is that currents tend to change after the tide changes in long bays. So in a long fjord like Portland Canal on the AK/Canada border will see the current go from in to out over 2 hours after high tide, whereas in a small bay or lagoon the change in current will coincide with the switch in tide. In theory, in in infinitely long bay, the current will switch at mid-tide (~3 hours off high or low). For the science geeks out there, you can show this using conservation of volume and assuming the force changing current velocity is water surface slope.

Wind is even more complex. And rips that form because of interaction between wind, currents, and waves can add a whole new dimension. Overall, there's lots of cool stuff you can do if you start conservatively and only push into difficult crossings once you feel comfortable with them.

When thinking about hazards, the thing we most fear is being partway through a crossing and having a strong out-bay wind come up that drives us beyond the reach of shore. Increasing waves repeatedly flip the boat and even if you manage to get in a couple times you're quickly exhausted and hypothermic... the end. So how do you avoid this unfortunate scenario? First and foremost think in terms of your outs. That one tiny island off the mouth of the bay could be a lifesaver. A decision to turn back 1/3 of the way through a crossing might allow you to cross wind and get to safety. If you're really screwed, throw your pack, connected to the lanyard, overboard as a sea-anchor and hope the wind dies before you do. Winds that come up quickly sometimes die quickly too.

Ice as a whole is actually not a great danger... it breaks up waves (effectively reducing fetch) and even wind to some extent. Beware large glacier bergs that might collapse. Andrew alludes to one situation where otherwise fairly benign ice and wind combine to become extremely bad. If you're running with the wind (generally fairly easy) and there's some ice in the water, ice can build up against the shore and prevent you from getting to shore. Instead you get pushed into a mass of ice that is shifting and grinding in the wind...

At this point I'm in danger of just rambling, so I'll call this good. Last thought: Paddling along a rocky coast in a packraft is really fun, and something to look for opportunities to do in a trip. Crossing bays can be extremely useful, but is really dull and more dangerous... not really something to be sought out unless you need it.

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