Anyone wanting more information on the term fetch there are plenty of websites on marine lingo and definitions. This post was supposed to be about considering the elements not about absolute definitions of words. Not to say that definitions are not important however that’s a subject for another thread
It depends on what boat I took to the water. That boat also makes the time for a storm to arrive a difference. If I am fishing, it all changes if the fish are biting.
Who I am with also makes a difference. I drove across the state for a race once, there was a tropical storm that was supposed to go by. It didn’t so we raced anyway. I think it was fun, but I wear glasses and couldn’t see much.
There are too many variables with all of it to make any sense of it. I live close to the east coast of the Gulf of Mexico. We get chop, rather than waves unless there is a major TS or a hurricane, where some folks get 4 foot waves from that kind of Fetch.
In the surfski I have faced 40 MPH wind and six foot waves. I might do it again if the beaches aren’t closed from a hurricane.
Mazer, I use mph inland because that is what is available. Of course anyone paddling more locally including recreational paddlers would use that.
What I did not realize except for Seadart’s post was that mph was a usual criteria in forecasts for paddling the Bay area. Anywhere I have paddled in salty stuff on the east coast, the marine forecast is always in knots.
Also, fetch is the distance over water that wind can blow without being interrupted, period is the distance between waves. In fact fetch can be a huge factor in inland lakes as well as the salty stuff. Lake Champlain for example develops a steady wind that has a long fetch running often to the north in Lake Champlain, making it an excellent sailing lake because of the reliability of that behavior. The same behavior makes the middle of the lake a remarkably bad idea for kayakers without a lot of skill and the right boat, and there are regularly problems when a rec kayaker decides to cross a stretch.
Variation in period is probably more evident in salt water than in lakes. While “lake waves” are often tricky because of how close the period is - and perhaps the Bay tends to have closely spaced waves - in areas like off the coast of Maine you can get much higher wave heights that are not a problem to paddle because the period can be 8 or so seconds.
And I totally disagree about knowing definitions. The diff between a four foot wave at a period of 4 seconds and 8 seconds can be night and day in terms of safe paddling. Not knowing the definition of the terms in a forecast for the water could get someone killed. This is a real difference in the elements someone could face paddling, using your term.
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Wind speed
Wind direction
Tide direction. Opposing wind and waves can make heavy seas. The two have to be correlated. Wind off shore and ebbing tide can deceive you. Sometimes that is a fatal mistake
Look at the clouds. What is going on.
Listen to the marine radio.
Wave height and period sometimes . Storms off shore can generate some high waves but with long periods. Still have to pay attention as the waves will break near shore and with fury
Tidal currents ( change according to the time before a high or low tide); factoring in tide delays .
Fog.
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Indeed! Especially if landing in a kayak with an ocean cockpit (8 seconds, please, my shins are banged up enough).
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Great time reading this thread. It’s interesting to see the consideration each contributor puts into boating. That’s the major difference between “seasoned” boaters and a novice; not the boat, how much a paddle cost, stroke style or even boat handling skills. It the intellectual approach. That’s what I’m learning most from the forum. On my last trip out. I was better able to sense the connection between the boat and the water. Even beyond balance. You need the brain of a chicken.
I’m a seasonal boater on Upper Chesapeake. Also have done parts of James River and Conowing to York, Pa. I don’t even do safety check to see if gear is in decent shape until air/water hits 65/65°. If one scale skew higher, I consider courses within a few hundred yards of shore. Earliest launch was 20 Mar one unseasonably warm winter. SF Bay has to be a rush; strong skills only. I heard all the precautionary observations that I take for the Bay. I’m systematic in prep, with a “flight check” procedure, and I won’t go out if I need immersion suit or spray skirt. When I take new paddlers. They jump in an go. Most tomes they go 1 or 2 miles and return because their arms hurt.
I record date/day, time, start point/destinations. Air/water temp, humidity, wind direction/speed mph. NOAA reports some station readings in knots, but I use mph. Tide H/L times and variation in ft, with anomalies, are based on the closest datum point to launch point. I don’t record current flow readings; they seem unrealistic, but consider how current will affect speed. I judge actual wind by feel on face and note mag compass bearing, height/intervals, noting presence of white caps or catpaws. I also sample monitor WX, ch 02 to collect conditions and listen for extended forecast for advisories and alerts.
The bay offers so many options, with launch sites for most conditions. Wind direction and speed is critical for deciding options. Worst is S SE wind over 10 mph, which blows the length of the bay to build that pesky word, fetch (both size and width of peaks and distance it has to build power). A novice probable doesnt realize the power that even a one foot wave has to pin you to the beach. Timing determines whether you can get to the head of tidal rivulets that can be navigated until 3 ft wide, then spiders fall in your boat; time it wrong, and you get up the inlet, but drag through seasonal sea weed on the way out as the tide drops.
The bay length is a perfect span so tide will peak at the Head of the Bay and the Ocean and be slack in the middle. You can figure out what happens then, because many of you seek such places where mother said don’t go. We have a mini SF Bay, two actually that I know of. Fairlee Creek and Still Pond. During tida reversals, water flows through the narrow inlet and I’ve seen power boats fall off to gain a better approach angle.
My 145 Tsunami handles 30-36 inch waves. Never found reason or misjudge conditions to encounter 4 ft waves, because that would probably unhinged me. As mentioned in a post, interval is as significant as height in large swell, and I agree chop is sick. Learned a new term haystack. Which reminds me. On relatively calm days, you can see debris, especially on high pollen count days, as it collects along a line to mark the river flow and the tidal surge. I’ve discussed bay features in other posts, so won’t elaborate, unless there is a request for specifics. There’s a good field book on the bay, short but detailed and under $10.
Been out in TS, both by pressing luck and misreading. Once, coming back from a 38.75 mile trip, I was dehydrated and bonked with 5 miles to go. NOAA beeping alerts. I just said take me sirenes, because I gave it all I had and I was good with it. They spit me out. Waiting for a better day. I learned to assess clouds indicate fair weather and look for signs of instability. If you wait for dark horizons to show, or the rumble of thunder, finish the last of your whiskey within the next 30 to 60 minutes, so you can heave the bottle into an approaching carnival ride. Hope this helps new listeners.
Agree about definitions; however, I don’t want to tell someone fetch and have them wonder what kind of wave is 30 miles between peeks. While talking about waves. Whe I read a Joseph Conrad novel I pairvit with a dictionary to capture every nuance. Please correct or expand on words that in my comments. I welcome it. As with knots and metric. The computer, or phone has all those conversions. Ain’t it grand.
Of the several definitions of fetch, the one Celia suggests is the only version I have heard from kayakers over the 14 years I have been kayaking in the NW.
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Never heard fetch used that way. Fetch is the area open water for which wind can stir up waves. Wave period is formal scientific term measuring the time between wave peaks and is reported by wave buoys and reported through various websites such as CDIP, NOAA and NWS. Waves are defined and recorded by amplitude, frequency and period.
NOAA and NWS reports and webpages are in knots, I had a brainfart when I typed mph. The most useful webistes for very specific local conditions comes as mph due to most of these sights catering to surfers.
I don’t like anything over about 25 knots, 30 is the upper limit for making headway against.
There are lots of other variable like fetch to consider.
Mostly I just look at it and decide.
“Nobody ever died on a portage.”
“Nobody ever died waiting on shore for a storm to pass.”
" I have to get home" should not be in your vocabulary.
No problem Seadart. My brain farts can be epic, and have witnesses when they happen playing in an orchestra. Lots of them.
As to fetch, l have never thought of it for other than fairly significant bodies of water. At least in one direction. Since a land mass stops the wind from being able to develop waves at least temporarily and it has to restart to some degree on the other side… I readily accept that my definition may not be textbook. But it gets me to the same physical effect as the other.
I don’t paddle oceans or even Great Lakes, so many of the numbers that are being considered here are somewhat irrelevant to me and many other inland paddlers. But that doesn’t negate the OP’s point about checking the numbers before heading out.
On rivers CFS flow rates are important, but they are relative to that particular river. I find gauge height (which for some reason unknown to me the USGS spells as “gage” height) compared to the average height for that river (near where I’ll be paddling) on that date is more informative. The trend lines are well worth noting as well… here’s an example of the USGS water data page (for those who are unfamiliar with using these) from where I paddled last week:
https://waterdata.usgs.gov/nwis/uv?05407000
Note the current CFS reading - 8650 CFS. That would be a roaring flood on most rivers, but is pretty mild for this river. That’s why I don’t rely as heavily on flow rate as gage heights and trends if I’m planning on paddling a river I’m unfamiliar with.
With regard to lakes and fetch, my old limnology text defines fetch as “the distance over which the wind can blow and bring about turbulence.” In measuring fetch in practice, we took a compass reading of the wind direction and struck a line on that heading on a map of the lake we wished to measure the fetch of. The length of that line was the fetch and is usually measured it in km.
Empirically determined calculations for the maximum height waves (surface gravity waves only - this doesn’t apply to waves generated at sea by storms, tides, seiche, or seismic activity, for example) can be reasonably estimated by Hmax= 0.332F^0.5 where H is maximum wave height and F is fetch in km. Can be converted to feet and inches afterwards if that’s more comfortable to you. Wave length (a distance, not a period and again surface gravity waves only), is ~20H.
Enough numbers yet? Makes a person just want to go paddle, doesn’t it? But in a reasonably informed way…
Jyak, wave height and period are of course first stops and so are reported in good forecasts for water bodies.
Fetch can have an amplifying effect, the longer time and distance the wind has to push water, the more challenging the waves can get. So for example at noon on a given summer day with wind going north, launching near the southern shore of Lake Champlain may put you in quite moderate conditions. Launching further north one hour or so later and trying to go thru the middle of the lake could have you in the gates of hell.
Paddling open water, and in my case often solo, means balancing a ton of conditions. And knowing your “home” waters helps a lot. I can, though not much these days, paddle fairly safely in major fog if l get caught near where l have been paddling in Maine for many years. I know how and where to duck home so l won’t get run down by a lobsterman trying to get home. If my heading is a little off l still know the area l am in. My risk would be greatly increased in most of Penobscot or Casco bay, because l am not so familiar with the shoreline or boat traffic patterns there.
One thing I personally like about this forum is that if you ask a question, not only do you occasionally find confirmation, but you will get even more valuable corrections, clarification, or technical details that some day will ring a bell. If a post about ocean current ends up with river levels. One day you’re going to be in a river and wish you paid attention. Hopefully. As long as we use the discussed terms in a coherent and recognized way. The reply will be, "are you talking about when the wind is building the wave or the other thing. Problem is I got to read all this stuff over again to fully comprehend.
I try to respond in a broad way to a reply and acknowledge understanding, but also in case a person outside the thread reads it. Hopefully, they gain a little more knowledge, or are encouraged to add something fresh. I started monitoring the forum for a while before I joined. Sometimes expressing an opinion doesn’t prove you know something. It’s may keeps you from saying the same stupid thing to someone else. It’s like. Do you tell a person they have toilet paper stuck to their shoe . . .
Gage height and the corresponding discharge are the most important numbers for rivers. Mostly they are used to decide on whether a trip can take place. In the West we run out of flow after the spring snow melt on many rivers. Spring is the best paddling. Summer is only feasible for trips on larger rivers.
For a canoe It is best to have at least around 400 cfs. For a raft of drift boat, 900 cfs or more. Some rivers are wide and shallow and more flow is desirable.
Or in the alternative, the height can indicate too much flow for a casual paddle.
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On our river French Creek the measuring location is at our normal put in. and yesterday it measured gage height of 1.8’ and today is 1.7’. I would say 95% of the stretch we run is ok at those numbers but the other 5% I may or may not be pulling out my pole. I had it out once yesterday. If I was taking someone new out for the first time in a lightly loaded rec-kayak or canoe lightly loaded I like to see a gage height of 2’ or a little more.
My bench mark is 2’ to go and 4’ seriously look at no go depending on who I’m with skill wise and responsibility wise. I often stop a few places when out for a drive when the water is high and check it out and when it hit 9’ a couple weeks ago people were still going out rec-kayaks and IMO no boats should have been on it. The local fire companies were busy for several days pulling people off fallen trees etc. Everyone lived this time so no big news stories except a couple local stay off the river clips. When they tell you to stay off please stay off.
Where we are at the gage height and the flow rate go pretty much hand in hand.
Local number are all different and learning whats right for your location is what counts.
The way the USGS provides the information there will always be a relationship between gage height and flow rate. They measure the gage height and use a predetermined mathematical relationship between the gage height and measured stream flow to provide the (estimated) flow rate.
Of course, each station has a unique relationship, so a gage height of X in one location equals a flow rate of Y. In a different location the seemingly same height of X will mean a totally different flow rate of Z.