I was looking at a google map of the Merrimack River and in Haverhill Ma it makes a 180 degree bend back on itself. It strikes me as a place that might be dangerous if the river is flowing fast. What are the fluid dynamics of such a place?
I see a section of the Merimack …
… oh , maybe 2-3 mi. west of Haverhill’s 125 bride , Ward Hill ?? There’s a 180 bend north of 495 bridges (actually the 495 bridges cut the bend off at both sides) .
On Bing Map’s birdseye view you can get a good look at the sweepers and strainers around the outside of bend . Merrimack looks to be oh , maybe about 350’ wide there ??
dont know for sure
I pass over the river before and after the bend when on 495 and it always looks calm. It is somewhat tidal though and goes through flat country. Tidal range is about 8 feet at Merrimacport…would be less upriver.
Hope you get to run the tight meanders
on the San Juan or Slickrock Canyon on the Dolores. Or for even tighter loops, the Dismal in Nebraska. The water does tend to spiral under against the walls, but if you’re not forced into the wrong course by a rock or tree, it’s easy to stay away from the walls. Just a little backpaddling, with the bow pointing a bit outward, will often do it.
New Terms To ME
What is a strainer or a sweeper?
Tamia’s “Whispering Death” article …
– Last Updated: Feb-16-11 1:04 PM EST –
...... will explain .
http://www.paddling.net/sameboat/archives/sameboat128.html
The faster the current speed , the more dangerous the condition becomes . All can be dangerous though . Even in a slow current (or still water) if one should get tangled up in a strainer and be unable to free theirself easily , the situation may progress to worse entanglement . We probably all at one time or other have weaved our canoe/kayak through a fallen tree on some back creek to keep on going ... in that situation what we don't want is to fall in and become entangled while in the water (some fallen tree passages are worse than others and should be avoided) .
There's a creek around here that has many of these fallen trees during the spring high waters . It's about a 5 mile run down creek to the takeout . If you go , you "will have to" weave through some trees partially above water . Along the way in the non-blocked flows you look down into the realatively deep clear cool waters and see the the ghost images of many a tree fully submerged just below ... falling out of the canoe in there screams you won't get out alive . The current is pretty fast there in spring , the spillway at the head is busting it's gut overflowing . Locals will know this as Tuckahoe creek (below the spillway) .
definitions
A strainer or sweeper is anything in the water that can snare you and/or your boat out of the current and hold you under.
Typically, it is a downed tree that has fallen into the river after the bank at the outside of the bend has been eroded and undercut, or a tree or group of trees that has floated downstream and lodged towards the outside of the turn.
It could, however, be a rock sieve, rebar or other debris that is stuck in the river.
The Mac’d have to be huge to worry
– Last Updated: Feb-16-11 2:18 PM EST –
It's pretty flat all through there. Early last summer I put in at Riverside Park (aka the Stadium) and paddled upstream to the second 495 crossing.
http://maps.massgis.state.ma.us/dfg/OFBA_GMAP.htm?OFBA_ID=145
Haverhill is considered the head of the tide. I don't know exactly where but I saw a good 3' change at the put in.
It was after a good hard rain, running what I'd call medium level (6-9K cfs?)and low tide.
Just below the first 495 crossing there are some riffles and the current picked up enough to make it hard upstream paddling.
Above 495 there it leveled out and the "hairpin" 180 was quite mellow.
A little farther up, with Ward Hill showing on river right there were more riffles and again going upstream was a lot of grunt work and eddy hopping.
I turned back at the second 495 crossing. Going downstream, the riffles required some minimal boat control to stay off the few surface rocks. The rest was slow enough that I had to work (a little) to get back.
The Mac does go big from time to time. IMO all bets are off when that river is in flood. But at medium levels at least there are no hazards beyond normal wind and water.
You can put in from Waverly Road/N. Main St. in N. Andover. That is just below the Lawrence dam.
I think it would be fairly easy to put in behind the car dealership on Rt 110 just down stream of the first 495 bridge. That would involve getting your boat up or down a steep bank with some poison ivy.
Of course you can put in at Riverside park. Look for a set of wooden stairs leading down to the water.
And you can put in out at Cashman Park in Newburyport. http://maps.massgis.state.ma.us/dfg/OFBA_GMAP.htm?OFBA_ID=75
isn’t 180 degrees
a straight line?
I’d be more worried about a 360 degree bend.
I’ll do 180 all day.
strainer or sweeper
They kill people. If you don’t know what they look like, then find someone that does to go with you. You might want to read a book…read up on dams, aka drowning machines, while your at it.
http://www.dnr.state.oh.us/watercraft/tabid/2877/Default.aspx