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Thread: Alaska Mat-Su valley ice thickness??

  1. #1
    cubpilot2's Avatar
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    Alaska Mat-Su valley ice thickness??

    I'll be getting back home soon and want to check my cabin due to the quake. (see if I still have one)

    I'm located west of Big Lake and west of the little Susitna river.

    Does anyone have any ice thickness reports yet? Figure I need at least 7-8 inch minimum on Bush wheels.
    Ed

  2. #2
    akjeffc's Avatar
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    I landed on a few lakes Sunday 12/2 in the Figure 8 and powerline area. 6-8 inches of ice. The edges had been cracked up from the earthquake, but were refrozen. No major cracks otherwise.
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    SJ's Avatar
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    I'm curious - does the earthquake have an impact on the usability of the ice?

    sj
    "Often Mistaken, but Never in Doubt"
    ------------------------------------------

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    skukum12's Avatar
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    I would imagine the immediate usability would affected by the thickness of the ice and intensity/frequency of the after shocks and air temp. The thinner the ice, the more wary I would be soon after. My neighbor/pilot friend headed to a local lake by bicycle a couple hours after the quake and watched people riding snowmachines all over the ice(6-8 inches) and cracked all over.

    If the air temp is cold enough, the cracks will immediately begin to re freeze. After the last "big" one a couple years ago I saw sections of ice that sank and slid under other sections creating landing gear removing areas up to two feet deep.
    "Always looking up"
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    SJ, The earth quake broke up the ice but the cracks quickly refreeze so no significant effect unless you are on it during the quake.

    Here a report from Red Shirt Lake, just west of big lake about 6 miles or so.

    On Dec 2, 2018, at 10:12 PM, xxxxxxxxxxx wrote:
    So xxxxxx & I just got back from Red Shirt today , there is 8 - 9 " of good ice . Couple inches of snow, a few cracks from the earthquake but we found no overflow or any open areas . We checked a half a dozen cabins . No structural damage that we could see , the ones we could see in had broken glass from things falling off counters and shelfs , no broken windows that we saw . We drove around the lake in our side by side 1,500 lbs , I think the lake is safe
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  6. #6
    SJ's Avatar
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    Being on it during the quake... that would sure be "interesting"....

    sj
    "Often Mistaken, but Never in Doubt"
    ------------------------------------------
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    skukum12's Avatar
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    Friends and I were in a 14' John boat on a lake floating around fishing. Had a small tremor which we did not feel. However, a 1 foot tall wave that stretched shore to shore came the entire length of the lake and passed us. I imagine the water under the ice would/could to the same thing and blow out ice on the opposite shore. Like the frontal wave that ice road truckers create by driving too fast across a lake.
    "Always looking up"

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    stewartb's Avatar
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    I'm a river guy. Earthquakes cause trouble on frozen rivers. Overflow appears where you've never seen it. Ice settles in places it never falls in otherwise. This one happened early. Not much ice very little snow so not much river travel yet.
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  9. #9
    cubpilot2's Avatar
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    Found this Ice thickness chart. Good info but no guarantees of course.

    How does real life experience compare to what it is saying?
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    Ed

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    TVATIVAK71's Avatar
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    Hit up Keyhole and Figure 8 and got skunked. Ice was 6-8” thick but just off the narrows of Figure 8 next to the east west pressure ridge there were some honest 4-5” spots. The loudest I’ve ever heard an early season Lake. Nonstop cracking and shifting noise and one huge one that made water push out of the holes. Anyway nice to be out.
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  11. #11
    cubpilot2's Avatar
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    Thanks for the report. That helps in my planning.
    So you must have had at least 6 inches were you parked your cub. What is the thinnest ice you would land on?
    Ed

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    TVATIVAK71's Avatar
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    6” is my minimum. A couple of lakes to the NW of Fig 8 had quite a bit of water on them as well. The big one north on the east end had a huge patch that was 2” followed by 2” of slush then 4-5” of solid ice. Didn’t see any holes drilled either. Might poke around tomorrow as well.
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    BC12D-4-85's Avatar
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    One Fall I landed with skis with my Citabria on 4+" of clear ice in mid-November. Put in tie downs 100' from shore and went to nearby camp. That night it blew 20-30 SW and the ice commenced to crack and work. The plane was ok but soon water covered the wet area around my plane in the 0 deg temps. Weight from the plane must have depressed the ice and water came out of the tie down holes. I moved it closer to shore where the ice was thicker for the rest of the stay. Yes more ice is better and plane weight can cause local problems.

    Gary
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  14. #14
    cubpilot2's Avatar
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    Is ice typically thicker close to a shoreline?
    Ed

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    stewartb's Avatar
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    That depends on the lake. Springs can make weak ice in shallow water, and that’s usually near the shore. If you watch a lake freeze it usually starts around the edges and closes in the middle last.
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    I'm not there right now, in KY. But my house sitter says there's open water in front of my house at the mouth of Fish Creek and Big Lake.

    Scott
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  17. #17
    stewartb's Avatar
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    A body of water is a pretty big heat reservior. It stands to reason that the most heat will be in deeper water and the warmest water will be at the top. Add flow and everything changes.
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  18. #18
    cubpilot2's Avatar
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    Quote Originally Posted by scott the cub guy View Post
    I'm not there right now, in KY. But my house sitter says there's open water in front of my house at the mouth of Fish Creek and Big Lake.

    Scott
    If I'm thinking of the right spot near where the road crossing of the creek at Big Lake; that it must be a warm spring feed. Its open for most of the year.
    Ed

  19. #19
    BC12D-4-85's Avatar
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    Water's weird. Has highest density near +39*F. Once the surface cools to that temp it sinks and warmer water below rises to replace it. Lots of mixing goes on especially in deep lakes and during windy or moving flowing conditions. Water near shore is less prone to mixing if left undisturbed and can cool off to freezing sooner. The sooner it freezes the thicker the ice.

    This year in Fairbanks we had the float pond freeze along the shore then overall with thin ice more than once. Air warmed up and the ice disappeared except right next to shore.

    But as winter progresses if the lake and ice level lowers due to drainage or whatever like a heavy snow cover the ice next to shore can crack (it's fixed to the bottom) and allow water underneath to rise up in the crack and overflow. Then it can be safer to park away from the shore and overflow on dry ice.

    Gary

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    A coworker once described snowmobiling on a Pennsylvania lake. Pymatuning Reservoir is sticking in my mind. As more and more traffic showed up, his party got curious about the ice and drilled a hole. I don't remember how thick the ice was other than it was thick. But it was over a foot down to the water under the ice. Is it a common phenomenon to have air under a large expanse of ice? I've never seen you guys talk of such a thing. jrh
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  21. #21
    BC12D-4-85's Avatar
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    Air space under ice - I've seen it but rarely. Some shallow lakes east of Tok AK. would do that. If the ice is thick without heavy surface cover it can form a stable bridge over lowering water below. Any drawdown of water level can leave an airspace but usually the ice will bow down until it's floating again.

    Gary

  22. #22
    stewartb's Avatar
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    Ice bridging happens all the time on flowing waters. River levels continue to drop after freeze up. One of the signs of spring is ice collapsing on the river trails. A few years ago a neighbor, who was nearly 80 at the time, fell through river ice onto a dry bottom. We found him and got him out. The chamber under a well traveled trail was a surprise.
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    Ed, nope...I'm at the other end, at fish creek and the mouth, the old big lake lodge is to my right.

    Open water there....scott
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  24. #24
    skukum12's Avatar
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    I hear Eklutna Lake is a good example of air under ice.
    "Always looking up"

  25. #25
    TVATIVAK71's Avatar
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    Dropping rocks is cool but seems to tell the story of a localized part of the surface, as we all know thickness can vary in feet or yards. A 20ish pound rock is what we mess around with just for messing around sake and in no way use it’s result as the sole basis to land. Anyway 4” or less that size rock causes a big hole or colossal damage at impact depending on clear or opaque ice. 8” or greater a sizable chip and it also sends the rock sliding for a ways. This veteran 19# 4oz rock impact was 2 inches deep on 9 inches of ice. Dropped from 100 feet at 60 mph.
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  26. #26
    cubpilot2's Avatar
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    Quote Originally Posted by TVATIVAK71 View Post
    Dropping rocks is cool but seems to tell the story of a localized part of the surface, as we all know thickness can vary in feet or yards. A 20ish pound rock is what we mess around with just for messing around sake and in no way use it’s result as the sole basis to land. Anyway 4” or less that size rock causes a big hole or colossal damage at impact depending on clear or opaque ice. 8” or greater a sizable chip and it also sends the rock sliding for a ways. This veteran 19# 4oz rock impact was 2 inches deep on 9 inches of ice. Dropped from 100 feet at 60 mph.

    I would think that it would be a bit “sporty” to toss that out if you are by yourself. ��
    Guess we need bomb racks under the belly. STCd of course. Hey that would work good for dropping the occasional pumpkin. ��
    Ed
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  27. #27
    TVATIVAK71's Avatar
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    Yeah, my kid does the dropping. I learned the hard way that it’s not in my best interest to do both.LOL Didn’t make it out to the pumpkin drop this year.

  28. #28

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    Minutes after the main shock we walked down to the edge of our lake on the Kenai. The shore was still vibrating as the lake sloshed back and forth under the ice. The lake cracked up through the 6" of ice and an occasional geyser of water shot up along the cracks, about 6" tops. It was interesting to say the least.

  29. #29
    cubpilot2's Avatar
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    There was a news report of someone going through the ice on Big Lake and made it sound like all lakes are unsafe.

    This is a copy of a report from Flat Lake.com.

    There was a mishap involving 2 snowmachiners Saturday night. They tried to ride through the Flat Lake channel, and broke through the ice. Mat Su Bouough emergency responders came to their assistance, and they got out safely.

    “A news report about the incident was inaccurate. There is no open water on Flat Lake or Mud Lake. We are plowing the ice roads on Flat Lake, and hope to start getting some driveways established this week. We are not aware of any unsafe ice conditions on Flat Lake or Mud Lake.

    The channels between the lakes never have dependably safe ice, and should be avoided.

    There is 2" of grey ice on top of clear ice on the lakes. The ice was fractured by the earthquake, but has settled down and we are traveling on it on Flat Lake without any problems. I measured almost a foot of ice in front of our cabin last Sunday.

    Access on and off Flat Lake has been impacted by a reoccurring pressure ridge, as well as water from the channel flooding that area. The earthquake may have made it a little worse. We're getting on and off the lake on the south side of the channel. Full sized pick up trucks started driving on and off there Friday.”
    Ed

  30. #30
    skukum12's Avatar
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    My wife and I went ice fishing on Sunday in between Palmer and Wasilla. Just carried our gear out onto the ice. The ice was about 9-10 inches and clear. Plenty thick for the 12 as long as I don't come across a hot spring. We will be waiting on thicker ice before flying out.
    "Always looking up"

  31. #31
    cubpilot2's Avatar
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    Posting this here as perhaps anyone flying that area could be on the lookout. Look for signs of going through ice.


    https://www.ktuu.com/content/news/Al...503097652.html

    From Flat lake.com

    IMPORTANT! If you're out on the area trails, be on the lookout for a couple who never returned from a snow machine ride out of Big Lake. They haven't been heard from since Sunday. Search parties are leaving from Southport and from the west end of Big Lake, by the old Call of the Wild today at 10 AM. Anyone with a snow machine who is available to help is encouraged to participate. Let's find these folks!


    Ed
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    mike mcs repair's Avatar
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