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Grooming: Icy Trails

by Phil Zink
February 16, 2005

This has been the most frustrating two weeks for both skiers and groomers in our region. To finally get 6"-8" of snow Jan 21-22 after only a total of 3" all season was exciting. To have about 1/3 of our base melt away 3 days later and then turn into a hilly ice rink was a disaster. This was followed a week later by 4 days in the 50's, setting three all time record highs and melting much of the remaining base. Now we have ice again.
 
The four variables I think are most important in determining whether an iced-up trail can be brought back to a safe, enjoyable skiing experience (using snowmobile powered equipment) are:
 
1. Ice Layer Thickness
2. Groomer Time Available
3. Base Depth
4. Grooming Equipment Available
 
 
ICE LAYER THICKNESS
 
John Tidd told me, when I bought one of his early Trail Tenderizers in 1991, that if you can dent an iced-up trail 1/2" or more with the heel of your boot it is probably worth your time to try and renovate your trail. I wasn't able to check this ice due to the flu, but I believe it was mostly beyond the capability of a well maintained Trail Tenderizer (TT) with sharp teeth, electric depth control, and an almost unlimited number of multiple grooming passes. This opinion is based on solid research (reading the Skinnyski trail reports for Three River's Hyland Park).  They never were able to achieve a skier rating of over "Poor or Fair" after the ice-up until their trails were closed. This was in spite of two snowmobiles pulling two TT's available to groom about 120 hours that week by 4 very experienced groomers (two shifts) as they do every week.
 
 
GROOMER TIME AVAILABLE
 
If the ice is thin enough, or soft enough, so that the TT can scratch it and create some granular material,  then the question is whether we have enough grooming time for the multiple repeated passes that may be required. The eight Three Rivers locations have the man-hours available to do this. Most of the other park system groomers in the Metro simply don't have time for more than 2-3 passes.
 
I was a volunteer groomer on a couple of Ramsey County. trails in White Bear Lake for about 10 years. Ramsey Co. didn't have snowmobile grooming equipment until the 2000 National Masters Committee donated a snowmobile and TT (I then retired from routine grooming). Ramsey Co. has one snowmobile, one TT, and one operator who does all the grooming at 5 locations spread over about 30 miles from Shoreview to White Bear Lake to Maplewood. He trys to groom at two or three locations every day, loading and unloading his equipment, and driving to the next location. When we have above a 4" base, Ramsey also uses their small Pisten Bully (never this year and for an average of less than 2 weeks per season over the past 5 years). I estimate that Steve Jorgensen, the very experienced Ramsey Co. snowmobile groomer can spend no more than 60% of his 40 hours per week (no budget for overtime so no weekend grooming) actually grooming. He tries to groom the Battle Creek Winthrop (BCW) venue twice per week, but with 5 locations and only about 24 hours of actual grooming time available, BCW probably gets no more than six hours of grooming per week. Perhaps Hyland has twice the number of K's as BCW, that means that each K at Hyland get over 4 hours grooming time per week. This is 8 times the 30 minutes per K that BCW gets per week. One Ramsey Co. groomer simply doesn't have time for more than 1-2 passes per visit. This Ramsey Co. example is much more typical of our area park system grooming time availability than the 3 Rivers situation.
 
 
BASE DEPTH
 
The depth of the packed snow under the ice layer is critical, because when you use the teeth of the TT to attack the ice you are digging down into your base. If your high-density base is less than 2.5", you will be getting close to the ground surface if you renovate deep enough to set a track (1.5" deep). If your trail is not very uniform, you need more like 4" packed base to risk renovating deeply enough to reset a track. This is because when you renovate with the teeth, you are LEVELING the trail surface. If the underlying ground surface is dished, crowned, rutted, erroded, bumpy, etc. you may soon be scalping the high spots. This exposes grass, dirt, rocks, leaves, etc. Not good for skis and resulting in a faster meltdown.
 
At Battle Creek Winthrop the 7" of new snow packed down to a base of 3-4" before the meltdown and the NM groomers hoped that by grooming it every day we could have it ready for the 30K NM classic race in 6 days. After the Mon. PM-Tu. meltdown we only had a 2-3" base which turned to ice that night. Ramsey Co. attempted to renovate BCW the first morning after the ice-up (Wed Jan.26). Steve couldn't cut the ice with his TT, and could barely negotiate the steeper hills with his snowmobile.
 
The NM Committee decided we simply didn't have enough base depth left to renovate deeply enough at BCW to set tracks and make a safe course, even with the state-of-the-art grooming equipment at our disposal. This thin base was compounded by the somewhat uneven underlying trail surface of the BCW trails (even though they are much more uniform than 5 years ago). When it was clear we wouldn't get any significant additional snow, the 30K NM Classic was relocated to St. Cloud. So the negative skier reports at BCW were simply uninformed. I fully understand their frustration, the NM Course Committee was even more frustrated after putting in well over 100 hours in volunteer trail preparation, shoveling, two days of grooming, etc.
 
GROOMING EQUIPMENT AVAILABLE
 
Most of the snowmobile grooming in our region is done with Trail Tenderizers. More then 70 have been sold over 16 years in our Metro area.  Probably 1/3 of these are used on private trails at cabins up in the woods. Most of the others are still in operation at park systems, golf courses, schools, etc.(my 14 year old unit now grooms a trail at Bethel). 3 Rivers does ALL of their grooming (except on the Elm Creek artificial snow loop) with snowmobile equipment, including over a dozen TT's and 2 of Tidd Tech's second generation (G2) groomers. One of their G2's is at Baker, and they have moved the other G2 around several parks. The Mpls. Park System also acquired a G2 this season and have been using it helping to prepare the COLL Trail (which melted out this past week).
 
Our son, Dave, bought Tidd Tech six years ago and moved it from VT. to CO. Last year Dave began production the G2. The G2 has greatly enhanced grooming capability over the Trail Tenderizer, especially with  icy trail conditions over a thin base as we faced ten days ago. I won't bore you with a full commercial. (Tidd Tech: Introducing the New Tidd Tech Generation 2).
 
It is interesting that William O'Brien State Park (WOSP) consistantly had the best skier reports on Skinnyski over the week of the ice-up period. Your own Jan 28th report is typical ("By far best natural snow skiing I've had since the meltdown--They've done a great job keeping the surface level/smooth--The classic track was incredible"). I called Randy Lorenzen, who does 95% of the grooming at WOSP to make sure he had read that one. He had and he loved it, so much that he was out adding the "few more passes" you suggested. This was on Saturday morning, on his own time I'm sure because as Asst. Manager he doesn't get overtime pay (and their grooming budget wouldn't cover overtime anyway). WOSP replaced their very limited grooming implement, which actually totaled over 2000#, with a new G2 exactly one year ago. Randy probably grooms at least 3 times as often now (they used to share grooming equipment with Afton SP-which also now has a G2). He really loves doing a first -class grooming job, and especially the compliments he now gets from skiers.
 
New equipment was a contributing factor in Randy's ability to handle the ice-up. However, it wouldn't have been enough if Randy had not been able to establish and preserve a somewhat deeper base. He had about 3" more snow to work with than we had at BCW (8" on top of a couple of unpacked in. before the storm). Most importantly, Randy was out rolling and packing during the last part of the storm, Sat Jan. 22nd, before the winds hit 30-40 mph. resulting in a lot of drifting in open areas. More snow drifted onto his packed trail, increasing his base. We skier's like to think the best groomers are skiers. However, we (the NM groomers) were sking the Seeley Classic while snow was blowing off parts of our BCW race course. We might have gained that critial 2" more in. of base if we were non-skiers, like Randy.
 
 
To summarize the above in some specific tips on grooming icy trails I would include:
 
1. ROLL AND/OR PACK NEW SNOW AS SOON AS IT FALLS IF POSSIBLE TO AVOID LOSS BY DRIFTING  AND TO ALLOW "BONUS SNOW" TO DRIFT ONTO YOUR TRAIL, ADDING TO YOUR BASE DEPTH.  (Tidd Tech: Don't Waste It).
 
2. DON'T ATTEMPT TO RENOVATE DEEPLY WITH A THIN BASE, ESPECIALLY WHEN THE UNDERLYING GROUND SURFACE IS UNEVEN. IF YOU ATTEMPT TO LEVEL YOUR TRAIL WITHOUT AN ADEQUATE BASE YOU RISK SKALPING-OFF THE HIGH SPOTS AND BRINGING UP DIRT.
 
3.SHARPEN THE TEETH ON YOUR TRAIL TENDERIZER. (Tidd Tech: Maintaining your Machine).
 
4. BE PATIENT AND JUST SCRATCH THE SURFACE ON YOUR FIRST PASS. LOWER THE TEETH A BIT WITH EACH REPEAT PASS.
 
5. AVOID OVERWORKING YOUR SNOWMOBILE WHEN RENOVATING. YOU CAN OVERHEAT AND RUIN YOUR ENGINE, ESPECIALLY WHEN THE TEMP. IS ABOVE FREEZING. (Tidd Tech: Snowmobile Cooling Modification Project).
 
6.  MAKE SURE THE REAR SUSPENSION ON YOUR SNOWMOBILE IS ADJUSTED TO BE AS STIFF AS POSSIBLE WHEN RENOVATING ICY TRAILS. THIS IS IMPORTANT TO PREVENT THE HITCH POINT FROM DROPPING WHEN PULLING HARD ON UPHILLS, AND RISING ON DOWNHILLS. WITH A SOFT SUSPENSION, YOU TEND TO DIG IN TOO DEEPLY, AND RISK GETTING STUCK, ON UPHILLS AND NOT DIG DEEPLY ENOUGH ON DOWNLHILLS. YOU STILL MAY NEED TO ADJUST THE DEPTH OF THE TEETH ON HILLS, BUT NOT AS MUCH  IF THE REAR SUSPENSION IS STIFF.

Addendum - December 17, 2012

It is now now much easier much easier to renovate icy, rutted ski trails than it was in 2005.This has been demonstrated at Battle Creek West over the past 24 hours (see John Fitzgerald's trail report). The ice has been restored to a very safe, skiable surface in 2-4 passes (depending on depth of ruts, footprints, etc.).

This has been accomplished mainly through the addition of depth control to the six year old G2 groomer at BCW. The depth control system uses a leveling bar mounted in front of the toothbar which absolutely prevents the teeth from digging deeper than the desired depth. We had the depth set at about 1/2" yesterday afternoon and this morning. The first pass doesn't appear to have much effect, but the second pass is amazing. You are shaving the ice to create a level, granular surface which provides fast, controlled skating. Unfortunately, we didn't have enough snow depth to set classic tracks.

The recovery from iced-up trails should be much quicker and more widespread this time as at least 16 G2's in the TC Metro are now equiped with the depth control system. These include units at most Three Rivers Parks and City of St. Paul venues, Theodore Wirth, William O'Brian, U. of M. golf course, and Battle Creek West. This probably covers about 80% of skiers in the metro. This is the first time any on these venues has had a chance to use the depth control system on significant ice, so you have to allow some time for the learning curve effect.

This depth control system fits any G2 built since it's introduction in 2003. The cost is under $200 and installation takes less than 5 minutes.


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