Microburst on Granby

[Dave@Granby]

Beautiful day of sailing on Lake Granby, Co. Light, 5 kt wind until about 1 PM.
I had been watching a darkening buildup to the north about 5-10 miles away. Seeing some rain coming out of the bottom, I said to myself, huh.. that's virga. I am usually very leary about tstorms on that lake because they can really build up in a hurry, and normally call it a day when they form.

I was single-handed and had just the full main up and close hauled when in a matter of less than a minute the wind suddenly blew up. And I mean really blew up. The waves went from ripples to about 5-6 feet with streaming, frothing whiecaps. I would guess about 30 kts of wind. Being by myself, I could not drop or reef the main. I just kept the main sheeted in and kept the boat feathered into the wind, but the gusts were still putting the rail in.

After what seemed like an hour of this, but was probably only 15 minutes, their was a lull and I quick like a scared bunny got the main down. The wind actually was not still satisfied and roared back again while the boat rocked around like crazy until it finally quit and became almost dead calm.

Total time of this event was about 30 minutes.

This is my first year sailing my new to me 23.5 and it made it through. It never rounded up and showed me how much it could heel. Not that I want to do that again. It also will cause me to head for my anchorage whenever I see any kind of a suspicious storm near Lake Granby. It's a beautiful lake at 8500 feet and I think it is the best sailing lake in Colorado.

What would you have done??

 

[Rick Macdonald]

I'm to the northwest of you, west of Red Deer Alberta Canada. On my smartphone I have bookmarks to three government web pages. Satellite animation of cloud cover, lightning strikes, and radar. The radar gives a 3-hour history of 20 minute nap shots. I keep an eye on approaching storms with the radar app. It has saved me many times. When I first got my boat 15 years ago I made the mistake of thinking that if a storm cell on the horizon was downwind, that it was moving away from me. Storm cells suck air up from all directions causing the towering cumulus nimbus formations. So even though the wind is going towards the storm cell, the cell can be approaching me dead-on. Having the radar app has made all the difference in the world. Simply watching clouds on the horizon has gotten me Hammered more than once back in the day!

 

[walt]

I dont have the same boat but Im possibly going to move to Lake Grandby for the summers in a couple years. That is about my favorite lake in Colorado but you have to really respect those storms especially during monsoon season. FYI, I currently sail often at Elevenmile and used to keep a water ballast Mac 26S there.

My .02 for your situation (which I have been in many times..). In places like that, you can usually tell by the clouds building that something is going to happen but what exactly will happen is going to be very unpredicable especially with the mountains all so close by. So you have to be able to reef both main and jib when its howling and if you single hand, you have to be able to do that yourself. I used to have a hank on jib and could drop it from the cockpit with a downhaul. Now I have a roller furler so can furl it from the cockpit.

I have to go up to the mast for my main halyard control and slab reef. Normally I would want to reef my main before reefing the jib - so I would have the jib deployed when I wanted mess with the main. In this case, I would put the boat in "heave to" (go to youtube and search on that term.. lots of videos on how to do it). Boats differ a little but when Im in heave to, the boat will be drifting about a litle over a knot and Im able to go up the mast and either reef it or drop it as I can stay in heave to with the main sheet loose. I can do this in a lot of wind. When doing this single handed, its of course a good idea to have a harness and be clipped in. Once you have the main taken care of, you can then reef or drop the jib which is a lot easier.

If you have an outboard, you could start it, get some forward motion directly into the wind and use some method to lock the tiller in place. This gives you some time to mess with the main and you may need several iterations of going between the tiller and main before you have things under control. This is also a good place for an auto pilot. Get the motor running with some forward motion, set the direction into the wind and hold it there with the autopilot while you drop the main (or raise the main).

Elevenmile is more of a fishing boat lake compared to Grandby and when those storms would come up, every power boat would beat me back to the docks (no slips there). So in those fast but fairly violent storms, I would just go to as protected of place I could find and drop the anchor and just wait it out. The storms that come up fast usually leave fast also. If you have to wait it out on the water, try and sit somewhere as far away from the bottom of the mast as possible (lightning). An easy and fast to deploy anchor helps here especially if you are single handed.

I would love to hear more about the overall sailing season at Grandby.. but that is not the topic here.. LOL.. Ive only sailed up there with my Hobie TI and its always been about this time of year.

 

[markwbird]

The old rule comes to mind, "If you think you might need to reef then you need to reef."

 

[walt]

Spend some time sailing at over 8000 ft elevation with close by large objects that screw with the wind (mountains) especially during monsoon season to understand this a little better. Ive had mostly good sailing experiences at Lake Grandby but one time the wind would make seriously large changes in speed and direction about every 15 seconds.. Craziest wind I have ever seen (almost). Within literally several minutes you might go from "this is fine, no need to reef", then to hmm.. maybe I need to reef... then to HOLY CRAP.. Hmm.. you had about 30 seconds to get that reef done.

 

[Dave@Granby]

I did not have the jib up because the short halyard that holds it at the top of the furler track had broken or come loose, allowing the sail to start creeping down the track. Can't fix it until I drop the mast.

The forecast for that day was for 76 degrees, 5-10 mph winds and 20% chance for scattered showers. If the forecast is 10-15 I go out with a reefed main. 10-20 and I don't go out. I had been watching this buildup for about 2 hours and it was barely moving or increasing in size. The ominous warning was when the virga started to fall. This was what they call a high base dry tstorm and the virga can produce these microbursts. I actually thought about that, but I talked myself into thinking it wasn't coming my way. The wind actually did a very odd thing right before the blow hit. It reversed direction 180 degrees just before... sort of like the ocean will go out to sea just before a tidle wave hits, I think.

Anyway, to make matters a little worse, once I did get the main down, my brand new Tohatsu 6hp would not run above a fast idle, leaving me ahull in the waves. I have put in high altitude jets in, which are even tinier than normal and the main jet had some blockage, probably from all the thrashing about. I learned a helpful trick... pull the choke full out and in a few times and the increased suction on the jet cleared it.

Finally, under control made it to a sheltered cove and anchored. Opened up the box of Franzia to fix the final problem.

I have sailed most of the bigger lakes in Colorado. Always wanted to try Eleven mile. The reason I like Granby is because it is very large, you can anchor out overnight, and the winds are fairly consistent, always coming up around noon. Dillon is beautiful, but it does not have any of those three advantages. The biggest disadvantage at Granby is the short season... Jun-Sep. I have anchored overnight so far this year 20 days.

 

[Pat]

Your radar's can now indicate the relative wind speed and direction of the wind, i.e. either toward the radar location or away from the radar....whichever is applicable would be shown by either red or green which is important you know your own location in relation to radar site.. This has proven helpful several times....the color of the wind line
will tell you if the wind (whatever the speed is indicated by the color) down draft or straight line winds are moving your way or away...but you do have to know your own location at that time, in relation to the radar...we seem to get a lot of straight line winds that are downdraft winds from a storm, hitting the land and where they are headed..the secret is not being where they are headed..pat

 

[Rick Macdonald]

Dave,

I forgot to ask if you have cell/data service on Granby? You need that to watch weather radar.

The abrupt wind shift is part of what I described. The surface winds you experience while watching buildups in the distance don't tell you where the storm is tracking. Where I live, the wind shift is always accompanied by a very noticeable drop in temperature. But by then it's usually too late unless you're very close to your marina!

After I got caught by storms a couple of times I got cautious and would leave the lake when any appreciable buildup could be seen. But then about 80% of the time it would bypass my lake totally. With the radar I can see where it's going and have plenty of time to get off the water.

There are probably better sites, but this is the first one I found. You want one with some history/animation to see where it's going:

https://www.accuweather.com/en/us/colorado/weather-radar

Granby looks to be surrounded by hills. I can see the Rockies from my lake but I'm not right in them. I can't say if the radar pictures will help you as much as they do me but look for a couple good sites and compare what they show to what you experience locally around the lake as those storms pass near you.

 

[Dave@Granby]

Granby has good 4glte coverage on Verizon. I watch several weather sites that have realtime Nexrad. I had checked the forecast, but this little storm wasn't showing itself as very big on Nexrad. It was just a deceptive little thing. The sun was shining. I usually head for cover whenever I see anything gray and building and looking to come my way. This time I didn't. Next time I will.

 

[VT Fitz]

The old rule comes to mind, "If you think you might need to reef then you need to reef."

Actually, I think it goes more like, "If you think you might need to reef, IT'S TOO LATE!"

 

[GGordonWoody]

The waves went from ripples to about 5-6 feet with streaming, frothing whiecaps.

Whoa dude! No way I'm ever seeing water that high. But if I ever did, I would have done exactly what you did - sail the boat and live to drink another day. Ok, I might have sheeted out, not in, just to spill some wind. Oh sure, definitely a flat main should move the center of effort forward, and reefing may have helped, and, oh yeah, I guess you could have rigged a tri-sail too. Blah-blah-blah, it means working a bunch of stuff when you're hanging on in terror. Short of placing a call to Skip Novak or @Dennis Kitchen, like you, I would be focused on keeping her on her feet using the tiller and the main sheet. Period. And I think Dennis has mentioned the single reef on the H23.5 doesn't depower very much anyway. Probably good you didn't get the jib out that day! Great story, I always learn good stuff from this forum.

 

[Rick Macdonald]

The reef on my 1995 H23.5 depowers quite a bit. I've been told its height is about where a 2nd reef would normally be placed.

 

[Daveinet]

At 30 if I had someone with me, I'd probably have just sailed it. Have done that once and had a blast. Above that, you have a couple of choices. In my first boat I had a burst of wind kick up while single handing. No warning, it just hit. In that case, I actually steered down wind, which kept the boat upright. Then blew the jib. I had a down hall, so I could pull it down from the cockpit. That got my under control enough that I run up front a secure the jib. I then just sailed with it, till it blew over.
If you don't have some form of Lazy Jacks, I suggest you setup some. Being able to get the main down in a storm and not loose it in the water or having it still be under power and catching wind while it is down can be critical. When we got hit with 50 mph winds, we just let the boat flounder while we pulled the sails down. Its surprising how much lack of steering you can get away with while you just deal with getting the sails down. Even though I had family with me, I still had to help get the main down. The boat its self was just fine getting blown about.

 

[Dennis Kitchen]

I think Rick is correct that the standard reef point on a H23.5 is at the place of a 2nd reef or close to it. It's really not deep enough though above about 25 knots of wind, at least not on my original baggy with shrunken bolt rope on the foot. But with a good sail and the luff and foot hauled tight as possible to flatten it this boat will sail! Hang on!
Dennis