Heavy Guys Spinning Out

[wnethercote]

We have a couple of 'heavy' guys (220lbs +) in Nova Ice yacht Club who struggle in medium to heavy winds because they spin out a lot.  They run stiff planks as you might expect, and normally set their runner planks full aft because they rarely hike at all.  They align their runners with the plank under load (weight plus 30lbs) and set the chocks for runners vertical.  They typically run 36 inch by 3/16 or 36 by 1/4 inch inserts.  Both run composite masts: one a Sherry and the other a Kent.

One of these fellows runs Kent-style chocks on his own plank and wondered if perhaps this type of chock wasn't stiff enough for heavy guys.  But Jeff Kent (with apologies :-)  ) is no lightweight either.

I speculated that moving the plank forward might put even more load on the side runners to make them 'stick' better.  Yesterday one of them tried this, with no effect, but then borrowed a 115 lb/inch stiffness plank instead of his own 135 lb/inch plank and the problem went away.  This suggests that he should set up his chocks so his runners have a little bit of negative camber (to use automotive talk) instead of being vertical.

Other thoughts?

Warren Nethercote, KC 3786

[eric_anderson]

Over the years I have gradually moved from very stiff planks to reasonably soft ones.  What causes a boat to spin out?  2 contributing factors are bumpy ice and gusty winds.  In both cases a soft plank helps.  Stiffer planks seem to be more difficult to sail in heavy wind.
A soft plank does not loose contact with the ice as much when you hit small bumps- better shock absorption.  When the blade looses contact with the ice there is nothing  to prevent you from starting a spin.
 At the same time a soft plank bends under load from gusts which mitigates  the power of the gust.  The increased power of the gust can start a spin.
The other thing is that runners play a big part.   Heavy flat sharp runners at 90 degrees helps.

In big breeze, if I am going to spin it will usually be in a gybe.   After you gybe, until you get the mast bent out on the new direction, the sail plan is a lot more loaded which in term loads the runners.   
In moderate conditions, I gybe and head up above my final course to get the mast bent out and speed back up then come down to my final new course.
If it is blowing hard and the ice is hard, I usually “stutter” gybe.  I start a gybe, and as soon as the boom comes across I keep the bow low.  I over sheet to initiate mast bend, and  then ease the sheet  to prevent a stall as I head up gradualy to the point that I can hold the boat down.  If I gybe aggressively, there is a good chance I will spin.

Just my opinion
Eric Anderson US 5193

[rlc]

As a 220lb+ sailor it seems to me there are several considerations here.  I think Eric is correct on the plank stiffness, but what about runner profile and sharpness?  If these guys are sailing around on really flat runners that aren't very sharp, they are likely to get into trouble. This is especially true on some of the rock hard ice I sail on in Wisconsin, but I'm not sure how relevant that is in NS.  In my own case I tend not to sail around on really sharp runners.  They are not flat and have about about 20 inches of .008 crown, if not more.  I also don't sail on 90 degree runners all that much, as 95 or 100 degrees seems to be adequate until it is really blowing.  I try not to make sudden sharp maneuvers, but outside of those situations, spinning out is not something I worry much about.  I'm not real fast, so some other opinions might be worthwhile.

US3433