Does this occur in Merlins?  Is there any (photographic) evidence of it?

Bethwaite reckons this is partly dependent on power to weight ratio.  How light would we need to be to plane upwind easily?

HAPPENS MARGINALLY OCCASIONALLY GIVEN GOOD SEA STATE AND CORRECT BOAT SET UP FOR CONDITIONS AND LOTS OF WIND.  ABOUT 10 KILOGRAMS.  LET'S DO IT.

Either that or a shed load of weight in the boat 20MPH winds and some balls!

This was discussed on the Y&Y forum recently. I think the outcome was that you can't really tell, and it doesn't matter. What is planing anyway? How can you identify the point when it starts to happen?

This is as close as it gets 
http://www.yachtsandyachting.com/photos/?s=64&PID=852

Isn't planing defined as when a boat lifts up over its own bow wave - you normally notice the sharp speed increase.

Thanks Guys.

It would appear that Guy Winders (frankly excellent) article in the library takes care of all my questions.

Essentially he says that it does happen in high wind (proven with GPS etc), it could happen in lower wind but we'd need to lose 10 kilos out of the boat or change the sail plan.

LET'S DO IT THEN.  10KILOS OUT. OR WHY NOT 20.  THAT WOULD MAKE A DIFFERENCE.

This is the thread on the y&y forum. Lots of technically-minded people adding their 2p.

http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=1476&PN=3

WHy not just lose the weight from the crew?  Surely some of our experts could come up with a Merlin Class diet!!!!!!!!!!

I AGREE TO A POINT.  HOWEVER THE MASS IS MUCH MORE USEFUL A METRE FROM THE CENTRE LINE THAN UNDER THE CENTREBOARD CASE.  AND I DON'T THINK THERE IS A 1.4 STONE, LET ALONE NEARLY 3, WEIGHT RANGE IN THE TOP 15 BOATS.  QND WE WOULDN'T HAVE TO PULL IT UP AND DOWN THE BEACH.

I'm thinking of cutting off my left leg

Enough already!!!  See the previous thread on weight reduction, we've been here before.......AND WHY THE NEED TO SHOUT?????

OK, so a reduction of 10Kg or even 20Kg out of the hull would get the Merlin planing upwind in a wider wind range, but the difference would not be that drastic or exciting - note the light weight Tasar which already planes upwind.  Those with older overweight devalued boats would be disenfranchised; would this minor gain in upwind performance attract enough new boat buyers to offset the loss of these owners?  

Note the effect weight reduction (and double bottoms) had on the National 12.  Is a split fleet and reduced fleet numbers really worth a small upwind performance gain now?  Consider that the earliest boats that can lose that amount of lead are the Winder Mk2s, currently appearing on the s/h list at £8000 upwards.  Given that the class is already perceived by many as expensive, what impression would it give if entry level minimum weight (read competitive) boats cost this much???  

As the MROA committee have concluded before, weight reduction will probably come eventually.  However, until a bigger proportion of the fleet is comprised of boats carrying 10Kg plus correctors, this would be very damaging to the class.  At the moment the Merlin is one of strongest racing classes - great fleet racing, new boats being built, competitive older s/h ones available.  Why fix what isn't broke?

If thee wants faster to go get a Brig(ferrari to you oiks) 
 or a 49er.18 skiff, int 14, etc etc.

You should probably add full battened sails, no restrictions on leech profile and perhaps concave topsides to the requirements. Smooth hull would help too. Be a nice boat, but not a Merlin...

Can confirm that NSM4 will exhibit this behaviour in a force 6.

Good fun too!

let's see the evidence! hand a camera to your crew as they hike out - should have one hand free...........