IT IS STILL A BALANCING ACT, BUT NOW WE THROW IN TIMING

AT POINT A IN THE SKETCH BELOW YOUR ARE APPROACHING THE DOCK WITH INTENT TO TIE UP.

AT POINT C YOU FIND THAT YOU HAVE LOST STEERAGE, BOAT IS DEAD IN WATER

WHAT CAN YOU DO AT POINT C TO HELP "SALVAGE" THE SITUATION.  IF YOU DO NOTHING, YOU WILL DRIFT INTO THE BOAT THAT IS AT THE DOCK. LOOKING BACK TO THE ARTICLE ON BALANCE IN THE AUGUST MAINSHEET, FIGURE 4, WE WILL SEE THAT IF WE PULL IN THE MAIN SHEET WE WILL CAUSE THE BOAT TO PIVOT INTO THE WIND.    ALSO AT THIS POINT THE MAIN SAIL WILL BE ABLE TO DEVELOP SOME DRIVING FORCE.  THIS WILL HELP TO GET US BOTH CLOSER TO THE DOCK AND PARALLEL TO IT.

HOWEVER, THE AMOUNT AND THE SPEED OF TRIMMING THE MAIN IN IS ALSO CRITICAL.  IF DONE TO FAST, THE BOAT WILL START TO PIVOT BUT WILL NOT HAVE A CHANCE TO GAIN ANY WAY, FORWARD MOVEMENT.  IF THERE IS NO FORWARD MOVEMENT THE RUDDER AND THE KEEL / CENTER BOARD WILL NOT BE EFFECTIVE.  YOU MAY STILL HIT THE OTHER BOAT.  IF TRIMMED TO TIGHTLY, THE SAME THING WILL HAPPEN. 

THE IDEA HERE IS TO TRIM ENOUGH TO GET THE BOAT TO START MOVING.  NOTE THAT THE MAINSAIL’S CENTER OF EFFORT IS A FAIR DISTANCE AFT OF THE CENTER OF LATERAL RESISTANCE.  THIS WILL TEND TO MAKE THE BOAT WANT TO START ROUNDING UP INTO THE WIND.  NOW THAT THE BOAT IS MOVING THE RUDDER WILL BECOME EFFECTIVE.  AS YOU START THE TURN TO GET PARALLEL TO THE DOCK, ONE WILL MOST LIKELY HAVE TO TRIM THE MAIN IN SOME MORE.  HOWEVER, WHEN YOU JUDGE THAT YOU HAVE SUFFICIENT SPEED TO MAKE THE DOCK, YOU WOULD ONCE AGAIN START THE SHEET, THAT IS LET THE MAIN LUFF AGAIN. 

IF DONE TO SLOWLY THE BOAT MAY NOT HAVE THE TIME THAT IT NEEDS TO START MOVING SO THAT THE RUDDER WILL AGAIN BECOME EFFECTIVE.  ALSO ONE MAY HAVE DRIFTED SO CLOSE TO THE OTHER BOAT THAT THERE IS SIMPLY NO TIME / DISTANCE TO TAKE DEFENSIVE ACTION.

THE QUESTION THAT THE OBSERVANT STUDENT MIGHT RAISE IS HOW DO I LEARN, FIRST TO AVOID GETTING INTO THIS SITUATION AND SECOND, HOW DO I LEARN HOW FAST TO DO THE TRIMMING.  THE ANSWER TO BOTH OF THESE QUESTIONS IS PRACTICE.  YOU JUST HAVE TO GO OUT AND TRY IT.  BUT TRY IT IN A SMALL BOAT FIRST.

PRACTICE IN A SMALLER, THEREFORE LIGHTER, i.e. LOWER MASS, BOAT WILL KEEP DAMAGE TO A MINIMUM.  THE BASICS ARE THE SAME.  THEN TRY IT WITH A LARGER, HEAVIER BOAT AT A VIRTUAL DOCK.  THEN AT A DOCK WITH OUT ANOTHER BOAT TIED UP AND WITH SOME CREW ON THE DOCK TO FEND OFF.

NOTES ON MASS, FORCE AND SPEED:   MOST OF US HAVE MADE THE OBSERVATION OR HAVE HAD DIRECT EXPERIENCE THAT THE BIGGER AND HEAVER SOMETHING IS THE MORE IT HURTS OR THE MORE DAMAGE IT DOES TO WHAT IT HITS.   THAT PROPERTY IS CALLED KINETIC ENERGY.  IT IS EQUAL TO THE MASS TIMES THE VELOCITY SQUARED ALL DIVIDED BY 2.  SO LONG AS WE KEEP OUR BOAT ON THE SURFACE OF THE WATER, THE MASS IS EQUIVALENT TO THE WEIGHT OF YOUR BOAT.   THIS KINETIC ENERGY IS VERY USEFUL THING.  IT IS RESPONSIBLE FOR KEEPING THE BOAT MOVING WHEN YOU TURN INTO THE WIND TO COME ABOUT.  IT CAN ALSO BE TRANSFERRED TO ANOTHER OBJECT WHEN THEY COLLIDE.  THIS HAPPENS WHEN ONE PLAYS POOL, BASEBALL OR TENNIS FOR INSTANCE.  IT IS ALSO WHAT DOES THE WORK TO TEAR UP THE METAL OF ONES CAR OR KNOCKS DOWN THAT POLE WHEN ONE HAS AN ACCIDENT DRIVING.

NOW YOU MIGHT ASK, WHAT IS THE VELOCITY OR SPEED SQUARED STUFF?  IT MEANS THAT IF YOU HIT SOMETHING GOING 10 MILES PER HOUR AND BREAK ONE EGG THEN YOU WILL BREAK 4 EGGS IF YOU WERE GOING 20 MPH.  OR THAT IT TAKES 4 TIMES THE DISTANCE TO STOP IF YOU ARE GOING TWICE AS FAST.  SO MORE SPEED GIVES YOU A LOT MORE KINETIC ENERGY.  THAT IS WHY YOU START SLOWING DOWN AT POINT B.  HEY, HOW ’BOUT THAT, WERE BACK TO SAILING AGAIN.

SO TAKE THAT SUNFISH AND PRACTICE SAILING UP TO THE FLOATING DOCK.  FIRST TRY IT ON A LIGHT WIND DAY.  THEN WHEN THE WIND IS BLOWING HARDER.  THEN MOVE UP TO A HEAVIER BOAT.  ONE THING TO WATCH OUT FOR ON THE CLUB’S FLOATING DOCK IS GETTING THE MAINSHEET SNAGGED ON THE CLEATS. 

HAVE FUN.

JIM

jimage@ucnsb.net

386-671-2548

We can be reached at 386- 238-SAIL (7245) or on the web www.halifaxsailing.org