Weighing | SB20 Class


SB20 Weighing Procedure

These notes are for the guidance of measurers or owners when weighing SB20’s. The SB20 Weighing Procudure is avaiable to download:

SB20 Weighing Procedure

The weighing needs to be done indoors in dry conditions or on a low wind day out of doors to get fully accurate results. However in 2008 it is so important to get a reasonable fix on what your boat weight by June 1 is that you should try and weigh even in less than perfect conditions and expect that you will get a reading that is up to 10kgs overstated. You may have to be weighed again later or just estimate extra lead to compensate until a better weight is possible.

Allow 20 minutes per boat on the crane and allow each owner time to strip all the movable gear and sails and kite bag anchor engine etc out the boat and sponge it dry before starting any lift.

Equipment Needed

– Certified Crane Scales                  1 Tonne capacity
– Chain Hoist                                       1 Tonne capacity (if no crane available)
– Padded counter weight of about 10kgs – preweighed and weight recorded.
– Spare 25mm certified lifting shackles
– Certified lifting straps
– Bright torch and batteries.
– Absorbent sponges and wipes.
– Notebook and pen.

Boat Preparation

– Ensure all equipment and ropes are removed, including spinnaker bag. Traveller rope, Tack line, Back stay and Jib cunningham rope may be ignored.
– Mast and boom and rudder and tiller and any fittings screwed to the boat can be left in situ.
– Keel crane is best be left in boat an weighed separately afterwards. They weigh approximately 11.kgs.
– Fit Styrofoam keel wedges.
– Spi pole and tack line should be left in situ.
– Make sure everything has been removed from down below. Use the torch to have a thorough look including in the bow.
– Ensure the boat is completely dry below decks. (damp is not good enough) You will find you need to tip the boat 101-5 degrees bow down and rock from side to side to make sure all the water is out. Do not forget to sponge out keel post socket.
– Engage keel hoist and raise keel just clear of trailer
– Disconnect boat from trailer tie downs, including winch clip.

All up weight

– Tare scales to zero with straps, shackles etc
– Fit straps and take up the load on the hoist whilst placing the lead counterweight in a position which facilitates lifting the boat level, usually towards the bow. If weighing without the mast, the counter weight may need to be directly on bow.
– Lift boat slowly until it is clear of the trailer, particularly at the bow and then check readout on scales.
– The boat needs to be still before a reliable reading can be confirmed. Make a note of this number.
– Deduct 21 Kgs for counterweight (assuming it is 10kgs) and keel hoist post.
– Add if not weighed with these items –
30 Kgs for Mast (If it was not rigged on boat)
7 Kgs for boom
10 Kgs for rudder and tiller
– The balance is the all up weight of the boat as defined by the rules.

It is advised but not essential to check these assumed weights are correct.
Keel weighing

It is recommended that you check what your keel weighs – the class weight limit is 327kg
– Lower keel onto trailer
– Remove keel post
– Tare load cell
– Attach to centre hoist on top of keel.
– Remove Styrofoam keel wedges.
– Lift keel very slowly with some one in the boat preventing the keel from swinging forward and hitting the front of the keel box.
– The keel needs to be lifted only about 300mm to be clear of the trailer bed.
– Swing keel gently fore and aft to ensure it is not touching anything.
– Note reading on scales.
– Lower gently to trailer bed.
– Fit post and re hoist keel on it gently until it swings into its natural resting position.
– Put wedges back.

Inaccurate readings will arise in the following circumstances:
– The boat is damp down below or the keel post hole has water
– The outside of the boat is damp or wet
– Wind which moves the boat will lead to incorrect readings.
– Keel weighing may be affected by friction in the keel box.
– The boat cannot be reliably weighed if there is any evidence of damp or lying water. Water easily gets trapped behind bulkheads and needs the jockey wheel lowered to its minimum for several minutes to get all the water down below to run far enough forward to be sponged out. On a warm sunny day a damp boat sponged out will be dry enough to weigh after 4 hours provided hatches are left open for adequate ventilation.

Note for Measurers.

– Please remember to be courteous to the owner.
– Weighing a boat is always traumatic for an owner and it often does not take much to upset him.
– Explain everything clearly and if you do not believe the boat is in a state to be weighed be considerate of the effort the owner has already made to bring his boat to be examined.
– Always provide a written record of the weights and any lead correctors needed to be fitted.
– Check and double check your adjustments before volunteering any data about the weights.
– Never offer advice about how to remove or add weight. You may be misunderstood or misquoted subsequently.
– It is a responsible job being a measurer, always be mindful of the reliance people place on you to be accurate and perform your role carefully.
– If you find the boat is overweight – then recheck thoroughly that it is dry and no water is trapped below.
– If still overweight then check the website for guidance on procedures permitted.
– Older boats tend to add weight with age and to add 2-3 kgs a season is not unusual for dry sailed boats – more if kept in the water.
– If the boat is underweight you will need to add lead by June 1 2008.
– The procedure for this is also on the website and in the rules.
– Knowingly racing without lead when it is required is a serious offence and rule 69 may apply.