displacement of our c34's

[Ted Pounds]

Ray,
Sorry to burst your bubble, but displacement and weight, as you use them, are EXACTLY the same.  Displacement is, as you say, the weight of the water equal to the volume of the boat below the water ("the weight of the water that is displaced").  To use your Catalina example if you put a boat in a full tank of water and weigh the water that spills over the sides it will EXACTLY equal the weight of the boat.  Now it is true that the VOLUME of the water displaced will vary depending on the density of the water, but the weight stays constant.  There is also another meaning for displacement, which you alluded to, with regards to documenting (sort of a federal registration) a vessel.  That has to  do with cargo volume which, obviously, is based on the volume of the boat.  It is also measured in tons, but has nothing to do with the amount or weight of water the boat displaces.

[Gary]

The following is from an earlier post called C34 Displacement and Tonnage.  Furthur info on the same topic.

According to our survey Gross tonnage is listed as 13 tons.  Net tonnage at 12 tons. And displacement at +/- 11,950 dry.

What is Gross Tonnage?

Gross tonnage is a measure of the internal capacity of a ship, tug or barge. It is a cubic or space measurement of all areas of a vessel with some allowances or deductions for exempt spaces such as living quarters.

What is Net Tonnage?

Net tonnage is a measure of the internal capacity of a ship, tug or barge's cargo space volume only.

Displacement: the direct measure of the actual weight of a vessel. Displacement tonnage is the weight of water displaced by the hull of a boat. A vessel floating in fluid will always displace an amount of fluid equal to its own weight.

[tonywright]

We asked the crane driver who launched my MKII hull number 1657 last weekend. It came in at 18,300 lb. (8.3 metric tons). This is with no mast, full fuel tank and empty water tanks. No gear on board except for anchor and rode. Two 122lb 4D batteries.

Where does the extra 5,000lb come from??  I guess I should not be expecting much acceleration under sail?

On that note, any opinions on the lifting points prescribed in the owner's manual? Most folks here set the aft lift point at the aft bulkhead rather than where Catalina has it marked in the manual.

Tony

[George Pyrpiris]

For what it's worth, I hauled hull #195 FKSR last month and the lift operator said 15000lbs but aprox. 14000 net , no water, no cushions, no provisions, boat was almost completely empty due to the work I was doing.  Boat is in water year round.  I thought that was heavy but at 18k lbs...wow...must be a mistake.
George
Fort Lauderdale, FL

[Stu Jackson]

If she still does 6+ knots in 12 knot breezes.....

[Ron Hill]

George : Your displacement sound about right to me.  Somewhere between 15000 and 16000 loaded! 

[Jack Hutteball]

For what it's worth, I finished bottom paint last weekend and asked the lift operator what the boat weighed as he was putting her back in...right at 1700 pounds with a full fuel tank and about 3/4 full forward water tank.  We have all the safety gear plus bedding and normal galley equipment on board.  Boat is not loaded for summer cruising yet.
Jack

[Jack Hutteball]

Oops, dropped a 0 there, should be 17,000

[Paul Blumenfeld]

I had my boat hauled this week and was told it came in at 18,000 lbs.  Full fuel tank and full starboard water tank, aft tank empty.  I've got lots of stuff on it, radar, 8D and 2 GP 27 batteries, bow and stern anchor, two BBQ's, small Honda generator, food for three, and oh yeah, some spirits!  Seems to sail fine and doesn't seam to sit low.  If this weight is correct should I worry about water in the hull?

[Ron Hill]

Paul : I'd first check on the travellift's strain gages to see if they are correct, as 18K is a little heavy!  If they are correct then you could have water in the hull.   

[tonywright]

Just a reminder: mine weighed 18,300 without mast, and with empty water tanks. That was after sitting six months on the hard, with the temperature hitting -30 degrees celsius at times (a home freezer is set at -18). That much water would have split my hull wide open when it froze. Somehow I don't think the weight is water! Maybe a bit more weight in the wing keel?

Tony

[Ron Hill]

Guys : Travelifts are notorious for never having the strain gages recalaberated !!  Like any precision tool (i.e. torque wrench or scales etc.) the reading can't really be counted on if it hasn't been re certified/checked.
Most yards do have a moisture meter to give you an idea of how much water your hull has assimilated.   

[tonywright]

Mine was lifted by a mobile "construction" crane, that has mandatory regular calibration. It must be checked regulary, so that they know how far they can reach safely with the load, and not tip the crane off its legs.  When my boat clocked 18,00 plus pounds, the operator had to override the safety warning, in order to reach far enough to put me in the water.  Other C34's in our club read 16-17K.

Tony

[Paul Blumenfeld]

I think Ron is correct about not being calibrated or someone not knowing how to read them.  I was there with the yard owner when she went back in.  This time the reading was 15,500 lbs.