sv Sine Metu
1963 Columbia 24, Hull No. 30 (Glas Laminates, Costa Mesa, CA)
- Length Overall 24′ 4″
- Length Waterline 18′ 0″
- Beam 8′ 0″
- Draft 3′ 8″
- Displacement 4050 lbs.**
- Sail Area 300
- Displacement To LWL = 383
- Theoretical Hull Speed = 5.69
- Sail Area To Displacement = 16.42
- LWL To Beam = 2.25
- Motion Comfort = 24.1
- Capsize Ratio = 1.87
- Pounds Per Inch = 515
- Original CCA Rating of 18.1
- PHRF rating is around 258
*Please credit Ted Brewer for these numbers and algorithms and much of the verbiage below. His book Ted Brewer Explains Sailboat Design is well worth study.
- B/Disp | Ballast / Displacement is an indication of stiffness and expressed as a percentage. Stiffness has to do with how much sail the boat can carry before heeling and so has a relationship to achievable speed. In other words, people cruising are likely to reduce sail if the boat is heeling dramatically and making the voyage less comfortable. A boat that can carry more sail before heeling can be sailed faster more comfortably.
- D/LWL | Displacement / Length ratio allows us to compare the displacement of different sized boats as being in a “weight class”. Originally cruising hulls were expected to be 300-400 or higher, but modern design is driving these numbers lower. You still want to see over 200-250 for an offshore cruiser and some of the most respected cruisers are much higher.
- SA/D | Sail Area / Displacement area in a non-dimensional number that gives an indication of light air performance. It is calculated as Sail Area divided by Displacement in cubic feet to the 2/3 power or in spreadsheet language: SA / ((Displacement /64)^.67) Note that displacement is divided by 64 to convert pounds of displacement to cubic feet of seawater displacement – seawater weighs 64 pounds per cubic foot.
- Comfort or Sea-Kindliness is a Brewer-invented term to account for motion comfort. A motion comfort number of 40 or more is quite acceptable. Note that smaller boats, having a higher beam/length ratio, have lower comfort numbers. Displacement in pounds/(0.65*(0.7*LWL + 0.3*Length)*(Ballast^(1.33)))li>
- Capsize Ratio (Cap R) Capsize Ratio should be under 2.0 for cruising boats. Lower is better for offshore use. Beam /((Displacement/64)^(1/3))
- Hull Speed is calculated from water line length: (1.34*(LWL^(0.5)))
** 4,050 pounds of displacement is without personal belongings, food, and crew. I will assume about 1,000 to 1,200 pounds will be added to the computations when Sine Metu is fully laden and ready to cruise.
- Engine System: 100 ibl Quietorque™ electric drive system from Electric Yachts.
- 48 volt, 3.8-kilowatt brushless electric motor.
- One bank of four, 50-amp hour Battle Born Batteries’s LiFePO4 Lithiums: Wired in series to a 48v configuration. There is also a 100-amp hour battery powering the house 12v systems. There is redundancy between the systems as the 48-volt side can charge the 12-volt side if needed.
- eDrive specs and performance curves can be found on this page.
- This is a photo of the original cast bronze tiller plate on this Columbia 24 and shows the boat’s pedigree; that it was built by Glas Laminates in Costa Mesa, CA in 1963, and that it is Hull No. 30. “Also of note is Columbia’s early model numbering scheme. During the mid-sixties, Columbia made three 24 ft models concurrently: the C 24, the Contender, and the Challenger.” Columbia Yacht Owners Association’s Hull Information tab.
- Soda blasted hull clean, applied three layers of Interlux Interprotect 2000e epoxy barrier coat (alternating white and gray layers), and painted two coats of black Interlux Ultra antifouling paint in July 2011.
- 1,800 pounds of lead ballast is fully encapsulated in the keel. There are no keelboats to fail on these little tanks.
- The prop is a custom made 3 blade and overpitched to 10:12 to take advantage of the electric drive’s high torque at low RPMs.
- This is a scan of Columbia’s / Glas Laminates early marketing efforts.
The original price lists can be found here: sailingsinemetu.files.wordpress.com/…/columbia-24-price-sheet.pdf
Hi, I stumbled upon your website and found it interesting. I have a Columbia with electric drive too. I am happy so far. I would like to know how you chose 120ah for engine batteries and 480 for the 12v/ house. My set up is 240ah for 48v and 240ah for 12v.
Sailing Sine Metu said:
The choice boiled down to saying yes to a pallet of brand new Lithium LifePO4 batteries or not for the traction bank. 120 AH at 48v is the most such batteries could be configured: my 12v system consists mainly of a 48v-12c DC to DC converter that can power all of my electronics (backup system) and two, 100 AH AGM batteries as the 12v primary system. This is charged via the 48v system by a Morningstar Tristar 45 charge controller (which is also a backup for the Tristar 65 charge controller for the eventual wind generator (an AmpAir 100 or a SilentWind)) and solar panels.
Are you using lead-acid or Lithium batteries? If you accept the ‘standard’ notion from those who are knowledgable in such things*, the general rule of thumb is that 120 AH of Lithium is about the same power as 240 AH of lead-acid batteries.
* Lithium batters can be 100% discharged without issue; Peukert’s effect; 2,000+ cycles; very quick recharge rates; and weight considerations.
For budget reason and ability to replace potential failure I used lead acid 6v batteries. The main bank serve for the edrive but can also fill the 12v bank via dc to dc converter.
If I had the money I would have invested in LofePO4 to reduce weight and space, but I am happy with the behavior of my edrive so far. What is the range on your setup?