Stability More or Less

The suggestion of  changing from iron to lead ballast on an Albin Vega 27

 

If we went to the trouble of changing the existing ballast to lead on an Albin Vega 27.   The centre of gravity (CG) of the total ballast could be lowered about 9 cm (3 1/2").  This could be useful for those seeking head room or storage.

 

The centre of gravity of the whole boat in cruising trim 2800 kg or 6175 lbs is lowered about 25 mm (1").   

 

Is that significant?  Well it would be a lot of work.  I changed the ballast on my previous sailboat a Halman 20 from steel punchings to lead and although it made the boat stiffer  her performance suffered slightly.

 

What does this mean in terms of increased stability when sailing.  In the drawing taken from the original owners manual at the amidships section of VEGA is shown the specs for a heeled angle of  20°.

 

The length of the righting arm is 32cm (121/2") and the righting moment is consequently  896 kg (6500 ft. lbs).

 

With the new lower centre of gravity (lead)  The righting arm would be increased by 9 mm 3/8" that is it.

 

Heeling at 30° the increase would be 12,5 mm (1/2") and the righting moment to 921 kg

 

This is an increase of 25 kg (180 ft. lbs) or 2.8%.

 

Important to note the manual states that the same increase in righting moment can be achieved by increasing the weight of the boat by 75 kg (165 lbs) or by moving one person weighing 80 kg (176 lbs) a distance of 31cm (1 ft.) to windward.   Allowing a light boat for the bay sailor interested in winning races and providing reserve ballast to be used by the long-distance cruiser or family sailor.

 

 

What I get from this is that the current design is an optimal one.  If you are the dude who likes to race around the bay the Vega is a light displacement sailboat and perfect.  For a cruiser ( for example) diesel fuel weighs approximately 7.2 pounds per gallon.  giving you room for an extra 23 Gallons which consequently increases your engines range by about a full day of motoring.  ( you could have a little more rum).   Food comes in at  5 to 6lbs per person per day.   Suffice it to say, this is  a beneficial thing.