Here is a link to an explanation of the comfort ratio calculation and an excerpt from the article.
https://wavetrain.net/2011/10/15/crunching-numbers-brewer-comfort-ratio/#:~:text=To%20calculate%20Brewer's%20comfort%20ratio,length%20is%20expressed%20in%20feet.
To calculate Brewer’s comfort ratio, you need to run the following formula: Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam↑1.33), where displacement is expressed in pounds, and length is expressed in feet.
As an example, let’s again consider a hypothetical 12,000-pound boat with a load waterline length of 28 feet. Let’s assume it also has a length overall of 35 feet, and a beam of 11 feet. Therefore, to find its comfort factor, we first need to multiply its LWL by .7 (.7 x 28 = 19.6) and its LOA by .3 (.3 x 35 = 10.5) and should then add these two results together, which gives us 30.1 (19.6 + 10.5 = 30.1). Next take the boat’s beam to the 1.33 power, which gives us 24.27 (11↑1.33 = 24.27), and multiply this result and the previous result by .65, which gives us 474.84 (.65 x 30.1 x 24.27 = 474.84). Finally, divide this result into the boat’s displacement, which yields a comfort ratio of 25.27 (12,000 ÷ 474.84 = 25.27).
What the formula purports to assess is how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. The formula favors heavier boats over lighter boats, as more weight always helps to dampen a boat’s motion, and also favors boats with smaller waterplanes. This refers to the horizontal plane on a boat’s waterline and is generally a function of length and beam. Boats that weigh less and have more waterplane tend to have a quicker motion, because more waterplane means there’s more area for waves to push up against and less weight means there’s less resistance to the pushing.
Longer boats obviously have larger waterplanes than shorter boats, but the exponential increase in their displacement always negates this. As a result, the comfort-ratio formula also favors length, though it penalizes beam. Generally, it favors heavy boats with overhangs and narrow beam, but longer boats may have considerably lower D/L ratios than shorter ones and still fare much better by comparison.
You can use the following guidelines to interpret comfort ratio results: numbers below 20 indicate a lightweight racing boat; 20 to 30 indicates a coastal cruiser; 30 to 40 indicates a moderate bluewater cruising boat; 50 to 60 indicates a heavy bluewater boat; and over 60 indicates an extremely heavy bluewater boat. If evaluating a larger boat, say 45 feet or longer, expect your results to be skewed a bit higher on this scale; if the boat is quite small, say 25 feet or less, they will be skewed slightly downwards.
Once again, increasing displacement to account for loads carried seriously affects results. Our hypothetical 12,000-pound boat, with its comfort ratio of 25.27, becomes decidedly more comfortable as we load it to cruise. Add on another 2,500 pounds for light coastal cruising, and the ratio rises to 30.5; make that an extra 3,750 pounds for bluewater cruising, and it becomes 33.16.
The 26 is listed at 8500 lbs displacement but at the annual bailout she usually tips the scales at 10,000. I suspect the 30s which are listed at 11,500 more often come in above 13,000. Filling the big water tanks and lockers quickly add on the pounds.
Mark Powers