until you made the first topic post, it would be my opinion that 95% (or more) of the readers of the forum had NO idea what a Bruce Number was, let alone having them draw conclusions or correlations from the calculated numbers. Kind of like comparing horsepower to weight of a car, or sail area to hull length - not really useful information.
here are the numbers you requested:
<u>18 Square Meter catamaran </u>
194 sq. feet of sail area and 330 lbs.
BN = 2.016
7.64 sq. feet of sail area and 3.5 lbs.
BN = 1.819
9.72 sq. feet of sail area and <font color=“red”>(*est) </font id=“red”>5 lbs.
BN = 1.823
<font size=“1”><font color=“red”>(*Estimated final weight - under construction)</font id=“red”></font id=“size1”>
In order for my F-48 to meet the same BN as the 18 Square, I have to get the weight down to 3.7 lbs. which would be quite a challenge.
Missing in the above number, is ANYTHING to do with actual sailing weight, and actual moving ballast. Also how far outboard the ballast is placed, wind strengths, water/wave conditions, and rig tuning. That is why I’m saying the numbers have little if any use for r/c mutlihulls. In the end, it will be my boat against your boat around a closed course. If I can tack, gybe, pick the favored side of the course, get a clear air start, hit the wind shifts, and have a bit more boat speed than yours, you must admit that Bruce Numbers have virtually no impact how we would finish. In fact, based on a different post about slightly heavier boats having a possible advantage to “coast” thru tacks or light air lulls, a lower number might be “more” important.
Finally, whether you use one of Doug’s patented reefable rigs, or you grab the sail area off a 36/600 monohull for heavier wind - suddenly the BN numbers change again - and my question remains - “So What” and “Which One Is Important?” I would submit that my lower sail area and lower BN number would be “more” competitive in heavy wind than your full sail area boat in the same wind strength.
All we have successfully done is to create more confusion with “numbers” for the beginning sailor. Based on the posted numbers, it “appears” that Doug’s X3 (whenever it happens to appear) should be faster than my 18 Sq. Cat, and if I could drop 30 lbs. <font size=“1”>(easy if I replace aluminum mast with carbon)</font id=“size1”> on my 18 Square - getting the BN down to 2.08 I should be able to beat a 32 foot Warren tri - or a scaled UP Open 60 ??? Come on - No correlation whatsoever! If it is, I certainly would be happy to race my 18 Square against Doug’s X-3 for the <font color=“pink”>“pink ownership slip”</font id=“pink”>! [:-eyebrows]
In the end, if the owner can keep the multi on it’s feet, sail around the course and finish, it matters little what the Bruce Number is. His concern is how many boats were ahead of him as he crosses the line.
Regardless - those are the numbers for what they are worth. Readers can draw their own conclusions as to how “important” the Bruce Numbers are. To me, if I was a buyer, I would be more interested in the actual racing “pedigree” and finishing history of a boat in various wind strengths and regattas.
<center>(in my opinion of course)</center>