boat brands - prejudice or reality

[Chiara’s slave]

Bob Fisher had a great story about IOR quarter tonner behaviour downwind. A 2 handed race, his co skipper was below, catching a few zees, the wind was in the high 20s with a big quartering sea. As we probably all know, those tiny transom boats were a total pig, so our Bob was sawing away on the tiller to try to keep it straight. All well and good til the tiller snapped off at the stock, the boat immediately broached. Pinned down pretty flat, the guy inside came to the hatch and said, ‘honestly Bob, can’t you steer straight?. Bob replied ‘Here, you try’ and handed him the tiller. I bet we’re all glad boat design evolves.

 

[Laminar Flow]

I’d love to see some of that, since it is utterly contrary to my own experience of racing contemporary designs against 1970s designs etc. I’ve shown you race results before, you know where sunfast 3300s beat well sailed 40 foot older designs to the fastnet rock in a heavy airs beat etc.

And, we're off to the apples & oranges again.
While I have done some ocean racing, including one race of over 3500 miles, I am only really interested in cruising performance, notably of the passage making variety.
When I refer to cruising, I mean living on board for extended periods of time and a boat equipped with all the necessary accoutrements, a dinghy & outboard, proper and redundant ground tackle, a cast iron crock pot, full tanks and a complete and intact tooth brush.
We can also, I guess, agree that we are now talking about displacement speeds, up to a relative speed of no more than 1.5, as spectacular as that in itself may be.
In this context, absolute speed potential is of less interest, rather than the ability to maintain reasonably high averages. The most important factor here is SA/D and DWL.

To put this into some realistic context:
While there is absolutely nothing about our tub that even remotely whispers speed, we quite consistently average 6.43 kn or thereabouts on multiday passages. We weigh in at a ridiculous 8.5t on a DWL of 28.25' (D/L 360) and have a SA/D of not quite 18.
While 6.43 kn may not sound like much, it should be noted that this represents 90% of the boat's nominal hull speed and, to be clear, a modern 40 footer would have to average (!) 8 kn to equal it. In light airs, though not to windward, we quite frequently keep up with or beat similar size "modern" designs. This is not a miracle, but simple physics.

To note: 0.9 (1.63, if you prefer metric) is considered to be the "indisputable" (I quote from a variety of sources) average, relative speed for sailing yachts.

When it comes to displacement speeds, not much has changed over the last hundred years. The physics have stayed the same and not all "older" designs had an artificially reduced speed potential, to make them "relatively fast" in the context of rating rules either.

Yes, "modern" designs are much lighter and this will allow them a much higher, ultimate speed potential, given enough wind that is. Many also have much higher SA/D ratios than some of the "older design" examples commonly quoted.
However, once loaded to the same extent, as I've outlined, and in a comparable relationship as to size, much of that advantage disappears. I think it rather disingenuous to insist on comparing, not only stripped out racers, but often considerably larger boats with one another and in complete disregard to the laws of relativity and similitude.

I am not surprised that you find your newer and beamier boat to be a lot stiffer and, consequently, faster. As I have previously pointed out: stability increases to the forth power of the beam and therefore even a small increase in beam makes a marked difference. Add to this a hull shape that moves volume and hence buoyancy to the beam ends and you end up with a considerably stiffer boat. After all, RM = GZ x G. Alas, as with all things, there are tradeoffs. The last time we were in Bas Sablons, I watched a local evening race, where a much narrower X-Yacht sailed circles around a larger, not to say beamier, Pogo in light conditions.