International 14 B6

My goals for the B6 design were as follows:

  • Increase pointing ability. 14’s are now 10+kt boats upwind but you still judge laylines by looking over your aft shoulder! Since righting moment is fixed, the best way to increase point is to reduce drag, both above and below the water.
  • Reduce cost. Since adopting prepreg construction in the top boats about 5 years ago, the ready to sail cost of 14’s has risen to around $50k USD. I cannot stomach that reality.

I’ve attempted to increase pointing ability by trying to reduce drag wherever possible.  Under the water, I have reduced the width of the hull to what is basically the practical minimum allowed by the rule.  This should reduce the windage and added resistance in waves.  Although removing it would reduce the cost of the boat, I have kept the jibing centerboard design since it improves the efficiency of the daggerboard (by allowing it to be smaller) and it reduces the added resistance from the hull due to leeway (more important in this design because of its deep forefoot).  Over the years, I have had a lot of experience watching fuller bows outperform finer bows in boats that have a lot of power for their length, the most obvious example being the IACC yachts.  It may be startling, but a 14 has approximately the same displacement to length ratio as an IACC yacht, so I think it is a fair guess to think that they would benefit from a fuller entry.  With the B6, I did this by fairing the boat out to a point 15cm or so forward of the bow whilst taking as much volume as possible in the mid stem (I am not a believer in the dreadnought bow on a 14 – why make it shorter than 14′ especially when you want to extend a bowsprit almost 3 meters forward from the upper bow).  I then “chopped” this surface off aft of the finished bow and faired it off with a parabolic surface so that the lower bow would be bulbous but not exceedingly blunt.  This “bulb” should just smack the water upwind in breeze but be fully submerged with the sharp portion of the stem at the free surface in light air.  It’s going to be really interesting to see how this shape performs!

Above the water, I have increased the height of the forestay to improve the effective aspect ratio of the rig and removed the upper spreaders and upper shrouds to reduce windage.  This has the added advantage of significantly reducing the rig weight (which is unmeasured weight in the 14 rule).  In order to keep the jib size reasonable (i.e. not make the main too small), I have reduced the J measurement.  This should allow us to achieve better headstay tensions for a given amount of shroud tension, further improving rig efficiency.  Since the hull is too narrow to provide a reasonable shroud base, I have moved the shrouds out onto stiff but relatively low windage rack supports.

Making the boat small helps minimize laminate area and hence reduces the advantage of using more expensive construction techniques.  The B6 hull and deck will be carbon/epoxy skins on a foam core.  The first boat is vacuum bagged wet laminate however I think our molds will work well for resin infusion.  I anticipate that we may offer a combination Eglass outside skin/carbon inner skin boat option to further reduce cost.  I have simplified the deck layout compared to the B6 by removing the underdeck chute trough and foredeck.  This reduces cost and should allow the weight to come in close to that of the prepreg B6.

-Paul