[PUP] Objectivity in boating publications

[John Marshall]

Brian,
	Your willingness to put your data out there, both modeling data and  
empirical tests, is encouraging and hopefully will motivate other  
manufacturers. Its crazy to me that this info is so readily available  
for sailing passagemakers but as soon as we move to passagemaking  
under power, then most of that data disappears, to be replaced by the  
largely meaningless A/B ratio and similar.

	While sailboats run their model all the way to the limit, it makes  
little sense to run the model for most powerboats beyond 90 degrees of  
inclination. The house is in the water then and the model changes  
abruptly -- you either have windows intact and lots of buoyancy from  
the house, or the windows break and you fill with water and go down  
like a rock. I would like to see the model run at both light ship and  
heavy ship weights.

So kudos to you and the Pathfinder 48 for putting the data out there.

John Marshall
Nordhavn 55-20 Serendipity


On Sep 17, 2009, at 7:03 AM, Brian Smyth wrote:

> Hi John,
>
> I just wanted to comment on this...
>
> As you may know, we build custom boats, usually from other designers
> designs.  Stability information is usually available from the  
> designers, but
> we normally do an inclining experiment anyway to verify the  
> hydrostatics.
>
> On our new design, the Pathfinder 48, we are including a full  
> stability
> booklet in the owner's manual.  This isn't really a big deal because  
> you
> only need to do it once for the design, and it provides the owners  
> with all
> of the information they could ever need.
>
> Any other Manufacturer should have this information available as it  
> gets
> generated during the design phase.....
>
> So, I guess I'm saying - I agree with you, it should be made  
> available!
>
> Brian
>
>
>
>
> I for one would like to see them push manufacturers to provide
> stability data (even if its just modeled data) on any boat that claims
> to be suitable for passagemaking.  There are programs that can
> estimate it based on detailed manufacturer inputs, and that should be
> one of the basis for comparison of boats. But its data that is rarely
> available for trawlers, or what data is there is presented in such a
> way that its hard to compare.
>
> A magazine editor could define the parameters that the boat
> manufacturer needs to provide and do their own run on the standard
> software that's available to any naval architect. If the boat builder
> wasn't happy with the results, he could defend why his boat does
> better than the model predicts. That would at least provide a first-
> level estimate of all reviewed boats, measured with a common  
> yardstick.
>
> Just one suggestion.
>
> John