On Thu, Mar 1, 2018 at 4:32 PM, Björn bjornmail@gmail.com [harryproa] <harryproa@yahoogroups.com.au> wrote:

 

What happens if the capsize was from pitching forwards?

A pitchpole where the boat ended up bows down would be a problem.  The self righting would not work.  There are a couple of solutions i am playing with, just need time.   However, I have pitchpoled my 7.5m test boat http://harryproa.com/?p=1753 a few times.  It always ends up on it's side with the mast pointing upwind, even when the true wind is close to dead astern.  Consequently, I am pretty confident that a pitchpole resulting in both bows going under would be pretty unusual (the boat would have to be well by the lee) and easily avoided by sailing a little higher.  

On Mar 1, 2018 04:36, "Rob Denney harryproa@gmail.com [harryproa]" <harryproa@yahoogroups.com.au> wrote:

 

On Thu, Mar 1, 2018 at 2:17 AM, ru-eno@online.no [harryproa] <harryproa@yahoogroups.com.au> wrote:

 

Hi Rob,
First I appreciated your updates on the 40-footer.  Nice looking!!!

​Thanks.​

About the self-righting.
Interesting concept, and it started me thinking for a bit.  Please bear with me for thinking aloud here..

​Go for it.  I need all the feedback i can get before spending time/money on a full size version.​

I assume this is for Bucket list, which is a racing machine and as such should be able to sail on one hull (or the two leeward ones) much of the time.  With slots for water entry just above your false floor the leeward hull(s) is not able to carry the weight of the whole boat unless it is already foiling.  So you need to get up on your foils well before the ww hull lifts.  For a very light foiler, this may still work, I guess.

​It is for any boat that fulfills the weight and buoyancy requirements.  Apparently, it was used on an A class cat in NZ 50 years ago.  ​

Maybe this could be made to work even if not foiling.  If the slots were higher up on the lw hull,  water would not enter the tank until the boat heeled over.  But then the water would not drain automatically after righting.  Slots at false floor level could then be opened by the crew to allow draining before sailing on.  But I suppose the problem here is that the tank may fill gradually during normal operation due to spray and waves.

​You are right about the lee side slots, they would have to be higher.  Draining could be through flapped slots, operated either manually, by water pressure or by gravity...  

Would it be better if the false floor (bottom of tank) was not horisontal, but tilted outwards (to lw), so the tank is more submerged when the boat is heeled over?

​Perhaps, but the drainage still has to happen at the lowest point​ and the higher this is, the less water will get in.  

Rune