-Hi Mike,
Don't want an argument but would appreciate a discussion. Can you give details to your objections to my ideas on the bows. If you mean an egg with the fatter part on the bottom for the bow, then I will agree, but it doesn't make sense to me to go the other way as you increase frontal resistance as you bury and increase wave impact. As well, you aren't keeping the boat as flat. Back from the bow the reverse is useful to provide a narrow boat with some decent accommodation, reduce spray and plausibly to provide hydrodynamic lift.
Another way of looking at it is that having the greater volume of the bows down low means you are peeling off the water and creating a hole rather than trying to force the ocean sideways.
Reverse stem ships coming out of the Scandinavian counties have shown significant savings in fuel economy and much better motion-
For the reverse stem consider the total time of impact of the bow on a wave. A reverse stem spreads the impact over a longer time and the angle of impact means that the pitching forces are damped hydrostatic ones starting earlier and spread over a longer time rather than the hydrodynamic forces reinforcing sudden increases in hydrostatic ones.
- In harryproa@yahoogrou
>
> Doug,
>
> While I'm not sold on Robert's reverse sheer idea (I like the egg
> cross section -- to each his own), I do think he has a point here.
>
> To test his theory, I'd cut two short hulls from scrap foam (30 cm and
> 45 cm each) and make some beams out of dowels or pencils.
>
> For the first test, attach the beams parallel for one test, buried
> into the hull pieces by at least 2 cm, and see how they will slide into
> and out of the holds in the foam.
>
> For the second test, attach the beams at a 30 to 45 degree angle,
> again with 2 cm bury, and then see how smoothly you can get them to
> slide in and out of the holes when both "beams" are in. I realize you
> probably won't toe the beams out at 45 degrees, but the point is to test
> the theory.
>
> In the end, I think you'll find that: a) either the beams need to be
> parallel, or b) the ends of the beams need to be parallel, even if the
> main portion of the beam angles out.
>
> - Mike
>
> / /
> Doug Haines wrote:
> >
> >
> > Still not sure...sidecar is a cruiser, harriwette isn't.
> > I have two boats, one is for sale.
> > The easy moving to and from the water/beach is the main point of
> > having a small one, so I'm trying to inmprove that part some more.
> > Pretty easy, if you can see making in demountable with the beams at
> > right angles, just turn everything on and angle and the beams where
> > the rudders are can work further aft.
> > So its a two part job, making demountable and while doing so putting
> > the leeward attachment point further back - hence beams will be
> > splayed slightly (same as toed?).
> > It is fun trying stuff on the small boat, should really make some models.
> > Mostly the sailversus underwater resistance laterally balance.
> > Realised the other day that it would bealance better if the front
> > rudder was actually up, hough I imagined the extra boards down owuld
> > keep it straighter!
> > How do you know how much total board area is going to be enough?
> > I s related to speed or is that just the turning effect of a rudder
> > that works better at higher speed?
> >
> >
> > Doug
> >
> > Where's tsst proa got to?
> > BTW, how about Capt Raps?
> >
>
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