[Rhodes22-list] Fw: Toys for Rhodes

[Roger Pihlaja]

> Art,
>
> Sorry, forgot to answer your other question re the depth sounder.
>
> Depth sounding transducers transmit and recieve their accoustic signals in
a
> narrow cone.  When the depth sounder transducer is mounted on a V-hull
> shape, it may work just fine when the boat is sailing on one tack.
However,
> when the boat is sailing on the opposite tack, the angle of the V-hull +
the
> angle of heel combine to cause the accoustic signal to be aimed at the
> bottom well away from under the boat.  If the depth sounder transducer
> receives a bottom echo at all, the nonperpendicular geometry will cause it
> to indicate a much greater depth than actually exists under the boat.
Your
> installation may apparently "work" in that it reports a depth value.
> However, theory predicts that your depth sounder would indicate a
different
> depth while sailing on starboard tack vs. port tack and the sensistivity
> would be much less on one tack vs. the other.  In other words, your system
> might be able to detect a bottom at 200 feet on port tack and only 75 feet
> on starboard tack.  The two preferred locations for the depth sounder
cited
> in the previous post are in areas where the hull is much flatter, thus
> minimizing these effects.
>
> If you do not observe these effects in your system; then, consider
yourself
> lucky because the bow is a poor choice for the depth sounder transducer.
>
> Roger Pihlaja
> S/V Dynamic Equilibrium
>
> ----- Original Message -----
> From: "Roger Pihlaja" <cen09402 at centurytel.net>
> To: "Art Shriver" <adshriv at verizon.net>
> Sent: Wednesday, May 19, 2004 9:42 AM
> Subject: Re: Toys for Rhodes
>
>
> > Art,
> >
> > The V-hull shape is very pronounced forward of the keel on the Rhodes
22.
> > How did you mount the thru hull for the transducer straddling the V?  In
> > addition, on the V, the transducer is much more likely to be damaged
> getting
> > on and off the trailer.  The preferred location I described is just to
> port
> > of the centerline, basically under the folding step in the head area.
The
> > folding step provides good access to the backside of the transducer for
> > installation and maintenence.
> >
> > Roger Pihlaja
> > S/V Dynamic Equilibrium
> >
> > ----- Original Message -----
> > From: "Art Shriver" <adshriv at verizon.net>
> > To: "Rodger PIHLAJA" <cen09402 at centurytel.net>
> > Sent: Wednesday, May 19, 2004 12:14 AM
> > Subject: Toys for Rhodes
> >
> >
> > > Hi Rodger,
> > >
> > > What is the reason for saying that the preferred location for the
speed
> > > transducer is to port.  I have been told by a couple of manufacturers
> > > that on centerline is best.  I mounted mine about a foot ahead of the
> > > shoal draft keel and the depth transducer somewhat ahead and very
> > > slightly to starboard.  Both work well.  I have a Navman system.
> > >
> > > Thanks for considering this question.
> > >
> > > Art Shriver  Teetotum, a '76
> > >
> > >
> > >
> > >
> >
>