Doug
(with link corrected)
I was not referring to a proa-ject. The background is as follows.
I have been pursuing the idea of going as fast as I can on water using my 1951 vintage engine for about 8 years now.
In 2005 I looked at commercially available hulls that I could convert to pedal power. I settled on the Pahoa OC1 as the AUD3500 price tag was better than the AUD7000 for a rowing shell. That was version 7:
V7 proved to be no better than my quick and simple V6 boat. V7 was a disappointment after spending almost AUD5000 on it. After a couple more attempts and going backwards I discovered Leo's GODZILLA software and produced the first of the V11 design; building fast and simple in aluminium:
This was very successful; about 0.5kph faster than V7 with my sustainable power.
The V11A design that followed V11 was a carbon fibre covered foam plug that I eventually pulled V11J from:
A clone of V11J holds the 24 hour world distance record of 245km:
So with GODZILLA I proved I could design the lowest drag hull for given displacement and power. When fiddling with the constraints I realised that I could design an easy-to-build flat panel hull that was not far behind the V11J design. That was around 2 years ago. I built and trialed V14 last year:
With V14 I averaged 11.5kph for the 404km of the Murray Marathon compared with 10.98kph with V11J. This is a fair comparison between performance. Both results were affected by some minor mechanical problems.
I live in Melbourne but grew up in Brisbane and Southport. I am interested in what Rob is doing with proas. The lw hull has a lot in common with what I am doing with my pedal boats - the best speed possible for the available power. I doubt that I will own another sailing boat but the proa would be my current choice if I ever go back to sailing.
Rick
--- On Fri, 16/7/10, Rick Willoughby <rickwill@bigpond.net.au> wrote:
From: Rick Willoughby <rickwill@bigpond.net.au>
Subject: Re: [harryproa] construction
To: harryproa@yahoogroups.com.au
Date: Friday, 16 July, 2010, 14:48
Your thoughts are similar to where I was 2 years ago. My flat panelled hull was aimed at easy building. I could not muster the will to carve another plug out of foam. I was prepared to give a little in performance with something easier to build.I was very pleased and a little surprised when the end result actually performed better. So the flat panels was not a performance compromise. This was not quite what Michlet had predicted. The Flotilla software goes some way in providing the theoretical understanding of why it is better.It would be reasonably simple to make a long slender lw hull for a proa using ply that has very good performance. AND likely better performance than could be achieved with a round section hull. It could be designed to trim flat or slightly bow up through a wide speed range.If you want to have a go I can provide input on the shape that should perform best.
Rick
On 16/07/2010, at 2:21 PM, Doug Haines wrote:
--- On Fri, 16/7/10, tsstproa <bitme1234@yahoo. com> wrote:
From: tsstproa <bitme1234@yahoo. com>
Subject: [harryproa] Re: Rudder lift?
To: harryproa@yahoogrou ps.com.au
Date: Friday, 16 July, 2010, 13:25
What if the same 12m. hull was only 1/2 tonne displacement?
Todd
--- In harryproa@yahoogrou ps.com.au, Rick Willoughby <rickwill@...> wrote:
>
> The length constraint or non-constraint is a function of design speed
> and weight.
>
> As an example a 1 tonne hull with a flat bottom designed for minimum
> drag at 25 knots results in a length of 12m. However this hull will
> not generate enough bow up moment through wave making to counter the
> moment from the rig to drive it at that speed. Extending the length
> to 15m will get close.
>
Rick Willoughby03 9796 24150419 104 821
Rick Willoughby
03 9796 2415
0419 104 821
__._,_.___
Messages in this topic
(133)
.