Subject: Re: [harryproa] harryproa for shallow waters
From: Rick Willoughby
Date: 9/9/2012, 6:51 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Luc

Low speed surface piecing props are hopelessly inefficient - maybe 20% if it is constrained by depth.  It is better to use a smaller prop and enclose it in a nozzle to lift efficiency - basically a jet.

In fact it is difficult to better a paddlewheel for shallow water operation but they would be an ugly addition to a proa.

Rick 
On 09/09/2012, at 9:00 PM, LucD wrote:

 

While Nol was discussing how Zeilen met Visie progressed optimizing Blind Date, he mentioned readying her for sailing the shallow waters the Dutch coasts are famous for. I guess originally kick-up rudders were meant to solve that.

If one were to build a harryproa dedicated for waters like the Wadden Sea http://en.wikipedia.org/wiki/Wadden_Sea with beaching capability would it make sense to consider:
1. an asymmetric lee hull?
2. and ww hull (also flat to lee)?
3. Low aspect schooner rig (for occasional rudderless steering) ?
4. As apparently these boats motor more often: Rick, you were involved in a discussion on slow turning surface piercing propellers in 2008. Would this application make sense to offset the loss of efficiency, in your opinion?
5. A double hull would not require lots of flat bottoms as a monohull
6. While transitioning from beached to floating the boat can bang the sea bottom without being best positioned with regard to tide and wind directions - Would there be a way to hold down the boat some longer on the bottom and let loose to have it float higher and have more room for maneuvering?

Luc


Rick Willoughby




__._,_.___
Recent Activity:
Visit Your Group
.

__,_._,___