PRAIRIE DORY

[egon]

Attached is a picture of a slough dory.
Note the full bows and stern designed to keep it dry. The mast is free standing and short as the design has intial stability but limited ultimate stability. The sail has been made from recycled materials.
The rudder can also be used for sculling when the wind dies down.

Egon

[Pat]

Your assessment of hydrodynamic stability is the same as what kept me out of ocean going multi-hull sailboats. Terrific initial stability but actually "conditional" stability with the ultimate stability being really poor. Big cats and tris are much more stable upside down than right side up. I once proposed to some multi-hull inclined folk that they'd be safer to design their craft so as to be the same right side up as upside down and have a means of disconnecting the standing rigging and cranking the mast up to the top side, reversing top and bottom. Similar adjustments would be required for accomodations and creature comforts below. That way, acknowledging the short coming of conditional stability, they could design around it. They muttered something about how at least it floats while upside down instead of going straight to the botom like any self respecting keel boat does when properly swamped.

The dory pictured doesn't look too weatherly and if she is as fine forward as in the stern might not be too easily driven. There is somethig to be said for simple lines and ease of maintenance.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[egon]

From reading I understand some of the Multihulls have hatches on the bottom that can be used for access when the top of the mast is pointing towards the center of eath's mass.

Remember the Fastnet race of a number of years ago in which inclement weather caused some deaths and many disabled boats. All the multi hulls went over and had most of the deaths.

Egon

[Pat]

Egon, Another "after the fact" safety feature for multihulls is the word "HELP" in large high contrast letters on the (the part they call) bottom. Helps someone discern it as a disabled craft and not a lost-overboard-shipping-container or whatever during any attempted airsearch.

I actually have sailed on multihulls and do appreciate the fun and excitement that can be had in the grey area between sailing fast with a hull up and flying and turning over. I have never done this offshore, out of sight of help or other thrill seekers, or at night. In larger boats (over 30 ft or so) I prefer the mundane world of deep keel ballasted displacement hulls that don't ordinarily plane. Of course, just for a day, just for fun, a ULDB like Stars and Stripes is an amazing ride. About the same class of rush as white water in a canoe, fun for a few hours but not something I could sustain for very long.


[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]