Designing Skeg/Rudder Flat bottomed boat

External Since: Jul 16, 2003 Posts: 15

Greetings group,
I am looking for books or online references for sizing and design of skegs
for low speed flat bottomed(dory) boats. Does anyone have any formulas or
rules of thumb for this kind of design work? My intentions are to power a
24'-10" dory with 10-15 hp via a motor well located in the aft third of the
hull. I am considering something full length tapering forward. John Gardner
recommends skegs on his dories when powered but leaves the reader with no
clues to dimensioning. I hope this stimulates some interesting responses.
Thanks to all, it's a great group to watch and read.

best regards, Mike
Gardner power dory in progress.

External Since: Jul 31, 2003 Posts: 458

"Mike Brannon" <brannonmichael RemoveThis @cox.net> wrote in message news:<bTAac.67737$1I5.59285@fed1read01>...
> Greetings group,
> I am looking for books or online references for sizing and design of skegs
> for low speed flat bottomed(dory) boats. Does anyone have any formulas or
> rules of thumb for this kind of design work? My intentions are to power a
> 24'-10" dory with 10-15 hp via a motor well located in the aft third of the
> hull. I am considering something full length tapering forward. John Gardner
> recommends skegs on his dories when powered but leaves the reader with no
> clues to dimensioning. I hope this stimulates some interesting responses.
> Thanks to all, it's a great group to watch and read.
>
> best regards, Mike
> Gardner power dory in progress.

You want the skeg to be forward of the thrust point only or you will
have trouble turning. Dual skegs work nice for beaching, and not being
a planing boat, you have some liberties I would think. I would take a
couple 16 foot 2x6's and taper them 5 inches high at one end, and say
1 1/2 inches at the other, and fasten them (I don't know how wide your
boat is) say spaced 24-30 inches apart, splitting the bottom into
three areas.. Like I said, being this boat is not built for speed, you
have some leeway here.
On smaller skiffs and prams, I make the skeg say 1" from the bow to
about midway, following the curve of the bottom, then sitting the boat
level, more or less continue a line horisontal to the stern and make
my skeg follow that line.
Scotty