Yes, those power dories are simplistic.

Check Ted Brewer:
http://www.tedbrewer.com/power.html
He has some light displacement hulls like the Quiet Times.
Good looking, good design for plywood planking.
His plans prices are very reasonable.
Contact us directly if you want to adapt that design to stitch and glue or
enlarge it.

BTW, check the Beebee book "PassageMaker". It explains what the prismatic
coefficient is and will answer your question about Buehler's calculations.

--
Jacques
http://www.bateau.com



"VG" wrote in message
...
By ultralight trawler, I wanted to mean light powerboat designed to be
used
in displacement mode. speed 1.34 sqrt(lwl). planning speed or even semi
planning not intended.

A GB 49 is 60000#. a nordhavn 43 is 53000#.

The GB42 is 34000# , but with 2 * 430 hp, it is not intended to be used in
displacement mode. The minimum power available is still 2 * 210 hp.
The GlenL boats (argosy klondike) are in the same weight range. But they
are
semi planning boats too. (cruising speed 12 kts).

So I would call a displacement mode boat 42 -48 # lenth weighting under
30000# boat as light.

Have seens the photos of the 48 duck built in wood from G Bhueler.
Its beyond my (and my father) possibilities. Financial, technical , time
....
It a boat in the 60 000 # range.

The pilgrim 44, 10 000 # on the other side, is rather simplistic and light
with its outboard engine. A scaled up canoe.

More interesting are kasten marine designs. But alas, the designer is
specialised in metal (steel ou alu).
A boat like the coast runner 48 ocean express 49 look more like what I
want.
But they are both semi planning aluminum boats, and only at the
preliminary
design stage today.


Also there are things I don't understand. M Kasten give 40 hp to reach 8
kts
on a 46.75 lwl, 32000# boat. G Bhueler claims 21 hp for 8.1 kts,with 46.3
lwl and 57000 # disp. Both single hard chine.

NB english is not my natural langage.
Thanks.



"Jacques Mertens" a écrit dans le message news:
...
Is ultralight trawler not a contradiction?
The boats you list and that some propose are all heavy as a trawler
shoudl
be.
How about a large dory? D. Gerr and G. Bhueler have designed some nice
ones.
Reuel Parker too.
That would be much easier to build, less expensive, lighter. A 50' dory
would move nicely with a 100 HP engine.