Re: [Paddlewise] QCC boats and water line length ........

Nick wrote;

(SNIP)

>We don't know the design constraints of the traditional designers, so we
>don't know what those overhangs were for. Therefore, we can't really
>comment about whether they did anything or not.

My comment was not directed at traditional boats. In fact, I have explained
elsewhere why some Greenland boats probably needed the long overhangs due to
their lack of reserve buoyancy and generally flattish bottoms. Don't know if
they adopted their ends because of this or the boats got flat and low
because they had long ends first. Interestingly the longish ends seem
confined to the Eastern Arctic.


(SNIP)


>For example, Navy designers must consider where they will mount the sonar
>system, or whether the ship will need to be able to get through the Panama
>Canal. These considerations can not help but impact overall efficiency and
>sea-handling characteristics. It is an oversimplification to say that the
>bow of a destroyer is shaped a particular way because that is the _best_
>shape for going fast through waves, period. You may be able to say that it
>is the best shape for going fast through waves for a boat that will fit in
>a lock and have a sonar system slung under the bow and other considerations
>I don't know about.

The sonar thing is interesting because some modern boats have more overhang
simply so the anchor will clear the sonar dome. If we expand the range of
observation to include a wide range of boats and ships we find that short
ends with flare predominate. We don't even have to restrict it to modern
boats. Viking long boats provide but one good example of  short ended boats
highly regarded for their ability at sea. My contention has focussed on the
net result of the end shape. Building excessively long ends into a boat with
little volume (as in the examples Nick provdies later in his post) fit my
statement that they look pretty (depends upon one's aesthetic values) but do
not do much.

I would contend that the very long overhangs of some (not all Greenland
boats) stand out because they do differ from most types of boats. Had the
Brits used the Aleut boats as a model this discussion might never have taken
place and we might be arguing the relative merits of bifid bows.

(SNIP)

>
>Early British sea kayaks were essentially knock-offs of Inuit designs. They
>buggered with these designs slightly to acheive slightly different
>properties, but essentially they let someone else skin the cat. Nobody
>(accept maybe the good Professor) really knows what the Inuits liked about
>their cats so their method of skinning is not neccesarily the best for us
>today. (SNIP)

Quite true to my mind.

It seems some may get the idea that I advocate only one specific rake. Not
so as a look at the full range of my designs will reveal. I try to suit
every hull characteristic to the design purpose. Having designed flatwater
canoes, whitewater canoes, racing canoes, power boats, sailboats, sea kayaks
for inland use, sea kayaks for offshore use, kayaks for racing, rowing
shells, ocean rowing shells, and, yes, one submarine that probably is better
having never been built and I have found each had different requirements
and, consequently differing end shapes. None have required long low volume
overhangs.

My comment concerned excessive overhang that serves no useful purpose other
than slavish bowing to an arbitrary aesthetic (see Nick's comment on some
boats). I have also criticised the rule mandated plumb bows of marathon
racing canoes that do not allow seaworthy shapes.


Cheers,
John Winters
Redwing Designs
Web site address, http://home.ican.net/~735769





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