Just entending the sides of the hull to the top of the swim step, where it
does not actually extend the bottom of the hull should not increase the speed
of the boat as significantly as extending the hull under the swim step.  The
"Bustle" on a sail boat has had two meanings thru the years  one is actually
shelf just above the waterline, that becomes part of the hull form as the
boat speed and wave form increase--thus picking up water line as the boat
heels and comes to speed.  This is a way of "bending" the measurement rules.
(Sometimes this is called a pooper scooper or sugar scoop)  The second form
of "Bustle" was a hump in the hull lines--in an attempt to alter the water
flow off the transom and also increase speed without increasing handicap.
Various measurement rules have been created to cover these modifications by
"girth" measurements etc.

Some boats have added a cockpit or have a full hull  extension under the swim
step and do lengthen the waterline.  This will increase the waterline and
theoretically increase speed (it may also change the handling characteristics
of the boat--the rudder and prop will be proportionately further foreward).
Some marinas will accept the documented length of the boat as its "length"
Other marinas and ship yards will actually measure the boat from the foreward
pulpit to the dinghy overhang.

The Carver 30 I have had a 36 inch hull extension--probably to attempt to
increase its speed, by adding an actual portion of a molded boat bottom under
the swim step.  Apparently this was done at the factory.  Most marinas have
considered it a 30 foot boat.  I cannot see any negitative effect on the
handling of the boat--the rudder post is at the very back of the origional
hull, and the rudder blade is partially under the the hull part of the swim
step.

Bob Austin

    I seem to remember a magazine article about a Seattle area

boatyard that was doing a brisk busness adding a sponson to the stern
of Bayliner 32's.  They had a purpose built mold that precisely fit
the hull. Apparently the added flotation really helped the boats that
used the optional diesels and added a genset.  The flotation brought
the boats back on their lines and apparently also increased max speed
slightly.
I have also  seen 17' Boston Whalers with sponsons added to
the stern to help support a larger outboard and fuel load.
Bob Austin has all ready described sugar scoop transoms on
sailboats.

Ross Fleming        rossflem@serv.net
S/V Renown          Gulfstar 39
Seattle, Washington

The Nordhavn 62 is the only boat in the line with a true bustle, and it is
about a 5 foot extension. It adds reserve buoyancy, prevents the stern from
squatting under load, allows the convenient fittment of stern thrusters,
adds an additional lazarette space, and eases boarding from the stern
immensely. It also increases the waterline length, and augments speed and
efficiency slightly.

Some of the boats have what we call an integrated swim step, so that it does
not change the LOA of the boat. This is not really a bustle...you just have
hull underneath a swim step of 1.5 to 2.5 feet wide which is in keeping with
our newer hull design. it also allows a big, deep lazarette and carries the
beam of the boat fully aft.

Disadvantages to a 62 type bustle are the need to rethink rudder placement
and size, as well as to increase the size of steering gear. The first bustle
fitted to a 62 helped a lot of things, but we had to increase the size of
steering hardware and enlarge the rudder a bit. I suspect these changes are
due in part to the nuances of that particular boat, but beware nonetheless.

Adam Cultraro

-----Original Message-----
From: owner-trawler-world-list@samurai.com
[mailto:owner-trawler-world-list@samurai.com]On Behalf Of
Thataway@aol.com
Sent: Wednesday, November 14, 2001 6:06 PM
To: trawler-world-list@samurai.com
Subject: TWL: More hustle with a "bustlle"

Just entending the sides of the hull to the top of the swim step, where it
does not actually extend the bottom of the hull should not increase the
speed
of the boat as significantly as extending the hull under the swim step.  The
"Bustle" on a sail boat has had two meanings thru the years  one is actually
shelf just above the waterline, that becomes part of the hull form as the
boat speed and wave form increase--thus picking up water line as the boat
heels and comes to speed.  This is a way of "bending" the measurement rules.
(Sometimes this is called a pooper scooper or sugar scoop)  The second form
of "Bustle" was a hump in the hull lines--in an attempt to alter the water
flow off the transom and also increase speed without increasing handicap.
Various measurement rules have been created to cover these modifications by
"girth" measurements etc.

Some boats have added a cockpit or have a full hull  extension under the
swim
step and do lengthen the waterline.  This will increase the waterline and
theoretically increase speed (it may also change the handling
characteristics
of the boat--the rudder and prop will be proportionately further foreward).
Some marinas will accept the documented length of the boat as its "length"
Other marinas and ship yards will actually measure the boat from the
foreward
pulpit to the dinghy overhang.

The Carver 30 I have had a 36 inch hull extension--probably to attempt to
increase its speed, by adding an actual portion of a molded boat bottom
under
the swim step.  Apparently this was done at the factory.  Most marinas have
considered it a 30 foot boat.  I cannot see any negitative effect on the
handling of the boat--the rudder post is at the very back of the origional
hull, and the rudder blade is partially under the the hull part of the swim
step.

Bob Austin