Efficient Riverboat for 15hp Outboard Motor
- Length - 11.7m (35ft)
- Beam - 2.13m (7ft)
- Displacement - approx 1800kg (1.8 tons) (includes
crew and tankage half full)
- Power - 10 to 15 hp High Thrust Outboard
for cruising speed of 7 to 8 knots (or 2 x 10/15) for
9 to 10 knots
- Simple to Build - Prefabrication Method - Most of
the major parts can be finished before the boat is assembles.
- Almost silent
- Drawings for all bulkheads and panels to allow prefabrication
of parts. Position of major interior items is given
on bulkheads for fast assembly of interior.
I recently completed a revision to this design for a
North American Client. It added more detail to the plan
to make it more user friendly. Also I managed to resolve
some of the aesthetic issues that had always bothered
my by altering the window size and position.
A little touch of le Corbusier - the great Swiss-born
architect responsible for modernism.
I have left the original drawing below - but the new
one is at the top of the page. "Smoke and Mirrors"
- but good smoke and mirrors!
the old drawing
The Riverboats have the
admirable qualities of being among the easiest boats to
build, having excellent performance with small powerplants
very easy on the wallet.
These properties are achieved through having a lot of
length for a given width. This results in minimum drag
underway and a large reduction in the amount of building
The smaller versions (less than 30ft) are also very light
to tow, opening up all sorts of cruising possibilities.
The original 30ft Tennessee was designed by innovative
American designer, Phil Bolger a few years back. Picked
up in this country by Duck Flat in Adelaide, over a dozen
have been built, each slightly different for use on the
Murray River, the Gippsland Lakes and similar areas.
The reason for the rediscovery of the design were a mix
of trailerability, a speed of 7 to 10 knots from a near
silent 4-stroke outboard/s making the long stretches of
Australian rivers into easy going.
The original Tenessee is a delightfully simple boat which
helps keep the cost down. This larger version provides
a permanent double berth in a separate cabin and room
for a larger galley and head (toilet/shower) compartment.
The advantage of this version over the original Tennessee
is that the plan has more detail and the hull has a double
floor to allow services (electrical, plumbing and tankage)
to be placed underneath.
Travelling is easy with the crew able to relax and take
turns at the helm while eating through the miles while
leaving only a minimal wake.
The extreme shallow draft allows exploration of waters
not frequented by waterskiers or jetskis and where birdlife
and quiet stretches are abundant.
The boats have a very smooth ride, with the fine bow
cutting through a steep chop with no pitching pounding
A major factor in the success of the boats is the availability
of the 4-stroke, high thrust Yamaha outboards - nearly
silent, smokeless, vibrationless, but with heaps of pushing
power - civilised.
35ft Riverboat - a live aboard home for a couple (with
occasional company) has been built on the River Kwai in
Thailand. A good galley, separate loo, cruising speed
of 8 knots with 15hp or over 10 with a twin 10hp setup.
For a discussion of the rough water handling properties
of the type please see the article on the 23ft Dayboat/Launch
that has a similar hullform. Dayboat/Launch
The plan does not have step by step instructions like
my smaller designs, but has comprehensive drawings for
all the bulkheads including the framing positions for
furniture (image right). This means that the furniture
does not have to be measured up seperately saving a great
deal of time and energy.