Construction Sequence

In the spring of 2013, I started to write a book called, 'How to Design a Boat using SketchUp 3D Software'. The subject matter was my design, 'Kalostyn'. After preparing a file of over 500 screenshots, I realised that, for the purpose of showing a beginner how to design a boat in SketchUp, the content of this design was too much.

In May 2013, I re-visited the idea. Instead of a book, I'd write an article, hoping that Chuck Leinweber would publish it on his Duckworks Magazine website, and I'd keep the design very simple so that I could describe the whole design process as succinctly as possible.

So I worked up a design for a 12', shallow 'V' planing boat. The idea was to keep the design simple, but to include all of the essential 'how to's' like the creation of lines in 3D space, intersecting planes to form templates and how to form and flatten the hull panels.

I was rather pleased with the resulting design, So I decided to work it up to a set of plans. A little fine tuning was needed to one or two lines and, as usual, I ended up redrawing her to be more to my liking.

Here she is. 'Kastri 12'


Length 12' 0"

Beam 5' 0"

Bare Hull Weight 210 lbs


Power Requirement:

From Crouch Formula calculations, power / speed estimates are as follows:


1 Person on board

500 lbs displacement

10 hp - About 22 kts


2 People on board

700 lbs displacement

10 hp - About 19 kts

15 hp - About 23 kts


3 People on board

850 lbs displacement

10 hp - About 20 kts

15 hp - About 17 kts


4 People on board

1,000 lbs displacement

15 hp - About 19 kts


List of Materials

Marine Plywood:


1 sheet


2 1/2 sheets


3 sheets

1 1/2" square timber for the temporary supports

about 20'

3/4" square timber for batten fixings

about 50'

Note: less will be required if all joints are taped and epoxy resin jointed

50 yard roll of 3" glass tape

8 yards of glass cloth to cover the hull bottom and overlap

2 gallons of epoxy resin

About 5 pounds of resin thickening powder

Styrofoam or empty plastic bottles for the flotation

Note that the hull bottom is specified in 1/4" plywood in order to facilitate bending the panels at the bow.

For heavy use the floor thickness can be increased by adding another layer of plywood, glued in place with epoxy resin.