Sailing yacht Hanna Maria

Hanna Maria is a 43’ long yacht, designed with classic features above water line and with fast modern lines below. After a one year design work, she was built during a six years period in Goteborg Sweden and launched the first time 1995 and has been sailing in Scandinavian waters since then.

Design

Building a boat, based on my own design, had been a dream for many years and when I started the design, I did not really believe that I would complete this project. I had for many years, together with my wife and our two children, been sailing an International One Design, designed by the famous Norwegian designer Bjarne Aas.

I am, by profession, a naval architect and have since 1976 been working at a model test basin, located in Goteborg. My professional specialities are design of mathematical models for simulation of ship motions. This work, together with my interest in sailing, led me into the design of a so called VPP (Velocity Prediction Program) that is used for predicting the speed of an arbitrary sailing yacht in different wind conditions. With this program as a basis, I started the design of my future 43’ sailing yacht. At that time, around 1987-1988, numerical design programs were not commonly used, why my design was made in the traditional way, by use of ducks and splines and on a drawing film.

Since I always had been sailing wooden boats before, the choice of hull material was easy. It should in some way be based on wood. After many discussions with friends and with my brother (who, during the same period, built a 10% larger boat, based on the same lines), I eventually choose a method based on wooden strip planking covered with GRP.

When starting the design, I put up some criteria that were essential for me:

It should be a long slender yacht with (in my eyes) beautiful lines and long traditional over hangs.
It should have good sailing properties.
It should be able to comfortably accommodate a crew of four.

The first criteria above are of course very subjective, but nevertheless of great importance. In contrary to most modern Swedish yachts, it should have a positive spring, and be supplied with a short distinctive cabin house, with fore end well aft of the mast. A high fractional rig is both good looking and practical, especially when choosing a self-tailing jib.

Length over all 13.2 m
Length in water line 9.3 m
Beam 3.14 m
Draught of hull 0.88 m
Total draught 2.27 m
Displacement 9.0 tons
Mainsail area 52 sqm
Jib sail area 34 sqm

Good sailing properties were verified by the VPP, that I previously had developed. Based on the VPP calculations a so-called polar diagram can be developed which well describes the speed characteristics in different weather conditions and in a relatively understandable way.

Polar diagram effectively shows the performance characteristics of a sailing yacht, for all wind speeds and directions. The diagram shows, for example that at 7 m/s the optimum upwind speed is 6.6 knots providing a VMG of slightly more than 5 knots

Since the sailing performance was important, I decided to design her with a deep fin keel and a separate rudder.

Lines and body plan for Hanna-Maria

Hanna-Maria’s profile

Construction

The actual building of the boat started in the autumn of 1989. I raised a canvas tent in a small boat yard in Gothenburg. All the frames and the floors I had previously manufactured in my own small workshop at home. Both of them in laminated oak and each frame connected to its own floor. Around the keel, there is one floor on each side of respective frame, in order to ensure that the keel forces are appropriately absorbed. Thus, the first task was to raise all the frames, totally 16, still applied on the moulds. The hull was built upside down in order to make it easier.

The keelson was laminated directly on the floors, using 200x10 mm oak layers, totally twelve on top of each other. Each layer was fastened to the one below, by use of both glue (aerolite) and stainless wooden screws. This work with successively laying the keelson was completed in spring 1990. It was then time to start the laying of the planking.

Construction plan

I considered strip planking to be a method that could effectively be used for an amateur as I considered myself being. Combined with an outer skin of GRP it provides a hull, which I believed to be sufficiently strong. The strips were cut with one male and one female side, making it easy to mount the strips together along the hull surface. Each strip was fastened to the next one by screws at spacing of approximately 200 mm and by use of polyurethane glue. In addition, each strip fastened to the frames by use of 50 mm screws.

Strip planking together with an outer skin of GRP provides a strong hull

The deck was built in three layers; bottom layer was 15 mm pine on top of 50 x 50 mm deck beams with a spacing of 400 mm. Between the teak on top and the pine I choose to lay a 3 mm GRP layer for water protection. The teak ribs. 16-17 mm thick, were sealed with thiodikt. All deck houses and skylights were built in mahogany. In 2016 the teak deck was, in order to prevent future possible leakage and general deterioration, covered with coelan, see Figure 1

Deck layout

The deck layout is illustrated in a number of pictures below.

Deck layout

Pulpit and bow anchor

Bow anchor winch

Fore starboard skylight

Interior design

The interior is described by a number of pictures below

FoAlding table

Navigation table and engine cover

Pentry

Door into toilet

Toilet

Forepeak bunk

Forepeak bunk and chair

Starboard aft bunk

Port aft bunk

Sailing and engine performance

Hanna Maria is showing the best performance in upwind and in beam wind conditions, very steady on course and a weather helm just as is it should be, with 3-6 degrees rudder angle in normal wind conditions. The deep keel provides sufficient hydrodynamic lift forces to minimize the drift tendencies. On the other hand, she has a large, wetted surface providing a slightly less speed in down wind conditions.

Due to its very v-shaped bow the boat is comfortable in head waves, although this means that in a following rough seaway, the boat is vivid, and the rudder has to be used more or less continuously in these conditions.

The main sail is designed with two reefs, of which the first is appropriate to use in upwind conditions exceeding 15-16 knots. The second reef is used in winds above 18-19 knots. In winds exceeding, say, 23-24 knots the jib is either taken down or reduced in area by used of the furling system.. The present sails are from 2008 and include a furling jib. Besides the practical aspects, this has also increased the flexibility significantly. The possibility to reduced jib area in rough wind makes the boat more enjoyable also in a rough weather. At the same time, I also supplied the jib with a stay sail club on a pedestal. This meant that the jib was cut slightly higher compared to a previous one. I was afraid that that would make the upwind performance less efficient, but on the whole Hanna Maria is now performing better than ever before.

With the new engine installed spring 2021 Hanna-Maria makes a speed of about six knots at 2000 engine rpm. At maximum rate of 3000 rpm she will make around 7.3-7.4 knots.

Equipment

Selden rigg - Complete rig with mast, boom, rodkick,stays, shrouds etc 2008

Main sail 56 m2 DC laminate, six full length battens, two reefs 2008

Jib 32.8 m2 triradial DC laminate 2008