Wednesday, November 30, 2011

Aluminium Boatbuilding

This post was prompted by me receiving the photo below from a client who is building one of my aluminium designs. I have posted about him before, his name is Brian Russell and he is building in Tennessee. The reason for the post? Well, the photo is just so gorgeous in its composition and shows up the framing system of the boat so nicely. And, of course, there is his pretty wife right in the middle of it as well, to add interest.

Brian Russell's Dix 43 Pilot. The black surfaces are
insulation, which highlight the framing system of
longitudinal stringers and transverse frames.

Brian is a professional sculptor, so he obviously does beautiful work and has a great eye for aesthetics to show it all off. Brian's website is at http://www.odysseyyachts.com/ .

This design is the Dix 43 Pilot, originally drawn for steel construction. Many have been built by professional and amateur builders from steel and a few have been built by professionals from aluminium. One of them, "Blue Pearl" was built by Jacobs Brothers in Cape Town and has cruised many thousands of miles, including voyages to both the Arctic and the Antarctic.

"Blue Pearl" in the Antarctic

Aluminium is a great boatbuilding material and well-proven in use. It is also a much nicer material with which to work than steel. It is relatively light, so it is easier to manhandle pieces by yourself than with steel, with less need for heavy-lifting equipment. It is also easily worked with woodworking machinery like power saws, power planes etc and it is a lot quieter to work than steel. It also has the advantage that it is not necessary to paint it above the waterline, so the increased cost of the material is offset to large extent by the savings in fairing and painting.

OK, so what is the problem with it that blocks most amateur builders from using it? Aluminium is a material that can result in an unsafe boat if the builder does not properly educate himself before starting construction. That education is needed in two areas, which are proper choice of alloys and correct welding techniques. Get these two things right and you will have a good boat.

Proper choice of alloys is important because incorrect alloys will result in corrosion problems that will seriously shorten the safe life of the boat. The aluminium must be marine grade, from the 5000 and 6000 series of alloys and they must be selected for their strength, welding and corrosion characteristics.

Correct welding technique is much more important for aluminium than for steel because it is a more difficult material to weld successfully. Correct preparation of the weld zone and cleanliness of the work area are needed because any contamination in the weld will adversely affect weld adhesion and strength. Aluminium welding is also badly affected if the inert gas is blown away, allowing oxidation of the molten metal. That means that there must be no wind or other air movement where the welding is going on.

So, any amateur who is prepared to take courses at the nearest Community College should be able to build a good boat in aluminium. You don't want to find out in 60 knots of wind and 50ft seas in the Southern Ocean that your welding techniques were not up to scratch. Do it right and you will have a boat that can take you anywhere in the world that you want to go.

See our full range of designs and much info on boatbuilding at http://dixdesign.com/.