Friday, July 14, 2006
Mechanicals
I've already made decisions of my engine and gearbox combination. I have chosen an Isuzu 4JB1 67hp diesel with a PRM Newage Hydraulic gearbox with a reduction ratio of 2.9:1. She will spin a 22 inch 3 bladed prop, a 40 mm shaft and I'll use a dripless shaft seal.
I've given a lot of thought to going fixed prop versus feathering and decided that on day 1, I'll go fixed and see how it turns out. If my ship sails ok with the fixed prop I'll keep it but if I find it is degrading sailing performance to an unacceptable level I'll go down the expensive feathering prop path.
I've placed deposits on my engine and gearbox and will get them delivered in about 8 weeks. I want them both on hand to physically drop them into the hull when we are fitting them up so I avoid any chance of screw ups with these critical items.
Corrosion Protection
Perhaps the biggest demon that haunts all steel boats and boat builders is managing corrosion in steel boats. Everything I've heard and learnt is tells me that the best time to get on top of this problem is during construction. I'm taking the following steps
a) I'm building under cover at all times
b) ALL my steel is being pre blasted to white or near white metal state.
c) I've chosen an interesting pre weld primer from JOTUN marine paints called MUKI 2001 which is a 2 pack epoxy based, low zinc primer designed for excellent weld through capability. Importantly for me I wanted a product that could be left intact in the interior and overcoated with subsequent primer coats so that I didn't have to re blast the interior.
d) choose good products and use plenty of them - I won't spare when it comes to paining later - I will probably use Jotun products for the rest as they have a good reputation and great service near here.
e) Think about paint adhesion during the build process - no sharp edges, weep holes so water finds it's way to the bilge, stainless is areas of chafe eg chainplates, bow where chain from locker might rub.
I'm also investigating a paint from a US company called Delta T which is a spray on zinc that adheres to the paint and provides galnanic protection like hot dip galvanising. I can see that a product like this sprayed on the deck as a base coat then overcoated with a strong waterproofing layer would in theory be very effective.
I've just had all my work so far sandblasted and coated with Jotun Muki - so I'll post some photos shortly.
MP
Some of the big considerations in building a steel hull
Many people have asked me why I would build a steel hull as opposed to other choices such as fibreglass, wood or aluminium. I'll explain my reasoning on this choice. This is of course a question with no right and wrong, just whatever reasons make the most sense for the individual boat builder.
There's no doubt that wood is probably the most aesthetically pleasing medium and the nicest material to work with. The interior of a wood boat is also the most beautiful and traditional. However it is extremely labour intensive and good boatbuilding timbers here in my country have become scarce and expensive.
Fibreglass is easily the most popular material and really the only choice for production boats. It is also reasonably low maintenance but more difficult to fit out. Material costs can also be quite high for a one off builder.
My personal feeling is that the 2 metals - aluminium and steel are the best choices for the one off or custom boatbuilder. I actually think that aluminium is probably the ultimate choice for a cruising boat. It is light, very strong and highly corrosion resistant. On the downside it is expensive (though not as much more that it is a big issue), far more exacting to weld, it work hardens over time and welds create a zone with much reduced strength than the metal around them.
For me though steel was the best choice. I'm going to take my family on board with me. Steel is the strongest material and safest bar none. It is also much more forgiving when welding which was important. I can weld both aluminium and steel but felt my level of expertise with steel was sufficient to build a steel hull whereas with alloy I would have felt it necessary to employ a more experienced welder to help out. These guys cost around $30 an hour which adds up real quick.
A steel hull also comes together pretty fast compared to other hulls which helps keep costs down. My boat will be immensely strong, waterproof (fully welded deck) and seaworthy - I trust Ted Brewer's design experience.
Mitch
Wednesday, July 12, 2006
Early Work Photos
The actual build part of this project was started back in February. This involved the process of lofting the lines to ensure all original dimensions were accurate and fair. Ted drew these plans some 25 years ago by hand "the old way" and therefore it is essential for the builder to loft the plans to large size and check dimension before the frame patterns can be laid down.
The best way to understand this is to realise that the original drawings are drawn at a scale of 1:16. So a drawing error of only .5mm translates to a real life error of 8mm which is large.
The process took me about 3 weeks working 3 days a week and although painstaking and hard on the knees was very worthwhile and enjoyable. A lot of quality time studying your plans and gaining a thorough understanding of what lies ahead. It doesn't make for good photography though as the fine pencil lines don't show up real well in photos.
The end result though is that I was able to draw out 18 very accurate frame and floor/keel patterns to begin construction. The attached photo shows my framing floor with patterns drawn out and frame construction underway.
There is also a photo with the shed I'm working in right now. I'm building in an area that was once a real hive of boatbuilding activity which has now sadly declined. What is left are a lot of underutilised facilities which fortunately I can rent for reasonable rates.
MP
Tuesday, July 11, 2006
Monday, July 10, 2006
Boat Design
This Blog will follow the progress of my construction of a Steel Hulled cruising yacht. I'm a first time boat builder and spent the whole of 2005 studying designs and building the skills needed to start building my yacht.
The design I've chosen is an old design drawn by Canadian Ted Brewer called the Alaska 43. She is a sturdy boat displacing about 16 tonnes that would more accurately be described as a motorsailer. I will attach some line drawings of my little ship so you can see how she looks in profile and interior layout. If you want to look at Ted's designs go to www.Tedbrewer.com where you'll see plans for a lot of nice boats.
I actually started building in February this year in some temporary space I've rented and over the coming weeks I'll add detail to bring my Blog up to date on progress so far.
The big plan with this project is to get her finished in anywhere between 3 and 5 years then go cruising with my wife and 2 boys. We'll start cruising the Australian coast north to the Barrier Reef and if all goes well and everyone is keen on going further we plan to take our kids out of school for a year and cruise to Europe probably via Indonesia, Sri Lanka, the Maldives, Red Sea, Suez Canal then spend at least 6 months in the Med and the canals of Europe. But that's a long way off and first she has to be built.
MP