Steel deep V proa, now on Youtube
Thank you for doing this experiment. If you were building a hull of a length of about 10m, how thick should the steel be?
I would go for 3 mm Corten or similar high strength steel. Corten is stiffer and stronger so there is less distortion from welding. 3 mm mild steel is strong enough, but I like the added stiffnes and toughness of Corten or similar steel. http://www.tibnor.se has 3.2 mm Hardox 450, but it is 3 times more expensive then Domex 355W (Corten).
3 mm steel for a 10 meter deep V vaka will have a weight of about 300 kg, and the vaka a displacement of about 770 kg. It is a small skinny canoe, not a yacht.
Do you think that the weld is strong enough to stand up to grounding?
What kind of paint are you using?
I would use a 8X50 mm flat steel bar as a keel, and weld the sides to that instead. I simplified the construction of my model, as I am new to welding and was already pushing the weight with 1,5 mm steel sheets.
I will use Rust-oleum Combicolor for my scale-model, and some kind of epoxy-tar on a large proa.
Rust-oleum Combicolor
International VC tar 2
Cheers,
Johannes
What is your Bmax
I cut the hull-sides at the wrong side of the draw line, so they are 183 mm instead of 180 mm.. The Bmax is also 183 mm (185 mm when I measure it now - must be the welding that have pulled it apart.)
Cheers,
Johannes
I am very inspired by two threads from boatdesign.net:
My one sheet steel boat project
and
Steel dinghies
In “My one sheet steel boat project” Hobo Hut builds a 9 foot multichine steel boat in about 30 hours, even though one must be careful when welding 16 gauge steel. It is much easier to weld 3 mm at high speed with duel shield MIG.
Cheers,
Johannes
What is your Bmax
I cut the hull-sides at the wrong side of the draw line, so they are 183 mm instead of 180 mm.. The Bmax is also 183 mm (185 mm when I measure it now - must be the welding that have pulled it apart.)
For 180cm max panel width to get 6300kg displ:
LOA 2000cm
LWL 1678cm
B 183cm
D 109cm
F 460cm (plus 15 cm tumblehome which doesn’t show on any of your models)
Your freeboard is very low for a 20 metre boat….........Wave clearance for Akas???
F 460cm (plus 15 cm tumblehome which doesn’t show on any of your models)
As usual I simplify my models as much as possible. I want to see the hull sail and how it is behaving in waves. Some tumblehome will add global stiffness and strength, and add some interior space and freeboard with less added windage then just more “regular” freeboard.
I have been sketching and calculating weight for some tumblehome on this model, but with 1,5 mm steel it gets too heavy really fast. It is not easy to weld a 15 mm wide strip of 1,5 mm steel sheet without burning holes and warping the hull-sides.
I don’t know what clearance I get under the crossbeams, but it is easy add height if needed. I guess my model will have 5,5 - 6 cm clearance.
This is some of the things I hope to find out when I throw it into the water soon.
I can really recommend building and sailing models. It is a very rewarding and educative process, as one gets a reality and experience that a computer never can give. Just by handling the boat in 3 dimensions and accidentally dropping the steel hull onto a concrete floor gives a lot of reality and understanding that a couple of lines and numbers on a screen never can give. I might be an old timer doing things the manual and old fashioned way, but I like working with my hands. It keeps my thoughts focused on something nice and rewarding instead of my sickness and tiredness.
Cheers,
Johannes
My kids choose high gloss black paint for my steel vaka.
I like it.
I think it has a dark and sinister appearance.
Cheers,
Johannes
It is floating a little bit lower then expected. I guess my calculations are off by 0,5 kg. I guesstimate the waterline to be at about 5,7 cm high It is hard to take correct measurments in constantly moving water. Over all I am very satisfied with my first steel vaka. I knew 1,5 mm thick steel was very close to what is possible, but everything turned out as I hoped it would.
I will not use as much negative rocker on the gunwale on my next hull, but I am very satisfied with the rest.
Cheers,
Johannes
Black steel Proa floating - Youtube
I lost my sail and mast. They floated away in the waves, and I am not man enough to go for a swim early November in Sweden.
I just want to show how it floats and moves in the waves.
Cheers,
Johannes
I can really recommend building and sailing models. It is a very rewarding and educative process, as one gets a reality and experience that a computer never can give. Just by handling the boat in 3 dimensions and accidentally dropping the steel hull onto a concrete floor gives a lot of reality and understanding that a couple of lines and numbers on a screen never can give. I might be an old timer doing things the manual and old fashioned way, but I like working with my hands. It keeps my thoughts focused on something nice and rewarding instead of my sickness and tiredness.
Johannes,
I agree that building models is very educational. When I was young I spent a lot of time building models. Often I would test them by towing them with a piece of string tied to a stick, as I have seen you doing in some of your videos. This way, I was able to get a really good feel for how hull resistance changes with speed, and to observe the way the hull creates waves at various speeds. No other method will give you the same level feedback as this completely hands on method. Later, I have been able to add a quantitative understanding of the hull resistance process to the qualitative one I gained in my my youth and build a complete picture.
Cheers,
Mal.
I read this thread a few days ago, but my connection sucked, so I couldn’t load the video. Finally, it loaded. I do love the long, low, rakish look of this craft. Looks like he has a really easy motion. In the video, I see the little waves just slide by. In one of the other vids with the wooden boat, I saw a friendly, curious, big, black dog. Looks like he/she likes boats too!
I have, myself, just learned how to weld. I started with a torch, then when I discovered how much oxygen cost, I switched to a little arc welder. Wood is beautiful, but metal is pretty cool too.
Happy sailing,
Rick
I bought a slightly used Esab Caddy 151i and a big box of 7018 electrodes. The difference is huge!!! It is so much smoother and better running compared to my AC buzzbox. The 7018 electrodes are very low spatter and good penetrating electrodes. The welds even resembles welds, and not just some blobs of metal dispersed over the general area were I try to weld.
Now I need 3 sheets of 3 mm thick 1,5X3,0 meter Corten steel and a box of 7308 electrodes.
The bottom weld is made with my new Esab Caddy. The one above is rewelded over partly grinded down old AC 6013 welds. I am helping my son to build a Box car with some square steel tubes. I need a lot of practise before I start building a proa.
Cheers,
Johannes