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erkki
16-12-2006, 07:11 AM
Hello there. Just wonder about those plate alloy boats. Donīt they have a tendency to after some time to get softnened up in the bottom. So that the material is curved in between the stringers. Heard about this some time ago. We dont have that many plate alloy boats up here in Sweden. So I would like some feedback on this one. Also read on a thread abot those ballast tanks. They are far from a new invention. This method was used to get a boatmodel named Fjordling 17 stable. This is back in the 60:ies. The unique with this one was that the ballast tunnel never had been built into a that small craft before. Altough it got to expensive to build in the end, and the production stopped, itīs still a very popular sportboat. It definetily has that cult aura that is hard to earn. Mainly because of breathtaking capacity in choppy water and high seas.

Finnflyer

stuart
16-12-2006, 12:32 PM
Finnflyer

Yes I have seen this problem but mainly on smaller pressed hull boats. I was only looking and commenting on a Friends boat the other day how his hull was caved in between each frame. Not a good and certainly not good for rid ability. Plate alloy boats could potentially have the same problem if the wrong grade and thickness of alloy was being used. The degree of V would also have an impact on this issue as well. I have seen one or two plate boats where the frames and stringers were visible in terms of outlines into the plate alloy hull. This is caused by compression and unfortunately water cant be compressed so the hull sheets give into the weakest point. I have never seen a plate alloy that uses marine grade alloy and the right thickness sheets with this problem. Maybe some others have but I doubt.

Stu

wessel
16-12-2006, 02:01 PM
It is simple physics i would have thought.

Boat weighing x kilograms, moving at y meters per second, smacks in to a wave with total surface area of z and a decellaration in velocity at whatever speed.....
Do that enough times and the sheet metal will start to "cave in" if it is either the incorrect grade of material, the wrong thickness of the right material or with insufficient supports (i.e stringers too far apart)

The better boat builders out there would have done their homework, and it will take a very long time for you to start seeing this developing along the hull. Or it is a very good boat but with a owner who likes wave jumping on a regular basis.


One of the reasons ,I would have thought , for not having metal boats in that kind of weather conditions is because your tongue will stick to the boat every time you lick it??? ::)

Wessel

HarryO
16-12-2006, 08:05 PM
It is simple physics i would have thought.

Boat weighing x kilograms, moving at y meters per second, smacks in to a wave with total surface area of z and a decellaration in velocity at whatever speed.....
Do that enough times and the sheet metal will start to "cave in" if it is either the incorrect grade of material, the wrong thickness of the right material or with insufficient supports (i.e stringers too far apart)

The better boat builders out there would have done their homework, and it will take a very long time for you to start seeing this developing along the hull. Or it is a very good boat but with a owner who likes wave jumping on a regular basis.


One of the reasons ,I would have thought , for not having metal boats in that kind of weather conditions is because your tongue will stick to the boat every time you lick it??? ::)

Wessel











As you do, when its a platey!. #[smiley=grin.gif] [smiley=grin.gif] [smiley=grin.gif] [smiley=grin.gif] [smiley=grin.gif]

erkki
17-12-2006, 06:55 AM
And why would I like to lick my boat...?? ;)

Stuart: I have followed your projekt for some time. Those weldingmachines you are using, are no common brands for me. So itīs a bit hard to figure out what gear is requirered. When I asked a pro welder about that, he said that a puls-mig or tig was the only way to go. This gear reduces the problem with overheating. As far as I understand you seem to be using regular gear. If that is the case, it would make my plans come through a bit quicker.

Fished today in fairly warm weather. + 2 C. About 10 degreas to warm. But canīt complain. No heavy icing on boat, and still chilly enough to hold the baitfish fresh.

Owen
17-12-2006, 07:29 AM
Finnflyer,
Pulse machines do have their advantages, but are generally priced beyond the reach of a home enthusiast.
The machine is Stuarts thread is roughly comparable to a Kemppi Kempomat range, which come form your part of the world.

see here
http://www.kemppi.com/inet/kemppi/kit.nsf/inet/kemppi/kit.nsf/0/98B9DCC0A8A239A1C2257181003BD28D?opendocument

Pulse does reduce distortion (if set up correctly), however given the thickness of the plate on your average plate boat, distortion can be held at acceptable levels without it.

cheers,

Owen

erkki
18-12-2006, 09:11 AM
Owen.

Thanks mate. The Kemppi is a very familiar brand. Good stuff, and widely spread. No worrys finding machines or parts.

Itīs a great thing with all your companys that is providing kits or palns for boats. We got nothing of that over here. Atleast not for the sportfishing category.

A small wory that has sailed up is that all companys wont sell the plans nor the NC-programs. I will have to buy a whole kit and freight around the globe. And that simlply will not happen. Our freaking governement will charge 30% tax on the sum of kit plus freight. And shipping costs bucks...So my selection is a bit limited. Who provides the best service, when it comes to just sell the plans? As far as I can recall, Curran was willing to sell just the disc, but that is some six years ago. Thanks in advance

stuart
18-12-2006, 09:20 AM
Finnflyer

I wouldn't use a tig welder, to much heat and way to slow. It does give a very clean looking weld though. You need to pump the heat into the alloy and move fast as well alternate your welding pattern so you don't concentrate to much heat into one area or you will get distortion. My welder is a uni MiG 270 its doing the job just fine with out getting a sweet up. I wouldn't go any lower than a 270 amp. I had a look at Kemppi welders and they do appear to be like mine so maybe they will do the job for you. I personally found welding alloy extremely easy, I did however take it very easy on welds in terms of not trying to Finnish the weld in one pass. If you work on welding 10inches at a time then moving some where opposite then you cant go wrong. of course their is much more to welding than that.

Stu

erkki
19-12-2006, 08:38 AM
Stuart.

Your input really takes the mystery out from this game. I work as a steelplater, infact most of the time we work with aluminium. The job is mainly to cover big boilers and pipes with plate. We get to a lot of welding as well. But that is fixing black iron to form scaffoldings on wich we fit the aluminium. All I heard about welding aluminium is how hard it is etc etc.

The story is that I visited Australia 2000, and allready then got amazed about the boatingindustri you have going there. I did not have the possibility back then to pull trough a boatproject. So I had to put the plans on the shelf. Now I getting in the need for a serious boat. The only serious boats Iīve come across are all from down there. I have tryed to import one, but since we went into the EU, european community, sort like your commonwealth, we have got more byoccracy(spelling?). Importing a boat from there is not impossible, but very hard and costly. So what remained was to build my own. But the fuzz about the welding have, since to now really scared me off. So iīm getting into a building mode again. Thanks to you and the other fantastic projects I read about on this site.

Altough I have not totally given up the idea to import a boat yet because It would save me some precious time. But building my own is starting to get a serious option. Thanks again.