Question For Experienced Steel Boat Builders

[M&M Ovenden]

Hi TimGoz,

The topside plates are indeed 3/16” , so is the deck plating. The cabin tops and bulwarks are 10 gauge.
Thanks for the thumbs up with the design, Murielle spent many hours working on it and I think she likes to get positive feedback

I would defiantly suggest MIG welding for any boat project. In my opinion the higher initial costs are easily offset by the speed of welding. I know not everybody does, but I always include my own labor costs when making cost/benefit decisions. Many very good boats are welded with stick, so hopefully I'm not offending anybody.

Hi Mike,

The reason we use the 75/25 is that we really hate spatter. Not only does it make a mess of your work, but somehow will eventually always find a way into your protective gear and give you a little burn. You can always grind it off, but grinding is also on the list of stuff that isn't so fun. Grinding it off on flat sections is pretty straight forward, but can get tricky in all the corners and curves of a boat. The amperage range that CO2 works effectively in is narrower than 75/25, and the settings we run for 3/16 plate is just about out of this. For thicker sections we just use different filler material (dualshield fluxcore). When you look at the cost of running CO2($40/bottle) or 75/25($75/bottle) over a project it's not a very big percentage difference, and those welds sure are pretty with the 75/25 (very little rework). I think Murielle really hit the nail on the head with her last post saying that the best way to reduce welding costs is to do it right the first time.

Cheers,
Mark Ovenden

[MikeJohns]

Mark
You are aware and well informed.

Presumably you are testing your welding? Nice flat welding can look pretty but ( although this does not apply to you/Murielle) novices often fail to get penetration with MIG they lay down beaut beads but never watch the puddle well enough to see what's melting, they end up with a nice flat cover weld . A number of times I've asked for a weld sample on flat bar and been able to break it easily with my hands, then there is a lot of grinding out and re-welding.

Some of the certified welders are the worst, one large welding firm here can produce two excellent welders, ironically both self taught. On commercial vessels we need certification but we want the non-certified welders from that firm.....have to play some interesting paper games at times.

Are you going to apply for any certification of the vessel ?

Cheers

[lazeyjack]

are you at work Mike? or playing on pc)

[M&M Ovenden]

Hi Mike,

We are not officially testing our welds. With any new process / position / filler material we have been doing 'at home' weld coupons. We clean them up and do face / root bends. We considered running some coupons at the local tech college, but it's pricey for a home project.

I guess that also answers the question of if this is a commercial venture – that's a no. There would be a lot of hoops to jump through. While I am always one to back regulations and industry standards, the hoops get a little too high and small. The big turn off for us is insulation. We want to have a comfortable dry warm interior and the best way we think is with spray foam. This is a big no for Transport Canada for passenger vessels. We don't have a captain's license, and don't suppose we will ever log any hours towards one. I'd love to get paid to take other people sailing, but it seems like a headache. I'm sure the odd “under the table” charter might come up now and again.

I would hazard a guess that the welds that fell apart for you had poor side wall fusion. One needs to be concerned about this with short arc MIG on larger sections. Going to spray mode if the work is down hand, and most larger out of position work could be done with pulse mig / fluxcore.

Cheers,
Mark

[MikeJohns]

Originally Posted by lazeyjack

are you at work Mike? or playing on pc)

Coffee break....

With this broadband I tend to stay logged on all the time so it's easy to get distracted.




Mark
Sounds like you're on the ball. Overall steel is very forgiving even to fairly dodgey welding. I have seen some real shockers on surveying some home-built craft some had even circumnavigated.

Cheers

[Thunderhead19]

In Canada "Boilermakers" are the tradespeople that throw chipping hammers at the guys in the white hard-hats.

A hungry-horse can be de stressed after with a big torch. The plate sucks up tight again if you heat it and quench it.

[lazeyjack]

thats called shrinking, I,m talking stretching