Thread: Going to give this a try

Hi Gazza,
OK I understand with power - its good fun experimenting if nothing else.
80x80x6 seems like pretty heavy stuff for the keel?
Sounds like you're happy with your new welder - I hope that all works out for you.
Regarding welding thick to thin - angle the torch/arc towards the heavier material and just nip the edge of the thinner material with the bead. If you find the thinner material melting and retracting away from the bead, then try cleaning it better and making sure the fit up is really good against the thick material.
Cheers
- Mick

Originally Posted by WelderMick

Hi Gazza,
OK I understand with power - its good fun experimenting if nothing else.
80x80x6 seems like pretty heavy stuff for the keel?
Sounds like you're happy with your new welder - I hope that all works out for you.
Regarding welding thick to thin - angle the torch/arc towards the heavier material and just nip the edge of the thinner material with the bead. If you find the thinner material melting and retracting away from the bead, then try cleaning it better and making sure the fit up is really good against the thick material.
Cheers
- Mick

Mick what would u use for the keel? the keel is the main support so the boat doesn't fold in half length wise, the original keel is timber i would assume hard wood covered with a 3mm thick aluminium cap than riveted every 5-7cm

Gazza I wasn't sure how you were going to use the angle. I was assuming that it was going to be a V shaped capping over the structural wooden keel, but re-reading your post I think I understand what you're planning - so I agree you need a bit of meat in the keel. I've never done what you're attempting so cant offer any practical experience. I've seen keels before which have been made of 2 lengths of angle (something like 32x25x3) welded back to back in an upside down T shape. The a angle is run through a roller to give the curve. I've seen the same with vertically orientated flat bar (something like 50x10).
Draw a sketch of what you're planning - how is the wood going to connect to the keel?
Cheers
- Mick

Hey Mick, the original idea was to weld the angle aluminium to the existing aluminium cap because there is enough meat on thecap i shouldn't blow holes in the aluminium but now im thinking of removing the entire cap, rivets and wood keel and just start fresh and weld the angle to the bottom of the hull

i'll try sketch something up now

Here's the sketch, i also picked up a old SIP MIG 150 top spool on wheels i was planning on getting rid of the existing torch as the last owner was running really rusty wire thru it and i was going to hard wire a spool gun to it

How is the aluminium attached to the wood at the moment? just nails?
How thick is it?
I'm thinking the thin aluminium is going to be really porous material that will be very hard to clean/weld to the angle directly.
It's hard to know without looking at the boat in person, but if you were going to go with your original 80x80x6 angle idea, then I would be tempted to beef up the thin aluminium skin by cleaning, then riveting on a reinforcing strip, weld that on, then weld the heavy angle to that reinforced strip (overlapping the previous weld) along both sides of the keel.
Hopefully the pic will make some sense.
Cheers
- Mick
Capture.PNG

Thats a good idea, here is how the timber is in place, there are rivets going side ways thru the aluminum cap thru the timber and out the other side that i forgot to draw in

I don't have the boat tipped over and cleaned yet but from what i can see someone has attempted to cut lengthwise along the cap to possibly remove the timber

I can weld on the angle like in your picture but the rivets that go up into the hull are to wide apart for small 50x50-80x80mm angle to reach the outer sides of the rivets so i think i will have to remove all the rivets and fill in the holes

I think your idea is best with the two strips being welded down these will probably need welding on both sides and it should relieve some stress on me, how i was going to weld 6mm to 2mm

I'll make the strips of something like 3mm that way i will be welding the angle onto the 3mm strip plus the 2mm existing hull thickness, so 6mm to 5mm

I just used a makeshift tool to measure the hull thickness, i used a large socket on either side of the hull than used vainer calipers to measure the over all width than subtract the sockets and my hull thickness is 2.2mm which i think i should be able to spool gun weld

there are previous repairs done by what looks to be a mig however its shotty as , one repair must have been a 60cm gash down the side of the hull it was than cut out and a new piece welded in place

there are around 400 rivets holding the keel in place so i think mig spool gun welding would be the preferred option with a stainless steel backing plate

this week im going to start on the boat, all 3 bench seats will need to be removed so i have access to under the seats to remove the paint for welding

i was in National Welding yesterday picking up some tig equipment and noticed they sell nylon grinding wheels for grinders will these remove the oxide layer before welding and without impregnating any contaminants in the aluminium?

I'd be pretty wary of using anything nylon where you intend to weld as you could create contamination issues.
I doubt this will be either a quick or a pleasant repair and you will need to be very aware or rippling, warping and twisting the hull. Once the keel is cut out, there is very little holding the hull in shape, so take your time and block everything up nice and flat etc.
Seing as you are doing some major cutting and shutting, why not just buy some proper keel extrusion and graft in the appropriate size and shape of 3mm ally to marry it up with your hull? A relatively easy lap joint between the 2.2mm hull and the 3mm ally and you should be good to go.
Is it really worth repairing this very old tinnie? I've not seen a tinnie with a wooden keel before and I thought I'd just about seen the tinnie of Noah's Ark.
You really need to make this a sound repair as you cannot get out and walk if your boat loses its keel or develops a substantial leak at sea.

Karl the hull is fully welded together just the seats are riveted in place and the keel is all external, the keel is riveted onto the outside of the hull

i have the boat on the grass and flipped over, let me see if i can take some pictures

Originally Posted by gazza2009au

Karl the hull is fully welded together just the seats are riveted in place and the keel is all external, the keel is riveted onto the outside of the hull

i have the boat on the grass and flipped over, let me see if i can take some pictures

Interesting, do you think the keel set up is a previous repair perhaps?

Nah the keel is original, riveted boat's is a very old design, either someone didn't know how to repair or or they just bodged it

my only worry about doing this job is blowing holes in the 2.2mm thickness but usually boats have a thicker bottom skin, i got the 2.2mm thickness from the top side

my pic's are crap u cant see anything with all those layers of paint and change of paint colour i will take some better pictures tomorrow when i grind off the paint so u can see what I'm doing

Karl would u suggest using soapy water and a scrubbing brush to clean all the dust and dirt off the hull? i need to clean it all off before i grind the rivets down lower than i can knock them out

What is the best way at tackling the aluminium after i have washed it, grinder with a fine grade flap disc?

Some pic's, u can see the hull is bowed pretty common with old tinnies (aluminium boats) after they get put on new trailers ever so often and people winch the down with tie down straps without setting up the runners, mine is bowed around 20mm should still be fine

i was surprised with the keel it measured around 60mm high by 45mm wide there about's but once i removed the outer skin the wood measured around 40x45mm there was a big gap between the wood and the actual hull for some reason

I'd consider a heavy duty pressure cleaner, manual scrub (maybe with a solvent) and a flapdisk.
But...
is there silicone or some other sealant under that middle keel strip? Is it that strip you want to weld to or on the outside edge of the existing rivets?
If there is sealant under the bit you're welding it probably won't stay watertight.

That is the bare bottom of the entire hull now Mick, the center strip and keel have been completely removed

what we are seeing strait up the middle is raw 30-40 year old aluminium that has never been painted because the keel was riveted over it

i have a pressure washer so i'll give it a wash than a scrub with a nylon brush than a wash with acetone just to make sure i don't embed any of the dirt than i'll use the flap disc than again use the acetone before welding

those are the step's im going to take i really do hope it cleans up ok

I'm thinking of using 50x50x3mm or 50x50x4mm i think the 50mm range should be sufficient the guys in the video were using 60mm something by 4.5mm thickness

last night i picked up this its a bit of newer equipment i really didn't want to put in the shed a ESAB MAGMA 150A MIG it can weld as thin as 2mm according to the chart so i think it should be better than using the spool gun

ah just forgot to mention i think the 50x50 angle will fit within the width of the old keel strip so i should be welding to the never been painted section and yeah there is a small amount of silicone stuck at the front and rear of where the old keel was, I'm hopping the acetone will dissolve it