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I have a single sheet of 3/16" for the bottom of the boat. Will it be good practice if I groove the plate half the thickness
and then bend it and weld only the outside groove?
Will I get the required quality weld, welding from one side.
Your advice and suggestions would be appreciated.

Dave

DAVE LUDICK,

what do the plans call for at the keel? Is there a [VKB] vertical keel bar? If there is and the weld shows the VKB as part of a weld from below where the two bottom panels make the sides of a weld groove and the VKB makes the 'bottom' or back of rhis groove (?) then: you won't have the exact same strength if you leave half the bottom panel uncut and only two side welds to the VKB inside the boat.

If I were building this design, since it has little or no convex shape to the after bottom panels, in body section; I'd decide about the bottom seam based primarily on the presence or lack of VKB. If there were no VKB or if the VKB isn't detailed into the keel weld, then your method is OK. If the plans show a VKB and a full cut seam then the designer wants you to have a weld that is inside and out for the bottom seam at the keel/rabbet line.

This seam takes a lot of abuse so welding inside and outside both edges using an open seam is quite different than putting a filler weld outside and all/only/both the structural welds inside. In the case of an open seam you create a fully fused T shape at the keel seam, in the case of the notched then filled outside seam all it does is replace the bottom panel's missing material in the saw kerf, which simply makes the bottom thin enough to bend.

One other note- the forward half or at least 3/8 of this garvey's bottom panels' outlines will have an 'orange peel' or flower pedal cut out away from the keel centerline. So the only part of the boat's keel seam we're really discussing is the after 1/2 or less of the bottom, where these panels meet in a straight line along their center edges at the keel.

If I were to design this shape boat, with a deck above the bottom, I'd call for at least a 1/4" x 4" VKB aft where the butts and rabbet lines are all straight, and I'd call for a fully cut seam holding the two bottom panels the full width of the VKB apart= 1/4". The forward keel bar has to be cut (or rolled on edge !) so to keep this weld seam uniform I'd leave the VKB showing in the root of the keel/bottom panel weld.

Weld quality is dependent on weld zone prep and MIG settings, but the strength of this joint is higher when all the structural members are fused by three continuous longitudinal welds; one outside and two inside as opposed to two inside and no fusion from outside.

Whether the plans call for an angle extrusion or not, and I have only seen a screen image of the lines in the catalog, I've suggest it was worth adding an inverted, equal leg, angle extrusion at the keel to cover the seam and provide some [tiny] lateral resistance and impact doubler if you run rocky rivers or beaches. This angle would simply fit over the weld seam while the boat is inverted and follow the seam up the forefoot to the bow plate, but it helps this light wt. class of welded skiff to steer a little better and bounce off rocks and logs much better.

Cheers,

_________________
Kevin Morin

Hi Kevin,
Thank you for that comprehensive, constructive and informative reply, you have more than answered my question.
Is there any way you could transfer all or most of your knowledge and experience immediately into this head of mine
so that I am not asking for info that might just be common sense or elementary.
Thanks once again you are a good man.
Dave

I was hoping Kevin would see this thread. He is our resident expert in aluminum boat building.

DAVE LUDICK,
you're welcome, but there are no thanks needed, Glen-L hosts the discussion- thanks to them for the lines and the Forum. We're all talking about boats, the single most important means of transport humankind has, at least its the most interesting.

You seem to be looking for the "Marine-Miracle-Metal-Mind-Meld", and I can offer one easily; in print. All you do is.... build welded aluminum boats for a few decades and 'just like that' your mind will have a long list of details about welded boats.

I enjoy the phrases, "All you do is...", and its close cousin; " Well, you just..." about as well as any two phrases in the language, because of the nearly infinite, unstated but necessary, conditions we put on the person when we use them with others.

If you want to be a brain surgeon, all you do is spend some time in school.
If you want to be a physicist, all you do is pay attention to math in school.
If you want to build a fair, smooth sided, welded aluminum skiff your first time building in this material, Well- yah just; " slap those sides on there and seam it up!" [right (!!) see how easy that was?].

We all know that a good percentage of the enjoyment of piloting your own boat is the private knowledge and personal memory of the work and effort that we experience while running along at the helm in that boat; and only other builders can appreciate that experience. My knowledge is mainly the result of thirty years of mistakes.

I'm more than willing to try to answer any questions about the building of welded metal skiffs, maybe we can reduce the number of mistakes you have to make building your garvey?

cheers,

_________________
Kevin Morin