Weld sequence

Mods and custom builds
Goingfishing
Posts: 15
Joined: Tue Jul 28, 2015 8:02 am
8

Weld sequence

#1

Post by Goingfishing »

image.jpeg
Interested to get other people's ideas on weld schedules. Above is a picture of the internal framing of a Jon punt I commercially build. I have added numbers and letters to the frames, in what sequence would you weld in these sections to control the distortion. Bottom sheet 4mm side sheets 3mm
kmorin
Donator 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Posts: 1735
Joined: Mon Aug 18, 2008 1:37 am
15
Location: Kenai, Alaska

Re: Weld sequence

#2

Post by kmorin »

g'fish'n,
My remarks are not from welding this type of framing very much. I've framed with the longs on the outside, (angles inverted with both legs' end touching the hull) and the transverse (usually hollow three sided bends of 5086 x 1/8" -3mm ) touching on their two legs' ends in the transverse.

2nd difference, beside welding on both sides of the sheet, all the bottoms were cambered or radius bent about 2-4" depending on chine width (5cm to 10 cm) where the cup improved the stiffness for welding, and made beach work with a load much more agile.

That said, I used to weld from the middle; outwards. I'd weld the center or each transverse (limber hole was lined with extrusion or bent sheet along keel inside) and the outside keel rail was welded from the center - toward the bow in stitches- then aft. I moved back and forth (forward and aft) on the sets of stitches, the weld patterns were typically 4" one side of along, skip 4" then 4" on the other side, leaving about 8" of a foot welded between the two sides.

The transverse frames in our skiffs ended up 100% both sides welded but that was done only in balance to the longs under the hull being welded. All the (long welds) chines, inside and outside and the entire sheer and side rails were welded before any transverse welding was done... the idea was the welded longs would resist the contraction ("hungry sides") between transverse by having the sides and bottom #1 slightly cupped outward (convex) and stitched so the panels were stiffened before the transverse welds could pull inward in contraction.

Probably not too helpful, as the designs were similar but stiff had major differences, if the description is too vague, I'll give it another go?

Cheers,
Kevin Morin
Kenai, AK
kmorin
Goingfishing
Posts: 15
Joined: Tue Jul 28, 2015 8:02 am
8

Re: Weld sequence

#3

Post by Goingfishing »

Kevin you pretty well hit the nail on the head.
Tack the side sheets on first.
Weld in the centre longitudinal starting mid ships. Chain welding 4" beads either side of the longitudinal centre out to each end.
Then the other longitudinals centre out.
Chines welded inside from centre out.
Install and fully weld transverse frames starting with centre. Front then rear. Then in between transverse frames.
Weld in transom.
Install gunnels
Weld external chines.

This has produced the best finished result, when painted some people think these are fibreglass boats.
kmorin
Donator 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Posts: 1735
Joined: Mon Aug 18, 2008 1:37 am
15
Location: Kenai, Alaska

Re: Weld sequence

#4

Post by kmorin »

g'fish'n,
In the earlier boats, I used to leave most shapes like longs and various rails' edges 'factory' since an extrusion edge is often rounded in the ASME standard shapes cross section. This small radius provided a small 'undercut' weld root increase, except in the case of flat bars where the fillet root would be more 90 deg to the sheet or plate.

After a while, I found I could increase the root face area, reduce the contraction, and increase my break bend performance (tests of all joints) by marking the weld pattern on any given frame elements' edges; and gouge out, sand off, cut a bevel to the long's edge allowing the weld increased root face area.

This had the additional gain of reducing weld face width thereby reducing face contraction and that reduced the distortions of the welds. The "print through" of the welds was not reduced but the distortions were reduced so I do that step in most hulls now.

Sure would like to see more, (many more) and more detailed pictures of your builds? Also, we'd all be interested to know where your boats are used? what work? waters? perhaps businesses use this shape and style boat?

Cheers,
Kevin Morin
Kenai, AK
kmorin
Goingfishing
Posts: 15
Joined: Tue Jul 28, 2015 8:02 am
8

Re: Weld sequence

#5

Post by Goingfishing »

Kevin. These are a design I have played with for many years. They are mainly used by commercial net fisherman working in shallow waters. This exact hull 18' long with motor, 900lb load mid ships and two adults only draws 4" of water.
They are liked because of the stability they offer, shallow draft, large deck weights and low horsepower required to push the boat. This hull loaded as listed above pushed by a Mercury 40hp 2 stroke outboard planes @8knts and top speed of 27knts.
They are a pram bow with a small V pulled into the last 2/3rd's of the hull, this is to help the hull to track when turning and to let the hull lean in and lift the outside chine in a turn to stop it biting in and tripping whilst cornering at speed.
image.jpeg

Here is a picture of the finished product prior to soda blasting and delivery.
User avatar
welder
Site Admin
Posts: 4667
Joined: Thu Jan 03, 2008 11:51 pm
16
Location: Whitesboro, Texas
Contact:

Re: Weld sequence

#6

Post by welder »

I would build a "jig" to pre build all the framing then install the welded out frame into the hull, I hate welding on my knees/shins.
Lester,
PacificV2325, Honda BF225
2386
Goingfishing
Posts: 15
Joined: Tue Jul 28, 2015 8:02 am
8

Re: Weld sequence

#7

Post by Goingfishing »

Welder I would love that option. These hulls are built around a single 6100x1525x5 sole sheet. The frames are fitted and welded into the sole sheet, it being the jig.
Post Reply Previous topicNext topic