Specmar 4.5 Build

[starbright55]

I've been following Carl's build closely and hanging on every word of Kevin's advice that he's been giving. This is going to be a slow process and I'm already a few months in with very little to show.  Since I am working in a one car garage, I have been working on items that take up space and are not structural in any way - the anchor locker, the bench seat, and the console.  Once those are "done" I can get them out of them (probably to the barn) and then I will begin on the hull.

This is a 4.5m/14'10 rib designed by Specmar - I chose it because it's super beamy at 7'9 (the same beam as their 17' and their 21' rib).  I took the rear bench seat / transom set up out of the 21' and used it.  This gives me a nice swim step for diving.
http://www.specmar.com/aluminum-boat-pl ... 34/[center] [/center]  
 
 
 
 
 
 
 

[starbright55]

 
 I ended up getting the aluminum cut at Alaskan Copper and Brass. They still charged shipping from Washington to their San Diego location but they were cheaper than Naimor and significantly cheaper than a local place.

Pickup day:
 

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Sorted and stored all the parts.  I was very impressed with the packaging and care Alaskan Copper & Brass took (It sure wasn't cheap!)
 
 
 
 
 

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[starbright55]

Don't ask my why since I went against my own reasoning, but I welded keel first. It came in two pieces and is 3/8" thick. I know, I know, it's structural, but on the other hand I was going to grind the weld off afterwards anyway.

Test coupons cut afterward to check for penetration. The test coupons had no bevel. You can see the weld got more than halfway through with no bevel and I was going to weld both sides and have a slight 45 on both side so it had a 90 opening. Heavily braced with two pieces of 3/8" bar on each side, it came together well and is perfectly straight!

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[starbright55]

I took all the folded parts to get bent up

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[starbright55]

I had never welding anything until I brought this boat kit home. I decided to start messing around with trying to tig but it's definitely not ready for primetime yet.  It looks ok flat and on a plate but inside or outside corners and haven't got a decent one yet (probably why I haven't taken any pictures of those joints).

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[m32825]

Good job starting a build thread and posting pics, looks interesting for sure!

    -- Carl

[gandrfab]

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[starbright55]

This was something time consuming but probably not necessary. The plans came drawn with rectangular scuppers. But, the designer also said "you may want to plug the scuppers if you're loaded heavy". These scuppers let water drain through the rear bench seat.

Since it's hard to plug rectangles, I decided to make them circular on the inside so I could use pipe testing plugs and plug them up if needed. The circular section is short so I can get inside when it comes time to weld it to the deck.

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[starbright55]

I cut small backing plates for the cleats that will go on the rear bench.

The layout:

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 Again, probably not necessary, but decided to plug weld the cleats onto the back plate from the bottom.  When I am confident in making a nicer looking weld, I will do the cleat to the backing plate and the backing plate to the bench.

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 Not my best tacks but they held and will dressed prior to welding around the cleat

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[kmorin]

starbright55,

The keel in profile seems like it might be hogged? Maybe the way its sitting and coloration in the photo? But to my eye, there's a hog. The vertical pitch of the forward (forefoot and bow stem) seems to kink/hog upward at the weld. (The profile view/image seems to show the weld pulled the bow section upward? If you compare the curve of the bow to the intersection of the keel bars at the weld.... seems a hard spot/hog/kink in the line of the keel?) The point I'm seeing is a few inches forward of the after limber hole/mouse hole/half circle cut in the bottom edge of the keel bar. (pic "keel1.jpg") There is a jog in the keel bar depth at the point of the hog- likely near the weld area but I can't make out exactly where the weld is in that image.

Typically a keel vertical ht. jog would be where the keel joint might change from a line (aft) to begin 'pulling up' the bottom panels' "orange-peel" curved bow cut. So if the bow is curved up - out of the 'fair' line of the original lines... it's possible the bottom plates keel line intersection will be impacted?

W/O sanding and acid etching its very hard to learn how much actual penetration is being shown in the 3/8" bar cross section of the test weld. It's pretty well accepted that you need to bevel this heavy a scantling part in order to get full 'droop'/penetration/root fusion. The common practice is to bevel (not everyone uses 45deg.) and weld one pass and make sure the weld sags/penetrates/"fuses the root and shows on the other side" and then you'd back chip into clean fully fused root, shown by the small bead penetration, and put in the opposite side weld. 

I'd say the overspray on the test plates' images seem to indicate you might be using 0.035" wire instead of 0.045"? Pushing the 0.035" dia. wire to carry enough wattage in this weld to melt/fuse/weld the first pass of 3/8" plate is probably outside that wire dia.'s range? I'd have suggested you consider 0.045" w/ run-on & run-off blocks but I agree tacking on side stiffeners would be good practice in this type of joint.

IF you are confined to smaller wire (?) then preheating using a temp. crayon would allow you to get the most penetration from the wire on that heavy a framing element. Beveling and preheating (250F w torch) then putting the weld in w tighter arc, less long-arc overspray & w run-on & run-off blocks; would make sure you'd gotten the best fusion at the center of the bar. Beveling the joint allows the wire to just melt/fuse/weld the narrow tip area first. That area of the material that is thinned by the bevel will take less weld wattage to join fully.

Back chipping the 2nd side removes the sagged in penetration bead that is considered critical to this joint; so the bottom of the V is cut clean clean (shiny) metal with nothing trapped in the root. Notice that a 'normal' MIG weld in aluminum may have gas bubbles trapped in the root. Leaving the bar edges 90 and butted as the weld joint will most likely leave a lack of fusion- but only a cleaned face and acid etch will confirm your method's results.

Regarding the TIG welds shown, I think you're making great progress - its not a skill that everyone has and takes practice to get all the related rates flowing together nicely. Inside and outside corners are a step above flat padding welds so practice is the only solution if you're going to get nice 'stack of dimes' edging for your console, seats and after locker/bulkhead/transom box? Those cut and bent pc. usually offer the best chance to put really nice looking TIG welds on the outside corners & the more practice you put in now- before you weld them- the better they'll look in a couple years when you're using the skiff.

Cleats being sort of 'external' compared to frames, hull longs, and decking; they can come last. I usually use TIG on cleats, even cast ones like you're showing. The reason is the two different masses to weld. The cleat material is thicker compared to the deck or doubler as in your design. So I find more control of the welds between thick and thin using TIG than I do with MIG.

When doing any plug weld, pocket/socket/keyhole weld as shown on the bottom of the cleat base its best practice to bevel the sides of the pocket. As I've mentioned and sure you've seen, the sides of the vertical hole tend to 'draw'/pull/attract/ground the arc instead of allowing the bottom to be fully fused at the edges of the hole. 

SO, unless the hole is tapered open at the top the weld only melts/joins/welds to a 50% size center 'bullseye' of thee bottom of the cleat. The entire side of the hole all around the perimeter at the interface between the two parts is left cold lapped or unfused. At the least, running a reamer around the drilled/punches/cut hole on the top of the sheet/plate surface will eliminate the peened out, drilled edge filings so they're not in the molten puddle. Leaving holes like those shown w/o at least reaming the top edge will usually result in excessive gas bubbles in the weld's lower depth. 

Scuppers, or in your case freeing ports are really nice if you expect to be in seas that will board your skiff. However, you have to be planing or at least moving with decent forward motion for them to empty the deck of water. Some designs will have enough below decks volume of displacement to allow the decks to run with water and not put in plugs. If your design's deck will be wet with certain loads and sea states (?) then a pretty common solution is the rubber flapper on the outside of the freeing ports/scupper/deck drains. 

There are commercially made self closing flapper assemblies that fit round different pipe sizes and attach with hose clamps around the OD of the pipe. A short nipple, similar to those you show, protrudes from the transom or even topsides and the flap covers that pipe. When the boat heaves, pitches or runs; the water inside, on the deck, runs outward and the flapper opens. When the boat's freeing port goes under water the rubber flap closed down on the pipe end and this acts as a 'check valve' to allow one-way water flow.

Some commercial boats put a 6-8" soft hose on these outboard pipes to give full size flow outboard but the hose collapses on itself when underwater.

Welding progress is coming along but I'd refrain from putting down beads on anything where they don't fully satisfy your standards. There is no rush to get this done- haste makes waste and all that. Do it right: once. Then you don't have to live with looking at your skiff and seeing how much learning was still in front of you when you did this or that job in the build.

Where to you buy the inflatable part of the skiff? Not familiar with these boats so I don't know if you have access to vendors of if this is another aspect of the build you'll have to learn to make? Not sure how the inflatable part connects to the welded part?

The link wouldn't work for me. It looks like the control words are at the end of the link string instead of surrounding the string? So to post a link you'd expect to type "[link]url.string.id[/link]" this is just an example there are several switches used for the bulletin board software to recognize what to do with images, links, web citations... etc. Yours maybe just a typo, but I found it returned 'can't find page' message.

Cheers,
Kevin Morin
Kenai, AK 
 

[starbright55]

The keel in profile seems like it might be hogged? 

W/O sanding and acid etching its very hard to learn how much actual penetration is being shown in the 3/8" bar cross section of the test weld. It's pretty well accepted that you need to bevel this heavy a scantling part in order to get full 'droop'/penetration/root fusion. The common practice is to bevel (not everyone uses 45deg.) and weld one pass and make sure the weld sags/penetrates/"fuses the root and shows on the other side" and then you'd back chip into clean fully fused root, shown by the small bead penetration, and put in the opposite side weld. 

I'd say the overspray on the test plates' images seem to indicate you might be using 0.035" wire instead of 0.045"? Pushing the 0.035" dia. wire to carry enough wattage in this weld to melt/fuse/weld the first pass of 3/8" plate is probably outside that wire dia.'s range? I'd have suggested you consider 0.045" w/ run-on & run-off blocks but I agree tacking on side stiffeners would be good practice in this type of joint.

IF you are confined to smaller wire (?) then preheating using a temp. crayon would allow you to get the most penetration from the wire on that heavy a framing element. Beveling and preheating (250F w torch) then putting the weld in w tighter arc, less long-arc overspray & w run-on & run-off blocks; would make sure you'd gotten the best fusion at the center of the bar. Beveling the joint allows the wire to just melt/fuse/weld the narrow tip area first. That area of the material that is thinned by the bevel will take less weld wattage to join fully.

Back chipping the 2nd side removes the sagged in penetration bead that is considered critical to this joint; so the bottom of the V is cut clean clean (shiny) metal with nothing trapped in the root. Notice that a 'normal' MIG weld in aluminum may have gas bubbles trapped in the root. Leaving the bar edges 90 and butted as the weld joint will most likely leave a lack of fusion- but only a cleaned face and acid etch will confirm your method's results.




 

This will be a mulitpart reply!

The weld is actually in front of where you see that change of direction on the top of the keel.  I marked with a red arrow where it is on the picture and you can see where it's marked on the plans.

The notch on the bottom of the keel is where the planing pad / delta pad ends and then the keel starts it's upward slope.

You called it - I'm using 0.035" (220v machine).  It's all I bought.  This weld was the only 3/8" to 3/8" butt weld.  Everything else that will attach to the 3/8"  keel will be 0.160".  On the actual weld, I did bevel each piece to 45 degrees on each side (so a 90 opening to weld into).  I made sure the depth of the router cuts were equal at ~1/8" deep router cut, 1/8" left flat in the middle, and 1/8" deep cut on the other side.  I even hit it with the die grinder on the opposite side before that weld was started.

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[starbright55]

Regarding the TIG welds shown, I think you're making great progress - its not a skill that everyone has and takes practice to get all the related rates flowing together nicely. Inside and outside corners are a step above flat padding welds so practice is the only solution if you're going to get nice 'stack of dimes' edging for your console, seats and after locker/bulkhead/transom box? Those cut and bent pc. usually offer the best chance to put really nice looking TIG welds on the outside corners & the more practice you put in now- before you weld them- the better they'll look in a couple years when you're using the skiff.

When doing any plug weld, pocket/socket/keyhole weld as shown on the bottom of the cleat base its best practice to bevel the sides of the pocket. As I've mentioned and sure you've seen, the sides of the vertical hole tend to 'draw'/pull/attract/ground the arc instead of allowing the bottom to be fully fused at the edges of the hole. 

SO, unless the hole is tapered open at the top the weld only melts/joins/welds to a 50% size center 'bullseye' of thee bottom of the cleat. The entire side of the hole all around the perimeter at the interface between the two parts is left cold lapped or unfused. At the least, running a reamer around the drilled/punches/cut hole on the top of the sheet/plate surface will eliminate the peened out, drilled edge filings so they're not in the molten puddle. Leaving holes like those shown w/o at least reaming the top edge will usually result in excessive gas bubbles in the weld's lower depth. 
 



 

Thank you.

Where everything lines up nicely on the console seat boxes, console, I will for sure wait and get better on the tig torch!

As for the plug welds, I did read all your info posted on Glen L about tapering and tig (all of the Glen L material you wrote was very helpful).  In this case I used mig, turned up the power, started at the outside, at a 45 degree angle, and watched the doubler plate edge melt down into the cast cleat.  I know it's probably not perfect, but since I doubt production guys do this, I considered it a "belt and suspenders" type approach.  When I get to welding the floor down, I see how a nice bevel will be important (those holes are cnc'd pretty narrow) and I agree it would be good to open them slightly.
 
 
 

[starbright55]

Scuppers, or in your case freeing ports are really nice if you expect to be in seas that will board your skiff. However, you have to be planing or at least moving with decent forward motion for them to empty the deck of water. Some designs will have enough below decks volume of displacement to allow the decks to run with water and not put in plugs. If your design's deck will be wet with certain loads and sea states (?) then a pretty common solution is the rubber flapper on the outside of the freeing ports/scupper/deck drains. 

There are commercially made self closing flapper assemblies that fit round different pipe sizes and attach with hose clamps around the OD of the pipe. A short nipple, similar to those you show, protrudes from the transom or even topsides and the flap covers that pipe. When the boat heaves, pitches or runs; the water inside, on the deck, runs outward and the flapper opens. When the boat's freeing port goes under water the rubber flap closed down on the pipe end and this acts as a 'check valve' to allow one-way water flow.

Some commercial boats put a 6-8" soft hose on these outboard pipes to give full size flow outboard but the hose collapses on itself when underwater.




 

The freeing ports through the bench will be ~2" above the waterline at a normal load.  I still might add flaps to the outside in case I'm back down and water becomes an issue.  And, if I'm running really heavy, I have the option to plug the inside.

I've used "elephant trunks" before on other boats but since these don't drain to the transom, I don't think I will try it.
 
 
 

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[starbright55]

Welding progress is coming along but I'd refrain from putting down beads on anything where they don't fully satisfy your standards. There is no rush to get this done- haste makes waste and all that. Do it right: once. Then you don't have to live with looking at your skiff and seeing how much learning was still in front of you when you did this or that job in the build.

Where to you buy the inflatable part of the skiff? Not familiar with these boats so I don't know if you have access to vendors of if this is another aspect of the build you'll have to learn to make? Not sure how the inflatable part connects to the welded part?

The link wouldn't work for me. It looks like the control words are at the end of the link string instead of surrounding the string? So to post a link you'd expect to type "[link]url.string.id[/link]" this is just an example there are several switches used for the bulletin board software to recognize what to do with images, links, web citations... etc. Yours maybe just a typo, but I found it returned 'can't find page' message.


 

That's the truth!  I'm not going to rush it.  I'm a season behind already due to family reasons.

I've talked to a few places  for the tubes.
Wing - Arcata, CA  https://www.inflatablesolutions.com/
Fast Collar (Lifeproof Boats) - Bremerton, WA  https://fastcollars.com/
Polaris - Surrey, BC  https://www.polarisboats.com/


Trying the link again:
Specmar Link
 
Kevin, thanks again for the thoughtful and detailed responses.  I have a few more posts and we'll be caught up to present day.
 
 

[kmorin]

starbright55,
I understand the hog in the keel now.  It's there because of the angle change in the keel due to cutting away the after V with a truncated plate/'delta V' plate. Once you show the keel bar in profile it's clear how the designer got that shape change in what is normally a straight line keel (aft the forefoot) or smoothly curving into the forefoot and up to the bow stem.

I'd say that a knife edge, no 1/8" land, butt-joint prep was better for 0.035" wire, and a little preheat, but if you got some penetration and back gouged the off-side in prep for the 2nd weld I'm sure it will be fine. Interestingly enough, there's not much stress on a keel bar even in V bottom boats unless they're really fast and will hit the water hard enough to flex the hull.  I often don't even use a VKB in skiffs this small as the longs adjacent to the keel will provide enough fore/aft panel stiffness for the entire bottom.

Might just scallop the top edge of the baffle toe rail and put a small dia. pipe along the top edge as hand-hold or even hinge a boarding ladder on?  It won't hurt to be there to deflect stern wash and maybe a hand-hold or ladder base would help if you're diving off the stern?

Regarding the scuppers under the after locker/inner transom- I'd say it was worth your time to add a little toe rail along the engine mount transom on both sides of the engine mount.  There's a direct shot for wash to come aboard as you slow down and the stern wake overtakes the hull. A short, 3-4" vertical, toe rail, with some limber holes along the lower side would drain the main deck but limit back wash every time you slowed or were in a following sea overtaking you.  Not a big deal but dry decks are safer for traction most times.

Keyholing/plug welding/pocket spot welds.... the deck welds will be much more successful if you open the top edges.  It sounds like you realized the drilled hole welds onto the bottom of the cast cleats needed to be angled to wet the root face of the welds.  Cleat doublers aren't commonly welded under there but won't hurt anything.

When you get ready to weld the cleats' perimeter base to the doublers you might consider tacking the two cleats back to back so their bases and associated cleat-to-base plate welds oppose one another? This will reduce 'curl' of the base plates edges due to weld contraction.  By letting the two opposing welds cool fully before taking the base to base tacks out the contraction of one will largely cancel the contraction of the other.  The edges will remain flatter than if you just put them on the bench, as shown, and weld.  In that case the bases will cup which makes putting the welds on to transom housing at the gunwale more of a pain in the stern (pun intended) to get a nice uniform lap weld around their perimeter.

I see the rabbet line drawn on the profile view of the keel but don't know if that's actually marked on the keel? IF not, I'd say it was very good to mark it w/ ink marker so you know when your keel side edge of the bottom panels are in the correct location on the keel.  In some building methods these two sheets are touching- there is no keel bar- and pulling them together is clearly shown where they touch. In this case you'll have the VKB in the way so having a rabbet line to push/pull/tack too will be helpful.

It will be interesting to see how the inflatable topsides are connected to the hull.

Cheers,
Kevin Morin
Kenai, AK
 

[starbright55]

I see the rabbet line drawn on the profile view of the keel but don't know if that's actually marked on the keel? IF not, I'd say it was very good to mark it w/ ink marker so you know when your keel side edge of the bottom panels are in the correct location on the keel.  In some building methods these two sheets are touching- there is no keel bar- and pulling them together is clearly shown where they touch. In this case you'll have the VKB in the way so having a rabbet line to push/pull/tack too will be helpful.

It will be interesting to see how the inflatable topsides are connected to the hull.


 

There's a sharpie line on the keel from the cnc that I have copied to the opposite side.  The bottom sheets should fit up to each side leaving the edge of the 3/8" keel external to the boat.  Any direct impact from straight on should hit the keel first.

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[starbright55]

Next project was the anchor lock - again practicing on things that are not structural. I can't say that my mig welds were pretty in any way (they're awful) but I'm pretty certain this won't fall apart.

As with the scuppers, I didn't exactly like how the hatch was drawn. I wanted a hatch gutter on all sides so that the front of the hatch was flush vertically instead of overhanging.

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I made a hatch gutter and cut out the lip from the front.  I haven't figured out how to tig the inside of the channel on the back two joints, but they are welded on the backside and super flush.

I still have the two  outside edges of the box to finish weld - they will either mig or tig depending on my confidence in how pretty I can make them.

 
 
 

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[kmorin]

starbright55, 
Do you remember a TV Show called "the Mythbusters"?  Adam or Jamie would say "WELL! there's your problem!" when they found something obviously wrong that caused some failure or mess-up in their builds. 

That's what I said when I saw your current pictures of the anchor locker assembly  (image; "interior.jpg") which is fully, totally, completely and utterly... structural.  IT holds the entire bow assembly together; I'd call that fairly 'structural'!! 

Are you trying to weld aluminum MIG with a steel MIG push-only gun system?  I noticed and LN-9 (Tweco-type) MIG gun in one photo "clamped.jpg" and want to comment on that tool for the job ahead. 

To be as frank as possible - you will turn thousands of dollars of well designed, well cut, and very handled aluminum into so much scrap with that torch.  Fact. 

Proof?  Looking at the welds inside the anchor locker assembly deck to side panels. No one, anywhere can show a decent quality aluminum weld bead with such a torch.  I've watched lots of "excusers'  videos", and read posts by other " Steel MIG enablers ", and other inexperienced welders attempt to justify this choice; but I've never seen any beads of acceptable quality run in marine aluminum with these torches. 

I've said this before, but will repeat it: aluminum wire will not evenly feed in a 'push-only' system over about 1' of guide tube. It will feed evenly in a push-pull system but they're expensive. Aluminum wire will feed evenly in a 1lb. type gun- pistol grip style- but it will NOT feed evenly in a push-only system even with short 6-8' stretch-out that is kept straight!! 

Your welds show this, to some extent, inside the anchor locker back welds the feed rate variation is completely obvious. What type of power supply are you using; you're using a Constant Voltage power supply for MIG.  If V=IR and you change the R of wire-to-work gap; then the power supply will vary the I to compensate in order to keep the V as uniform as possible. In other words, IF the wire is fed with any variability in rate- then R is constantly shifting in value.  The power supply is designed, built, and operates solely to vary the welding current (amperage or I) to try to keep the V (voltage) as constant as possible. 

The wire feed is in effect surging the amperage as you weld, it goes up and down with the wire feed speed changes and your will not be able to - and no one else ever has- produced uniform, controlled size and wattage beads needed for  good hull construction of a welded aluminum boat.  Essentially, you're fighting the machine to put down a uniform bead as if someone were standing at the power supply twisting settings up and down while you try to compensate at the torch!!! Ain't happenin'. 

Aluminum wire is very flexible, many times less rigid than the same dia. steel. A drive motor is pulling wire off the reel in the cabinet & pushing it into a (hopefully) plastic liner inside the torch stretch out but the wire is not exactly sized to the wire guide.  SO, as the wire is smaller than the guide bore and very flexible, it bunches up and coils up inside the guide tube.  When enough wire energy is coiled up as a spring- it springs out- rushing past the contact tip and shortens the arc cone down to the puddle.  When the wire is not surging into the puddle at higher rates than set as WFS; it is coiling up due to the resistance in the contact tip from micro arcing and friction drag that impart the welding power to the wire. 

This cycle repeats where a starve-the-wirefeed and long arc results in overspray from too long an arc; then over-feeds the wire and the arc gets very short and the weld mode may actually shift into 'short arc mode' until the tip drag again coils the wire back up in the guide and slows/long arcs.... rinse and repeat. 

This is shown by the puddle size variations in your MIG bead not shown in your TIG bead- IMO, illustrating that you clearly know what you should be working to put down but the system is preventing you. 

Can you continue to 'glop' your skiff together?  Maybe, but the result will be a pile of scrap (note the S ?), with no resale value and constantly in danger of having cracks, and weld failures as you'll need to constantly grind, sand and finish your welds to tolerate the poor appearance achieved when a 'steel only' torch is used where either push-pull or 1lb. gun is needed. 

I'd advise you consider getting a more suitable welding torch, and practice a bit with it before any more welding is done on your skiff.  OF course I'm spending your money freely.  On the other hand, I think you'll ruin your investment by attempting to weld with a push-only system. 

I've never found anyone who've succeeded in producing acceptable welds without one of the aluminum appropriate wire feed systems.  I'd rather see you TIG the entire boat than to use that Tweco-type feeder. 

Rant off. 

The locker's coaming need not be 1/2 as deep as the legs you show.  A 1" deep coaming around a deck hatch will work fine to shed water in that application.  I realize it's largely done but just a note about that design, now the hinge system has to be offset to allow the 'legs' of the hatch to clear the coaming.  

Cheers,
Kevin Morin
Kenai, AK
 

[starbright55]

Kevin, thank you again for the detailed response. I am almost caught up to present day with my posts and will take everything you've conveyed under advisement. Please keep ranting! I will soon be real time and you can help me prevent making future mistake!

[starbright55]

That's what I said when I saw your current pictures of the anchor locker assembly  (image; "interior.jpg") which is fully, totally, completely and utterly... structural.  IT holds the entire bow assembly together; I'd call that fairly 'structural'!!  
 

My comment that the anchor locker assembly is not structural is correct.  Every boat built of this specific design was built without an anchor locker.  The boat was designed that way (without).   I asked for it to be added, on deck, since I plan on anchoring frequently.  This will be the first boat with an anchor locker up front.

This is shown by the puddle size variations in your MIG bead not shown in your TIG bead- IMO, illustrating that you clearly know what you should be working to put down but the system is preventing you. 

 
 

I think what you are commenting on here is that I was playing around with the double pulse settings on the machine.  I knew this area would never be seen and wasn't structural so I wasn't worried about it.  Next time I'm working on the boat, I will probably just practicing filet welds again (It's been a busy summer and it's been about a month since I've touched anything boat related).  I will do some straight push beads without any of fanciness and I'll take some pictures to post.
 

I'd advise you consider getting a more suitable welding torch, and practice a bit with it before any more welding is done on your skiff.  OF course I'm spending your money freely.  On the other hand, I think you'll ruin your investment by attempting to weld with a push-only system. 

I've never found anyone who've succeeded in producing acceptable welds without one of the aluminum appropriate wire feed systems.  I'd rather see you TIG the entire boat than to use that Tweco-type feeder. 
 
 

A spool gun is always a [relatively cheap] option.  My machine can accept it if needed.

I had a friend said the same thing - It would be possible TIG a boat this small.  Tack with the MIG, finish with the TIG?  Of course, an option.

The locker's coaming need not be 1/2 as deep as the legs you show.  A 1" deep coaming around a deck hatch will work fine to shed water in that application.  I realize it's largely done but just a note about that design, now the hinge system has to be offset to allow the 'legs' of the hatch to clear the coaming.  
 

I totally agree.  It was designed with 1.5" channel and that is definitely overkill.  But, I think I bought two 16" sticks of it already (came with my original order kit).



Again, I love the feedback.  I took a 2 hr. TIG class last fall and all we did was aluminum.  What I can't find locally is anyone with any aluminum MIG experience so your comments are very needed and useful.
 
 
 
 
 

[m32825]

What I can't find locally is anyone with any aluminum MIG experience so your comments are very needed and useful.

I found it more difficult to track down good resources on aluminum MIG than TIG. I think part of the problem is that it's hard to get decent video with MIG. TIG is more photogenic, and most sites favor content that shows well.

[kmorin]

m'25,
Jody @ weldingtipsandtricks.com, w/ channel on utube, offers some decent aluminum MIG videos. He's most often working in thicker material but.... a MIG vid. is a MIG vid. when you need to get some idea of gas coverage, wire feed vs arc length and weld puddle conformation. Most of his Al/MIG video's, if I recall, show at least some whip/weave/patterned beads and don't show a clean mechanical drag weld that is more appropriate to thinner material. 

However, since you're working in 0.160"-5/32" material; whipping wouldn't be out of the question.  However, I still think the 1 lb. gun would be a much better choice over trying to put down decent beads w/ a Tweco-type push MIG torch.

cheers,
Kevin Morin
Kenai, AK

 

[starbright55]

 I've still been practicing. And practicing on non structural parts.  This is the bench seat.

It didn't come together real well on one side.  As much as I wanted to MIG the gap (because it was going to get sanded and radiused anyways), I cut all the tack and ground it down a bit, a got the gaps to <1/16".

open joint.jpg (38.25 KiB) Viewed 25044 times

 You can see the gap was just there and couldn't pull any tighter since the top was already flush (blue line)

top.jpg (62.27 KiB) Viewed 25044 times

 
Chose to TIG this for practice (but the inside was stitched via MIG).

PXL_20240916_002411825.jpg (88.07 KiB) Viewed 25044 times

 

PXL_20240916_000641673.jpg (120.12 KiB) Viewed 25044 times

 There were some good sections, some not so good sections...that's what practice is for




 
 
 
 
 
 

[starbright55]

I think I may have mentioned it before - I didn't want two hatches in the bench as it was drawn and I didn't like the gutter set-up. So, I modified it.

This is southern California, but no, I didn't weld in flip flops

unwelded.jpg (160.03 KiB) Viewed 25044 times

 
Again, practicing, trying different things.  This was also MIG'd from the back.  I wanted to see if I could give it a little whip....bad idea since I was planning on sanding it down flush.  Ooops

whip.jpg (48.94 KiB) Viewed 25044 times

 

boo boo.jpg (111.27 KiB) Viewed 25044 times

 

So, the next section I just pulled a straight stringer bead since I knew it would get sanded

mig stringer.jpg (133.61 KiB) Viewed 25044 times

 

 
 After the bench gets done, I will move on to the console.  Then all of those [mostly] finished items, can go out in the barn so I have room for the hull.
 
 
 
 
 

[kmorin]

Starbright55,
I noticed the fit-up of a joint that is not good practice; if I understand the image? In image titled 'whip.jpg', it appears the end of the leg of the angle extrusion that forms the seat top hatch coaming; is flush with the top edge of the vertical side?  Regardless if there's a back weld, this is poor practice as the weld (especially MIG) simply sits on top since there's no V groove or bevel of the materials to allow a mechanical penetration. Therefore weld fusion relies solely on the MIG bead's depth of penetration?  I'd say by sanding this weld off- its essentially not even welded?

Better practice for all of the welds in this category are to lift the lower edge of the angle's leg thickness to the top edge of the vertical plate so the two joints are 'inside edge to inside edge'.  Without this geometry to form the weld zone - the actual edges of the two parts are not going to be joined except inside by the MIG fillet.  Using an outside corner weld fit with inside edges/corners touching, or even slightly gapped, is best practice because, as the bend break test of these joints will show, full fusion is obtained - your method leaves 80-90% of the parent metal edges un-fused- not welded.

Next, sanding off the bead flush for appearances sake will only further weaken an already questionable design of these joint. As there is very little penetration, when combined with the top bead being removed- those types of joints are not good practice.

If you are dressing off the welds, and have only a grinder/sander to do the work (?) consider adding a router with a round-over bit to the tool selection.  The method there is to sand the two sides flat to the surrounding parent metal then use the guide bearing on one side and the table on the other to guide along the weld to be dressed and round over the shape into a nicely finished surface.  IF there are 'tracks' left from the router ? following with a series of ScotchBrite (tm) pads on a grinder to smooth the surface to a final finish.

If you're going to continue to fit the edges of parts flush instead of 'inside corner' (?) then I'd recommend you bevel each part so they form a V groove along the side where the outside MIG weld bead will lay. This would provide at least some depth of weld allowing for a greater root face penetration; if you'll be dressing the top beads off MIG (a practice not well accepted, or widely practiced) unless there is extensive joint prep to insure root bead remains.  Otherwise- why weld?

To confirm if I'm wasting your time or not; simply weld a set of coupons with both methods then finalize the surface by sanding off the bead as shown on the flush edge parts and bend the two coupons.  I already know the results, but maybe you'll convince yourself why others don't use the methods shown?

Cheers,
Kevin Morin
Kenai, AK