True Grit Aluminum Build

[polynimbus]

Got the last of the seams welded out (switched to TIG for the plate butt welds, I was worried about plate distortion but didn't get any measurable "pucker"), and performed the first of what I expect to be a few flips this weekend. The boat sure grew once I could see the full internal volume without all the building fixtures. Flip went smoother than I expected, only about an hour beginning to end. Used a single sling in the back and the bow eye, with a cross-spall where the sling crossed the shear to keep the sides in position. All of the original fixture spalls are still in, I will keep those in until I get the raised shear and gunwhale installed. It's now on the trailer to move it under cover for winter work.

The plan now will be to back-gouge and weld all the inside seal-welds now that they are down, in position welds. I anticipate a few cold spots from the outside welds so I will use the gouging as an opportunity to check penetration and cut out any issue welds. Once I flip back over to install the stern tube I can dress the outside welds again (at least that's the plan). After inside basic welds it will be on to the bulwark/raised sheer...still head-scratching the junction between bulwark and gunwhale top.

[JimmY]

I'm no welder, but those are some nice looking welds. Impressive build you have going there.

[Kevin Morin]

polynimbus,
I actually prefer to weld the inside hull seams and other welds overhead, standing flat footed on the shop floor, as compared to having to kneel down and reach below my knees with the torch to weld when the hull is keel down doing the same welds.

My experience with the over head welds is that the vastly improved 'reach' and freedom of movement with the torch overhead, or at should ht., allows me to put in much better welds compared to crunching-up my chest while kneeling down.

Back gouging seam weld penetration is easier for me working under an up turned hull as well; since i can get near the work while next to the tool instead of being near the work while having the tool hide the cutter from me with the blade guard.

Hull looks nice.

Cheers,
Kevin Morin

[miked54610]

This is my first visit to this website.

[johnmick658]

Great

[polynimbus]

I know the purists here probably think aluminum builds are sacrilege, but I figured I would give an update in case anyone has insight or if it can provide insight to anyone going down this road in the future.

Bulwarks are mostly complete, and most of the internal weld out is done. Using masonite for skin templates and transferring to the flat sheets has proven to be a good way to get patterns for the skins. I tried a few different methods, but with practice it's the easiest way to get semi-rigid patterns that transfer well to the aluminum sheets. It also is an easy (and cheap) way to verify both sides are symmetrical before cutting the aluminum. If one side has an anomaly it's easy to fix it and recut a $10 template before committing to the aluminum.

The forward two bulkheads and berth tops are in, so it's starting to get easier to picture the layout and get a better idea of how I will finish the superstructure out. Most of the True Grit builds I have seen so far vary substantially above the waterline (which is a good thing) so the flexibility in the design makes for a fun experience in visualizing exactly how you want it to be laid out.

Next steps are to finish the top cap (gunwhale the term might be?) all the way around and get the carling all the way around. Should give it enough torsional rigidity to remove the temporary spalls (this long of a boat seems to want that "railing" structure to give it real strength until the sole is in) and start with tank/engine considerations.

[JimmY]

Nothing wrong with an Aluminum boat. I just worry about all that beer without a home!

But seriously, the skills are different but I can appreciate the work you've done. It looks great. Keep posting.

[psychobilly]

How’s this build coming along?

[polynimbus]

Still making progress. The hull is pretty much welded out, got the bulwarks and carlin in and welded, and the top of the berth is complete. I cut the template for the windows for the front of the cabin so I can get the windows ordered. I opted to sweep the window forward (we are in the northwest and it's much more common on offshore boats up here). I wanted to check the look and visibility before I order the windows (they are custom and spendy so I don't want them to be wrong).

We flipped the boat back upside down to install the stern and rudder tubes and clean up a few bottom welds, as well as finish the bunks and paint the trailer. Finished the electrical as well, so the trailer is pretty much done. Next step is to paint the bottom of the hull (once the stern tube is in and the welding done) and put it back on the trailer for good. I am thinking a float test would be prudent just to double check for leaks before the tanks and floors go in.

Any opinions or advice are welcome, definitely many decisions to be made.

I attached a picture of the Tubby Tug side project too, Mostly just a fun project for the kids to help with.

-Joe

[JimmY]

Awesome project, and the Tuby Tug is really cute. Shinny!

[psychobilly]

Look’n good!

[Roberta]

WOW!! Both looking Great!!

Roberta

[Kevin Morin]

polynimbus,
The trailer looks like it has wooden bunks, but a few rollers here and there? Not sure but wanted to remark that the bunks shouldn't be covered with carpet and be left with the boat on them. Even w bottom paint you're setting up a crevice corrosion cell w carpet. The plastic trailer bunk covers are a much better cover for wooden trailer bunks as they are non-reactive and allow water to drain.

Hope you'll consider etching your boat at this stage of construction? Get rid of the mill scale which not only isn't vapor proof- will actually hold water vapor and initiate a crevice corrosion cell - they begin as little "white flowers" on aluminum sheet that hasn't had the mill scale removed mechanically or chemically.

With small router tabs in the windscreen's window cutouts- not sure why the blanks were left in? I don't thank that little tab in the router cut path is going to keep the window panel from warping when the perimeter is welded; do you? IF a bunch more tabs were left- then there might be some weld warpage resistance? but with these few small tabs- I don't see much contribution to the panel's stiffness? The corner of the house being about 90 or so will probably stay fair? But the middle window intersections will have a harder time in my experience. We usually include some extrusion inside (or outside) the two middle vertical seams to help keep the panels from warping. Even then, its common to have to come back with a pair of 16-20" crescent wrenches to help fair the panels' cutout inner edges for either rubber or aluminum clamp-in bezels for windows.

If you have pictures of the keel/skeg/shaft log work they'd be very interesting as they have been discussed once or twice here in the past.

Nice looking projects, thanks for the progress images and notes.

Cheers,
Kevin Morin
Kenai, AK

[polynimbus]

Kevin,

Thanks for the reply. The tabs in the windows were just to keep it rigid during handling and the press brake operation, I was worried about it getting "floppy" and hard to brake without bending through the thin parts. Once it is in place and tacked I will pull them out. I plan on running T-bar on the inside of those bends to give the panel some strength back. Like you said, the cabin corners should stay reasonably true.

Good info about the bunks, I have only ever made trailers for fiberglass boats and that's always carpet. I'll look in to the plastic covers.

As far as paint/finish, I was planning on DA sanding (180 grit?), then etching and priming the bottom, and doing anti-fouling over that. The Total Boat system looks the most promising https://www.jamestowndistributors.com/p ... gJB-_D_BwE but any advice there would help. I have to install the rudder/shaft log first, but after that the bottom welding should be complete.

One unrelated question, what are your thoughts on removeable vs nonremovable fuel tanks? The location called out is right under the back cabin wall, which means they will be difficult to replace so I am trying to find solutions to be able to snake them back out (removeable floor). In your experience, are tanks almost always removeable (without cutting the boat apart)?

Thanks,

Joe

[Kevin Morin]

Joe, using a hollow shaped extrusion for window reinforcement provides a conduit/chase/raceway for wiring to go to the cabin top- lights, antennas, electronics.... Stitching to the two sides of the window panels won't distort hardly and will give good extra stiffness over a T stitched with the T leg forward? Ak Copper and Brass sells a 'hull stiffener' extrusion that works well, but a half pipe or other U shaped extrusions will do this also.

Painting aluminum is a pretty big topic with lots of experiences and opinions. I think the best mechanical anchor pattern is produced by sand blasting/media blasting, next would be sanding of some sort and last would be just pure chemical bonding. The best is chemical bonding over a mechanically established anchor pattern. After mechanical abrasion, etch with acid, then rinse and while wet apply a chromium solution to get a chrome oxide film- before the aluminum oxide can form. Then add the primer and topcoats of whatever system you'll be using.

Don't know Total Boat, but I would suggest you may want to contact Agate Pass Marine in WA, and his handle on the Aluminum Alloy Boat Forum (AAB.com Forum) is "Chaps". His business is coating, re-coating and repairing coatings for boats in the Puget Sound and he has many articles there on the AAB.com Forum. His wealth of knowledge is based on being active in that business, for years, of coating welded aluminum boat bottoms.

I have built boats with built-in tanks (where hull panels were part of the tanks), separate (from the hull) but welded-in tanks and fully removable tanks where the boat structure was designed to be able to remove the tanks - some with screws and bolts other with a skill saw but still provided for removal.

My preference is for fully removable tanks that can be either cut out or unbolted with provisions in the design for tank installation, removal and re installation. With that being said, its not always 'affordable' or 'reasonable' to remove the tanks in all designs. Many locations, as yours appears, are hard to make removable without making some accommodation to the bilge framing aft the tank, and the deck over an area equal to the tank's Plan View size/dimensions. Screwed in deck hatches that seal completely but could be removed are always a pain because the screws that hold them down almost invariably corrode and make eventual removal a real pain in the stern.

Modifying the after deck framing to allow a tank to slide its fore and aft dimension out - under the after cabin bulkhead isn't very simple- the frames and longs all have to be designed to accommodate this tank volume to more at least 50-60% aft before its clearly in an after deck hatchway for lifting.

On the other hand, if you build your tanks with a water bottoms sump (I have a tank building thread somewhere in the Materials/Metal category that shows my explanation of how to design a reliable tank) and tend it regularly- therefore cleaning any water bottoms out so they can't become corrosive inside the tanks... ? TheN....there's little to ever concern about tank corrosion/failure if the metal isn't strain hardened to failure cracks by a too small die on a press brake- and the outside of tank is allowed to dry off with both air circulation and a correct shape.

I built some tanks in the late 70's where the Skipper said I was crazy and "just build them like I say" and they eventually failed due to poor maintenance and were rotted from the inside out. I also sold and installed tanks in that day and age and they're still in service- (but not all!)

another thing to avoid like the plaque is foaming a tank into a space in the bilge as is common practice on some production boats. This is assured of failure as the foam will hold water and promote crevice (sometimes called poultice corrosion too) corrosion - even if the tank is painted (in some cases).

Hope you'll do a bit a research on the subject and then decide how to install your tanks- they can be welded in and still have a ready means for removal with a saw. But well built (including acid etching before putting the tops on!!) and then regularly pumped out for water bottoms will make whatever installation you choose last much longer than; plate w mill scale intact, bedded on raw rubber bedding, w no sumps, no means to inspect inside or out, and no air (bilge air) circulation to allow the tanks to dry off from any ambient air condensation; and especially no copper alloy based metal fittings anywhere near, on or in fittings on your tanks!!

Cheers,
Kevin Morin
Kenai, AK