25' Alloy Build

kmorin
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25' Alloy Build: bottom longs

#26

Post by kmorin » Sat Apr 28, 2012 1:17 pm

Because the bottom is not framed transversely and is 1/4" there were two places where the shape was distorted so the layout for the precut longs was not used, instead some temporary transverse shapes were tacked under the hull to hold the shape and the longs were scribed to fit. This was added labor that I should have avoided by framing the hull differently but it didn't work out that way. (older and wiser)

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here one of hte 4"x1/4" longs is shown being fit to the (changed) curve of the buttline near the keel, and the outer buttock line former (sheet edge off cut from 1/4" bottom) is already fit and tacked. Since the longs were on 9" centers of 1/4" on a 1/4"bottom the 2x4's provided a quick line up and scribe to fit location.

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here three of the longs are fit showing their relative depth and location, the outboard ( full ht @ 27" Offset) long reaches the deck and is notched for the future deck beams. (The corresponding notches are not cut into the 2"x3" angle now stiffening the keel's top edge.)

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and the process of adding the longs, one being recut during the fitting process.

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once the longs were in we began to fit the deck beams which are 2"x 2" x .187" 6061-T6 on 12" centers.

These beams are cold bent to the 1" camber of the deck at the transom which flattens as the deck runs forward to about
dead flat where the deck begins to follow the upper chine seam in profile, into the forward rising curve. That is about 15' forward the transom. Therefore the deck is a ruled line from side to side forward the cabin as it slopes aft and would drain without the need for camber to shed to the sides.

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To connect the deck beams to the longs a short angle leg was fit to the side of each and welded. These vertical struts made the deck beam(which will pocket/socket/keyhole ) weld to the deck above, tied to the long wise framing on a 12"x9" grid over the entire bottom of the boat.

Nearest the camera are a pair of 1/4" plates that connect the hull to the deck and transom they are at 9" offset from the keel so there is a full plate at the transom at the keel, and the first two longs to insure there is a full plate 'box' to carry the engine's load(s) into the hull and not allow the transom plate to move in any way fore and aft. So in those areas the legs shown forward are full height plates that connect to the deck beams and were eventually keyhole welded at the deck.

I'll explain the conduits in the next post.

Cheers,
Kevin Morin
Last edited by kmorin on Sat Apr 28, 2012 2:54 pm, edited 1 time in total.
Reason: typos
kmorin

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25' Alloy Build: deck and bottom framing

#27

Post by kmorin » Sat Apr 28, 2012 1:56 pm

Just above the images show the longs on the bottom, the deck framing beginning and some unaccounted pipes and conduits under the deck framing.

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to allow the shift throttle cables to run from the helm under the deck aft to come up just forward of the engine a conduit of 3" pipe was built to provide the room for the electrical, controls and various other cables in one run. No fuel is included in this particular conduit. The pipe is 6061-T6 and the long radius sweep of the middle 45 was done by segment bending. But I did not have any butt weld long radius 90's for the forward and after turns upward in the run.

I looked for local pipe bending services and for mandrel bend segments on line both were pretty costly compared to making a 'rain gutter' type of 1/8" plate 90 which is what I ended up doing. This allowed the correct radius for the two shift throttle cables that determined these two shapes. I'd have preferred mandrel bent segments, of the correct radius, but this was faster than finding and shipping those pieces.

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As the pipe was in segments, not bent at the ideal location for the final layout; I butt welded the conduit into a shape that would fit the geometry of the required locations of the ends. [Uphill, TIG w/ 1/8" pure tungsten, 5356 filler, 126PPS 60% Hi, 45% background, 300 A peak; 68%EN; 250Hz; full V groove single pass in four quadrants.] Last, with caps welded on the ends the entire conduit was pressure tested at 4psi before installation.

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If you drew a nearly vertical straight line (which I didn't do here) from the top right (1") pipe to the lower right pipe or corner of the squared conduit opening, that would be the cabin's forward bulkhead so all three conduits come out of the deck just aft this line. The top (port) pipe is a propane cabin heater fuel line conduit, that runs to the same aft starboard locker the main fuel line conduit connects to the cabin. The lowest 1" pipe houses the main fuel line aft from the tank. This boat's main fuel tank will be just forward the cabin bulkhead on deck and the fittings will run inside the cabin bulkhead and then down into the conduit to come up in the after locker where the filter will be located.

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a little closer view of all three conduits installed prior to the deck beams going on. Scrap/offcut strips are used to weld the pipes to the framing nearest that point in their runs to keep them from vibrating or 'buzzing' against any frame element or breaking. The mounting is not needed for structural requirements its to break up any running harmonic vibration and make the tubes super rigid in place under the deck. No fuel will be inside the pipe wall, the two smaller pipes will carry hoses rated for the two fuels they convey to the heater (forward flow) and the engine (flowing aft).

cheers,
Kevin Morin
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25' Alloy Build: Decking Installed

#28

Post by kmorin » Sat Apr 28, 2012 2:49 pm

with the bottom framing and welding largely done, where the welding was stretched over several different framing steps to fill in the work flow and move the heat of contraction around the boat slowly; its time to put on the deck.

You may recall that I didn't want to kneel down on the deck beams and weld below my knees because of my old carcass's protesting and the poor quality of my kneeling position beads? This means the Davis Jig made the boat possible by allowing the hull to turned up in the positions shown and welded by simply reaching into the bottom. Sometimes I had to stand on a ladder, but even then I was upright and had both feet planted so the welds weren't suffering any more than my unpracticed MIG bead does regularly!

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by draping the sheet over the bottom's deck beams and clamping the side cuts can be scribed, and fit and the keyhole penetrations laid out for router/drilling then the fit sheet laid on the hull to tack. The bottom of each sheet was hand buffed with a 3M Scotchbrite(tm) pad to remove the mill scale since these sheets would not fit into the drum sander in either direction.

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lower topsides to deck seams were all welded with TIG. this allowed a keyhole to be carried along the two knife edges of the bead and insure decent penetration with good uniformity. The weld was done with 5/32" pure tunsten; 126 PPS @ 70% Hi, 55% background; 300 A peak; 72 EN; 120 HZ AC; 0.035" 5356 wire filler and the welding rate was one of these 8" welds was 6-8 seconds or an inch per second.

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to keep the work flow going the forward framing fits were ongoing while the after deck plate's keyhole welds were being done. These welds were done while the deck was vertical (shown) so they could be done uphill to clean the socket with gas while doing the fill. Blue tape was put on to keep dust out of the remaining welds while the weld tops were sanded during breaks in the welding process.

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Fitting the third 5' wide deck plate by draping on the frames, clamping down and scribing the outside fits, deck plate butt joints all fall on one or another deck cross beam to provide full weld backup for these seams.

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Eventually the entire bottom was decked and welded, then air pressure tested to about 2.3-2.5 psi, and I had about 8 leaks total. Unfortunately five of the leaks were within a few inch of one another in one transverse deck seam. Evidently I didn't clean the U shaped groove between the two deck plates backed by the top of one deck beam as this MIG weld had almost all the pressure leaks. I suspect that I was merrily welding along and failed to notice dust, or other contamination in that 8" long weld since there was so much porosity in the one area. After gouging the weld out and rewelding it tested OK so I'm blaming my poor weld prep for my high number of leaks in that one weld. ( :banghead: )

I found that building a hull as a 'hollow' surfboard is functional. I'm not saying its the best way to build, and to accomplish this I had to draw the deck line intersection in a way that allowed this form. Both decisions were based on my fear of being able to climb around the topsides for the work if I didn't make the bottom (lower topsides) to deck seam at this point in the build.

I would do this again, and wonder if I will regularly try to build the more conventional method of adding the full height topsides and then forming a deck with a T type joint; instead of an outside corner that is fully welded then air tested before the upper topsides are mounted?

It is more work in the sense that this adds at least two full length welds to the more traditional method of building. However the speed of the TIG gun coupled with the advantage of an less agile welder/fitter being able to access the joints better leaves me with the conclusion that this was worth it for me.

So, for the home or one off builder that is less flexible but wants to produce a sound hull, I'd say this method was worth considering but it does require the Davis Jig to make it happen. The weld quality I (was able to) put inside the structural framing and the very improved access to those welds made the time and cost of the Davis Jig worth the effort. A hundred times on this skiff I've been able to create weld positions that allowed me a fighting chance at good work, not that I was always able to rise to the challenge.

Next we'll need some (upper) topsides.

Cheers,
Kevin Morin
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Re: 25' Alloy Build

#29

Post by Napa Mike » Mon Apr 30, 2012 10:37 am

Thanks for all your posts Kevin. Very cool!

Mike

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25' Alloy Build: reference notes

#30

Post by kmorin » Sun May 06, 2012 2:49 pm

AAB.com, I've received a few emails regarding this build so this post just makes some notes for those reading.

First this is a one off boat, I'm not building fulltime and don't have a crew of builders, and the work shown is being done in various rented shops, with a couple of welding power supplies and hand held electric tools like saws, grinders and sanders. This means that many of the advantages the build could enjoy in a fulltime shop are not available like experienced, younger workers familiar with welded boat building or tools and rigging that are geared to boat building.

I did not use NC cut pieces because the relative cost was higher than the project could afford, where my time is not critically important and the boat is not being built on a schedule; I have NO deadlines. So the work to layout and cut parts would/could have been saved or extremely reduced- but that is something I'm contributing to the build- something not present in a commercially viable builder's economic equation.

Design decisions. I tried to explain at the outset this design was reviewed by the boat's owner at each stage and the decisions are his not mine. I may have decided, and many readers may have decided to draw different shapes or arrangements for my/their own boat, but this was my attempt to 'draw for someone else'.

If you have a blank sheet of paper, how, exactly, would your boat look? That is the point where we began, not with my previous hulls or my own boats, but what did the owner want to see? That includes the cabin and stern arrangement.

In answer to several question about the stern arrangement. First we started with a 22' to 23' boat and planned to have a full width bracket all the way across the transom to get the most extended waterline length and planing area. When we designed for that and purchased sheets (25' topsides side sheets) for that size boat, it occurred to the owner that by enclosing the area above the extended transom bracket the same amount of material would yield a 25' long (LOA) boat.

Therefore the logic/path to the current layout is the full width transom extension or engine mount became extended upward as well as aft-resulting in a longer boat with the same, or more, deck area of the boat planned originally.

No, this is not my first skiff build, and yes I have built a couple hundred skiffs and do not (even try to) show every single decision point in the posts. The reason is that the posts are intended as a review not a tutorial, the idea here has been to show the basic steps not to create a building tutorial/educational article to support other builders. The post hopefully shows the fundamental work is not all the complicated (this ain't NASA) and works to encourage others to learn to combine their existing skills to consider building for themselves.

I hope this reply helps those who have asked to more clearly understand some of the decisions that formed this boat? I'm happy to continue receiving personal emails and will always attempt to answer any questions in those emails. Since I'd received a few common questions- I thought I'd reply in this post to summarize some of the conditions influencing this build here for everyone to review.

Thanks for reading.

Cheers,
Kevin Morin
kmorin

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25' Alloy Build: cabin

#31

Post by kmorin » Sun May 13, 2012 7:32 pm

I have a Skipper who knows boats, and knows what he wants, and his wife is involved in asking good quality questions and is First Mate. So this boat is built to suit two very knowledgeable Alaskans who have been on the water and out doors together for a good while; they know their stuff.

That means you can ask direct question provided sketches or a mock up and get a direct -yes or no- or a question that exposes just what missing information would be required to arrive at the yes or no answer. If you've built for others, boats or houses, or anything that gets built you may realize how much of a Godsend this couple is to boat building.

I drew a cabin that they reviewed for quite a few months, coming back to ask about details, and nudging my pencil this way and that, exploring different concepts and making their own adjustments as we went along. They went home and used chalk in their basement to layout their cabin and put up boxes and furniture and walked around in the space.

So the cabin represents their ideas of a weather helm for their use.

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I wanted to shape the cabin in a way that was as attractive as a 'doghouse' type helm can be. Lets face it, a rectangular
box in the middle of a skiff is not always a thing of beauty! So I began with a curved dodger below the forward windscreen and split the rolled piece top and bottom. The bottom will form the tank the upper portion is the under dash area for wiring, instruments, fittings and what not- including stowage.

The entire structure forms a very stiff box beam to carry the entire forward windscreen glass and framing without any difficulty in 1/8" 5356. Further in this same vein the lower side panels have a 2" shelf below the window band at the top of the lower panels. I could have, most of the time int he past I have, pressed this shape but I wanted the sweeping curve to show when the cabin was just atop the sheer.

So it was curved and cut and TIG welded, and the curve was a bit of work compared to pressing a 90 and accepting a straight line. Here we're also just beginning to show the Skipper his dash, as my modeling did not explain well enough so I made most of the parts in cardboard to confirm this shape.

Not work that most boats can afford- stopping work to mock up a helm station in cardboard, but time was not as important here like it would be in other more commercial arrangements.

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here a window opening is cut in a curved bottom and top panel that has a pressed end flange, not very clear in this image. The side is stiffened by a press formed U or short legged channel and the brow has been cut and tacked to the upper edge of the window band.

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heat sinks stiffeners and clamps all hold the side panels while some of the sequence welds are added during the tack up and weld out of the cabin.

The helm/dash has been built but took a few steps to add to the flat deck at the top of the lower house sides.

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a 2/3's round pipe segment is shown tacked to the outer edge of the flanged side panel and on the forward side that same arrangement means the pipe and the two flanges forms a hollow vertical section giving this corner adequate strength and still remains hollow for a wire race.

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the sequence of assembly was somewhat complicated by the weld access to the various places of the helm. If this had been made as an entire bench built sub-assembly it may have been much less time consuming to weld. As it was, the bent piece forming the main instrument and helm pump panel ended up with a segment of pipe to house the outboard mulit-display instrument, and that created a weld sequence requirement which was done prior to adding the forward windscreen panels.

The two forward panels were bent on both side to form flanges that were then joined out side with pipes ripped to form an rounded segment that would create a final roll form of the corners and intersection of the two main forward windscreen panels. the hole shown will be at the bottom of the hollow strut on the starboard side and create a vertical (leaning) conduit for wiring and cables from the overhead to the under dash area.

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a half round pipe segment of a smaller size pipe abuts the forward edges of of the center flanges of the two forward windscreen panels this is not a wire race but simply a trim piece to create a rounded forward edge on this vertical strut.

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another look at the forward vertical struts between the windscreens trimmed with a pipe segment to attain a rounded shape. Somewhat visible is the side post/strut at the starboard corner with its 2/3 round pipe segment tacked.

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a little dark, but the forward port side post/vertical/strut with its pipe segment rounding the shape. This pipe is covering a hole like the one shown above, in the dash/helm flat surface where the pipe butts and when welded will provide a wire race.

Cheers,
Kevin Morin
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Re: 25' Alloy Build

#32

Post by Sculpin » Sun May 27, 2012 1:15 am

Very cool build Kevin. That walk around cabin looks great. I love how you can envision things and make it happen. Awesome build :thumbsup: . Where are you at now?
John
Sculpin
23' Edwing

"Trying to go for tuna on the cheap you are asking for trouble. The ocean is a mean LITTLE GIRL that wants to kill you". - Shawn Hillier

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Re: 25' Alloy Build

#33

Post by kmorin » Sun May 27, 2012 10:31 am

Sculpin, I'm close to done with the skiff but hadn't posted more photos, which I was trying to post in sequence.

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down to details and some brackets, she'll be ready for rigging in a week or so.

Cheers,
Kevin Morin
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Re: 25' Alloy Build

#34

Post by edwardn » Mon May 28, 2012 10:57 am

Hello Kevin

I second what Sculpin said ...

The last photo in post #26 you showed how you re-enforced the area to support the engine loads and you wrote this:

Nearest the camera are a pair of 1/4" plates that connect the hull to the deck and transom they are at 9" offset from the keel so there is a full plate at the transom at the keel, and the first two longs to insure there is a full plate 'box' to carry the engine's load(s) into the hull and not allow the transom plate to move in any way fore and aft. So in those areas the legs shown forward are full height plates that connect to the deck beams and were eventually keyhole welded at the deck.

From your pictures and explanations i think i understand this part but i was wondering if you have any pictures and or explanations or steps in building the transom were the engine clamps or bolts on and how the engine forces are dispersed from that point to the hull.

Regards
EDD

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25' Alloy Build: engine mount frame

#35

Post by kmorin » Mon May 28, 2012 1:43 pm

Sculpin, EDD
Like all skiff designers, my attempts to make a walk-around cabin look really good are just that; attempts. If a boat is less than about 28' maybe 30' long her side height and profile view is 'too tall' when you put a standing ht cabin in the middle of the deck. The same boat will look fine with a full cabin and truck profile but the 'dog house' (or fort as they call them in Florida) is one of the most difficult to draw elements of 25'ers for me.

I tried to solve this by cutting long sweeping curves at the base of the window band, and one again at the brow. This does help the mass up that high in a relatively sort profile to look 'livable' but I don't think there's much way to make it really as nice a proportion as any designer would really like to have seen?

These long curves were MUCH more work than was realistic, meaning it would have been extremely expensive to do for builder's paying a crew to fit and weld. The long TIG welded seams were only possible for me using the TIG gun and the pulsed TIG bead possible with the Miller inverter power supply. Even then, the several welding hours in many positions that were implied by these welded instead of pressed seams was lots of work for a few curving lines.

EDD,
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I built the bottom as a "hollow surf board" and the engine splash well, was just sheeted in on the deck, the transom was a flat plate butting all the longs.

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when fully formed the main hull transom area is just plate to form the lockers, transom and engine splash well.

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The engine will be mounted on a hydraulic jack and that is bolted to an external frame of 1/2" x 3" x 3" 6061 T-6 angle that was made into a 18" x 18" (rough dim.) frame and welded to the transom below the deck. At the deck line, across the 'floor' or the splash well is a 4" angle and bar frame that slopes aft and it tapped to allow a cover over the conduits and transducer well that passes through the hull at this point.

I'm not positive of the exact numbers but the transom jack frame bolts on above the 3" angle frame by some dimension that allows the steering cylinder to fold down above the 3"frame when the leg is up.

The reason for this external frame arrangement is to keep all the bolts outside the hull's 'envelope'. If the stern were a full width bracket or mount with a lip then the bolts can penetrate and not as much intrusion into the below decks void as would be the case in this arrangement.

A reminder that this skiff evolved in shape (size). First came the 22-23'er with a full bracket, then the bracket was boxed in above, and by following the transom's angle up; the result was a 25' skiff. The decision to enclose the volume above the engine 'bracket' to make that volume into enclosed hull was made by looking at the full bracket as a materials and labor cost that made a 'basis' for the boat. The bottom was not extended, just the bracket's 'corners' filled to created lockers and taller (full) transom.

Hope this helps make sense of the design and clarifies the construction?

Cheers,
Kevin Morin
kmorin

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25' Alloy Build: main fuel tank

#36

Post by kmorin » Tue May 29, 2012 1:35 pm

I'd intended to present this one-off 25' build in sequence for those who are interested in this type of aluminum boat information. But this thread hasn't worked out that way. But getting back to the rough sequence of construction where the cabin and tank were made well in advance of the hull; here is some info about the main fuel tank. This tank is incorporated into the forward cabin bulkhead ('dodger' is a term used by some for this shape). So its forward outer wall is taken from a curved/rolled piece of sheet.

If you looked at the first posts of the original design this shape is a series of three cylinder parts. First the main curve is an inclined segment of a long curve covering the main forward cabin lower area. This main cylindrical section is bounded by two smaller diameter sections/segments that form rounded corners of the dodger.

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the original roll was done by Metal Magic, Kenai AK a fine fab/forming shop in our area with very skilled guys, they worked from a flat template I provided that had each of the three circular/radii intersecting one another and the two side flats. The original sheet is 1/8" 5086 H-116 and was buffed in a drum sander to remove mill scale and give the surface a sort of finish.

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Standing vertical instead of the final incline hopefully shows the three cylindrical segments/sections that were used to design this tank/bulkhead form.

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In order to make the layout markings for the final cuts, the upper most 12" would be cut off to join the cabin and the rest become tank; the shape had to be stablized using a couple of 2x4's tacked in using offcuts screwed to the 2x4's and the offcuts tacked inside the rolled sheet.

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the rolled panel was inclined on a temporary work table to scribe the top and bottom cuts which are inclined to the blank, and then a set of baffles was cut out and tacked to the bottom plate straddling a single transverse internal baffle/stiffener.

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the fill is 2" pipe downcomer, there will be a water bottoms sump of 3" sched. 80 with a 1/2" floor below the tank bottom and that cup is shown here with the fill cap lock fitting and a tank top doubler plate.

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Here the water bottoms sump is shown welded into the tank bottom below the bottom panel and the main front curved seams are done at this stage as well. The back of the tank is not on, that was keyholed to the baffles' aft edges after the draw and water bottoms riser were installed.

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here is an image of the water sump from inside the tank before the after wall is installed. The purpose is to collect the water/condensate into the sump to allow the tank to avoid internal pitting better and to allow the skipper to pump out the bottoms separate from collecting them in the fuel bowl/filter/coalescer.

Not everyone is this concerned with fuel handling, lots of boats will just pull all the junk out of the tank up the draw riser and then deal with all contaminants in the filter; that works fine. (but) My skipper and I agree that this step is worth the effort since both our experience with water bottoms is similar; so the effort was made to add this sump.

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once built the tank was fitted to the forward bulkhead to make the fill cut out and confirm bolt up to the cabin frame. Here the cabin is not etched so the coloration of the tank and cabin are the same, in most of the other later images the cabin is etched to a white metal coloration.


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the fill was mitered a bit to incline the twist cap fitting for access while keeping the fill out the way. The down comer/filling well is welded to legs inside the tank so the top doubler is not really necessary to avoid break out around
the fittings. I put the double there to stiffen that corner of the tank but it was/is not really needed as the tank is rigid and the down comer/fill well is not flexible.

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the cabin was etched to white metal last fall, but the tank is not etched yet. So this image showing the tank being fit to the deck and bulkhead shows a difference in aluminum coloration due to the difference in etching one and not the other. Here the tank is fit where it will stay but the welded in deck supports are not installed.

I have only done a volume check roughly after the tank design was modified for the fifth or sixth time due to other elements that are near; the cabin bulkhead size, the helm and interior equipment spaces and the area/volume below the dash/helm area needed to enclose the equipment mounted there. This means I don't know the exact volume of the tank except to say its in the high 40's maybe as much as 50 gallons but not quite.

Any enclosed volume of aluminum can be a tank and they can be shaped to whatever volume is needed. They're just welded metal boxes so there is complete freedom to design then as you want. In most instances they're rectilinear or roughly straight line boxes so that at least some of the seams can be pressed/brake formed that reduces welding which is an expensive labor component in a build.

Welding for enjoyment at the hobby level is what this boat is about- to me- so the design of the tank wasn't limited to straight pressed line box elements. I did pressure test this tank to 2.5-2.8 psi and found a key hole weld I'd sanded off where a TIG crater 'back out' was too fast. The material choice of 1/8" is not up to many standards of gas tank thickness but the same agencies accept press formed tanks of much thinner material and I've not had any problems with 0.125" tanks in the past: if they were made well.

I don't find pictures of the fuel draw and water bottoms riser so they're not included, here. Welding wise the tank was MIG welded inside with 0.030" MIG 5356 wire and the TIG welded outside with the same exact alloy but a little larger diameter wire. Most of the TIG was done in a Pulsed AC setting of 126PPS, with a high frequency of 250 Hz to narrow the arc cone and concentrate the depth of penetration; with an AC wave balance of 70% dcneg and a pure tungsten 3/32 diameter with pure argon at 12 cu/hr flow using #8 gas lens ceramic cup on a 300A water cooled torch; cold wire feed.

Cheers,
Kevin Morin
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25' Alloy Build: cabin roof

#37

Post by kmorin » Tue May 29, 2012 7:47 pm

Let's top off the cabin build and move back to the hull?

To make the forward cabin corners into rounded shapes I cut segments of 1-1/4" pipe or ripped those pieces into 3/4 rounds. The forward edge met a flange bent onto the forward windscreen panel and likewise, the after edge met the flanged edge of the side panels. These were beveled butt welds between the pipe wall and the 1/8" with about 70% bevel at nearly 45deg.

The fillet was wire feed TIG at 126PPS, 250 Hz; 72% Bal; 3/32" pure tungsten; pure argon @ 10-15 ft^3/hr #8 cup w gas lens but with the Dynasty 300 set to 250 all amperage info is lost as I was using a torch mounted pot to control wire feed and amperage. Weld position was up/down/horizontal as the seam presented itself for access by the right hand torch.

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image of the forward cabin post where the 1-1/4" pipe was butted to the round the intersection of the two pressed flanges; prior to welding.

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Not a very well lit image of the inside of the same joint but the two flanged edges of the forward windscreen panel and the side panel are fairly visible?

Image
A hollow brow allowed a wire race to be kept inside the enclosure, created the window overhang, allowed the cabin shape to be offset in a shadow line at this long curve, and made a decent channel of the intersection of the cabin side to the roof panel. This was made with a flat bar horizontal to the upper window side panel sheet, then a curved brow side panel edge to edge above this horizontal piece and that was edge to edge with the cabin top.

The forward (horizontal piece above the wind screen panel's) flat plates was cambered transversely and the forward edge an other transverse curve as viewed in Plan View. The bottom of this plate is fairly well shown in this front on image.

Image
Here the temporary transverse camber frame is holding the lower brow (horizontal) piece and the rough pipe segment is shown prior to trimming this brow corner at its top edge. Also the flange on the inclined side of the cabin side is visible, near foreground, while a vise grip with a temporary stiffener is shown on the starboard side, since we're looking through the cabin prior to fitting the two windscreen panels.

Image
a sheet of 1/8" was draped over the brow and cabin sides and pulled down to deform this piece. For those who are drawing at home (? not sure if you do?) the cabin roof is neither flat, or a cylinder. By pulling the cabin roof into a warped cylindrical section the shape becomes more appealing and less geometric. The centerline is straight from stern to forward along the centerline, but as the two sides meet the cabin that line is cupped/curved/sweeping instead of straight. By pulling these small, shallow dips into the side of the cabin sheet two long slow parabolic shapes a deformed into the top's surface. Lots of effort for a fairly subtle shape change, but that is how the shape was created.

Image
the after overhang just keeps the doorway/companionway/slider dry from rain and most spray, and its framed as a direct transverse camber frame boxed to the sides like the brow.

Image
the top was later framed by welding a pair of flat bars stacked flat to the under side and one another. These bars, one a 1/4" x 1-1/2" wide the the other a 1" x 1/4" flat bar are on 12" centers and centered to one another. This makes a very low profile frame, no loss of height inside, but stiff enough to walk on when welded. This cabin top is not intended for a walking surface as no access is provided but it will hold a man's wt if necessary.

I guess I have a few pics of the cabin for another post so I'll show some other details a little before we finish the hull.

Cheers,
Kevin Morin
kmorin

edwardn
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Re: 25' Alloy Build

#38

Post by edwardn » Sat Jun 02, 2012 9:37 am

Thanks again for the detailed photos and explanations, you have shared allot of your insight into what it takes to plan, design and build a boat, I will be the first to admit that I don’t know much about it but am trying to learn so information like this invaluable to a person like myself with future plans .
Cheers
EDD

hipacboats
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Re: 25' Alloy Build

#39

Post by hipacboats » Tue Jun 05, 2012 9:28 am

Thank you for the very informative posts of your build. You do beautiful work. I will be starting a build as well in a couple of weeks and will post the status. I purchased the plans for the Cope 23 so its not made from scratch like your build but should be a nice boat when finished. I am interested in seeing some rigging photos and explanations as well in hopes of learning the details of a well rigged boat.

kmorin
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25' Alloy Build: rigging out

#40

Post by kmorin » Tue Jun 05, 2012 10:57 am

hipacboats, I won't be involved in the boat's rigging out, the owner is taking the boat at the welded-only stage. I'm not sure when I'll see the boat again and due to work (skipper's) schedule I'm not sure when the work will be done?

Looking forward to your building photos, you purchased plans and cut files; then had the materials cut?

cheers,
Kevin Morin
kmorin

hipacboats
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Location: Maui, Hawaii

Re: 25' Alloy Build

#41

Post by hipacboats » Tue Jun 05, 2012 4:56 pm

Yes,
Bruce Cope sent the cut files to Alaskan Copper and It should be getting cut right now. I'm hoping to pick it all up on Friday. I actually live in Washington and will be building the boat in Bremerton. Really looking forward to it. Salmon season is just beginning down here so I am anxious to get going.

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aluminumdreamer
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Re: 25' Alloy Build

#42

Post by aluminumdreamer » Sat Jun 23, 2012 8:30 pm

Another awesome thread by Kevin. AAB is lucky to have such a member.

pjay9
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Re: 25' Alloy Build

#43

Post by pjay9 » Tue Jun 26, 2012 9:03 pm

This is sooo interesting...amazing boat being built to do a job! More PICSSSS!!! PJ :thumbsup:
2009 Raider 185 Pro Fisherman, 2005 90Yamaha, 2012 Yamaha9.9HT, 2008 EzLoader roller, 2004 Dodge TCD dually, 2005/2015 Lance1161

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goatram
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Re: 25' Alloy Build

#44

Post by goatram » Tue Jul 31, 2012 10:26 pm

Kevin
I will parrot what the others are saying; to include this is good info to know. The terms are some what Puzzling at first but with the pictures and from rereading your posts I am starting to understand.

I am taking the path as well towards building my boat. Terry aka Reel Song, you and Bruce of Coldwater Boats and Russ's Dad aka CWB are my Mentors. You all don't know it maybee but you are. I got my eye on the boat I want and it is the only way I can afford it is by building it myself. All the stuff I do to my Northriver aka Northrisser is practice for my bigger build. :smitty:


First piece of the project is in hand; a Lincoln 350MP. Got a good deal from a AAB member here. My current Miller 250 mig will be sold with my Spoolgun and the recently acquired argon and argon/CO2 mix bottles.

Thank-you.
John Risser aka goatram
33' RBW with twin 250 Hondas (Aliens)
2015 Ford F350 Dually
Master of R&D aka Ripoff and Duplicate

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JETTYWOLF
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Re: 25' Alloy Build

#45

Post by JETTYWOLF » Tue Nov 13, 2012 12:46 pm

aluminumdreamer wrote:Another awesome thread by Kevin. AAB is lucky to have such a member.

Ya got that straight :!:

Aluminumdreamer,
what's going on with your boat? Ya still have it??

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Tookalook
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Re: 25' Alloy Build

#46

Post by Tookalook » Mon Jan 02, 2017 6:05 am

Wow That was the best read that I have ever had on the net. Fantastic Post,well done Sir Thank you
26 ft. Kingston Sea Sport
18 Custom Skiff

kmorin
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Re: 25' Alloy Build

#47

Post by kmorin » Tue Jan 03, 2017 12:45 pm

Tookalook, thanks for the kind words, glad you enjoyed the thread.

Cheers,
Kevin Morin
Kenai, AK
kmorin

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