25' Skiff Build

Steel and aluminum boatbuilding. See: "Boatbuilding Methods", in left-hand column of the Home page, for information about alloys.

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Yofish
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25' Skiff Build

Post by Yofish » Wed Jan 16, 2019 10:43 pm

DAY ONE:

OK, after spending WAY too much time trying to post multiple pix I apologize for doing it one pic at a time save someone telling how to do it otherwise reliably. I absolutely hate working hard for no reason.

Here is how I go about building. Shown is the forward bottom plates laid on a grid of 2x4's on the wheeled dolly I use to build off of:
1 (Large).JPG

Yofish
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Re: 25' Skiff Build + 1

Post by Yofish » Wed Jan 16, 2019 10:47 pm

After lightly tacking bottom plates, principal frames are added on one side:
2 (Large).JPG

Yofish
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Re: 25' Skiff Build

Post by Yofish » Wed Jan 16, 2019 10:50 pm

Frames added between along with longitudinal scantlings:
3 (Large).JPG

Yofish
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Re: 25' Skiff Build +3

Post by Yofish » Wed Jan 16, 2019 10:53 pm

Bottom now pulled together after making more substantial tacks along center of bottom plates:
4 (Large).JPG

Yofish
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Re: 25' Skiff Build +4

Post by Yofish » Wed Jan 16, 2019 11:00 pm

Next forward frame tacked in the center and forward longitudinals inserted:
5 (Large).JPG

Yofish
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Re: 25' Skiff Build + 5

Post by Yofish » Wed Jan 16, 2019 11:08 pm

Bow pulled up and collision bulkhead inserted along with station one:
6 (Large).JPG
That's all folks for today. One days work.

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sproggy
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Location: Welwyn Garden City, UK

Re: 25' Skiff Build

Post by sproggy » Thu Jan 17, 2019 2:02 am

Interesting to see that - thanks for sharing.

Kevin Morin
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Location: Kenai, Alaska

Re: 25' Skiff Build

Post by Kevin Morin » Thu Jan 17, 2019 2:37 pm

Glen-L Readers, notice that Yofish has removed mill scale where the welds will be located? Where the longs/buttock longitudinals and frames will touch or intersection the bottom panels- Yofish has buffed/wire wheeled/sanded or otherwise removed the mill scale so the welds can be put in onto "bare" aluminum.

There is still oxide, which forms on aluminum in a few seconds' exposure to air.... but the mill scale, a shiny, water vapor retaining, galvanically different material from the 5086, 6061 alloys shown... is removed during set up to tack. The remaining oxide will lift when welding to some degree- but a few strokes with a hand held, SS, wire 'toothbrush' will scarify the oxide to facilitate MIG welding between tacks.

Also, Yofish has done the work to create outlines/profiles/shape cut outs of the various parts. This can be done by #1 purchasing a kit- which included cut files to be sent to a plaz/laser/NC router company to cut your parts; #2 lofting your own 'card model' as I have shown in other posts- and scaling the resulting shapes/outlines/profiles up and relofting for hand cutting (Something Yofish has done COUNTLess times..... but now, prefers to avoid) and #3 taking a Glen-L wood boat plans package- creating your own scale model /builders model and "take off" the shapes of the parts as in #2.

Note the longs, xverse frames and bottom panels in way of these intersections ALL are stripped to facility tacking and welding out.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin

Yofish
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Re: 25' Skiff Build

Post by Yofish » Thu Jan 17, 2019 9:05 pm

DAY TWO:

Now the hull is raised to move the supports and flopped over again to add one side of the aft 7':
7 (Large).JPG
Then flopped again to add the off side:


8 (Large).JPG

YAY! Two pics! I'm testing the limits....

Yofish
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Re: 25' Skiff Build

Post by Yofish » Thu Jan 17, 2019 9:21 pm

The last aft frame is placed then the chine flats added:

9 (Large).JPG

Both chines on and longitudinal scantlings inserted:

10 (large).JPG

Yofish
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Re: 25' Skiff Build

Post by Yofish » Thu Jan 17, 2019 10:01 pm

Kevin is quite correct re. surface abrasion. I use both flapper wheels and a stainless wire wheel. The flapper for 6061 as it can be gnarly given the way it is formed and wire wheel on sheet is my preference. Many builders do not do this. fact is, if one is building an inspected craft it recommended but I hear one can get away with solvents. In my experience, it is the ONLY way to approach the matter.

Couple of notes for anyone interested in a little more process:

Tacking is somewhat minimal except when one gets to the stem where the tension of the material gets rather extraordinary. The bottom plates on this skiff are out of 1/4" 5086 (overkill, but you do what the victim wants) and I'm here to say that one DOES NOT want those bitter end parts to come un-assed while standing the the bight, so to speak. Welding the athwart framing will remain minimal as over-welding creates hogs. Of course, water tight frames have to be water tight and we live with it.

The longs are chain welded and I weld all the outboard chains while in this state. My boat building buds think I'm nuts but It has never created a problem. Likewise I never concern myself with the direction of the weld nor sequence. In my opinion it is an advantage to just keep truckin' in the direction one is going, because!! you are preheating in the direction you are going!! I've read, to me, silly thoughts on this matter:

11 (Large).JPG

In order to get the athwart framing minnie-jinny, I make the bottom mouse holes with a dart that points to the center line:
12 (Large).JPG

Yofish
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Re: 25' Skiff Build

Post by Yofish » Thu Jan 17, 2019 10:45 pm

FIT UP:

To me, it is essential to make fit up the best it can be. Gaps, though acceptable within range to the USCG and ABS are unacceptable. scantlings must be tight to the connecting surface, especially with longitudinal scantlings. Notice the complete contact of the X and Y's here:
13 (Large).JPG
LIVING WITH PLASMA:

I've had parts cut with plasma and router. If I had the option I would prefer router hands down. Alas, in my world it is too expensive; that is that. So called hi definition plasma has served me well wiht a few quibbles. With plasma, there is the heat affected zone problem wherein with (especially) long parts they (can, not always) have discontinuities:
14 (Large).JPG
This is one of the (very long) chine flats. I do not know exactly why this happens but my best guess is the combination of HAZ (heat affected zone) and in-built tensions within the material as processed. It has, to this point, never created a serious problem. Those long skinny forward longs? Laid atop another they are never the exact duplicate.

Tomorrow will be the misery. Putting on the sides...

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aero_dan
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Location: Cassville, Missouri (SW MO)

Re: 25' Skiff Build

Post by aero_dan » Wed Jan 23, 2019 11:17 am

This is a fantastic build! Please consider asking Gayle to include in the builders blog area. I think the increased coverage would be greatly appreciated. :D
Better, faster, cheaper. Only ever found 2 of the 3! (But still lookin.)
So many boats, ...so little time.

Yofish
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Re: 25' Skiff Build

Post by Yofish » Wed Jan 23, 2019 10:33 pm

aero_dan wrote:
Wed Jan 23, 2019 11:17 am
This is a fantastic build! Please consider asking Gayle to include in the builders blog area. I think the increased coverage would be greatly appreciated. :D
Thanks for the kind comment, but I have no idea what you are talking about...

Yofish
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Re: 25' Skiff Build

Post by Yofish » Wed Jan 23, 2019 11:18 pm

After some time with the sniffles, I'm back on track. Add more scantlings in the 'slam zone' being, that area of the hull that is where slam loads are most likely to occur. In this case, the area unsupported is 12.5" x 18":
15 (Large).JPG

Now the misery of putting on the sides. I work alone thus the only way I can do it is from aft to forward with the aid of falls. The difficultly, as one can imagine, is fighting the tension of the curve in the bow and not having a way to manipulate the plate to make it easier, i.e. being able to tweek the top outboard to make it conform better to the curve:

16 (Large).JPG

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