Scrambler update

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

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eurof2
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Re: Scrambler update

Postby eurof2 » Wed Jun 14, 2017 4:30 pm

Kevin,
Thank you for your answers on here. And for all the extra information. I really appreciate it.

As to the location of the bow piece, after talking with Gayle from GlenL I finally realized it was a mistake on my part. The dimension was turned perpendicular to the rest of the drawing and I didn't recognize it as that. My day job depends on my ability to read drawings, so the fact that I missed that is kind of embarrassing!!

As to the side frames, I was guessing that having the gunwale plate on the top was taking over the strength requirements that the side frames were once doing, but don't have any where near the knowledge on it that you seem to have so it was good to hear you explain pretty much what I was thinking. It is too bad I just now realized it as they are fully welded in now, but I guess I can cut them out if I decide I don't want them in the interior later on.

Thanks again for the information

Kevin Morin
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Re: Scrambler update

Postby Kevin Morin » Fri Jun 16, 2017 10:53 am

eurof2,
You're welcome to my few cents of opinion. When discussing metal boats, I usually attempt to get in the wider points, IMO, in order to make the discussion as useful to others' explorations as possible- so I get long winded hoping to address as much as I can in a reply?

Do I infer you don't have the bow (pram) plate installed but you have already welded the topsides to the transverse frames? That sequence seems a bit strange - that is why I'm asking.

In general I've made it my building sequence to get the entire hull 'formed'/tacked up/shaped before adding final welds? My question arises from the first post- where you inquire about the location of the bow plate in reference to the frames/keel - and now you've mentioned that the topsides frames are welded in?

We've seen numerous metal boats, here and other sites, where the weld sequence was "Out of Order" that resulted in many hull panel's become misshapen, distorted and wrinkled due to out of sequence welding- so I'm asking about your boat based on my reading of the posts.

Pictures always welcome, and they offer many words of explanation. I'll post some here to show my building sequence as an example.

Image

While not a pram shape, here is a picture of a tiny 14'er I did some years ago- the entire skiff was tacked up- and all the 'shaping' or edge to edge fits of all hull panels were tacked so they were clean and fair- before any weld contraction was added?

Middle left is a flat bar temporarily tacked to the starboard bottom panel- to fair the chine until the chine flat is tacked on. (This building technique does not use internal frames to form the boat- not as common a method of building: framing in internal structure is added after the hull is formed.)

Image

Notice that the shape had to have some 'fairing strips' to keep bulges out of the bottom as it was pulled up - and the bow needed some closure- or tension strips to keep the shape for the chine flat to be added? But at this point everything is just fit and tacked. Welding before all the edges and hull panels were tacked- would have distorted the edges and made a clean shape very hard to achieve - IMExperience.

I've found that welding in sequence was pretty important to end up with a fair, clean and wrinkle free boat? Just curious because of your remarks and questions.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin

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gap998
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Re: Scrambler update

Postby gap998 » Sat Jun 17, 2017 4:24 pm

I know it's not strictly relevant to this build but those tips may be useful in a stitch & glue design too.
Gary

Planning a whole fleet, but starting with a Zip...I think.

"Just when you think you've made something idiot-proof, someone builds a better idiot!"

Kevin Morin
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Re: Scrambler update

Postby Kevin Morin » Tue Jun 20, 2017 11:53 am

gap, the metal boat assembly method I use is essentially stitch and glue- the outlines of the panels are generated either in the PC or off a plate model- and then scaled up to 'real size' to skip lofting. Edges of all panels are held to edges adjacent and the wire or stitches of the plywood and epoxy method; are tack welds that are left in place- dressed down (shown on another thread on the Forum) and welded over eventually.

The primary difference is the glue. Managing the mix, handling, application and dressing or sanding when done- with epoxies is a cold process with little or no set up state forces. When the glue 'dries' the hull panels are fixed in place by seam tape or strips and cove beads of glue. But when gluing by welding (!) there is contraction to plan. However if the welds are uniform, placed on the hull seams and supports in a planned sequence- the cooling contraction and shape changes can be balanced and offset so the hull panels remain fair.

Perhaps the most difficult item we see in new metal boat builders is the required time to become truly proficient at welding- especially aluminum MIG welding- the back bone of fabricating welded aluminum boats. Adding correctly mixed-by-weight epoxy is not quite as challenging to learn- and it is applied in a less critical to success method and if you add too much glue to the joint it can be removed without distorting the entire hull panel. Not so with welding so many first time welded boat builders find they have not taken adequate practice time they experience 'buck fever' to get building! The "glue" is the primary difference in the metal and ply hull materials using a panel outline approach.

But, I do agree with your remarks that the two methods are similar in construction sequence.

It should be noted that unless you've done a metal boat or two - many first time builders would find this "metal-stitch-and-glue" method kind of intimidating- even though it works well for me. However I've build quite a few welded boats and made countless thousands of mistakes while becoming familiar with this process.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin

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Scot2640
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Re: Scrambler update

Postby Scot2640 » Wed Jun 21, 2017 10:34 am

I really admire your welding skill. I wish I learned to weld, seems really cool.
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Kevin Morin
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Re: Scrambler update

Postby Kevin Morin » Wed Jun 21, 2017 11:10 am

Scot, thanks for the kind words, IMO; learning to weld like learning any other skill is mostly practice- like driving, playing piano or drawing- or cutting out metal boat parts! Begins with the interest and practice - well- in the case of welding and metal work there's plenty of reading and research that will help the practice time be most productive.

Thanks again, Cheers,

Kevin Morin
Kenai, AK
Kevin Morin

Kevin Morin
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Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: Scrambler update

Postby Kevin Morin » Wed Jun 21, 2017 11:10 am

Scot, thanks for the kind words, IMO; learning to weld like learning any other skill is mostly practice- like driving, playing piano or drawing- or cutting out metal boat parts! Begins with the interest and practice - well- in the case of welding and metal work there's plenty of reading and research that will help the practice time be most productive.

Thanks again, Cheers,

Kevin Morin
Kenai, AK
Kevin Morin

eurof2
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Re: Scrambler update

Postby eurof2 » Tue Jul 11, 2017 10:39 am

When I said final welding, I was only referring to having the frames final welded including the side pieces of the frames that I was asking about having been omitted in some of the pics that other Scrambler builders have posted. I am by no means going out of order on the weld sequence. I am a machinist by trade, so I have also seen out of sequence problems on many projects in the past by both my self and others.

I have all the framing tacked up at this point and am waiting on the side and bottom skins to arrive. I have ordered them, but it was not available locally in the longer lengths needed, so it had to be transferred from another city for me.

The plans for the scrambler call out building all of the frames first and then assembling as a sort of internal skeleton. After that the skins can be put on over the top of the upside down skeleton. That is the point I am at right now.

Thanks again for your help. This is my first boat so any details are always good to hear about and learn from.

I am thinking if I do another boat, I would prefer to find one that is built the opposite way. Build a jig the approximate shape of the outside of the boat and then build from the outside - in as it appears you did with the boat in the pictures. I dont know if it is any easier or not, but it seems to me that process makes more sense.

Kevin Morin
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Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: Scrambler update

Postby Kevin Morin » Tue Jul 11, 2017 2:20 pm

eurof2, glad to hear your Scrambler is still building; sorry to infer you'd gotten out of sequence, I guess that goes to illustrate how limited a text exchange can be?

I think any discussion of boat building needs to include an acknowledgement of "how did we get here?" as part of the context of evaluating building methods? Framing boats with a series of transverse shapes (Body Section hull cuts @ 90 deg.s to the keel plane) really comes from two facts of history. The first fact is that pre-plywood (ie. before the 1930-40's and especially Carlos Riva's 1/2 hull molded laminate experiments) wood boats were made of strips of wood. Regardless of the planks' final dimensions they were usually pretty narrow compared to the length- so.... to hold them in shape to one another either permanent or temporary frames were about the only solution?

Further, not only was wide, uniform thickness wood sheathing totally unavailable, temporary fastening of wood really came about after metal was available in removable fasteners. So for the majority of boat building history - dowels/pegs/trenails or rope was about all that held things together with some tar or pitch to seal the seams!

We take plywood and epoxy pretty much for granted today, (not to mention copper wire or wire ties and glass cloth) but they're all extremely recent developments; compared to the length of history of boat building

What about metal? Frankly, sheet marine aluminum and the tools to work and weld it are even more recent developments. Therefore it seems natural to me that the methods for building in this newer material are less refined or less widely known as these methods are still in major innovation and experimentation stages of human adaptation to building small welded metal boats.

I have a couple of threads on metal boat building, here in the metal category, in which I try to post a public demonstration of some of the methods I've learned to use. Others have posts in various sites, and forums about their ideas and experiments, and taken as a whole; the ideas of efficiently building in sheet metal products is becoming more widely known.

Are transverse frame sets necessary if you have a 5' (1.5m) wide and 25' (7.7m) long sheet of aluminum to form a bottom of topsides panel? Well not really but the frame can help in several ways- first a set of frames allows a simple 2d method of making a correctly shaped fixture to hold that larger sheet and second frames can usually be scaled up 'flat' without the need to find the final lofted shape of the outline of the hull panels.

So with flat carpentry skills- the set of frames can be a means to find the hull panel shapes using more widely known x,y layout skills. The frames can become a building jig, or temporary, or they may be incorporated into the final structure by welding to the hull panel (skin) when those hull panels shapes are defined by the temp frames.

On the other hand, the frames are some amount of material and labor and they may not be needed in the final hull? The method shown on the other thread consists of creating a builders plate model and discovering the shapes' outlines and then simply scaling up the curves using a fairing method that will assure a cleanly tacked up hull form. Are frames needed- not if you have huge sheets of metal and a "hot glue gun" (welding system) able to fuse the newer material.

However, frames can help reduce the practice or need to acquire new layout skills and allow the final form to be reinforced by incorporating the original building fixture (frames) with the final hull by welding. On the other hand, there are methods that are adaptations of similar layout and fairing skills that begin with work directly on the hull's skin or panels and then framing elements are added once the shape is established fair and clean- or tacked up.

If you read the 'stitch and glue' books and articles I think you'd see a similar building methodology? I think that frames help the newer builder to have something to anchor their work. That is; building frames to a set of plans' dimensions or lines pages scaled in a table of offsets give a foundation for a new builder. This is critical to the first time home builder- at least in my view. I think we've had several discussions on the Forum about "why was this done?" in a give design: "Why do the plans show that?" instead of another way.

Let's take board stretchers for an example? Before epoxy glue and low cost routers- scarfing a 12:1 aspect ratio glue scarf in a pari of 12' boards to get one that was 24' was not often shown in plans except those which would be done by professional building yards. Now a glue scarf is somewhat common and everyone does them with great results! But if you were Glen Whit drawing plans packages for garage builders would you have spec'd a scarf joint that was almost a day's work that relied on glues that might make the day's work result in a reliable permanent joint? Not likely.

I think frames for metal boats can be updated to a more effective method of building but they are a foundational method that allows the inexperienced to succeed where they would have much MUCH more to learn if they attempted to begin by creating their own hull panel layouts and outlines. There's lots more to discuss on this topic of methods of building and final structural details but I'd hoped to make a review of a few basic pro's and con's for this topic.

Pictures of your build would make a good addition to the thread? Always interesting to see metal boats being built.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin


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