"River Rat" AL version

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

Moderator: billy c

Hobby
Posts: 5
Joined: Tue Dec 08, 2015 10:09 am

"River Rat" AL version

Postby Hobby » Thu Dec 10, 2015 2:35 pm

Hello,

I'm going to attempt the fabrication of the "River Rat" in aluminum and I'm currently putting together a plan. I've ordered the plans and just went through the materials list. Using metals depot.com I came up with around 9k in materials (using mostly 6061 for pricing, I know I won't be using this for most of the boat, however there wasn't much choice and figured it would give me a worst case scenario IRT pricing).

Some quick thoughts followed by a request for advice: So, I want to put a lot of thought in putting a good plan of attack together for this project before I start so I don't get frustrated with it or run into issues that could have been alleviated with a little prior planning. One question I have is should I purchase all the material and do all the cutting prior to beginning welding, or should I purchase and cut as I progress? I feel the logical answer would be to purchase and cut as I progress, but wanted to get some feedback from those who have actually built before.

I'm also really debating on having the cuts done professionally or attempting myself. I have no idea how much labor costs are and even not knowing that I'm having a difficult time deciding... any thoughts that would push me one way or the other? I realize having it done professionally will be faster and the chances of me messing up cuts is prob pretty good, which could get expensive.

Also, looking to find someone who has done this particular boat before. From reading the forums, the only person I've Identified is "BillyZ". Anyone else out there?

Thanks,

Kevin Morin
Posts: 695
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: "River Rat" AL version

Postby Kevin Morin » Thu Dec 10, 2015 5:07 pm

Hobby, Great Project. While not familiar with the costs at the metal supplier you listed, my first response is the prices seem astromnoically high? I'm in Alaska so all of our metal comes up on frt. hauling ships, and we're only paying 4.50 or more a pound- I'd say the cost of thess 1,200 lb of metal should be more like 6k-6,500$ ??

Of course an online metal store will be charging for cut small sheets and pieces not for 5x25' long sheets so I'd expect the 9.00$/lb. to be high, even for today's high prices?

In my experience buying metal the more you buy in an order the less you pay fro the entire order together. If you buy a cut 2x2' square online, I'd say that 9.00$/lb may be roughly what it takes to cut and sell that piece to you, and keep the sheet it came from as remnant so... the smaller buy is more costly.

However in my experience of buying metal, buying a 8-10 tons at one time brought me lower costs. So, my idea is that an entire boat -purchased at one time will cost less than if you buy each piece over months; I'd called this retail versus wholesale as a means to describe the idea.

2nd Question is separate, should you cut all at once? That's much more involved and there are unknown variables in your skill set, experience, project plan and other items that make the answer irrelevant - ATTTTTT this point.

Now the last issue to try to reply is
Hobby wrote:I'm also really debating on having the cuts done professionally or attempting myself.

What would anyone cut for you? This plan set does not give outlines of hull panels, they have to 'lofted' or taken off the frames, plate model or plans all depending on your choice- the Plans package provides the shape dimensions but not a 3D model.

So at this time, I'm not sure what you mean by "cuts done professionally" because what someone else would cut is not clear.

Let's review some basics in this regard for me to try to paint a picture of my understanding, hoping that understanding will give you more insight into what seems to be your question. #1 in the River Rat plans section there are three different Views of the boat (side) Profile View, outboard not sectional; (top) Plan View, looking down on the boat; and 9(end) Body Plan View or the Section View. All these are the 'lines' of a boat and I have a post discussing the "Views" just below that ( I hope) could help make these three views clear?

Next, one of each of these views (all flat to the page as Hull Intersections) will be provided by the Plans Package to show you what to build for each location of the boat; but you have to combine the three views- there is no 3D model- you make that yourself. From these three (flat) drawings you can construct a set of flat frames on a 'strong back' frame to hold the frames in place, while you put sheet on the frame. So each set of flat drawings gives ONE dimension set, X, Y and Z from which YOU the Builder, construct a 3D real hull.

What does not come in a plans package of this type (used for many centuries!! and especially the last hundred years extensively) is a 3D model of the boat! Also since there is no 3D model the hull panel outlines, the outline shapes of the two chine flat and the topsides ARE NOT provided- the builder is expected to be able to "fit and figure" these shapes for himself. IN fact; that is what the trade 'boat building' means, someone who can take the flat page plans and turn them into a 3D shape, fair true and clean.

What is the other or Computer approach? The other method, is to buy from the Pre-Cut plans "packaged" designs offered where all the framing, all the structural and all the hull panels shaped and outline are outlined by computer software so they can be cut by Numerical Control (router cut, plasma cut, laser cut) tables where the cutting device is totally controlled by the computer shapes - taken off of the 3D model (not a 2d model) of the boat, and therefore able to predict the shapes of the surfaces. The amount of information you're buying his MUCH greater- so the cost is higher and the work is more complete when you buy kits- but you've paid for the tech & tools for the work done.

The surfaces of a boats' hull and structures in traditional plans are determined by the builder as he progresses in the traditional boat building plans offered by Glen-L; However; the shapes are all cut-outs if you buy plans from the Pre-Cut Kit catalog of plans.

You cannot, except at some expense, get someone to convert Glen-L plans from the traditional methods to the newer methods unless they #1 had permission from Glen-L (?) #2 had marine software to do the computer work of 'developing' the surfaces and structural elements in computer outlines & #3 you paid someone qualified to do that work to give you the 'new' cut files (terms used to describe the computer guidance commands to guide NC table cutting.)

I hope that makes sense, its kind of a basic reason that recently Gayle made the announcement of the new alliance between the Glen-L catalog of plans (traditional methods even in welded aluminum) and the SpecMar (Specialty Marine Designs Co.) pre-cut files plans packages where the layout and marking, all the way to cutting all the many shapes are done for you in the NC package.

The cost of these packages is for #1 Plans AND #2 Computer Work to create surfaces of all the parts; framing, hull sheeting, trim, mounts brackets....AND #3 to plan to take all those shapes out of sheets, bars, angles in the most economical way-"nesting" the parts so there is the least waste. All this cost is for all the services hired that are included in the pre-cut NC package.

Hobby, please let me know if this clarifies more planning items in your project? I happen to be writing a series of posts (thread is near this one) about doing all the work- ALL this work to build a welded boat- by hand. The posts have begun to address many of the fundamentals of doing this work but we haven't even gotten to plans, modeling, plate take-off, fitting, or any other really detailed work! [We've got a ways to go!]

I've not built this boat but I've built lots of welded aluminum boats, and would be happy to try to answer any questions in your planning if I'm able.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin

Hobby
Posts: 5
Joined: Tue Dec 08, 2015 10:09 am

Re: "River Rat" AL version

Postby Hobby » Thu Dec 10, 2015 11:21 pm

Kevin,

Thank you for all the information.

I'm still a little bit unclear about the plans, but will find out soon enough when they arrive. Im thinking it might be due to misunderstanding terminology... when it said there were: "FULL SIZE PATTERNS for the stern, and half section patterns for the bow piece, transom, and frames" I assumed those were templates to be used in cutting.

I look forward to reading what you're working on.

Kevin Morin
Posts: 695
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: "River Rat" AL version

Postby Kevin Morin » Thu Dec 10, 2015 11:31 pm

Hobby, the plans include templates but those are not computer files they are usually Mylar (plastic drafting film ) or heavy paper patterns. So, you could tape them onto parts (sheets, plates, bars) and center punch through the patterns and make lines... but there is still manual layout, fairing of any curves and cutting, dressing the cut edges- all manually done.

My point about the cutting "being done by professionals" was- with traditional plans- they'd have to do the same labor that you'll have to do... anyone will have to do the manual steps, so there is "nothing" for anyone else to do- but cut the same work you'd do manually. Most sets of 'templates' will show you how to assemble the frames, keel, and other items from sheet and extruded bars- you still have to manually cut them and then tack and weld them into the final shapes.

This means that you'd be hiring the boat built - essentially- by someone else! If you follow the other post, you'll understand the skills you'll have to develop to do the work yourself. Having templates of some of the sections, Profile of the Keel (or forefoot of the bow stem's run to the sheer) and the Body Section of transverse frames (not sure how many frames or bulkheads in this design) or a Plan View, sheer clamp or guard deck, are all helpful but they still require layout, cutting and fairing. If you hire this done ???? then you'd be best to find a shop to build your boat for you.

IMO all these skills are well within reach of anyone who wants to learn them, but I'm NOT saying they can be learned without practice and care to details!

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin

Hobby
Posts: 5
Joined: Tue Dec 08, 2015 10:09 am

Re: "River Rat" AL version

Postby Hobby » Fri Dec 11, 2015 3:53 am

Ahh, got it. Makes sense. Thank you

SunFun
Posts: 37
Joined: Wed Jan 07, 2015 4:49 pm
Location: White Bear Lake MN

Re: "River Rat" AL version

Postby SunFun » Fri Dec 11, 2015 8:29 am

Hobby,
For prices of metal, check out Discount Steel dot com. I'm not sure where you live, but I go to their store to by my metal for small projects. the quick comparison I did shows they are much cheaper and should give you a better idea on costs. I usually find that the prices are even cheaper in person vs the website, but this site will give you a better idea on costs.

As for the grade of aluminum, Kevin will know what you need to use, but 5052 is much cheaper than 6061 if that's what you would actually need.

I would hate for you to give up based on bad cost data.

Scott

Hobby
Posts: 5
Joined: Tue Dec 08, 2015 10:09 am

Re: "River Rat" AL version

Postby Hobby » Fri Dec 11, 2015 12:51 pm

SunFun wrote:Hobby,
For prices of metal, check out Discount Steel dot com. I'm not sure where you live, but I go to their store to by my metal for small projects. the quick comparison I did shows they are much cheaper and should give you a better idea on costs. I usually find that the prices are even cheaper in person vs the website, but this site will give you a better idea on costs.

As for the grade of aluminum, Kevin will know what you need to use, but 5052 is much cheaper than 6061 if that's what you would actually need.

I would hate for you to give up based on bad cost data.

Scott


I hear you. I'm in the Gulf Coast of FL (Eglin AFB Area) and there are a few local places to get material. I'm away on travel for a while and was just using the depot and 6061 as a worst case scenario so i can financially plan for it. If its a lot cheaper, which I'm sure it'll be, that'll just be more funds for all the other things (electronics and other luxuries).

Thanks,

Kevin Morin
Posts: 695
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: "River Rat" AL version

Postby Kevin Morin » Fri Dec 11, 2015 5:59 pm

Hobby, SunFun, the boat's shape/design/purpose would work fine in the Pac.NW rivers, some of which are pretty hairy and rock lined; bottom & shores. That River Rat would be best served with 5086 bottom and chine plates but could probably get by with 5052 (significantly less expensive than 5052) sides and decks, bulkheads and most other parts. 5086 will take some pounding before it punctures but the more malleable (softer and less rigid) 5052 has it following among river boat (jet sleds) builders too.

Most extrusions are only widely available in 6061-T6 which while strong is more brittle BY COMPARISON (not a fragile alloy!) to 5086 or 5052 both of which will bend and deform more before tearing (shear failure). Pipes, bars, T's angles and other extruded shapes will most commonly be sold in 6061 even if there is a cost increase and a tiny long term corrosion issue when compared to the more durable 50 series when in constant contact with salt water.

Hobby, if the boat will be used primarily in Florida waters(?) and not the Pacific NW rivers(?) I'd say that 5052 alloy will provide fine durability. 5052 is easier to form, softer and less impact resistant than 5086- while being able to absorb lots of impact energy and bend without tearing too. But the cost savings, between the two alloys, is worth considering the boat's cruising waters to see if the harder, stronger alloys are worth the extra money they cost?

Without seeing the chine detail plans, the decision on where to change alloys if at all? is not too informed, so when you get the plans package and get home let us see a detail of the chine (in Section) and the verdict on rocks in the future of the boat's use, and we could be more helpful?

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin


Return to “Metal”

Who is online

Users browsing this forum: No registered users and 1 guest