help with understanding longitudinal stringer /farming

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North
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Location: Nova Scotia

help with understanding longitudinal stringer /farming

Post by North » Thu Aug 29, 2013 7:21 am

Sorry about the long post.
Two things I need help understanding re: my upcoming build of a Glen L Double Eagle, 23”er:
1. Once frames are standing in correct position (upside down build), how are the longitudinal tee stringers ran, ie:
Plans show tee orientated so it looks like one piece of tee would be welded against hull plating, with the flat part of the tee being parallel to the plating, and recessed back /sloted into the frames. But on the plans it says” with extrusions (rather than making up tee from flat bar) bend to curvature and fit intercostally between frames – do not notch into frames”
and I got this explanation on the net ” When two sets of frames intersect, openings in one set must be cut to make way for the other. Those which are not cut are known as continuous frames. When smaller frames butt into larger frames without being continuous, they are called intercostal frames. Therefore, ship construction requires two methods of framing. One method uses continuous transverse riblike frames with intercostal longitudinal between them or sufficient plating thickness to eliminate longitudinal members altogether. In this method the transverse frames are spaced about every 2 feet along the length of the ship. Ships built by this method are known as transversely framed vessels”

I have looked at some build pics ( of a mumby 48 catamaran) and it looks like they ran the tees longitudinally in large slots in the frames. Then, I believe they welded up the hull plating to the longitudinals, and then welded the longitudinals to the frames (by filling in the slots).
I thought this is what would be recommended here, but now it looks like I am to cut short piece of tee, and insert in between the frames, to eventually form long longitudinal members. Is this correct?
I have a hard time seeing that this would produce as fair of a line/ shape for the hull plate, as if the slot method was used. The general notes does say that if you use flat bar to make up tees you can “notch notch flat bars into frame first in full lengths, and then weld flat bars on the inside edge intercostally, to make “tee” longitudinal in place. I WOULD THINK THIS WOULD PRODUCE A MORE FAIR HULL THAN CUTTING AND WELDING ALL SEPARATE PIECES OF TEE AS ABOVE.

Please advise me how you folks have done it, pros and cons and what you would recommend. I would like to know what material I am to order (ie tees vs flat bar to make tees) soon.
2. Specific to the Double Eagle plans; Perhaps I am getting mixed up on the different possible tank locations, and therefore tank bulkhead locations with the possible inboard vs inboard/outboard (or outboard) versions. My problem is that it looks like all bottom frames are ¼” thick plate (or flatbar) except where the bottom frame doubles as a tank side. I will likely be using a diesel inboard and therefore will want the integral tank, in the proper location.
For stations #1 and # 2 page 4 says 3/16” bulkheads/bottom frames but pages 5 and 6 say ¼” bottom frames for these stations.
For station #4 page 4 says ¼” bottom frame /tank but page 5 says 3/16” bottom frames/tank bulkhead.
I need to know which to follow for the inboard diesel I am building.

Thanks for any advice!

Lane253
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Location: Kent, Washington

Re: help with understanding longitudinal stringer /farming

Post by Lane253 » Thu Sep 12, 2013 2:53 pm

Your full size print should show your outer lines to the transverse frames. How ever your standard drawings should indicate the cutouts for 1 1/2"x1 1/2" x3/16" T members or larger T's since I'm not familiar with your boat DWG. Page 2 of your standard set of dwgs. should indicate the cutouts for the transverse frames. You are absolutely right that it would be stupid to cut short pieces of Tee stock. You wouldn't have any fairing at all. Oh, you don't even want to try making tee, it would add a lot of time to building that baby. Lane

North
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Re: help with understanding longitudinal stringer /farming

Post by North » Thu Sep 12, 2013 6:09 pm

Thanks very much for the additional info. Don't have the plans on me for a few days, but will look when I get back.

I did ask this question on another, metal boatbuilding specific site, and the consensus was (I realize they are not the designers, but are experienced builders) that flat bar only (not tee) placd in the slots of the transverse frames, so that they were perpendicular to the hull plate, would be sufficiently strong, and that the tee was not necessary.
Basically what the design calls for in making the tee out of flat bar, running continuous falt bar along the frames, but then not following the plans where short flatbard pieces are welded on the inside of the long ones, to make tees.

Thoughts???

Lane253
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Re: help with understanding longitudinal stringer /farming

Post by Lane253 » Fri Sep 13, 2013 6:51 am

North, I would agree as well. Slotting the frames may take more time, but as long as you make your slots accurate it will be easier to bow the flat bar. Tee's definitely are harder to bow as you get closer to the tip of the bow. Since I live fairly close to Seattle I forget that some people live in more remote locations. And don't have unbridled access to every extrusion available. I have tried to find extrusions to make more elegant gunnels. But, most of the extrusions are proprietary. Do you have those issues living in Nova Scotia? Regards, Lane

North
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Re: help with understanding longitudinal stringer /farming

Post by North » Fri Sep 13, 2013 1:01 pm

I even had troule gettin gquotes on the sheets in 5'x20' lenghts, and for example, there is a large setup fee, as it is cut from a roll (not locally) so the price isn't bad for say 4 sheets of 5'x20' sheet - but price 1 5'x20' sheet of a different thickness, add in about $500 for setup.
Had trouble finding even tee in proper dimensions - for example was quote 2"x1 1/2" tee, not 2" x 1" tee, per my request. That's the closet they could come.

Waht boat are you building or did you build, and was it in alumium?

Can I get your thoughts on this???
Have the full sized paper patterns for the frames (that is half width full patterns as hull should be symetrical -may not turn out that way...)
This is likley common, but there are not separate paper pattern sheets for each frame, but rather 2 large sheets with multiple frame lines on each, with reference lines for centerline, waterline, etc.

Plan guide says to use carbon paper to trace out each frame onto material and then cut out frame parts. Then trace out again on layout board for tacking together of parts.
I did buy a new jig saw, on sale, and some alumium blades and will see how it cuts - if it cuts well, with it and/or skill saw, this method could work out OK.
I don't think this method would not lend itself to using my plasma cutter, as I would have to stay back from the line, and then would have to grind, router or file to the line, and this would be freehand.

I can only get carbon paper in 8 1/2" x 11" sheets and I think it would be a mess to lay them out under each line, for all 7 frames, transom ,etc - but maybe I am wrong....


Although he built in wood, a fella on the Glen-L site had the big patterns photocopied (about $60 ) so that he had a separate sheet for each frame. I was thinking I could cut or rough cut them out with scissors, and then maybe use a can of spray glue, to "lightly" adhere the pattern to some 1/2" or 3/8" mdf board. Then use jig saw to cut out patterns for frame parts.
I would then use either my router table and flush cut bit or first use my plasma cutter to go around mdf patterns (this would leave maybe 1/4" - 3/8" material, depending on if or what I use for a guide). I could then use the router table and flush cut bit to take off the extra material.
This would cost extra for a couple of sheets of mdf as well, but I would then have the mdf patterns, in the unlikely event that I build another one...

Please give me your thoughts on pros and cons, or better ideas!
Thanks!

Lane253
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Location: Kent, Washington

Re: help with understanding longitudinal stringer /farming

Post by Lane253 » Fri Sep 13, 2013 5:17 pm

North, OK, I'm going to give you the down and dirty on the layout of your frames. Oh, to answer your first question. I am building a Snake Shooter hull out of aluminum that I have changed many aspects of. Mostly in the stern. I love a challenge. I have worked in the construction industry for thirty years as a commercial plumber/pipe fitter foreman. So I have plenty of layout and engineering back. That being said, it doesn't mean I know everything. I've noticed there are not a lot of people on the forum lately. To bad, because there are some really smart guys on the Glen L forum.

Anyway, back to the good stuff. First of all, didn't you say that you were building a double eagle? So, your full size half frames and your big carbon paper that you are going to buy on Glen L's website. I would buy three packs.In case you tear a couple or cut them, like I have before. The are about $8 US. Each. They are 2'x16'. And you fold them over backward to let you draw in mirror image. So lay a sheet or two of 1/2" sheet rock on the floor of the shop. Buy a roll or two of "Ram board" at what ever mega hardware store you live near. Ram board is thin cardboard that makes sweet patterns. Because of the size of your patterns you may want to duct tape two strips together to make you full frame pieces. You boat is a pretty deep hull I think. OK, your half patterns and the doubled over carbon paper. Lay your Ram board down on the sheet rock then lay the carbon down where the first frame is located that you want to trace. Then tack your full size half frame contour dwg. down to the sheet rock and make sure they are all nice and snug. You don't want anything to move on you. Find your center line, and trace that down first. (Draw a center line on to your sheerock even, it makes it easier to keep track of all those different pieces). If you own a gasket cutter kit they are very handy for the next step. To keep track of the bottom of your V hull on all the traceings, take a gasket punch and cut a nice 1/2" hole right at the intersection of centerline and the angle of the V. At the top edge of the hull line is the cross hatch line to tell you where to stop drawing your line. Mark it. This is where your straight edge is going line up after you trace the other side of the hull. And you will mark the top cross hatch also. OK, now you have drawn half of your frame contour. Now, pull the pins out and look at the back of your drawing. You should see a really nice dark black line for you to flip your full size sheet and carbon over and make the lines for the other half of your hull frame contour. Remember to mark your set up lines before moving your paper drawing from one side to the other. And any other markings that are pertinent to each frame member.

I read another post that you wrote about frame members. You were asking if it was necessary to us wholesheets. YES!!! It is absolutely necessary to use full sheets for every frame. Accuracy accuracy accuracy. Can't stress it enough. Also,remember this; aluminum warps like crazy. Just add heat! And a perfect sheet piece can look like shit.
Sorry, getting off track. Once you get the contour drawn you can start drawing in the cut outs. And snipe the corners and all that fun stuff.

North , I just realized something. You need to buy your material in a boat building town. Like Seattle or New Orleans. I am sure that you could purchase your twenty five foot sheets and all your extrusions at one time and have it shipped directly to your shop for a whole lot less.$500.00 for setup fee is robbery!!! My 5086 .125x300"x 48" cost $502 each. The .190 x 48"x240" cost $434.00 ea. Because aluminum is light and flat you should be able to afford shipping. In Seattle: Alaskan Copper and Brass. They have anything you can imagine. In New Orleans: Aluminum and Stainless steel. I am not sure of their shipping policy, but I am sure they want to sell material. I'm pretty partial to Ak. copper and brass only because, if you need it they got it. Well North I think I gave you enough to chew on for a couple hours. I want to take my kayak out for a spin before dark. Lane. P.S. home page down the left side under boat building supplies. You will find carbon transfer paper.

Lane253
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Location: Kent, Washington

Re: help with understanding longitudinal stringer /farming

Post by Lane253 » Sat Sep 14, 2013 5:04 am

North, Good morning. Hey man, that router table will come in handy too. But its really easy and clean to cut your full sheet frames out with a worm drive, (skill HD 77)saw. Just buy a 7 1/4" 40 tooth per in. Fine finish cut blade for you skill saw. It will cut really clean, then use your jig saw with wood blades to cut the curves. Also, I hope you have bought Stephen F. Pollards book already. Everyone who builds an aluminum boat should have "Boat Building With Aluminum". I still read it. I don't know how many times I have read it cover to cover. His web site is full of boat designs that you can buy all your pieces precut and then you weld it together. His company is "Specmar.com". It isn't as cheap as buying your plans from Glen L. But you are building your boat in the more modern style. Meaning you are basing your strength on longitudinal frames as apposed to transverse frames and longitudinal stiffeners. Another tool that is really handy to have is a portable power plane. To fine tune some of your edges. Stephen Pollard recommends a Porter cable spiral cut blade. But I use my Makita power plane with a straight blade and it cuts clean. Once your frames are all cut you will need a bunch of flat bar to bend around the inside edge of the frames and weld them on. Stay back a 1/2" or so from the inside of your frames edges. This will help to keep you from burn through and distortion of the parent metal. And remember this recall important step. While you are building. Tack first, then short welds staggard back and forth. One weld on each end, the one in the middle then the other side of the material. Don't put your chain welds directly across from eachother either. Make the frames strong , but don't completely weld them out, they don't need it. And shove a piece of 2x4" in between the top edges of your frames before starting to weld them. Edge to edge, because that sheet will shrink like crazy when heat is added. Clamp the frame down while you weld too. It is amazing how it distorts on you. Buy about 18 stainless steel tooth brushes from the welding store and a couple 4 1/2" wheels for your little grinder. Some 3/32" x4 1/2" cutting/grinding discs for aluminum are handy too. You need one "Pferd" TC Bur TC-F-121-4 ALU. For your die grinder. This little bit that you welding shop can get you if they don't already stock it, will cleanly cut your cold starts out while welding. Its hard not to have cold starts. Unless you have a super high end machine or are using a high end TIG machine. But I wouldn't want tig the whole boat, you would be welding for ever.

Your welding wire should be 3/64" or .047. For your mig gun, if that's what your going to use for a welder. Some .035 will come in handy for little stuff, but the big wire will weld most everything. You want any wire that is used for structural purposes or inside/outside the hull to be 5356 alloy. It is the most corrosion resistant and stronger than 4043 wire. You can use 4043 on things above water line that need to look pretty and strength isn't of concern. 5356 is harder to weld than 4043, so practice with scraps and cut them up and do bend/break tests on them in your bench vise. It will help you know how good your welds are. Bevel both sides of your piece that you are going to weld to your 5086 sheet piece (your frames). Beveling will give you great penetration. Before I foreget, diamond plate is hard to find in 5086. So, 5052 for your diamond plate on decks and stuff is OK. It looks cool too. When your welding with the 5356 you will notice that there will be tiny splatter around the edges of your weld. Just shorten your stick out and move in a little closer to your material. Just make sure you aren't to close. You want that hissing sound not a crackling sound from the arc. Spray transfer is what you are looking for in your weld, not short arc. It's weird to get used to, but you'll figure it out fast when you know what you are looking for. Let me know if you have more questions. Glad to help another builder. Lane

North
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Re: help with understanding longitudinal stringer /farming

Post by North » Sat Sep 14, 2013 6:11 am

Lane- Thanks very much for taking the time to write the detailed recommendations, last night and this morning.
There was alot of very helpful info and I still have a couple of question, I'll put at the bottom, if you don't mind.

A few notes:
- Already had bought Double Eagle plans a couple of months ago, but just ordered 3 packs of carbon paper from this site last night - will take 2-3 weeks to get here, going through customs and all. But, I will not begin work in earnest for about a month anyway - still nice sailing weather here, and I have to take the mast down, boat and docks out, etc in a few weeks.

-Have a nice welder power source (Miller XMT304) and a couple of older XR push-pull setups, one is a 15ft whip and the other a 30ft. Bought the second as I found it for about a 3rd of the price of the the 1st one I bought, and could not pass it up. Was going to sell one later, but likley will keep it for spare and parts in case one goes kaput. Can put .047 wire in one and .035 in other and just leave there, if I have different sizes to work on.

- Have been practicing with 5356 wire, as I knew that was recommended for the hull. Definitley getting spray transfer and playing with heat settings between 24- 27 volts. Bend tests seem good, but I know of an experienced aluminum welder, who I think I can pay to come over for an and help me get started with setup and technique.

- Have both .047 and .035 5356 already. Never tried 4043.

- have Stephen Pollard's book and am very familar with specmar site. Almost bought his 20' Orca design last year, but we had just had a baby, and I decided to wait a year. Then I decided to go with the Glen L plans, as I really wanted to have an inboard (used) engine and not pay $8 - 12K for a new outboard. As well, local CNC cutters/metal supply wanted way more that Yarde Metals in Eastern USA (CT) but still was not really worth it to drive all that way, and trailer supplies back.

- I think I can get OK prices locally, but have to make decisions to only get large quantities cut from roll, if I am getting 4-5 sheets of same thickness, and use precut stock sizes of readily accessible alloy like 5052 for other parts.
Was thinking 5086 for hull and deck (1/8" x5'x20' sheets)and 5052 (1/4" x 5'x 12') for frames - but that will depend on your answers to my next questions:
I now understand your process to transfer lines to ram board and idea of using drywall underneath so you can "pin" to it, but:

1. This may sound stupid, but when you said frames should be one piece, do you mean that it is completely one piece, or is it still 2 pieces (port and starboard frame pieces) that are welded together at the keel/ centerline, directly to each other, or both to the stembar or keel, depending on location?
If it is to be one solid piece of frame, cut from sheet, I am wondering how large of sheets I will need for the frames, and how well they will nest together, to minimize waste.

I won't get into any questions about things like plating as that is a few or more months away - I would just really like to understand the process of getting the frames cut out, then the flatbar welded on to form 90 degreed on inside edges, and the get them assembled and start the longitudinals.

2. I know the specmar cnc kits likely have the slots cut in the frames (for the longitudinal flatbar), but should I cut the slots when building the frames individually, or once all erected, lay a flatbar or chalkline at the proper location and mark and cut them then?

Really appreciate your help!!!
Darrell

Lane253
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Location: Kent, Washington

Re: help with understanding longitudinal stringer /farming

Post by Lane253 » Sat Sep 14, 2013 8:26 am

Darrel, It is really important to cut those frames out of one sheet, starboard to port. They will nest together OK. You should start laying out those frames now so we can talk about things like what size of sheet to order. I am getting the message that you do have a pretty decent supplier? So, you can nest those frames economically, I am hoping that the supplier offers 6-8' wide sheets. I think 5052 would probably be fine for your frames. My cost difference at Alaskan Copper and Brass isn't that much different. I have considered doing that and then rolling on some rhino liner or some other high quality undercoating throughout the entire bilge stem to stern. It would also help with sound deadening besides keep the bilge portion of the hull protected. I would think about low expanding pour in foam for the floatation portions of the hull. Hey, I have a pretty cool idea for making sure that any water that gets into the foam filled parts of the hull makes it to the bilge. I am pretty sure you have heard of PEX pipe? Well PEX is very economical and salt won't ever break it down. Just cut pieces of 1/2" and tape them down to the inside of the hull and then pour your foam. Makes that the cleanest bilge in town. And if goop ever plugs one of the lines, you just push a little piece of wire or cable down it and its cleaned.

Are you really dead set on slotting your frames? The reason I ask, is when you build the old fashion way ( the Glen L way),it is much easier to cut the frames down on the outside edges like they tell you to and then weld the t-bar to the edges. You need alot of big vise grip clamps and a bunch of cheap little ratchet straps to keep your frames from moving all over. But it makes really clean fairing. When you are done with framing. Talk to ya soon. Lane

North
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Location: Nova Scotia

Re: help with understanding longitudinal stringer /farming

Post by North » Sat Sep 14, 2013 10:06 am

OK, will try to use full sized frames. But, have to wait about 3 weekds for teh carbonb paper - didn't want to pay an extra 30 $40 for expedited shiipping.
My plan is that whenI get the carbon paper, I will make my templates out of the ram/comstruction board, and then try a few combinations of nesting them together. I think the only size sheet I can get economically, in small volumes is 5'x12'. I will check again.A couple of sheets of that shoudl do even teh full size nested frames, and have some scraps for other stuff.

I tried using my regular circular saw and did not have great luck. But I have sicne read about the difference in torque and lower blade speed of the worm drives, and think I should order on of those. There a few choices in the $200- 260 range, with free shipping in Canada (Dewalt, Makita, Milwakee, Skill). I have read reviews and some people like and dislike all brands - any recommendation?

I don't follow you when you say do it the way the Glen -L plans show. I read the general notes which says you can use flatbar (I assume by cutting slots) and then weld smaller pieces of falt bar inbetween the frames, on the inside edge of the long ftabar - basially forming a tee OR use flatbar but they tell you to cu tshort pieces and fit "intercostally" between frame members.
I have read all notes on the plans, as well as the Aluminum building guide, but unless I am misisng a booklet or something, I have not seen how else they say to do it.
Please assume I know nothing( not far off) and if you have 2 minutes, describe really simply the "old" way that the Glen L plans say to do it?

Thanks again!!!
Darrell

Lane253
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Joined: Fri Jun 22, 2012 5:53 pm
Location: Kent, Washington

Re: help with understanding longitudinal stringer /farming

Post by Lane253 » Sat Sep 14, 2013 12:33 pm

Darrel, I'll make this short because I just wrote you a long response and this stupid forum wouldn't let me upload the pictures I took for you to see. So, first off buy a skill HD77. It is the best and lightest of all the worm drives. The DeWalt version kicks butt pretty good too. In fact my DeWalt rep. Just made a point to tell me last week that, if I bought new saws all from him and if any of them went bad in three years. They would replace them. I was buying six new saws alls for a project at The Boeing Plant Where they build the 737's at. This building was built in 1939 just before the war. The piping that we were cutting out has been there since the building was built. He must have confidence in their tools. Anyhow, I am going to give you my personal email. laneinman253@gmail.com. Take a picture of you frame page and attach it in an email. So I can see your frames. And I'll send you some pics that I think might help you understand the Glen L way, or the old fashion way.

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

Re: help with understanding longitudinal stringer /farming

Post by Kevin Morin » Sat Oct 05, 2013 2:07 pm

Lane, Darrell, I'm a welded aluminum skiff enthusiast but have not been around the site much recently since the metal section here at Glen-L is not as frequented as the other threads due to fewer builders taking on the extra cost of tooling, time to learn and overall expense of materials.

But while there are fewer of us discussing welded metal boats, there is not an accompanying lack of interest among those who want to build in metal.

If I were cutting frames for a transverse and long's type of framed boat I'd cut from plate but not bother with the misconception of making individual frames of single pieces. Welding frame section joints is fine and allows the frames to be built of narrow strips of sheet that can be cut on the band saw to the highest level of accuracy. Then once the 'floors' or bottom frame pieces were camber cut on the 14" vertical band saw, I'd roll their outer edges on the 6" belt sander to have a perfectly smooth and even curve. Same for the topsides' verticals.

Then I'd weld them together at the chine and sheer, if the plans called for transverse deck beams I'd add them in the frame tack-up to restrain the keel and chine shape, and then V both sides and weld them with a collar tacked to the sheer to restrain that dimension too.

I don't personally design with the frame and skinned hull method so I don't build with this technique. But the idea that frames need to avoid joints is not well founded.

Notching longitudinals into transverse frames depends on your lofting ability; If you can build a builder's model accurately then the notches can be done while on the band saw and drill, and if not (?) they can be done when the frames are up using an angle extrusion to layout fair lines fore and aft along the surface the frames. This is 'lining out' from plank on frame days of wooden boat building.

As to the longs, being T's angles or Bars:

Its important to realize the customers of the very widely diverse Glen-L design catalog. A designers (Glen and Ken) have to design for people they don't KNOW!!! So the welds may be heavier, the scantlings a bit heavier and the resulting boats have a bit more weight; in order to take into account those whose skills are not a developed as a full time metal boat builders'. We have had one discussion some time ago about one of Ken Hakinsen's (sp?) designs having a bar at the chine on which to weld the bottom and topsides, and it was learned by someone here, that he called for that to allow lowered skilled people to successfully build a welded skiff but not because it was needed if built by someone with the knoweldge to get a knife edge fit to the sheets.

This is just one example of the caution that is used in these designs so we have to discuss the frames and scantlings as they're drawn and couple that discussion with your present skill level in order to well understand the use to you boat of a given framing element.

So, while I have not studied the design/plans much, I would venture that if flat bars were used as hull longs, notched into the frames, even if their notches were not completely fair to the eye; the hulls would turn out safely over strong to serve a lifetime without even bothering to add the T or L to the longitudinal flat bars' inside edges. these flange elements would add some stiffening, without doubt, but they may be overkill if the bars are on 12" or less centers in the Body Plan view and of a section 3/16" x 1-1/2" or more?

If the longs are 1/8" x 1" or something that fine? I'd move to an angle of a similar leg section and make square notches in the frames.

Integral fuel tanks:

Just don't do it. I've seen and built integral tanks in aluminum boats and have to suggest you consider adapting the design to a removable tank design; even if the tanks' top surface is flanged to weld into the deck structure? I've repaired hundreds of boats and built my share of tanks and I have to say that for the new builder, integral tanks is not a wise design choice.

Hope these remarks work as more grains of salt for your learning/building experiences.

Cheers,
Kevin Morin
Kenai, Ak
Kevin Morin

North
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Location: Nova Scotia

Re: help with understanding longitudinal stringer /farming

Post by North » Mon Oct 07, 2013 3:39 pm

Hi Kevin,

Thanks very much for the detailed reply. It seems that all of the (metal) boatbuilding forums have been a bit slow lately - hope they are all enjoying their boats, before the colder weather takes over!
I read all of your comments and can't apply some of it, as I don't have a band saw, for example - but will use new worm drive skill saw and possbily router to get as close as I can.
Here is where I currently am at.
- transferred frame patterns and made construction paper/ cardboard templates of each frame, mostly to see how they would nest as whole frames ---as you can guess did not nest well. Then took cross measurements of each frame, for futire reference,and checked to see how they would nest if I made one cut / weld at the bottom vee (leaving each bottom and side frame as a single unit - therefore 2 pieces instead of the 4 as shown in the plans. I don't mind making more welds, but think that welding frames from two pieces will still be worth it, as they nest very well (basically in L - shapes and then of course more vertical L shapes towards the bow)
- Have yet to fully nest them all but believe I can get all frames from one sheet of 5' x 12' x 1/4".
I will eventually order 20' or 25' sheets for the hull, but it is not a stock size, so want to be careful to know exactly how much I need before ordering - I assume that once the frames and stringers are all up, I would use constructions paper, or similar to draw out required hull pieces and then see what I need, nesting them together as possible.
- if I use flatbar, due to lack of lofting skill, I will use your second method, holding / clamping each peice at it's desired position, and then marking each frame for the slot cut. Not sure at the moment what the best tool (that i own) to make that cut would be. Skill saw woudl work well for dept hand straightness of cut, but I would require somethiong like a 3/16 - 1/4" curf, so not sure if I could buy a "fat" blade or put twp blade together ,etc...
-plans call for 2"x1"x3/16" tees for stringers, so do you think that if I slot flatbar in instead, something like 1 1/2" x 3/16 or 1/4" would be appropriate, or 2" x 3/16" or 1/4"? I am concerned about having a tough time "bending" the flatbar near the bow, but then again, plans say I can cut this from sheet if required (with the curve necessary).
Appreciate the good advice on the tanks.
Any further insight would certainly be appreciated.

Kevin Morin
Posts: 739
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: help with understanding longitudinal stringer /farming

Post by Kevin Morin » Mon Oct 07, 2013 6:19 pm

North, I understand the framing idea to use L's instead of U's the entire beam of the skiff to nest onto the plate material with less waste.

I'd cut the bar notches with a Bosch Jig Saw, I've used the current model for 40 years and still rely on them. Use Pam or generic pan spray on the blade even few counts of 4 (1, 2, 3, 4 spray...) and they have a fine selection of blades- best is about 6-8 teeth per inch for aluminum.

Haven't seen the waterlines in the forefoot or bow area of your design so commenting on pulling the longs into the frames and the stem is outside what I can say. But you can bend flat bars with a very simple jig and a hydraulic jack- extremely reliably and accurately if you have the notches already cut with the frames up and trued. There are many bar bending ideas online that will provide a small three point fixture that will create curves in the stiffest flat bar- on edge.

Curve cut bars as longitudinals may be harder to layout than just stations or other flat parts since they're often on the diagonal and that requires a bit of lofting. It is not hard, but is not as simple as doing the work from a Body Plan to arrive at stations/frames/transverse shapes. I'm not in any way saying this method if good building, just mentioning that if the bars can be formed by lots of tiny bends (kinks) then you avoid having to take time to layout the diagonals on the lofting table to get a pattern.

cheers,
Kevin Morin
Kenai, AK
Kevin Morin

North
Posts: 293
Joined: Mon Jul 15, 2013 6:29 pm
Location: Nova Scotia

Re: help with understanding longitudinal stringer /farming

Post by North » Wed Oct 09, 2013 12:35 pm

Thanks Kevin, for the additional answers and advice.

I did buy a new jig saw- Dewalt not Bosch, as it was on sale and other members have said it worked well on aluminum.
Will get some time to practice cutting with it, and the new worm-drive skill saw in the next 2- 3 weeks - right now busy getting the sailboat out of the water and trailering it home, cottage winterizing, etc.
Also waiting for a couple more quotes - found a friend of a friend who bought alot of aluminum for large power cat, and he is trying to get me his pricing - so just waiting for that before ordering plate for framing, flatbar for stringers and some other odds and ends.

Thanks for stopping by this board and helping out!
Darrell

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