Aluminum Jet Boat Plans

Discussion in 'Metal Boat Building' started by Trigger, Jun 21, 2005.

  1. Trigger
    Joined: Jun 2005
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    Trigger Junior Member

    I have made a futile attempt at finding plans for an aluminum jet sled. Is there any plans on the internet besides Glen-l's. I wanted Ken Hankinsons design but can't get a hold of any. I want to build a 20' inboard sled like a Fish-rite, Jetcraft, Boulton, etc... Any help would be appreciated.
     
  2. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    jet sled plans

    Trigger, it might help if you could give a bit of back ground, have you built a welded aluminum boat before this project? Do you currently weld aluminum? What power package (engine and pump) are you contemplating? Are you looking for a design for fresh waters only or salt water and fresh? (some of the sleds have more deadrise forward than others to accomodate a swell in salt water.)

    How complete a set of plans will you need? just the lines? lines and framing? plate development? weld details? Will you need to consult with your designer during construction about details?

    Which layout are you planning? Open with a standup console? step through windscreen? cuddy and windscreen?

    Its easier, on all forums, for anyone who might offer information to form a good quality response when you provide more precise details. I think all of these items may help you clarify what you're looking for, and any potential respondants' reply.

    Cheers,
    kmorin
     
  3. Trigger
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    Trigger Junior Member

    Kmorin,
    Thanks for the reply. Never built a boat before. Welding and fabrication is no problem. I have been doing that for years. I want a 350 w/either a Kodiak or American pump (price will determine). Fresh water, lakes and rivers. I want to do as much as I can with the build, but the more info as in lines, framing, plate development the better. Walk through window section. Attatched image is the basic sled I'm after, minus outboard motor.
    Thanks again,
    Mike
     

    Attached Files:

  4. kmorin
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    kmorin Senior Member

    experience

    Trigger,
    you didn't get to specific about the fab work regarding aluminum ( do you weld the stuff? Y or N ?) and I've seen many steel fab hands fail unutterably in the miracle metal.

    You should determine EXACTLy what you'll do and what you'd hire out, especially as regard the cutting of the parts; hull panels, frames and bulkheads. Will you expect to be using an NC plate cut file set? Or, will you be laying out and cutting the hull plates and framing by hand; (ie skill saw etc,) ? A vast world of difference here in plans and the level of purchase by the builder.

    Since you're looking for an almost flat bottomed sled with little or no V section forward, the hull is much more simple to build. Also, the alloy for strictly fresh water skiffs is not as expensive (5052 instead of 5086) and forms less expensively.
    Was your reference to a '350' engine displacement or horse power? If engine displ; then the pump is somewhat more tame than the 10" needed to soak up the 350 horses.

    All these items will help refine the work of selecting a plans package, or help you to submit them to someone to design one for you.

    Cheers,
    kmorin
     
  5. Trigger
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    Trigger Junior Member

    Yes I work with and weld aluminum. It is a 350 cubic inch engine. I've decided that I'm going to buy the software and design my own sled. I build things for the challenge and the enjoyment that the finished product brings. Designing it will make it just that much sweeter.
    Trigger
     
  6. kmorin
    Joined: Apr 2005
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    kmorin Senior Member

    marine design software

    Trigger, this forum has a rousing ongoing discussion of marine design software and will be of good assistance in trying to select a package.

    What I suggest you keep in mind is the design cycle, which doesn't get the press it should. This cycle takes you from the general to the specific in a tightening helical path. Hand sketches of ideas and very generalities become scaled hand sketches become rough scaled preliminary drawings become an entry to the CAD software.

    It too easy to get sucked into a method where you rely on the PC's lines to start your boat, if you don't draw well by hand at least get some battens and work with them by hand-then enter the PC. At least sketch and scan and draw on your original sketches w/ CAD instead of beginning alone in the PC.

    If you follow a design cycle with some care you can avoid redrawing parts of your boat that were not clearly thoughtout in a previous (more initial) stage of your design work. One nice thing about the marine design software is the reduction in lofting, you can cut from the sheet development output files without fear of wasting material.

    I also suggest that you avoid a V in the after bottom sections -convex camber runs better under sleds and then bring in the V forward amidships section. This is an easily done in a single pc bottom for a sled the size you're discussing.

    I'd also suggest that the engine beds are the main longitudinals and they can be formed 16-18 ft x 12" plate 1/4" with a flange press broken of 2.5" or 3". These work well in sleds of this type as main "backbone" you don't need any keel of any size with these two members. They'll carry the engine and pump, stiffen the engine boat and can be made as the main pc.s for setup of construction tackup.

    good luck and I hope you can take time to keep everyone posted on your decision tree as it evolves, it will be interesting to learn which software you select.

    Cheers,
    kmorin
     
  7. Trigger
    Joined: Jun 2005
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    Trigger Junior Member

    Thanks for the advise. My job requires alot of sketching both rough and scaled drawings. I also use a CAD program, although it is not in boat design, it should help me some. I'm not sure which software is the best. I have been following the threads on them. I'm leaning towards ProChine3 as it looks like a decent low budget start, but no firm decision yet. I will definetely be around this place, I have alot to learn and there is alot of knowledge here. I have been looking for suppliers of slotted chine to no avail.
    Thanks again,
    Trigger
     
  8. kmorin
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    kmorin Senior Member

    jet sled design procedure

    Trigger, I read on some of the forums remarks about the different marine software packages and one remark kind of stands out. I'll paraphrase as the quote is beyond recall " the interface needs to be intuitive to your thinking". What this remark was observing is that regardless of the software features, power and costs; your individual effectiveness will be more related to how you react to the interface.

    I have undertaken to examine each of the major packages- Nautilus (Prosurf and ProChine) Autoship (Acad based) MaxSurf , AeroHydro, Multisurf, ... well there are more.

    I want to discourage you from taking this time as I've spent hundreds of hours downloading and setting up tests of features lists and tool functionality.

    I can summarize it all by saying the remark (unattributed to its wise author) is true as far as I can say. I can't begin to discuss the number of tools and methods I've tried to learn to give FAIR review to the different packages. ALL of them are strong and will design boats. ALL of them will give you results if you can 'see' how to run them. ALL of them will require a learning curve (time investment) and ALL of the marine software packages do about the same thing. Some more than others and of course they all claim for themselves the 'best' title.

    If I could suggest any package it would be the package of software that seems the most obvious to you. If you load the demo and run it 'naturally' -that's YOUR package!

    I've worked in Prosurf, MaxSurf, Rhino and several of the others until I'm blue in the mouse hand.

    Real estate people have the three rules of sucess in real estate: Location:Location:Location.
    I believe the rule applies to marine software : Interface:Interface:Interface.

    How do you interact and what work flow method is required to draw a boat in this package or that? In the end, I think this is what will be more productive for you, choosing the software that is the closest to your 'way of thinking'. Once you buy some of this expensive code- you're invested and will become an advocate or advesary. If you choose wisely, you'll become an advocate and sing that software's praises. If, on the other hand, you choose poooorrrly, you'll become adveserial toward the publisher and the software. It is not easy to choose, not easy to become proficient and is subject of very long threads on this forum.

    My best wishes for a wise choice

    Cheers,
    kmorin
     
  9. kmorin
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    kmorin Senior Member

    Aluminum extrusions at the chine

    Trigger, many highly regarded production builders use an extrusion at the chine which holds the bottom AND the side. I think this is the slotted chine you were referring to?

    I would suggest that it is poor practice to incorporate this into your design for several reasons. The reason its used is to minimize welding while leaving a nice extruded seam for visibility at the chine. These are both questionable reasons in my opinion.

    I think hull seams should be fully welded inside and out AND the appearance of a weld is 'welded'.

    The edge of 5052 plate has experienced exfoliation (peeling into layers) when it was used in these extrusions in salt water although it took a decade to show up. Also it didn't happen consistantly so there may have been factors that were not obvious.

    The edge of the side and the edge of the bottom plates are NOT welded in the slotted chine hull joint. The lap weld occurs some two or three thicknesses back from the edge of the plate and then it occurs between 6061 or 6063 depending on the alloy of the chine extrusion and the 5086 or 5052 hull plates. It is accepted practice among aluminum builders taken as a whole; that the hull should be one alloy if possible; add the 6061 on as rails, strakes, or chine guards but don't mix the two in a hull seal weld. This may not be a valid rule of thumb, but that is what happens with the slide-in chine extrusions.

    I know other builders who are certain that the weld near but not on the edge of the plate makes the remaining fraction of an inch of plate loose its heat treatment without being mixed in the puddle and fused to another plate. They are certain that the deterioration inside the unwelded socket of the slotted chine extrusion is poor practice. These two builders work much more in repairing jet sleds from builders whose freshwater designs are running in salt water in Alaska.

    My experience is very limited with this method of building, but I'd like to encourage you to seriously consider the advantages of inside and outside welding instead of just inside welding between the two differing alloys. I have been involved in repairing a few sleds that were damaged due to rock impact at the chines. The inside seal welds failed and the chine opened up.
    I have built a few skiffs that were lost in a storm while towing in the Gulf of AK, one was found years later on the bottom of a log pile. The boat had been crushed and the folded into a pan- but the chines, transom and frames were intact to their adjacent plates. In fact the hull plate tore more often than the welds failed - so it will be really difficult for me to buy-in to inside welded chines without a fully welded outer seam at the edge of each hull plate or panel.

    just my dime on slotted extrusions at the chine; when the going gets really tough they aren't as bullet proof as double sided welding.

    Cheers,
    kmorin
     
  10. Big-A
    Joined: Jun 2005
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    Big-A Junior Member

    i also posted on this form about a aluminum boat design's.
    i know all about the welding process, this is the simples part of the job
    i would need plans that would include boat detail lines and lines for framing
    maybe some forming if nessisary. i have all the resourse's at hand just want to find the one i love and start cuting. i will be putting in our 79 dodge 440. out of are r.v that we dont use any more. its runs perfect i will do some upgrades such as 850 carb, cam, intake,bearings oil pump upgrades ect... new aluminum pipes for the cooling system and a new jet drive probley ameriacan turbine what do u think?
    i cant figure out how to attach a pictures so that everyone out there can see what i want to acomplish but some time i will do that
     
  11. Arrowmarine
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    Arrowmarine Senior Member

    Interesting to hear the other side of the coin on this one. For what it's worth, here is my view on slotted chine extrusions. First let me say that MY experience with edge to edge type chine constuction is limited. I feel both have their advantages. I have repaired both types extensivley and have seen both fail as well as seen both hold up under extreme impacts. I can only assume how much easier the construction process must be using extrusions, especially when joining a heavy 3/16" 25' side to a bottom plate. Mayby I'm wrong. With extrusions, I regularly install a side of this size with one helper and myself. Set and clamped in, ready to tack in under 5 min.. I see a lot more material deflection with edge to edge construction. You can have the option of not painting the outside of the hull and still look clean whereas if you have a weld on the outside it either has to be ground and finished or welded by a superb welder to make it look nice. I have never seen failures due to "exfoliation" that I could tell. I have seen this "peeling" occur with dry sheets that have never touched water. (Defect in the manufacturing process I'm told by Alcoa) I have seen problems with welding 6061 stringers to 5052 plate, so I can agree with that issue, but I have been using 5086 bottoms with 6063 extrusions and 5052 side plates for 20+ years with no evidence that makes me question this method. One thing extrusions do for me is they act like battens when wrapped around the bottom edge. making for fair hull lines. They can be set at the correct frame angles so when the sides are put in, the hull shape is very close to its final resting place. In other words Less Stress. For an amatuer builder, I would say go with the extrusions. I seriously doubt you will regret it, and if you do, I will stand corrected.
    By the way, I can hook you up with extrusion suppliers. Email me.
    Anyway, my two cents. Peace, Joey
     
  12. Thunderhead19
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    Thunderhead19 Senior Member

    I have some experience with the phenomenon known as crevice corrosion. If you only weld one side of a slotted chine extrusion, there is a risk of creating an oxygen depleted area that is exposed to seawater. The oxide layer on the aluminum sloughs off or is rubbed off by a small amount of flexing in the chine and can't be replaced in the expected way. Then other insignificant sources of corrosion (the tiny copper content of 60 series extrustions for example) can become major propblems. I have never enountered a problem with welding 60 series to 50 series plate that couldn't be attributed to a combination of factors, like crevice corrosion. Small areas that can trap seawater should be sealed up well.
     
  13. Arrowmarine
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    Arrowmarine Senior Member

    Good Info JD, Something I have not seen but definately makes sense.
    Joey
     
  14. Trigger
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    Trigger Junior Member

    Thanks for all the advise guys. I've been playing around with ProChine3, it's pretty cool to see it take shape. I'm not really sure of what I'm doing at this point, but I'm learning. I will definetely be asking more questions.
    Thanks again,
    Mike
     

  15. kmorin
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    Location: Alaska

    kmorin Senior Member

    chine extrusions benefits

    Joey, good points about the benefits of chine extrusions regarding set up, fairing and aid in building. I agree that chine extrusion would really help there and I hadn't given that much consideration.

    Almost always built with a crew of a few and most often hanging sides was done with four guys. It was fast since there were many hands, but I've done it alone with rigging it only took about a day to do 10 minutes work.

    I think a stringer type bead, fast hot and drag style along the outside of the slotted chine would allow the one-off builder or working team to have the advantage of the setup without building a weaker joint.

    Most of the shapes I'm concerned with have 2 chines and a "flat" between the inner and outer which doesn't lend itself to use of the slotted shape as well, so I'm very likely not giving this material its due.

    Your observation is right on for a single chine sled shaped hull; the slotted chine extrusion would save lots of build effort and often these boats spend considerable time in fresh water.

    My preference for a cover angle shape welded over an inside edge to inside edge then double welded joint is likely overbuilding; due to long association with Alaskan commercial fishermen. Without taking off my shoes, I can count the number of recreational boats I've had the good fortune to build.

    Cheers,
    kmorin
     
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