metal boat project

Here is one of my current projects. The entire boat was developed using Rhino3D and most parts were water-jet cut. Everything fit perfectly. It was actually quite spooky considering I felt there would be issues arising from the different plate thicknesses which ranged from 1/4" bottom to 3/16 sides and 5/32 frames (in addition to all the complex forming). It went together like a toy.
Also shown in the pictures are Mike, Patrick (smoking fool), and Jim (welding under swim deck), they are the build crew. We were compelled to move the consoles forward a couple feet to meet the customer's needs. This is an 18' boat with a beam of 84" and is to be powered with a 115hp Suzuki outboard. She'll weigh in at a hefty 2500lbs with the motor and 35 imperial gallons of fuel. You'd have to do something pretty outrageous to even put a dent in this boat. Finished photos are coming up, and I'll let you know how the sea-trials go at the end of next week.

 

Nice welds. I see you are using a Miller. Is it one of the pulse on pulse ones?

 

that's our TIG machine

 

I thought tigs were too hot to use on aluminum due to warpage of the sheets?

 

No way man. Tig machines do a beautiful job on aluminum. As long as you buy a high frequency machine specifically calibrated for aluminum there's no problems at all. If it wasn't so fiddley, we'd TIG almost everything. That said, pulse on pulse does a pretty sweet job too, and it is much quicker. We don't have one though.

 

the finished boat turned out quite well, there were some last minute modifications including moving the consoles forward about a foot, but alll in all it performs exceptionally well. We took off the 115hp motor and put on a 140hp. It averaged 47mph over the measured mile wide open, and could be turned hard over at half throttle without any slip or instability.

 

Thunder - was waterjet not very expensive compared to high - definition plasma cutting where you are, or do you have your own machine?
Just interested to know.

Paul.

 

Actually we just got our own water jet machine, around 8 weeks after sea trials!

Water jet was more expensive (about 10%), and we had to wait in line for several weeks.

We had our most recent boat done in high def plasma cut, (a 24' cabin cruiser..I should post the photos of it too) and we've had no end of troubles with poor cut quality and mishapen parts. We went with plasma this time because we were facing time deadlines and thought we couldn't afford to wait. My boss blames the contractor, I blame the software....

Our original cost estimates showed a real savings using WATER JET over plasma because of labour saved in de-burring and fitting after we recieved the parts.

It's funny though, the water jet table we purchased will more than pay for its self before this time next year. But then we make other products too on a rather large scale (Holland America scale...wink wink, nudge nudge...) see www.amstel-metal.com

 

Thunder -

This is probably more suited to me than you and does not make for an interesting thread for you or anyone else with what I am asking here and going on about at boring length but could I just ask you a few more things if you don't mind as this is very relevant to what we do every day. Bear with me please.

If there is poor cut quality and mis - shapen parts, it must be the contractor, as the software only tells the machine to cut whatever it is told to. In other words, whatever it cuts should still be of good quality, even if it is a wrong or wrongly shaped part. Certainly not any mis - shapen parts all of which you will already know. Perhaps their consummables were about to wear out, nozzles, swirl rings and so on. We put new ones in every time we begin to cut a boat kit and once completed we use the part worn ones for less accurate work on some other projects which is acceptable for them.

The fit of the kit may be down to the design and software however, as a good fitting kit should fly together - we always find that it takes one or two new kits cut for the first ever time to completely iron out any mm or parts of a mm alterations - just to tweak the sizes in practice.

Our high definition plasmas need little or no de - burring, obviously depending on the plate thickness, and certainly none up to 12.5mm, so this angle surprises me. Was it definately high-definition or just ordinary plasma cut do you think? and also, is their machine a new - generation type high - definition plasma or an older machine? What was the plate thicknesses?

Thanks for the info and bearing with me,
Paul.

 

What was happening, was that the parts actually arrived with corners sniped off. Sometimes the snipes were long and slender and gave the misleading impression that the part was square when it really wasn't. I think this was a software issue because when we converted the file from Rhino3D to a DXF file, several of the line entities turned into splines with only two control points. These splines were "joined" to other splines. In some software the verticies appeared at the joint (like theyre supposed to), but in the toolpath generation software the verticies were a mathematical projection of where the point might lie on a NURBspline of a particular stiffness. Their machine was brand new, and it had recieved maintenance immediately prior to our project. They never discussed required tolerances or cut quality at all with us beforehand either. It was definitely high def plasma though.

 

Thunder - Ah! - understand now.
Yes, probably was the way the software converted the modelling into parts. We use our SigmaTEK version 7 nesting software to draw and also to covert everything for nesting.
We sometimes use a designer to take a finished project from the working drawings/model to the profile stage but this of course costs money to do.
It eliminates most of the problems we are talking about however and means the build can be fairly quick and straightforward.
You would need to check each part before cutting at the profiler in some detail which we would have asked you to do, in other words, you would approve the final parts before we would cut them.
It may be that you need compatable software of high quality to enable this function to be carried out successfully if you are going to cut out the middle stage on a regular basis. The designers could tell us if any have read this please.
Anyway, thanks for the info and i will follow your projects with interest.

Paul.

 

Side Rail of Stormcruiser

Thunderhead19, very nice clean boat- I always enjoy looking at boats with the "Rybovich Leap" at the sheer, and your skiff shows a nice balance of that line. I couldn't see- does the chine reverse? I didn't figure out what the two 'folded-leg' plates were for at the transom waterline? Transducer brackets- so the screw don't pentrate the sealed hull?

I wondered, after looking at this clean sided power skiff if you'd considered that the hull extrusion side rail's shape might have been included in slight changes to the current design configuration?

I'd have been tempted to taper the extrusion's side legs (forward) from 2" down to 1/2" and bend it upward and around the topsides as it ran forward. I'm pretty sure the tapered legs would have made the otherwise stiff material flexible enough to cold wrap the topsides cleanly.

In alternative, I'd have liked the end cap forward to have a longer ratio of taper, it seems a little abrupt to go with the lines of the rest of the rail.

Aft, it looked like the hull stiffener might have made a more flowing design contribution to the side, transom and engine mount deck transition by continuing along the same line and forming the outside edge of the engine mount/deck? This would have given that deck an outboard edge with the nicely tapering edge but still rounded by the extrusion's radiused edges. This may have been a site to consider adding a bolt-on rubber extrusion that could extend from the engine mount aft all the way foreward along the rail's line.

If the side rail were a bit longer and thinner foreward then a bit of the sheer might be mirrored in a slight upswept curve

Just a thought about integrating the side rail and the lines of the transom treatment with the foreward topsides by using the external rail as a link- so to speak.

I noticed you'd welded the windscreen fronts panels to the sides instead of breaking the plate like the gunwales of tread plate. Was this less work or did it provide more design gain in some other area?

I found the gunwale treatment very tightly radiused and clean looking and was interested to learn what had decided the weld at the windscreen's similar corners? They appeared to be welded -perhaps they're bent and I wasn't seeing the photos clearly.

Thanks for the great pictures, she's a very nice looking skiff.

Cheers,
Kmorin

 

Kmorin-
I believe tht what you pointed out on the transom was in fact the transducer brackets.

I agree wholeheartedly, the rubrail looks like an afterthought because it was an afterthought. It is hard to tell, but the leg does taper, I guess it would have looked better if it ran out to nothing about three feet from the bow and, as you pointed out, integrated into the swim beck.

As for the windshield, we kicked around a number of different ideas. Because the fronts of the consoles and the (not yet installed ) door, form a smooth arc, and we can't get the curved glass we want for the front panels, we just made the entire windshield one section that attaches separately.

This boat design, like many prototypes, continued to evolve while it ws being constructed. If you do that enough times, you can get backed into a corner, and wind up with a few features that look less than natural, that can't be fixed without tearing half the boat appart. The rub rail, on the other hand, is an example of the company CEO interfering with my work gang behind my back. It happens all the time. I go down to the shop every morning and inevidably wind up asking Pat, "Who told you to do that?".

I don't mind though, hence my motto...

'Forward, the Light Brigade!'
Was there a man dismay'd ?
Not tho' the soldier knew
Some one had blunder'd:
Theirs not to make reply,
Theirs not to reason why,
Theirs but to do & die,
Into the valley of Death
Rode the six hundred.

 

Designed versus Shop-built

Thunderhead19,
Thanks for the heads up, that rail did look out of place since it would have looked different if it had come from the same hand that had drawn the rest of the boat.

I looked more closely at the middle photo of the painted boat, from the stern, and found two large zincs bolted to the stern brackets so eventually it became clear what they would do.

Given the 'impromtu' nature of the design 'team' I appreciate your motto a bit more than I had in the past.

Cheers,
Kmorin

 

I've posted the 24' boat I mentioned as a new thread Metal Boat Project 2