Microcatarmaran

OK, I did the phone call today. :/
Well, apparently the process is "very simple", but even if the boat is < 3 m, I have to do the certification with a certification authority like Bureau Veritas or similar.

Apparently what I need is to do a technical drawing, collect all bills of materials, write a statement of construction that I need to verify by the government (that's like 5 €).

The certification authority first approves the technical drawing, then comes for a visit in the middle of the construction and at the end, to verify I'm doing it according to the plans.

I've asked if he knows maybe about how much this costs he said he doesn't know. I've asked if it's 300 € (or something I've read on forums) he said, that it's according to length of boat, but that under 5 m is not that pricey and it could be in that ball park. I've written an email to the certification authorities to see how much it costs. He emphasized that it's no biggie though, in sense that they aren't anal or anything.

Apparently I can also sell the boat normally after 5 years.

Well, if this is true, then if I decide to build it I rather do a bigger one directly, not step by step.
Apparently is also no biggie then if I build a larger boat. He said there is no problem if I go after 5 m (which is when it becomes taxable), that they do all the paperwork and that I just pay the tax. Also that the registration of the boat is like 20 €/year, so no biggie.

Or maybe I can get papers from Romania/Bulgaria or from some other "flexible" EU country.

 

Well good news but wow, such bureaucracy.

 

Welcome to Slovenia. ^.^
You know, Austria-Hungary was all about bureaucracy. We keep the tradition alive.

 

OK finally I got Bureau Veritas on the phone. They said the check is 340 € + travel expenses. That if I build it for myself I just send the plans first and we maybe meet and discuss more (if it's something wrong). That I also need to collect all the bills for the material. As for the mid-check: only if it's needed they come in between the construction (but that for small or uncomplicated boats is not needed). Then at the end we do the final check. Also that they try to lower travel expenses by having multiple clients in the same day if there are more clients in the location.
I've asked on average what's the final price then and he said 500-600 €. Oh well.
He said that I shouldn't worry much for standards if it's for personal use.

 

I think I'll put on hold the above project and maybe do something simpler, like the suggested pedal boat.

I've found through the forum this project: Open High-Performance Pedal Boats – OpenWaterbike Project https://openwaterbike.com/

Maybe I'll do this for start. Theoretically illegal, but in practice I doubt any officials would be bothered by it.

 

That's an impressive boat for what it does.

Good luck.

A pity about your money grubbing politicians.

 

Hi Sebaseba
Would you mind sharing that spreadsheet?

 

Hey,

I actually made now an online form as it's easier for me (I'm more at home in online apps).
That would be even easier to share, but I haven't totally finished yet.
I'll share when I finish it roughly.

Some of the equations can be found here:
* https://ocw.mit.edu/courses/materia...-2015/lecture-notes/MIT3_054S15_L17_panel.pdf
* https://www.amazon.com/Cellular-Sol...id structure properties&qid=1588960889&sr=8-1
* https://www.amazon.com/Reinforced-P...orced plastics handbook&qid=1590473148&sr=8-2
* Beam Stress & Deflection | MechaniCalc https://mechanicalc.com/reference/beam-analysis
* Loaded Flat Plates - Roy Mech https://roymech.org/Useful_Tables/Mechanics/Plates.html

Re

 

Decided that I need to start somewhere. I started with the pedaling part, the gear box. First working prototype (although the last bevel gear's hole is wrong so it shakes).

Where the drill machine is, you are supposed to have the cycle cranks. Then it goes to two sets of gears, which each add 1:2.583 ratio, then to a bevel gear set, which are in a 1.533 ratio and change the axis of rotation so you can add a propeller. In total 1:10.23 ratio, so with a typical cadence of 60 rpm you can have the propeller at approx. 600 rpm.

The gears are 3D printed with PETG, I'll try with polyamide (Nylon) too once I upgrade the 3D printer. Also the gears need to be thicker in order to withstand the force and of course I need to add bearings etc.

 

Nice!

I guess you have considered a normal bicycle bottom bracket, chain and cogset. They are cheap and a chain is like 97% efficient. But I guess with 41:11 you don't get that high ratio. Of course plastic gears are better in (salt) water. It might also be good to include the 90° redirect with the gearing.

The size of the propeller is also a gear ratio. So maybe a larger propeller will need less RPM and be more efficient for both gearing and transmission of force to the water.

Will you have two 90° redirections? Do you plan to rotate the prop for steering or a separate tiller?
Or have the prop shaft at a shallow angle? (long tail?) Or use a double cardan / CV joint to adjust the angle?

Just curious, feel free to ignore me

 

I considered that or maybe also belts from cars, but I don't know. I'll see.
I bought this US $2.13 34% OFF|Stainless Steel Grinder Soft Flexible Shaft Axis Adapted to Electric Drill|Power Tool Accessories| - AliExpress https://www.aliexpress.com/item/4000532201523.html?spm=a2g0s.9042311.0.0.62244c4dnRKEtb for the shaft.

 

Have you seen something like this?


I think sticking with the 3D printed gears and shafts is best. Not perfect but no problem with corrosion and allows you full design freedom. And you could have metal gears made later too if you want. There are also cheap replacement gears for angle grinders you could use.

I'd build something compact like in the video but so that it can rotate. Two 90° redirect gears would allow you to combine the pedaling, gearing and turning into one compact unit so you don't need a separate tiller. Then put it into a kayak / canoe / trimaran with a bigger round hole so you can take it out easily and rotate it.

 

Oh I just realized what you meant with belt drive! It can be used to change the rotation 90°.

 

I think this video shows the optimal solution. Simply use the a bottom bracket and crankset and have the chain go straight down through a long tube, twist 90° and drive the propeller shaft. The chain should be very efficient, or at least more efficient than 3D printed gears and the parts are cheap.
You could use a large sprocket or additionally add a bottom bracket gear (schlumpf drive?). Or use a bigger propeller.

 

I think you're going to find the flex cable too "squishy" when you pedal it.
9mm spring stainless steel in a two meter length would work well.
If you can make 70 rpm instead of 60,
and use 6 or 7 to 1 for the ratio instead of 10:1
with a larger, more efficient prop, you would have better results.
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