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Author Topic: Shallow water hydrographic survey RC vessel  (Read 18199 times)
Platypus
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« on: June 12, 2013, 02:45:18 PM »

Hi there,

Left some personal details on the "Roll Call" and now I'm trying to make some sense of my project.

First things first: the project is not a model boat, but a survey vessel Undecided Undecided Undecided

I'm a hydrographic surveyor and currently working at the Dutch Ministry for Infrasctructure and the Environment.This Ministry is divided into regional offices and my main working area is the Dutch rivers and their forelands (is this correct?). We have three survey vessels (about 15m long, 1,5m draft) that survey rivers, harbors, canals and all waterways that have a direct connection to these main rivers(i.e. river Rhine and others).
We used to operate small boats to survey the shallow parts of the river that could not be surveyed by our regular survey vessels because of their draft. But to launch the boats we had to use four wheel drives, trailers etc..... To make a long story shorter: we developed a shallow water RC survey vessel/catamaran/prototype.


With the following specs:
  • length: 2.25meter
  • width: 0.90meter
  • weigt: 66kilo; 30kilo are lead acid batteries  Grin
  • cruising speed: 1.5 -2.0m /sec
  • max speed: 3.5m/sec   
  • motors: 2x maxon EC45 48V 250W with 4:1 gear
  • Run time: just under 3 hours at survey speed
  • Propeller: 110mm 4-blade

On board it has Survey grade GPS receiver (cm level accuracy), video camera (obstacle detection), motion senser (roll, pitch and heading info, 0.1 degree accuracy), small form factor mini ITX PC, 1-channel video server, WiFi backhaul system (for data transmission and RC, operating range <8Km). THe actual survey sensor depends on the type of survey we want to do. Single beam echo sounder, sonar or multibeam echo sounder. All survey data from the vessel is transmitted real-time to a shore radio/station and interfaced with hydrographic survey software "QINSy". This way we can follow/see the vessel projected on a topographic background, see the online results from the survey (bathymetric data or sonar data) and have quality control with regards to data gathering.
A video of the real time data gathering can be seen via: www.youtube.com/watch?v=JrUCzjsZmHY

This all Cheesy leads to a few questions that i have, and the reason why I put in my registration. I would like to build a catamaran vessel with waterjets and brushless motors!
Just to bring up the discussion here is what my (rough) plans are:
  • length: about 2 meter
  • width: minimal 0.5meter with the possibility to go to 1.5m, variabel
  • weight: around 40 kilo, running the vessel on Headway LiFePO4 battery cells
  • cruising speed: 2m/sec
  • max speed: minimal 6m/sec, don't laugh........
  • motors: Red Leopard 5692, 730Kv or 1000Kv ?
  • jet units: MHZ Jet 52
The Hull design would be based on a wave-piercing catamaran design with a near flat underside.

Hope this makes some sense!

Other questions that run through my mind: what about run time, efficiency, is gearing possible/necessary, etc, etc.......

Regards,

Adri

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LUV2squirt
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« Reply #1 on: June 13, 2013, 04:46:10 PM »

Thanks for taking the time to explain your objectives in a concise manner. Here
are the first things that come to mind.


I think the move away from lead-acid batts is a good one. The new vessel will
reduce payload so much with the newer battery designs that it would be possible to
have a totally redundant dual battery system. A telemetry system could provide
constant feedback of the available voltage in the batteries being used. When they
are running low, a servo controlled solenoid system could switch to fresh charged
batts on the fly.

____________________________________________

I have questions about the jet pump selection. Please correct me if I am wrong
but the MHZ Jet 52 pump does not ship with a grate, does it? Since this is a shallow
water design, I would think a grate would be essential. I would not only install a
grate, but due to the low speed design, it will be easy to add some screens mounted
behind the grate to keep all but the finest river debris from entering the pumps. A
grate combined with a screen will improve the reliability of the craft a lot by
keeping all the sticks, twigs, foriegn objects and all but the smaller gravel
(inconsequential) from ever entering the pump housing. Having to interrupt a scan to
clear one of the pumps will become a PITA very quickly. With proper screens this
should not be an issue.

When and if the screens become matted with algea or leaves, you will be able to
clear them (purge) in most instances from the helm by coming to a halt and then
momentarily use reverse full thrust. This should clear the blockage in most instances.

Since you will have live video telemetry, consider aiming one camera at the pump
nozzles. The water coming out of the nozzles is the same as the volume of water
that the impellers can suction from the waterway. This would provide real time feed
back about any blockage of the screens and when it may be advantageous to purge them.

______________________________________________

The message you posted earlier did not state if there was a desire for only one
copy of the small craft or a need for multiple copies.

A lot of small hull development is done in plywood for obvious reasons. A prototype
(functional test) hull can be made very quickly and economically. If any changes are
desired, it is easy to do either minor or major surgery and alter the boat either a
little or a lot (again, quickly and economically).

If FRP hulls (Fiber Reinforced Plastic = figerglass) are the ultimate goal then they
become easy to obtain by using the prototype as a plug (positive mold) and making a
two part mold (negative molds) using the plug. Properly constructed and cared for, the
hull mold and the deck mold can produce numerous copies of the prototype.
Note: Haje74 knows the molding subject very well.

______________________________________________

As to "run time, efficiency, and gearing" the electric experts here can help with that.
I'm sort of a die-hard gas (petrol) boater. Zoom Zoom.

Looking forward to reading more about you fascinating project.
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LUV2squirt (AKA Squirty)
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« Reply #2 on: June 13, 2013, 10:04:13 PM »

If you want efficiency, go with a brushless motor setup running Lipo or LiFe batteries.

The most efficeint pump on the market by far is the Swashdrive pump which is now being made by Jettec. This pump is also the most robust pump on the market.

I have uysed MH$, Hobbyking and Swashdrive pumps, the only one worth while is the swashdrive pump.  Definitely worth the coin.
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Haje74
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« Reply #3 on: June 14, 2013, 12:20:19 AM »

Hallo en welkom!

Dat is een serieus project zeg Smiley.

I would recommend to go for the slightly bigger drive like the MHZ 64 or maybe even the 80, considering the wheight of the vessel. Two of these would probably give a more efficient drive-train for your project; you plan to propell a 40 (!) kg hull at 11-12 knots!

Remember, you are building a serious piece of equipment ment for professional use. This type of application asks for low maintanance and 100 % functionality every time. They don't have to turn at high rpm's like all the toys  Wink we like to get the most out of... lower revs and therefor less stress on the material including less maintanance is the way to go here in my (humble) opinion.

Als je eens hulp nodig hebt bij de bouw; ik woon in Zutphen.

Succes met dit mooie project!

HJ
« Last Edit: June 14, 2013, 12:09:44 PM by Haje74 » Logged
Dreadrock
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« Reply #4 on: June 17, 2013, 04:24:34 AM »

G'day Adri,
 First off i have no knowledge of hydrodynamics etc, just opinions and thoughts, i think all of the comments thus far are extremely valid.

My personal thoughts would be to go with custom made pumps. Reasons being, it's a large vessel, expensive equipment and there will be a lot more weight than our little toys. As stated, our toys are designed to go fast and perform well, run times/efficiency don't really play a big part in the equation, it's all about the fun and adrenalin.
 I would think a pump of a larger size with impellers of greater pitch that can produce adequate thrust at low rpm would be more suited.
Gel cell/sealed batts would be my prefference coupled with a suitable motor/controller, think mobility scooters, not real fast but go all day long.

 I have not looked into readily available motors, pumps, ESC, Batts etc, in all honesty i'm still trying to get a handle on the whole electric world. A couple of things to keep in mind whilst LIFE, LIPO etc and their related speed controllers/motors are awesome power plants and far superior in weight/performance/technology from what we had say 10 or even 5yrs ago, they do have their short comings such as potential for fire etc. I personally know of 1 guy that lost his entire workshop and everything in it due to a LIPO fire and a couple who've had models destroyed due to ESC's bursting into flames while in use.
 I'm far from saying don't use the technology just be aware of it, i've personally got about 20 or so lipo's in my workshop and run 5 models on them regularly with no problems so far (touch wood).

Not real sure on your goals here either, is this a prototype, a personal venture or both? Either way i wish you all the best with it. And keep us all posted with what your up too, it's a very interesting project and i'd like to know how it all goes.
Cheers Nigel
 
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Haje74
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« Reply #5 on: June 18, 2013, 12:25:39 AM »

G'day everyone.

Adri, reading back your initial post you seem very sure about the selection of your components. Would you please be so kind to elaborate about the reasoning behind your choise? Maybe I have jumped the gun with second guessing your decission you see...

You might have some brilliant insight we completely missed, and last thing I want to do is nip your ideas in the butt without knowing in detail your goals...

Still my first feeling is that the 52 is just too small for the job.
Now that I've decided to build my own drives for the Valentijn-class lifeboat, I do see options for the drive-selection issue (if there is one that is...) for your project; you could for instance use the 64 or the 80 as a basis to work from, and redesign the internals to better fit your needs. This way you would be able to make the drive fit its purpose perfectly, increasing its efficiency at lower rpm and so reducing stress on the materials and therefor wear...

You might even find small jet-units on the market, as small as 100 mm dia used in kayaks and such.

Hope this makes any sense...

So, if you have time please share your thoughts on how you came to this list of components and share your comments on what direction you want to go with this. As you can see all of us want to (and are able to) help you by sharing their knowledge, but we could assist you better with just a little more guidance Grin

Cheers,

HJ
« Last Edit: June 18, 2013, 01:37:19 AM by Haje74 » Logged
Platypus
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« Reply #6 on: June 19, 2013, 02:39:36 AM »

Hello LUV2squirt, Dicko, HJ and Dreadrock ( in that specific order  Grin)

Last evening I was busy trying to compose another post and was nearly finished and than hit a specific button on my keyboard and the entire post vanished..... Angry

It is about 11 in the morning so here we go again.


----------------------------------------------------------

Moving from lead acid to LiFePO4 batteries is based on experience with the original vessel. Although Lead acid is tried&tested the power / weight ratio of the LiFePO4 is something I can not ignore. Some time ago I was in contact with Jim Delgado from http://headway-headquarters.com/ to get some info on their Headway LiFePO4 battery cells. They can configure/build battery packs to custom order. Still, you have to be careful with these type of batteries (damage, shorting, water!)


The MHZ 52 is shipped without a grate, you are right. But it should be fairly easy to make a grate to fit. The idea of screens/filters crossed my mind also, although I was wondering that it would block the free flow of water through he unit. I should experiment with different filter size. The idea of pointing a camera at the nozzles to monitor the performance is not bad. Maybe even in combination with monitoring Amps. Purging/cleaning the screens by using the reverse option is good. Will these units give me some reverse movement of the vessel?

This project is a one-time only, I'm not planning on fabricating a serie of vessels. The initial idea was to build a single float in wood, lamining this with epoxy and create a mould from this model. The final model would have a sandwich layer epoxy hull.

First idea of the hull is something like this:

The hull is based on a wave piercing hull and on this drawing the sides are flat, but these need some tappering. The biggest width of the hull is lower than can be seen on this image

----------------------------------------------------------

I don't know how MHZ units compare to the Jettec. I spend some hours googling and because the German border is close Cheesy by I opted for the MHZ Jet 52 units. I did have a look at the Hoby King units. Did not see much info on the Jettec units. They are hard to come by, I think.
I contacted MHZ with a few questions. They responded although it seems that they have to answer many question. It could be my mis-interpretatio! Undecided.  But that is why I came up with my first idea of using the MHZ units with the Leopard motors. Questions about which specific motors to use are still unanswered. Do I need low Kv for even more torque like the 540Kv and what will the power consumption be if this is run for 90% of time at about 1/3 of max RPM?

Seeing that a MHZ 64 or 80 unit is capable of propelling a manned water craft, two Jet52 units should work on a 40 kilo vessel. Maybe I should adjust my wishes for the 6m/sec speed and make this a max speed of 5m/s.
The Kymera company makes a Jetboard that seems to be propelled by a 80mm Jetunit

Like I said, if this works on a vessel with a person on top; what would two Jet52 units do?

Conclusion: I'm rather confident with the hull but the propulsion is an issue. Like dreadrock posted: it is both a prototype and personal venture. And the general idea was to use available products (motors, batteries, jets) to build a vessel that is the next step compared to the original propeller driven vessel: more run-time, less weight, higher top speed, to go into even shallower waters, more module-like design for hull and connecting frame.

Ciao

Adri

PS: HJ, Renkum-Zutphen geen probleem, leuk om eens wat nader te bespreken. Wanneer? Contact via info_at_echopro.info



 
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LUV2squirt
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« Reply #7 on: June 19, 2013, 06:52:46 PM »

This is just my inexperienced opinion but I'm convinced a pair of Jet52s will provide
plenty of propulsion. There is no minimum speed which must be reached to perform a
scan is there? Just so long as the craft has sufficient propulsion to handle any
adverse wind and/or currents then that is all that matters as far as velocity is
concerned isn't it?

One other design criteria that I forgot to mention is the impellers will perform
best if they are well submerged at all times. When these pumps cavitate it means the
impeller spins in an air pocket and that equals zero propulsion. This is where the
temptation to have bigger pumps than necessary may diminish the reliability of the
propulsion - especially if they do not stay submerged fully when waves and other
water surface disturbances happen.

Since this parameter means the pump and motors will probably be well below waterline
then an automatic bilge pump will be needed. I recommend a twin pump (float actuation
switches and backup power supply if possible) system. In fact, I prefer to twin
everything = pumps, switches and power supplies.

________________________________

The image of the craft: Please correct me if I am wrong, but what I see is part of
one sponson. And I think the cylinder in the lower part of the sponson is the intended
location for the jet pump? No big deal - just providing feedback as to what I am able
to see.

Helpful hint about graphics on this forum. Most graphics posted here must be resized
to a smaller total size. I use MS Paint to do it. Others like IRFanView. If graphics are
not doing what you want. Try reducing size to a lower percentage, resave at that size
and then post. You are not doing anything wrong, it's just a peculiarity of our forum
software and most of use have learned to adapt to it.

_________________________________

Reverse thrust: You will have reverse thrust but the pump nozzle must stay under the
water and the top lip of the nozzle should not be too close to the surface of the
water.

What is going to be a lot of fun is your craft will have two methods of steering.
 - the pump diverters will provide steering while in forward motion
 - the twin propulsions will also allow you to steer and also pivot the craft
like a FS twin engine boat with Forward - Neutral - Reverse (provided the electric
motors can spin backwards).
The second method means you will also have steering while in reverse! But you
probably already knew this. It's a work boat and it should have advanced steering.
« Last Edit: June 19, 2013, 06:54:33 PM by LUV2squirt » Logged

LUV2squirt (AKA Squirty)
Dreadrock
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« Reply #8 on: June 20, 2013, 04:43:43 AM »

G'day Adri,
 Ok cool a little more to work with,
I looked up your power supply and WOW that is potentially 1 seriously sweet set up, with the option for about as much run time as you want!!!!! Working backwards the 5692 is working/rated on/at 6s so 22.2v.
Here's what i've come to learn thus far with the whole electric world in a nut shell.....a basic formula to work with is...... KV X Volts = RPM X Pitch = Speed - (20% for drive line/losses etc)possibly more with jetdrives))
Ok so, based on a few contributing factors....http://modeljetboat.com/forum/index.php?topic=12.0
All our pumps are working in the same sort of rpm range...around 15-16k Rpm,
So based on 24v system =..@ 730kv = 17520 rpm -20% = 14016 rpm
                                     @ 1000kv = 24000 rpm - 20% = 19200 rpm
       or at 20.6v system =  @ 730kv = 15038 rpm - 20% = 12030 rpm
                                     @ 1000kv = 20600 rpm - 20% = 16459 rpm
OK so my guesstimate based on the batts would be the 1000KV on 20.6 v, paralleled to the max = mega run times...so it's looking more custom batts more than custom pumps..
 On that i still believe that larger pumps would be of a greater benefit to your project, here's a link to a couple of larger versions http://www.mhz-powerboats.com/category-11/category-22/?language=en&Antriebe=Jet&page=0&view_mode=default
 It'll change a few things but you'll get the general drift
Cheers Nigel

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Dreadrock
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« Reply #9 on: June 20, 2013, 03:42:41 PM »

Oops missed a bit here, if sticking with the 52mm sized pump i don't think you could do better than the jettec/swashdrive, they have a mechanical seal on the front (no water intrusion) and stainless steel impeller (with overlapping blades), stator, shaft and an intake grate as standard. The pumps are serviceable, as in wear ring etc etc. All in all as far as of the shelf pumps go, very nice and definitely in a league of their own, as the saying goes you get what you pay for.
http://www.jettec.co.nz/#/shop/4563486095/Jet-unit-from-Jettec/2208552
I noticed that they're out of stock but i'm sure Adam will have them back in stock again shortly.
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Platypus
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« Reply #10 on: February 21, 2014, 08:25:25 AM »

Hello Guys,

due to the economic crisis  Wink it has been a while since my last post. Time to get going again and pick up where i left.

This is what i saw on YouTube:
http://www.youtube.com/watch?v=b6qM2dVFUt0
a kayak driven buy a Graupner Jet 5 Antrieb. According to the text powered by a 12V 80Ah battery.

So my original plan of developing a catamaran driven by 2 MHZ Jet 52 units should work  Grin Grin Grin

Within a few months it should be possible to build a rough version of the catamaran. And during the summer some further testing could be done for finetuning.......


Next stop:  EBay!!!!

Until next time, Ciao

Adri
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Haje74
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« Reply #11 on: July 05, 2015, 02:48:47 AM »

Adri,

How's your project coming along?

HJ
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Platypus
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« Reply #12 on: February 25, 2016, 04:23:32 PM »

Hello HJ & others,


progress on the new build has been slow. But that is one side of my project. Basically the catamaran is a floating platform for a choice of sensors. And regarding sensors i have made progress. The reliabilty of the old vessel (as seen in the introduction picture) has been greatly improved by a better controlsystem and software. I am now able to do run choice of hydrographic sensors: multibeam echosounder , side-scan-sonar and singlebeam echosounder. So the sensor configuration is working 100%.

Based on the feedback i have gotten sofar, it would be possible to build the next hull this summer.

I know........ Wink Wink i mentioned this before but the drone industry is booming.
Much focus is on the air drones.
But you could call this vessel a marine, or aquatic drone. And because of the attention it has been give lately i could generate some funds to continue with the next design.

Until later,


Adri

PS: HJ, still in Zutphen and working on your waterjet? If you have some time to spare........ would like your advice on some issues.
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Haje74
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« Reply #13 on: March 25, 2016, 04:56:51 AM »

Hi Adri,

Nice to hear you're making progress. Yes still in Zutphen, but not making much progress on the dualstage jet. I ended up ordering 2 54 mm jets from China.. If you need any help just  let me know.

Cheers,

Hendrik Jan
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Platypus
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« Reply #14 on: October 18, 2016, 12:33:44 PM »

Hallo Hendrik Jan,

totally missed yor reply to my post: sorry!!!   Embarrassed Embarrassed

I you have some time left please visit www.echopro.nl and use the email address tot contact me.

Cheers and best regards,


Adri

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