Cheap to run, cheap to build electro plywood cruiser ?

[ASM]

HI Willallison

I think the foam core/balsa core is more expensive here too, and as a home builder, much easier to work and get marine plywood. Foam is also a new field, and although one should not be hold back by that, it actually does !

Pericles,

Thanks for the links, especaill the boat builder one is interesting.


I am now in the process of putting all info in 2D CAD, so I can print 1:10 or other scale sections to make a model. Also playing around a lot with the interior, though this should be done in a later stage it is so much fun trying different things out.

[Guest625101138]

Originally Posted by ASM

.......
I am now in the process of putting all info in 2D CAD, so I can print 1:10 or other scale sections to make a model. Also playing around a lot with the interior, though this should be done in a later stage it is so much fun trying different things out.

Building to 1/10 scale is likely to create difficulty in getting the weight low enough. You have to build the whole boat and fit a drive system with total weight less than 2kg. If you go up to 1/8 scale it will reqire much less effort to get the weight in correct scale.

Rick W.

[ASM]

Rick (and others)

When making the 1/8 scale then, what does that do for the 2.5 t real life compared to ~2 kg for the model ? Is the factor 1250 then (so 10 kg in real life = 8 grams in model ?
This would be interesting to know for simple balance test in bathtub to see how much degree 'hang' one has with a certain weight on the outerside of the model vessel (so people walking on one side of the vessel).. this must show the stability of the low, heavy keel and the possible advantage of the small outriggers.

[Guest625101138]

Mass and volume a cube powers of the dimension. So 1/8th scale results in a factor of 8^3 = 512 for weight. Hence the 2.5 tonne boat equates approximately to a 5kg model. You should be able to build the model within this weight without getting very clever with weight saving, A 75kg person will be equivalent to 150g.

I did stability analysis on the hull and it is very stable if you put batteries in the keel. You could stack a few people on one side without risk of rolling.

Rick

[ASM]

Hey all

Look they have stolen my idea !!!

http://www.dsehybrid.com/DSe_Brochure_WEB_080425.pdf

haha kidding.. but good to see my brainchild was already in some-one elses mind on the other side of the globe and actually build.. proves it is possible !

[ASM]

O, forgot to mention, scrool the PDF till you come to the SPQR page 4, the single hull with amas, and single engine powered....

[ASM]

Rick, and others.

Just found this link, might be slightly off topic , but interesting from hull design and propeller design point of view for solar powered boats.

http://www.deltalloydsolarboat.nl/boot

[Guest625101138]

Found the site hard to understand as it is not a familiar language. Hull is interesting. I do not think it as good as the ASM mono-tri or my variation of it.

The prop is something I am familiar with. This link shows one I designed for a pedal boat:
http://boatdesign.net/forums/attachm...9&d=1209597236

Here is the boat being used for training by my Canadian friend:
http://www.adventuresofgreg.com/HPB/...9_archive.html

I design for efficient operation. I am continuously rated at 120W and hence have to work hard to get good results.

Rick W.

[ASM]

Sorry for the Dutch language, just the pictures were interesting, the propeller design triggered my thoughts to your design, that's why.

The boat has been build for the solar challenge 2008 here in holland, were one needs big surface for solar panels on a efficient hullform, but also time trials and a minimum of 8 km/hr on average to be prooved before admittance to the race.

[ASM]

Just a quick intermediate update, started sketching the interior and changing the superstructure to a livable area. Have asked quotes to several companies and persons to CNC the frames and hull plating in 4 mm plywood for a 1/8th scale model as suggested by Rick...... will sending more updates when available.

[ASM]

Still working/thinking on the 1/8 scale model. As I will need to cut shapes in the framesections to hold the electrics, shaft and motor, how does this 1/8 scale reflects to the power needed to install ? In other words what kind of electric model boat motor do I need to choose, so I can take the measures for it and pln them in the CNC files ? This planning would be far better then trying to cut out shapes once the bare model hull is finished and I have to put in the engine somewhere..... PLus need to think of stiffening up the frames sections in the keel if I need to 'eat' away too much would to place the electric motor....

BTW I am thinking of using a steerable POD unit as the electric drive, this saves a shaft and its alignment problems, no rudder needed, just a POD (saildrive) in the flat aft section and done ! Or am I too optimistic ?

[Guest625101138]

The 1/8th scale curve is attached. Something like 2.2kts is equivalent to 6kts at full scale. You see this is where the curve kicks up.

The curve makes no allowance for losses. Realistically you could double this power. Still not an issue. You can get motors that put out 50W that weigh a few grams. Powering it will be trivial. I expect you could push it up to 6 knots.

I favour an outboard. It is easy to pull off to work on and can be made to tilt up if it strikes an object. There may be an issue of it coming out of water in heavy weather but I intend to swing a big prop and the motor is speed regulated.

My electric outboard weighs 20kg and will put out 4.5kW continuously on 48V. It is able to do twice that in a burst.

Rick W

[ASM]

Rick

Thanks for the info, so it ooks like I only need ~4 Watt engine to do the scaled 2.2 kts speed...

As for the outboard version, problem overhere is theft of these things, plus something hanging off the back and no clean lines (or one must eat away interior space aft) at the back. On the other hand, nothing to run through the hull construction and it might be an early testversion without going to details and expensive investments when in testphase.