RTR weight of our boats?

[hughb]

When looking at build logs or when people list the specs of their boat, I hardly ever see the boat's weight mentioned. I thought this would be an important factor for speed, handling, even amp draw. Additionally, the CF inlays and filling sponson tips are important steps but must be considered with the final weight of the boat.

What sort of weight should we be aiming for? What do your boats weigh?

[1coopgt]

Interesting. I've never done anything to my RTR boats. Zelos Twin 36 or my Zonda. I just put batteries in and go . No CF inlay or filling sponson tips. Didn't think they needed it. Then again I just run for fun. No clubs or club racing in my area. Plus I don't think either fit into a category to race at club level. Could be wrong on that one. Interested to see the replies for this.

[Fluid]

I think the OP means the weight of the boats ready to run (all packs, drive lines etc.), not the weight of a commercial RTR boat....




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[1coopgt]

Hope so, thanks.

[NativePaul]

Weight is very important for boat efficiency, in Naviga racing where everyone in the same class has the same power available to them so efficiency is everything we are pretty weight obsessed. Mini class boats have a minimum weight limit of 450g, all the other classes have no minimum but weights to strive for are about 1kg for a Mono1 or Eco, 1.1kg for a Hydro1, 2kg for a Mono2 and 2.2kg for a Hydro2.
My personal boats are:
Mini Eco, Tenshock Mini Eco, (now called swordsman) 430mm, Turnigy rs450, castle30, 3s 1700mAh, 23.5mm 450g
Mini Hydro, Steven VanGraff 450mm, Mege 16/15/3, castle50, 3s 2200mAh, 432, 475g
Mono1, Tenshock '08 580mm, Leopard 2860, 2s 6600mAh, seaking 120, 435, 1235g (I no longer race this boat and it has numerous LEDs both above and below the waterline for running at night).
Hydro1, Rasch Mongoose, 600mm, Leopard 2860, YEP150, 3s 6200mAh, 435, 1180g.
Hydro2, H&M Dr Super Evil 920mm, Gool RC 3680, YEP150, 6s 6200mAh, 1815, 2.5kg.
Cat1 SAW, H&M Agitator s 610mm, Neu 1509, Suppo200, 3s 5000mAh, 632, 1450g
Cat2 Aeromarine mean machine 29", Hacker B50L, Suppo200, 4s 6600mAh, 440, 2.4kg.
Supercat, Aeromarine Sprintcat 40/80 36", Neu 1521, Suppo 200, 8s 6600mAh, 445, 4.1kg (although it is currently in SAWs guise with a Neu 1527, Suppo400 (6x FET boards from a pair of suppo200s on a single driver board), 6s 6200mAh, 450, unweighed but probably about the same 4.1kg.
Mini Hydro Sprint, Greased Weasel Racing Least Weasel, 450mm, Mega 1630, Suppo200, 3s 1800mAh, 632, 520g.
I also have some fun running boats, and I aim for about 500W/kg with those, which works well for me regardless of their size.

I think as this forum is mostly American much less heed is given to weight, as boats in their classes are size limited, and have either no power limits for IMPBA or more power than that size boat can handle in most classes for NAMBA, so overall boat efficiency isn't really needed and weight is not really an issue, indeed heavier can be better as when powering a hull to its limits extra weight means extra stability.

[hughb]

Thanks for the responses everyone, Fluid you're right in what i was referring to, though it would be also interesting to know the final weight of commercial RTR boats as well. Companies would no doubt factor weight in order for their boats to be more efficient and use lower power gear (therefore less expensive) for still moderate performance.

Paul you obviously are very cognisant of weight, how do you balance that against adding strength to the hull, especially for racing?

I'm concerned with a Mean Machine 29 I'm building. I've added ride pads, appox 60g total of resin/fibreglass to the tips and centre of tunnel seam, and separate inlays into each sponson (which only added 30g to the total weight, i remembered to check). Already the weight of the bare hull is up to 1.4kg. Motor, batteries and ESC will add at least another 1kg, then all the ancillary items will bring the boat to over 3kg surely. My first ground up build was a Delta Force 28 cat that came in at 4kg total, and it was a nose-heavy dog to drive, I'm trying to avoid it with this build.

[Jesse J]

I’m convinced that there are two factors in the “non-Paul-weight-obsessed” category.
1) altitude. The less dense air at 5280 ft above mean sea level is much less lift on my boats built for Houston racing at 95ft above sea level.
2) salinity. Fresh water is less dense than brackish or sea water. I don’t recall which is “stickier” than the other, but I know that setting a boat up in fresh water needs significant changes to set up for brackish or saltwater racing.
This all with the same weight boat...

[hughb]

Wow even more to consider than i would have realised!

[Panchothedog]

I think on your mean machine c.o.g. balance will be a much bigger factor than total RTR weight. I built one as a twin. Dual aqua craft 36x56 motors, two 4s x 3800 batteries. I don't know what it weighs but it feels heavy all loaded up, but balanced at about 28% from the transom it is a great running and handling 48-50 mph boat. One of my favorite boats to run and I own 10. If you are building a single I wouldn't worry too much about over all weight, concentrate on component placement.

[hughb]

Thanks Pancho, that puts my mind at ease. I'll be transferring over the gear from the Delta Force, so will have a TP 4050 (or 60?) motor, so should be plenty of power