Cuda by Dive-Xtras: complete review

This is a review of the Dive-Xtras Cuda. There's been a lot of chatter about it on some of the forums, but nothing detailed has been placed into print besides what's available on the manufacturer web site.




After roughly 40-50 dives on the Cuda, I have come to really appreciate some of it's advantages. Of course, there are tradeoffs, too, and I have come to see them as well.

The Cuda retails for US$4500. If I had been willing to accept one with a sequential serial number, it would have been shipped the next day. However I am vain, so I had to wait a couple of weeks for delivery of my custom serial numbered Cuda.

When delivered, it was a plain, unassuming brown box. Despite the box's goodly size and 65 lb. weight, it arrived unscathed:





When I opened the box, I was pleasantly surprised by the neat, orderly appearance of the contents. Someone put a lot of thought into the customized packaging and shipping of the Cuda, and it's all "green" (recyclable) packaging, too.




After quickly un-boxing and unwrapping the stuff, here's what ships as the standard Cuda:



(L to R) 42 V charger, spares kit, 42 V battery, nose section, tail section

With the exception of charging the battery and lubing the O-rings, the Cuda comes completely ready to hit the water.

The tail of the scooter

At this point, I'll walk around the Cuda, and point out some of the things that are different from the Sierra, as well as some of the stuff that's kind of hidden.

The first thing that jumps out at you is the tail. It is immediately obvious where all that speed comes from, with a motor that dwarfs the standard Sierra's. The motor is so big it barely fits despite some tight machining and the thin walls allowed by metal construction.




It's tempting to dismiss the Cuda as just a Sierra with a big-block engine shoehorned inside; I know I did. Careful comparison in the above photo, though, shows the Cuda tail is a completely new piece, with subtly different dimensions and more rounded contours.

The handle is the familiar Dive-Xtras one, with what is standard for the family, the index finger scooter trigger, and the thumbscrew trigger lock. As much as you'd think the thumbscrew lock would be quite easy to loose, I haven't had even a close call in 400+ dives with this design.



The trigger action is unremarkable, it feels just like Sierra (more on that later). Also visible in the above photo is the prop hub drain, to allow the hub area to drizzle out the excess water when the scooter is stored standing on its nose (thus avoiding rust in the shaft seal and clutch).

The handle comes complete with molded-in thread inserts for the optional (but highly recommended!) compass mount.




Also, as if you couldn't figure out the lineage, the Cuda trigger strut is machined with the model. The opposite side has the serial number.





The Cuda retains the reliable double seal of the Sierra, with an active barrel-type o-ring seal, and a static fixed o-ring. This combination has never leaked a drop for me or any of the folks I've dove with, and has been very easy to maintain.

The Nose

As we move to the nose of the Cuda, the first thing that's noticed is that there are only three latches. In conversations with Ben McGeever, he indicated that three latches are all that are really necessary, and it has the advantages of lighter weight and (most importantly) makes it definitely incompatible with older Sierra components.





Dive-Xtras was positively rabid about weight reduction with the Cuda, and it shows. There's the slots in the shroud struts, and the extra internal machining in the tail. There's an ounce here, an ounce there, and soon it's pounds.

The nose especially is a place the fat was trimmed, and one that isn't immediately apparent. Surplus wall thickness was removed between the locations of the interior support rings, a process which removed over 6 pounds without impacting the depth rating. Again, this machining is something that doesn't catch your eye, until you know about it, then it jumps out at you from across the parking lot.



Weight reduction has been so effective, that despite the huge motor and longer body tube, the Cuda (no battery) only weighs 4.6 lbs more than the Sierra (no battery).

Moving on to the interior, we notice a departure from the Sierras: near the bottom you can see an extra support ring. The Cuda battery is quite a bit bigger and longer than the standard battery, and needs this to keep the battery straight. And at the bottom, the included weight bags to trim the scooter.

Also on the inside, another nice touch regarding quality:




Here's the sticker that shows the nose passed a 15-minute vacuum test. There is a similar sticker found in the tail.

On the front of the nose is the sacrificial zinc anode. This really works, as there isn't a speck of corrosion on our very experienced Sierras, who have had about 2/3 of their life as salt water dives on board live-aboards.






There is one last thing the graphics on the side of the nose. These are very thick urethane-coated stickers with industrial strength adhesive. Once they're on, they don't come off, unless you're willing to break a fingernail or two. So, they're lightly applied at the factory -you get a chance to peel them off- and thus you need to apply some pressure to firmly seat the stickers before diving.





Here it is, the last chance! Once you press down on this you won't get them off easily. Which is okay, they've been incredibly durable.




Personally, I like the graphics. They do look tres cool and keep the scooter from being just another black blah tube. And JanetÃÔ a girl, and is inordinately pleased with the flower graphics.

The electronics

The Cuda is a 42 Volt scooter, unlike the almost every other scooter made which are 24 Volt. It uses a brushless DC motor, like the Sierra.




Keeping the two voltages, and scooter models, from being confused has obviously been thought through a bit. The charger is a different color (black), the battery is bigger (won't fit in a Sierra) and especially, the plug configuration has been changed:




The Cuda plug is on the left, the Sierra on the right. The Cuda plug has been glued together so it can't be disassembled and then reassembled, to fry some poor unsuspecting Sierra.

The electronic motor controller is a bit more robust than weÃ×e seen before. It has extra heat sink fins and slides into a nifty little holder/heat sink. This makes for a very clean install that's the best yet and a long cry from the ziptie of the Echos.




The battery is quite a chunk, here you can see it next to a standard Sierra battery. This is the current standard Cuda battery, which is 42 Volts at 13 Amp-hours, or a total of 550 Watt-hours. Hence the model name of "Cuda 550" eh?




The battery charger has an extra LED and the lights are a bit different, too. When the battery is roughly 90% charged, the green LED lights up and flashes; when it is fully charged, the LED becomes a solid green. I've seen that a fully discharged battery will take about 8 hours to fully charge.

All NiMH powered scooters have low-voltage cutoffs. On some scooters, when the voltage drops low enough, the protection circuitry cuts off the battery, and from that point on the scooter stays dead. The Sierras will cut out as voltage drops below 20 volts, and as the battery voltage recovers a bit from resting, you can get a few short bursts of power from it.

The Cuda is different. As the battery voltage drops below 35 volts, the Cuda cuts to speed 3, and continues to run. This is nice you get a warning about low battery, and if you react by clicking down to cruise (150 fpm) speed, you can run about a half a mile until further battery protection kicks in.

On Shore

Assembling the Cuda is very similar to the Sierra, you stand the scooter on it's nose, slide in the battery, connect the tail and snap the tail on the nose.

Speaking of the battery, it comes from the factory clean and (obviously) unlubed. The first couple times I thought I couldn't get the battery out of the nose! I pulled and swore, then Janet pulled and swore. After a couple of dives, we lubed the battery seal liberally with silicone grease, and poof, the problem instantly disappeared.




Once assembled, the Cuda makes a nice package. However, at 50 lbs it is about 14 lbs heavier than the Sierra, and 20 lbs lighter than the Gavin. This doesn't sound like a lot until you heft the three side-by-side.





The big strength of the Sierra is it's so easy to use for beach entries and on boats. Most boat crews wince a bit when they see scooters, and they positively smile after picking up a Sierra. The Cuda is heavy enough on boats that it's not truly at home there, although the same could be said for other scooters in the same weight range like the N-19 or the smaller Mojos.

I find myself first staging the Cudas in the water, where before, I would feel happy walking into the water from shore (wearing doubles) carrying the Sierra. It's not that the Cuda is really heavy, it's that the Sierra is so light, if that makes any sense.

Diving

Just in case someone has been asleep for the past 6 months, the Cuda is fast. Real fast. But we'll get to that in a moment.

Once the Cuda is in the water, all it takes a dive or two to fine-tune the Velcro weight pockets. It's easy to end up with a perfectly weighted scooter, as the Cuda agreeably is not prone to nose-heavy, or, tail-heavy.

As those already familiar with the Sierra know, a really handy feature is the speed shift, and the Cuda has this as well. This involves pulling the trigger, then rapidly clicking the trigger, twice for faster, and one click for slower, somewhat similar to clicking a computer mouse. The electronic motor controller senses these clicks and speeds up or slows down the motor, all without any penetrations of the hull for control knobs. (in fact there are only two penetrations in the hull: the propeller shaft seal, and the main hull o-ring.)

Speed & Manuverability

Unscrewing the lock and pulling the trigger is a treat. The Cuda has 8 speeds available through the speed shift, and it starts at speed 3. At 182 fpm, this is the equivalent of speed 5 on a Sierra. So the Cuda starts out at the top end of the Sierra, and just gets faster.

It is tough to talk impassively about the Cuda's speed without quickly lapsing into superlatives. It's that fast. You start out calmly talking about the thrust smoothly stepping up incrementally, and the next thing you know you're babbling about being "a chipmunk riding the back of a cheetah running down an antelope" (a real quote).

I do know what my first Cuda experience was like, and I'm not ashamed to relate it: the beginnings of self-doubt. This was in 30 of vis, in a single tank, and stuff started coming into view so fast, that I started thinking that "this is too much for me!" However, (whew!) you get used to it very quickly, and now the speed is just a tool.

I find that I rarely run around constantly at speed 8. It's a big stick that I use occasionally, like turning the corner at Catalina Island and pushing through some serious current that leaves regular scooters moving forward at a crawl. Or slowing down to look over a part of the wreck, and clicking up to 8 to catch up without being "stranded behind". Knowing the scooter has the thrust to tow two at "normal speeds" is great too. So, it's not something that's used all the time, but really, really nice to have.

But that's enough talk about subjective feelings regarding the Cuda's speed. Here's the empirical data. This data has been collected on the Tahoe Benchmark racetrack in both the Tahoe standard configuration (single, BP/W, drysuit), as well as what we've standardized as the Tahoe tech gear configuration (drysuit, doubles, aluminum 80 stage).





Vic and I have been zipping up and down the racetrack in doubles gathering data on a variety of scooters, and the doubles data is a complete letdown. There is nothing magic, just that your greater drag increases power consumption (watts) proportionally throughout the scooter's speed range. Yawn. The Cuda performed very well dragging around a technical diver, topping out at 233 fpm, and very stable.

Speaking of stability, if you're used to the easy, wrist-flip maneuverability of the Sierra, the Cuda will be a change. The longer body gives a directional stability that is great for cruzin and covering long distances. At midrange speeds, like speed 3, you can certainly maneuver quite well, as you can see here.



Oddly, the Cuda becomes less maneuverable at it's slowest speeds, like speed 1. It quite happily maneuvers at speeds 3 through 5, being quick to turn and easy to "yank and bank". And at speeds 7-8, the powerful thrust overwhelms your efforts at abrupt direction changes, and it takes real muscle and grunt to get the Cuda to suddenly head sharply somewhere else.


Range & Torque

Something we've really come to like on the Cuda is the range. The speed gets all the talk, and range is the aspect that really should be mentioned more.





The Cuda tested at 4.9 miles at 150 fpm, and at 1.7 miles at 254 fpm during the Tahoe Benchmark. Our additional testing in tech gear resulted in ranges of 3.7 miles at 144 fpm, and 1.5 miles at 233 fpm. This extra range is really nice, giving the punch to add quite a bit more distance for a significant stretch of scooter touring. And it's a warm fuzzy to know there is so much extra range available when you're quite a ways from home.

Something that's worth mentioning is torque. Here I'm referring to torque in it's correct sense of the word, the rotational force exerted around the long axis of the scooter. The Cuda, when clicked up to speed 8, will exhibit some significant torque. As a diver you feel this through your shoulder and upper arm as strain. I'm not a weightlifter, so at a constant speed 8 I begin to really feel it at the end of a Ž¼ mile run. I have learned to "cheat" by rotating the handle down to the 3:00 o'clock position and locking my elbow, which lets me run flat-out for about 2/3s of a mile.

However, when you click down to speed 6 or 5, the torque almost disappears. Our favorite speed has been speed 6 with doubles, as you easily lope along covering some serious ground at ~210 fpm. Although the lack of torque isn't in the same league as the Suex ADV-14A (which exhibited zero, as in not any, torque due to it's clever battery arrangement) It's small enough that at the end of a 2-mile constant-trigger run I haven't really noticed it.

A last comment on in-the-water manners regards the speed shift. The experienced Sierra driver typically has learned to rapidly shift speeds with abbreviated, half-throw clicks of the trigger; this doesn't translate well to the Cuda. The motor's magnetic field is big enough that definite, full-throw, rapid clicks are required to send the proper signal to the electronics. This is certainly not difficult, and folks that need to re-learn this are probably displaying symptoms of becoming lazy. That would be me, actually! All it took is a dive or two of being very definite on the trigger, and now that I've burned in the appropriate neural pathways, all is well.


Summary

Having the Cudas has put Janet and I through quite the preference upheaval. When you first start diving the Cuda, the overwhelming speed and power are intoxicating, and you want to take it on every dive. However, we love to travel, and primarily boat and shore dive, and the extra weight of the Cuda would seemingly make it a poor match for these.

That extra 14 pounds really does make a difference, you see. After talking it over, Janet and I caved in to reason, and agreed that the weight made the Cudas not an ideal match for our favorite types of diving.

Still, oddly enough, every time we go on a beach dive, the Cudas are along for the ride, and the Sierras are in the cabinet at home.

And flying places has all kinds of issues: airline weight restrictions, handling the scooters on board boats, 8 hours to charge; this is the environment that the lightweight Sierra was designed for.

So, what do we take on trips now? Darn it! The range and power of the Cudas are really making our Sierras lonely. <Sigh> ...Anyone interested in buying some Sierras?

All the best, James

Another great post. Thanks for taking the time for such a good write up.

Hunter

Thank you James for an impressive report on the Cuda and the Sierra. I have both actually and agree with you about the comparisons. I wish that they had a travel case for the Cuda. The one for the Sierra is perfect and keeps the scooter safe and scratch free. The only other thing I noticed is that the tow cord on the Cuda doesn't allow for the scooter to be stowed if necessary. The cord doesn't reach through the nose ring to allow for it to be easily stowed. I learned a great deal about both of my scooters from reading your report and look forward to the next one. I have used them primarily in quarries until my next big trip. Are there places that you would recommend to travel to that allow or are scooter friendly? Or dive operators that are scooter friendly? Thanks again for the report. Impressive indeed!!

Anthony

Thanks for the good words, Anthony.

Janet and I actually still use the Sierra cases for traveling with the Cudas. The tail, charger and the battery go into the travel case, and we place the nose into the luggage we carry our scuba gear in. The inside of the nose has been a great place for clothes.

As for locations that are scooter friendly, may I refer you to two movies:

Endless Scooter (full size found here )

and

Endless Scooter 2

Generally, we've found that no dive op has turned us down when we show up with scooters; however, the Aggressor live-aboards have been universally superb at adapting to our scooters.

All the best, James