Scooter weight and stability

[Niels Doorduijn]

List,

A question to those who use scooters with multiple stages: how much does the weight of some leigher models scooters - like an X-scooter Cuda or SS N19 - affect the stability when scootering? I recon that such scooters would be less stable than heavier scooters, but is it noticable?

Rgs,
Niels

[w ripley]

The answer to your question probably varies from scooter to scooter. What we (my buddy and I) do is to float the scooter in a large tub, and add weight to it until it is neutral in the water (fresh water). We do have the tow line to our crotch "D" ring + clip & the emergency tow line + clip on the unit when we do the float test.

Then, it's a matter of opening up the case and installing the weight you have found that you need, off setting that weight to one side to counteract the torque of the scooter. You just have to play with it over several dives to get it placed where you like it, especially to adjust how the nose points (up or down) when running.

My buddy also floats his with a extra clip or two that he can take off in a cave - where there is no rock to dock the scooter on and where the floor is very silty - so that his scooter is slightly positive, floating above the cave line. Being able to alter the total weight while under water has it's advantages.

And, we typically throw in another 1/2# to 1# in the nose when putting the unit in salt water.

[Niels Doorduijn]

deleted after reading the posting below

[w ripley]

Sorry, hit the "submit" button when meant to hit the "preview" one.

To conclude, being neutral is being neutral. It may take more weight to achieve this with a larger unit, but the balancing act is pretty much the same. Once the unit is properly balanced and tested and fine tuned, they pretty much handle the same.

"Stability" is relevant to the diver using them, IMO.

While the lighter ones are easier to carry on land, of course, the ones with less mass and length are somewhat easier and quicker to maneuver when running. Some could call that being less stable, and maybe on very long & straight runs that could be considered by some as an annoyance.

The impact of torque varies with the unit and that's where the larger ones with more mass may have a slight edge on initial startup stability.

Personally, I don't know anyone who would not trade a long and heavy unit for a short and lighter one that gives the same thrust and run time. You still have to manhandle them, regardless of mass, when going in the ear, for example, regardless how "stable" you think your unit is.

[chilldive]

List,

A question to those who use scooters with multiple stages: how much does the weight of some leigher models scooters - like an X-scooter Cuda or SS N19 - affect the stability when scootering? I recon that such scooters would be less stable than heavier scooters, but is it noticable?

Rgs,
Niels

From my experience, and what I've been told by those who do longer exploration than I, is that the longer (thus heavier) scooters are more stable when you're towing a load. The small scooter is more like a sports car and the larger one is more like a sedan. With the larger scooter and multiple stages and/or spare scooter or battery packs, you don't have to steer so much or "fight" it. You just point it ahead and it almost drives itself. I'm used to larger passage ways. You probably need to adjust based on cave conditions.

Also, with more gear, there's more drag on the scooter, so burn time can become more of a factor.

[rjack]

Even a short Gavin is noticably straighter running than a X-Sierra. Of course you'll want to turn a Gavin eventually and it won't turn as tight because of that "stability".

Its all tradeoffs.

[Meister481]

The 19 has some torque spin to counter, but it's very steerable. To counter it I just put my other hand on the shroud to keep my right hand from getting sore on long dives. In fact, my 19's sitting on the kitchen table charging for use on Tuesday morning at Little River. 2 al 80's and a set of 125's makes for a full day of fun at Little River.

Might as well enjoy the caves before I do the IDC on Thursday, no fun there.