Underwater Scooter Motor Choice

Boats, Jet Skis, Kayaks etc., including hovercrafts
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markz   100 GW

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Underwater Scooter Motor Choice

Post by markz » Dec 12 2016 7:36pm

Whats the best motor selection for an underwater scooter that scuba divers use. I just want to be able to use it within 20 to 25' from the surface. I found this number for underwater pressure 0.433 psi/ft. Also most scooters go 2.5-3.5mph, the cheapest one I found is $200usd called Sea-Doo Aqua Ranger Scooter. I want something fun that goes fast, I have access to sealed boxes and sealed connectors so the controller and batteries can be sealed easily. I have been looking at mechanical seals and I think something like this would be good

http://www.ebay.ca/itm/13mm-0-5-Interna ... Swo4pYDqh-
http://www.ebay.ca/itm/WATER-PUMP-SEAL- ... Cg&vxp=mtr

because it comes with the lip,


or this
http://www.ebay.ca/itm/John-Crane-Mecha ... SwPcVV2npM

and all I'd need to do is add a backer plate to the shaft so the seal doesnt move backwards on the shaft where it enters the water.

There is also something called the Stuffing Box, but I think the mechanical seal would be better.

Am I going in the right direction here?

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amberwolf   100 GW

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Re: Underwater Scooter Motor Choice

Post by amberwolf » Dec 12 2016 9:55pm

I dunno about specific components, but keep in mind that water is really hard to push thru, and takes more power than pushing thru air.


If you want it to be fast it'll take a lot more power than to go slow; much more than for the same thing to go fast in the air.


BTW, you might want to ask a mod to move this over here
https://endless-sphere.com/forums/viewforum.php?f=39
where the other watercraft stuff is. ;)

I don't know that any of the stuff there applies, but htere's a couple of "diver" and "rov" threads that might have some useful info. (I havent' read them, just glanced thru titles).

markz   100 GW

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Re: Underwater Scooter Motor Choice

Post by markz » Dec 12 2016 10:14pm

Thanks for noticing my mistake, I thought I'd put it in Electric Watercraft.

I need a huge motor I know that, basically a box that has handles on it, with a motor inside the box with a shaft and seal it with from water ingress, about 10psi.

This guy made his own from a trolling motor https://www.youtube.com/watch?v=S37R4xCgzk4 since I dont have a trolling motor, just a bunch of dd motors mine will be bulkier since I will need gearing of some sort.

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amberwolf   100 GW

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Re: Underwater Scooter Motor Choice

Post by amberwolf » Dec 12 2016 10:28pm

You'll also need a battery that can handle the load, and is big enough to give you the time you want to use it for.

There's a boat project somewhere around here that uses a DD motor with a chaindrive to the prop; maybe that would give you some ideas. Sorry I cant' rmemeber whose it was. :(

markz   100 GW

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Re: Underwater Scooter Motor Choice

Post by markz » Dec 12 2016 11:38pm

How long would a tank of oxygen last when no work is being done, just aiming the scooter to where you want to go.


Seadoo Underwater Scooters
RS1 - 500W 7kph 1.5hrs 22V 12Ah 21lbs $1500
RS2 6kph $1100
RS3 5kph $950
VS 5kph $650
GT1 4kph $450
Pro 3.2kph $350 65'
Dolphin 3.2kph $220 15'max depth

*Would having two Pro's at 3.2kph generate a linear speed increase to 6.4kph?







I found this
https://endless-sphere.com/forums/viewt ... er#p793181

These are just some references
https://endless-sphere.com/forums/viewt ... r#p1121476

https://endless-sphere.com/forums/viewt ... r#p1152417

kevbo   100 mW

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Re: Underwater Scooter Motor Choice

Post by kevbo » Feb 02 2017 6:12pm

In the 1970s either popular mechanics or popular science had one of these as a do-it-yourself project. It used two electric trolling motors attached to a plywood box that held the lead acid batteries.

Most of those magazines are archived...I'm curious now, let me see if I can find it for you.

Edit: My google-foo is strong today. It helped that I recalled that they called it a SCUBA-tow.

https://books.google.com/books?id=cNQDA ... ow&f=false

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