When reviewing these resources, please consider carefully the date it was posted as well as any warnings.
Lloyd Bailey's sells an o-ring kit for Mako scooters... http://www.lloydbaileysscuba.com
Milwaukee Resistor Corp.
voice: 1-414-362-8900 ... ask for John
part numbers: 2 each of # 061813603.000E @ $14.33 each (these are 300 watt, 3 ohm resistors) 1 each of #301813602STD @ $ 8.54 each (this is the metal stand to hold the resistors)
wire two in parrallel
[All diagrams, photos, and information Copyright 2000-2003 Robert Laird.
Not for use, duplication or distribution without express permission of the author.]
How often should one burn test? How often is your ass depending on that scooter? The batteries cost $60 each, so if you life is worth more than that, test them all of the time and you will only get 100 dives before you throw then away. If they ever get hot (>110) throw them away . If they get hot during charge or discharge, throw them away. When burn testing, how often should one take data points? Look a the discharge curve, and check it when it should be slipping, mostly to see if the batteries are in phase. you are burning at 70(16/33)C, so look a the curve. They should burn for 95 minutes before they hit 20 volts.
You're cruising along on your brand new scooter and suddenly it just stops,
2500 feet back in Deep Verne Hormendes. There is no flow, neither you nor
buddy has a backup scooter. What do you do next?
Step 1. Pin the trigger. This is done by inserting a hairpin (the kind
that goes in a clevis pin, not the kind that goes in your hair, though I
guess that could work in a pinch...but I digress) into the hole you have
previously drilled in the trigger. This prevents the trigger from being
accidentally depressed. This should be done anytime the scooter is not
being used, i.e. anytime it is put down. You can not imagine the mess that
is made when a scooter that is clipped to a line gets bumped and comes on.
Step 2. Set the blade pitch to zero. All towed scooters must have the
blade pitch set to zero so that if they come on for whatever reason, the
thrust will be minimal. Just imagine the consequences...ouch.
Step 3. Run the leash along the BOTTOM of the scooter and thru the tow
loop on the bottom of your Gavin or thru the handle of the Mako which has
been rotated so it is on the bottom of the nose cone. Note: You can not
just turn the nose cone around. You have to take out the 4 (or is it 6?)
screws that holds the handle down, turn the handle around and the put the
screws back in. Gavins and Makos do not tow for shit from the top. Try it
if you don't believe me.
Step 4. Clip the scooter to a butt d ring on your crotch strap. It is
called a butt ring because of where it is roughly located. Ideally, when
you clip the scooter off, it will pull up snug against the bottom of your
tanks and rest on your thighs. If not, shorten the leash by wrapping it
around the handle.
Step 5. Grab your partners crotch strap, put your head in the crack
between the bottom of his tanks staring down at the floor and hang on.
You need to practice this...it is not as trivial as it sounds, and, like
all cave diving skills, requires repetitious practice for it to become
If a scooter sticks on, most of the time it is
1.) debris around the trigger or on gavins, the magnet. Check to make sure
the trigger has come out, and if not pull it out. You may need a knife.
If it is a Gavin magnet, gently pull back the magnet. This is minor.
2.) Failed reed switch, magnet or relay. This is major. If you tried no.1
to no avail, your only option is grab the blades. This sounds horrible,
but is no big deal. Start with your hand flat across the blades, fingers
close together and apply pressure, like when you tried to stop a fan as a
kid. When the blades feel resitance, the clutch will disengage, the motor
keeps turning but the blades stop. Once disengaged, the clutch usually
will stay disengaged until the motor stops and the clutch reseats itself.
However, turn the blade pitch back to zero just in case. Hold the blades
while you do this or you may reengage the clutch.
Note: Once the clutch is disengaged a couple times, for whatever reason,
it will be stripped and must be replaced. The Arnie clutch from Arnaold
jackson at American underwater Lighting with a delrin seating service and
aluminum clutch plate is the way to go (about $75) and it never wears out.
Again, this should be practiced, but not too often unless you have the
If your scooter suddenly stops, most often the wire that goes from the trigger to the magnet has failed either breaking or jumping off the track of the pully in the handle. On makos, there are two triggers. Some will disconnect the left as it is never used. I did not when I had a Mako, but MAKE SURE THE LEFT HANDLE IS PINNED!
To prevent the wire from pulling off the pully, open up the handle. Their is an eye on the pully thru which the wire runs. Find an old tank neck o-ring and cut it. Thread the o-ring thru the eye so it sticks out about 1/8". Cut off the other side leaving about 1/8" slack. Your wire will never come off track again.
If your scooter won't run, try the little black switch on the rib near the handle on Makos or the magnet on Gavins. You may be able to manually engage the read switch. Though uncomfortable, this is preferable to being towed. If this does not work, have your buddy tow you out.
Don't forget ( with this heat lately ) that the batteries in our scooters can not tolerate temperatures above 110 degrees. If you leave them in a hot vehicle, shed, or other place where the temp rises above 110, just throw them away and save yourself the hasle of trying to figure out what is wrong with the scooter.
Also don't forget that these relays need 20 volts to pull them in, but will maintain on less. That means if you have a battery that you got hot, it will dog the voltage down but the scooter keeps running if one battery is still strong. However, when you let off of the trigger, it takes a few seconds for the voltage to rise back above 20 to allow the relay to work, so it will make you think there is something wrong with the reed or relay. Remember we can test those separately without running the motor.
What this looks like on a burn test is one batery goes to 8 volts, but the other stays at 12, and the current runs in the 14 amp range, but does not "crash". You may even see the voltage appear to climb back up from time to time, as if the meter were bad. When the scooter is actually running, the combined V=IR is made up for by the fact that the potential of the one battery is near its peak, and can deliver against the perceived reduced resistance which is a due to the loss of the voltage that the motor sees to determine its RPM, and thus its wattage output.
This then results in "reed switch syndrome", where the operator makes several unnecesary trips to Radio Shack for new relays, or makes the mistake of phoning me up and telling me that the reed switches are no good.