knot meter

R

rhewitt

Member II
Got "No Bad Day" on the hard and took out the knot meter to see why it is not working... the impeller is is bad shape and other wise nothing to see.
This is the OE data Marine that came with the boat in 1988. The growth here in San Juan del Sur, Nicaragua is BIG and we dive and clean it every month.

Any thing to look for or the check...? How do I get a new impeller?

www.sailingnicaragua.com See the fun we have with the Sea Scouts and guest too.

Thanks,
 
Tom Metzger

Tom Metzger

Sustaining Partner
Ralph - If you spin the paddle wheel the meter should give an indication. There is a method shown in the owner's manual on this site to determine if the meter is working if spinning the paddle wheel doesn't work.

Look under "Resources", then "Common Ericson Equipment", then "Datamarine 5000". It's on PDF pg 21, or page 38 of the manual.

Parts can be obtained from:

DMI Marine, Inc.
18 Commerce Park Road
Pocasset, Ma 02559
main phone number: 508-564-7491
fax number: 508-564-7497
email: dmi@dmimarine.com
http://www.dmimarine.com/
 
R

rhewitt

Member II
Went to the "Resources" page and then gear.... it was not readable as some other type just on hold...
Any other ideas?
 
mherrcat

mherrcat

Contributing Partner
Can you post some pictures of the speed transducer and measurements; diameter and length?
 
wheelerwbrian

wheelerwbrian

Member III
I had an old email from dmi that had diagnoses procedures --

Test speed instrument


1) Remove the coax cable from the BNC connector found on the rear of the speed instrument. Bend a paperclip into a U shape and place one end of the paperclip into the center hole of the BNC connector on the rear of the unit. With the other end of the paperclip tap on the outside of the same connector (essentially shorting the inside pin to the outside collar) rapidly while watching the display. If the speed increases as you tap then the instrument is capable of producing a speed, you should be able to see at least a 5 knot speed with rapid tapping. If not you will need to send the knot meter in for service. If this is ok, proceed to the next step.

2) Re-connect the cable to the rear of the knot meter and locate the SX-120 speed sensor in the hull. Follow the cable back 10 feet and disconnect the cable at the junction. Perform the same tap test at the end of the cable leading to the knot meter by shorting the center pin to the outside shell and have someone observe the reading on the knot meter. If you can produce a good reading on the knot meter then the inter connect cable ($30.00) is ok, and you will need to check the SX-120.

3) Remove the speed sensor from the thru hull fitting. Spin the paddlewheel by hand. If the display shows a speed you will need to replace the P-121 ($15.00) paddlewheel assembly. If it does not show a speed, you will need to replace the SX-120 ($120.00)
 
Stu Jackson

Stu Jackson

C34IA Secretary
There's not much to analyze. Just follow Tom's suggestion and get in touch with DMI. They sent me new impellers (I bought a handful with the shafts, too). They also repaired my 1986 depthsounder - I sent them the unit, they refurbished it and added a new alarm board. That was in 2006 for a twenty year old unit.

My knot meter died after years of faithful service when a friend of mine sailed our boat over a log in a heavy chop. Bang, boom, crash, and the knot meter stopped working. Broke a couple of vanes off the paddlewheels. Easy fix. If you don't have a dummy plug, get one, easy change in the water.

DMI is just fantastic. Hope they stay in business forever. I might just call them and order more spare parts, just in case!:cool:
 
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