nasa marine clipper duet problem

[normskib]

Just a little tip for anyone having problems with the speed calculator on the nasa marine duet I've had two boats fitted with the devices and after a while the same problem the depth gage works but the speed gage stops or only works when it feels like it ! But now I've found that if you put the boat in reverse give it a good old thrust, preferably against the current it works like a dream give it a try !!!

 

[LittleSister]

The depth gauge and speed gauge use entirely different and separate transducers. It's only the display head that is combined on the Duet.

Weed accumulating on the hull, and/or weed or creatures living on the paddlewheel of the speed transducer will slow or stop it. Reversing is a good trick to free up a very slightly stuck paddlewheel, as can be slacking off the speed transducer lock nut and turning it a little one way and the other before locking it off again making sure that it is correctly aligned for and aft. However, if the boat lives in the water sooner or later that won't be enough, and you will have to withdraw the speed transducer from its tube (don't forget to have the screw cap immediately to hand to stop the inflow of water!) and wipe/scrape off the growth and crud on the paddlewheel, being careful not to damage the bearing on which it rotates.

It's also a good idea to withdraw the speed transducer and put the blanking cap on before the boat's antifouling is scrubbed or pressure washed off, to void any damage to the paddlewheel.

The depth transducer has no moving parts and rarely gives trouble If there is a problem, it's most often that the oil in/on which it sits in the tube (to give good sound transmission betwwen the trasducer and the hull) has drained out an needs replacing or topping up.