Log Impellors

campbell

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29 Dec 2001
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Have fit a NASA Log with a through hull impellor , everything worked OK on the hard , but since launching the log impellor is not working I am assuming the it is jamed.

I beleive that you can take the impellor out the hull fitting and blank the fitting with the cap that comes with the log .

Is this advisable to do afloat ?

How long do i have to take out the impellor and put the cap on ?



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There is no problem at all about removing the impellor and putting the blanking cap on except that you get about half a bucket of water in the bilges - and up your sleeve each time you do it!

Just take care not to drop and lose the blanking cap while yu are fiddling with it.....

If its just a matter of spinning the impellor to get it to start, you can do it single handed, and simply put your hand ( or foot?) over the hole.

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I have a NASA log which jammed on Friday night when we set of for Cowes. I managed to lift it out and just managed to spin it with my finger. I wouldn't recommend doing it while underway, as you do get a lot of water coming in. This makes it a little difficult to get it back in again as you can't see the fitting properly.

In reality there wasn't that much water, but at the time you do have visions of flooding.

Poggy

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Before you try removing it ,check it is fully down in the tube by slacking the plastic nut a bit and see if it is fully down.It may have been pushed up into the hull by contact with something during launching(lifting slings for instance)

Also check the little arrow on the top rim of the impellor bit is facing forwards.

When mine failed it needed the conection between the cable from the paddle wheel and the fitting in the back of the display unit cleaned.

Take care not to damage the plastic threads if you do remove it.I held a piece of sponge over mine rather than try to thread on the lid in a bit of a panic....

Hope this helps ,my NASA instruments have worked well.
 
We have a NASA log and moor on the Hamble. It often jams because the Hamble seems to have a species of small shrimp which likes living in log impellor recesses! The degree of jamming depends on the elapsed time from last use of the boat, if just a short time (1 to 10 days) we find a quick burst of going astern will often clear it. If not ther impellor has to be withdrawn; we do this at anchor or at moorings with at least two people on board. Remove log and have sponge/rag available to stop inflow of water, then screw blanking cap on, as previously said do not lose blanking cap in bilges! Give log impellor a good wash and scrub a bit with soft pan brush and replace. In fact little water gets in if you are quick about stopping inflow. Good luck Barry

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Try going forward at full speed and when you're up to speed, slaken the retaining collar and turn the assembly 180 degrees so that the arrow is pointing the wrong way. Return it so that it is pointing the right way and repeat a few times in rapid succession. You might just free it by doing this and you won't get a couple of pints of water up your sleeve!

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My log refused to work all last season, despite regular withdrawal and cleaning of the paddlewheel. When removed from the hull and spun by hand it registered speed on the display but zilch when replaced. Last week in the boatyard I noticed by chance a very slight build up of antifouling around the outside of the hole. Cleaned this off. Log works. Good luck.

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