Nasa speed log reding slow

[rafiki_]

I have a Nasa Target speed log and since Rafiki was re-launched this year, the log is reading very slow, 1.9K when GPS reads 5K.

Any thoughts?

 

[lustyd]

Did you calibrate it, or just fit and hope? The instructions will take you through calibration

 

[Gwylan]

Apples & pears?

I have a Nasa Target speed log and since Rafiki was re-launched this year, the log is reading very slow, 1.9K when GPS reads 5K.

Any thoughts?

Depends? Are you measuring - comparing speed over ground with speed through the water?

 

[thalassa]

I have a Nasa Target speed log and since Rafiki was re-launched this year, the log is reading very slow, 1.9K when GPS reads 5K.

Any thoughts?

The Nasa log impeller has two small ceramic magnetic cylinders inserted in two of the vanes. One can fall out, as it has done in my 'old' boat. It then reads less than half of the true speed.
I bought two new ones in an electronics shop and epoxied them in.

 

[[70521]]

I have a Nasa Target speed log and since Rafiki was re-launched this year, the log is reading very slow, 1.9K when GPS reads 5K.

Any thoughts?

Have you tested it out over a measured distance?

 

[machurley22]

I have a Nasa Target speed log and since Rafiki was re-launched this year, the log is reading very slow, 1.9K when GPS reads 5K.

Any thoughts?

You've probably lost a magnet if it was OK last year - or possibly been a bit careless with the anti-foul though I'd have thought this would be more likely to make it stop turning altogether.

 

[rafiki_]

The Nasa log impeller has two small ceramic magnetic cylinders inserted in two of the vanes. One can fall out, as it has done in my 'old' boat. It then reads less than half of the true speed.
I bought two new ones in an electronics shop and epoxied them in.

Many thanks for this. Will have a look. Not sure if I can pull the paddle out while the boat is in the water? Any views?

 

[Hardley]

Nasa Speed log

Yes it can be done on the water, I do it every year before lift out, don't want the Yard damaging the Paddle Wheel.
You should have been supplied with a plug, which you would normaly fit during the winter.
I find less water gets in if you can put a list on the boat, weight on opposite side to paddle wheel.
Have plug in one hand and remove Paddle wheel with other hand, insert plug quickly, or have rolled up cloth ready to stuff in hole whilst you think about getting the plug in place.
It helps to keep water in a small area if you build a cofferdam around the Paddle wheel area.

 

[rafiki_]

Great, I'll give it a go. Many thanks as ever for the helpful people on this forum.

 

[rafiki_]

OK, have purchased a blanking plug and new paddle wheel from NASA, so I hope this will do the trick.