Hello,

I would like your opinion on this subject,are these tachometers a "must have" item? SenDEC makes one I think but I am not sure if they are so important,what do you think?

They are a VERY important tool to have during testing. Let's you see how the engine is revving when trying different props, pipes, settings, etc. In my opinion it is as important if not more important than a speed measuring device (GPS).

I agree. The Sendac is only good to a little over 18,000 rpm, though. That's fine for most Zenoahs, but 20,000 rpm is possible with the latest engines if the pipe is short enough. This may be too much for the rod bearing, though. There are some tachs that read to 20,000 rpm, but I like the Eagle Tree data logger when I'm exploring new territory. It takes time to use, but it gives continuous rpm and speed readings. This tells you what's happening in the turns, the most important part of the race.

Lohring Miller

lohring,I checked the Eagle Tree Dta Logger,but don't you think that it is expensive? I mean that you have to add many sensors and the GPS receiver,so the cost is too high.. :

Not to sound contradictory to the posts above .... I have a Sendec tach, but seldom use it any more.

Might just be once your boats get set up and you do minor tweaks, speed in most cases is not the reason for the changing of props/set-up. Usually for better handling or some other odd trait your trying to correct, speed become a non issue in that case.

** But would agree if you do a lot of building and boat set up tuning , it is a GREAT tool to keep your engine spinning in the preferred/optimal RPM range.

JMO,
Scott

I find the Eagle Tree logger to be best as a tool to help where I have no experience. It is complicated and requires lots more effort to use than instruments that measure peak speed or rpm. We first used it for straight line speed efforts and it helped with propeller selection and hull design. However, so did a radar gun and standard Garmin GPS.

Lohring Miller