Having read somewhere on this site ( I can’t find it now!) that turning a 34” crash tender at speed can be a problem I have been thinking about ways to Reduce the risk.

The obvious way is to pilot it carefully, turning gently, or slowing before turning sharply. But that requires the pilot to be paying attention. I’m not sure my young grandson would take that care, even if I do.

So, is it a good idea to mix throttle and rudder to overcome this issue. It seems to me there are two options:

1. Reduce the rudder throw based on the throttle setting. i.e. mix such that as the speed increases, the maximum rudder throw reduces. Or
2. Reduce the throttle based on the rudder demand. i.e. mix channels so that the boat automatically slows based on the rudder demand.

I haven’t found any reference to this on this website, which make me think it isn’t a good idea, but I would be interested in any thoughts from those with much more experience than I have. Also, can these mixes be set up on an fs- i6x transmitter?

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There is a commercial unit on the Technobots site that does the job ( at a price). It will drive a bigger motor if the stripped down servo solution can’t provide enough drive current.

https://www.technobotsonline.com/fingertech-tinyesc-v2-1.5-to-3a-antweight-motor-controller.html

🔗

I have it in mind to do a blog, but don’t simply want to repeat material in some of the excellent blogs on this site covering Crash Tender builds, including yours. I’d want to cover details not in existing blogs. I’m currently waiting on parts from China before I’ll have anything new to show.

Yes, in a couple of days time. Even though they say it isn’t necessary, I don’t like the idea of not sealing all the decals.

I managed to fit the Trimline tape together with the rest of the decals. The tape didn't want to stick properly where it folded over the spray rails, so I tried heating it carefully with a hot air paint stripper and then pressing it into place while warm. That seems to have done the trick and it still looks to be OK this morning. A hair dryer would have been safer (cooler) but I don't have one and I didn't dare 'borrow' one from my wife!🤣

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Thanks Robbob. Very timely. I’m planning to add Trimline to my Crash Tender later today. At least I now know where to go for a recommended alternative if it doesn’t go well.

Wish me luck

Doug, interesting to see those old circuits with lots of discrete components. I have a Heathkit analogue voltmeter built in the 1960s by my Dad when he used to repair valve TV sets for friends and neighbours.


I built a new servo tester yesterday. Photos show the new and old versions. 18 discrete components in the old one providing a multivibrator driving a 74121 monostable. Two components in the new one, a 10F220 PIC chip and a rotary encoder. Didn't really need another tester, but wanted to see how simple I could make it, in preparation for future developments.

Wow Martin!! This looks great. Can’t wait to see more details on the build and trials

I don’t remember McGregor offering kits in those days. They may have, but the cost would probably been out of my reach. There were companies who advertised in RCM&E who offered kits to build radio equipment, often based on articles in the mag.

My 27MHz set was scratch built. I worked for a company at the time that had an engineering workshop that I could take advantage of at lunchtime. So the case was folded from aluminium sheet and then covered with red vinyl. The sticks were turned from Perspex. The circuit board was etched in the lab. Sadly I got a better job elsewhere and lost access to the workshop 😠

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I’ve seen that problem using a PC. Already learnt you have to load pictures first, then add the text. Otherwise the text disappears.🤔

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Doug,
Here are a couple of photos of the inside of the Tx. It used a PP9 battery, cheaper in those days than rechargeables! It was based on a circuit in an Application note published by Ferranti. I don't have the original receiver as it was unreliable and I replaced it with one built from an article in RCM&E, which I do have somewhere. I do have the case that I used for the original receiver though, it was a plastic soap dish (!) which I subsequently reused to house a servo tester based on a SN74121 which still works and I have started to use again.

Here is my Crash Tender together with the homemade 27MHz transmitter. Built in the early 1970s. The collage photo is from 45 years ago, sailing on the boating lake in Llanfairfechan, North Wales. Recently rescued from the garage covered in dust. Diesel replaced with brushless motor and on the water again. Now in dry dock for a major refit!

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Yesterday was a special day. Having been inspired by this website, I got my 34” Crash Tender back on the water for the first time in 45 years! I built it in the early 1970s. In those days it had a Diesel engine, and a home built 27MHz radio. Even the servos we home built from kits. Then I got married, bought a house, raised a family and the boat was confined to a shelf in the garage. How things have changed in 45 years.😁 I have equipped it with a brushless motor, Li-Po battery and 2.4GHz radio. Great to see it on the lake yesterday. Now I don’t have to worry about making it move with an unreliable motor and radio I can have a go at adding some scale fittings and fixtures. Never got round to that the first time. The build blogs on this site are awesome and a real inspiration. Watch this space, working monitors and searchlight next.....