Chris Craft Rivierra

Often forgot about but boats are a great way for the youngsters to get into radio control or even the oldies!
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Joined: 19 Jun 2019, 04:09

Chris Craft Rivierra

Post by bluejets » 01 Jul 2019, 01:54

Started this build some 15 years ago and getting close to finish now.
Model is approx. 1/5 scale built from GL3 aircraft grade plywood with the interior having inbuilt flotation chambers and timber internally sealed with glass and epoxy.

Engine built up from a casting given to me by a mate of mine George Punter. I think it was to see how I'd go with a bit of a challenge seeing I managed the first engine build in the Neptune ok.
There were no drawings, just had to make my own as I went. Most started as a scribble with pencil and paper and later transferred to Desktop Pro cad. Sadly all files were lost in the 2013 flood here.

Engine is 25cc four stroke running on methanol/castor mix with glow ignition. Single updraught carbie, had 4 initially but just too hard to tune. Also had a magnetic drive water pump with the intention of on-board heat exchanger but the need to know the cooling was actually operating while in the boat was not really practical so opted out for the usual ' pumped up by the prop" arrangement.

Tacho is operational, being a 0-5V signal derived from the flywheel pulse. Originally this was a frequency to voltage converter driving a series of LED's arranged in a circle on the dash but I later changed to the present servo driven gauge. Still uses the original converter but now, with a very simple picaxe code and some mapping and gearing, voila. Steering wheel also turns as the rudder turns.

Presently looking at perhaps using a telemetry receiver to send back the fuel level. Already has the probes fitted to the tank so may be fairly easy to get this addition. Trailer is made from scrap stainless tubing I found at the local scrap metal merchant for $5.00 ( bargain) and wheels and tyres come from rc stuff on Ebay.

Told my mate we are almost at the testing stage for the boat, he said "what about getting it back from the middle of the lake?" So presently knocking up a basic pusher boat ( Springer Tug)

Video ( not very good quality) of the engine running here.......
IMG_9497.jpg (28.46 KiB) Viewed 986 times

Spike S
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Joined: 16 Feb 2018, 14:59
Location: Salisbury UK

Re: Chris Craft Rivierra

Post by Spike S » 01 Jul 2019, 07:04

Lovely piece of metal sculpture there. Sounds gorgeous as well.
Good to find another pickaxe user here !
Last edited by Spike S on 01 Jul 2019, 09:18, edited 1 time in total.
Spike S
(Tune for maximum smoke)

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Re: Chris Craft Rivierra

Post by PaulJ » 01 Jul 2019, 08:30

'Fantastic job, well done! The motor is an incredible achievement and I just love the tacho ;). The boat too is a great project...... Please post a video of it performing on the water in the fullness of time.


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Joined: 16 Feb 2018, 14:11
Location: Warwickshire

Re: Chris Craft Rivierra

Post by Martin » 01 Jul 2019, 12:13

Very nice.

What's the lubrication for the bottom end? Is it a wet sump or does it just rely on what oil manages to leak past the piston rings? If it's the latter do you have any special after-run procedure to flush the residues away?

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Joined: 19 Jun 2019, 04:09

Re: Chris Craft Rivierra

Post by bluejets » 01 Jul 2019, 23:58

Thanks for the replies.

Martin, Yes, it is as you say, oil past the rings with a breather on the front cam gear cover to allow oil fumes to lubricate that area when running. It appears this is satisfactory from an initial tear-down after the first couple of runs. It does not need all that much as the "vapour" seems enough.

Cleaning out of the interior normally not really a requirement as far as "gunk" goes as the bottom sump is well down from the mechanics however I do back-feed a cleaner ( usually kero followed by some light machine oil) through the breather and drain out through a sump plug in the lower rear section of the sump.

The exception to not requiring cleaning I quickly found after a short run with nitro content fuel. Removal of the sump revealed the acid formed by the burning fuel is not kind at all to 4140 crankshaft steel. :) O.k now with plain 4:1 methanol/castor(castrol_M) though as it was just an experiment at the time with differing fuels.

New V8 in the pattern stage will have spark ign with pump fuel and oil pump through the crank arrangement. Boat for that not decided yet.

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