advice on self righting boats

[denis smith 4Participant @denissmith4]

Hi all, im new to the boating circle, I fly rc aircraft, drones and cars so thought I'd try boating so need some advice please, I would like an electric speedboat or cat, it doesn't have to be mentally fast just something I can play about with, with my 6 year old grandchild, but as im 60 I don't fancy paddling out or swimming if I flipped it, so have been looking at self righting models, but doesn't seem to be many about, I have been looking at the joysway mono and the recoile but really wanted something bigger say 24" but only found the joysway infinity and as you have to add xtras would take it over my budget of around £120 or just over so really looking for rtr if possible , I did find a atomik barb wire which was perfect but only vailable in the usa, I think its equivalent over here is the joysway rocket but the self righting version takes it over my budget plus you have to ad xtras, so any suggestions would be great thanks

[denis smith 4Participant @denissmith4]

[Malcolm FraryParticipant @malcolmfrary95515]

Some boats self right because they have a large air bubble trapped in the superstructure and ar unstable if inverted. Some of the sporty boats rely in thrust inertia – if upside down, a sudden burst of violent throttle will cause the boat to turn around the motor and often wind up the right end up.

A rescue boat is often the best option, something like a "Springer" (google for further info on them)

As somebody recently said "Good, cheap, now. Pick any 2"

[ashley needhamParticipant @ashleyneedham69188]

Firstly Denis, welcome to the forum, the font of all things contentious.

As Malcolm suggests, getting two boats is probably the easiest option, something cheap, and then something not quite so cheap.
I would bear in mind that small children and fast boats do not mix, and if interest wains, and YOU don't have sufficient interest to continue with the fun, then probably two cheap boats may be a good thing to think on.​

Even the cheap ones go well nowadays (no suggestions), usually the battery is not up to much though, and often getting a half decent battery will extend the running time considerably.
Ashley

[denis smith 4Participant @denissmith4]

Thanks guys
I’ve bought a Rio. The large one and the joysway mono x which is self righting so I can use it if i flip the Rio. But to be fair the Rio is pretty stable

[denis smith 4Participant @denissmith4]

Forgot to ask guys. But where do I find marine grease and which brand is best thanks

[ashley needhamParticipant @ashleyneedham69188]

Marine grease for…??

If it says grease the propshaft then so be it. BUT we do not agree on greasing/oiling/using fairy cake icing on propshafts on this forum., Emotive subject.

Ashley

[denis smith 4Participant @denissmith4]

Well blow me down ?????? Most of my local model shops advised grease shaft after a day's use and so do my insructions, to me it makes perfect sense to lubricate something that spins so fast, but then again im new to this so could you explain why not and whybyou guys are so set against it please

[shipwrightParticipant @shipwright]

Hello Denis,

Main reason is that energy is lost via viscous friction. Actually I think grease is ok if rpm are lowish – say no more than 1000 rpm. However, most models are operating at several thousand rpm and at that level of rpm the loss will be largish (you might find that you are losing 50% of the energy delivered by the motor to the shaft with the other half delivered as energy to the propeller).

Ian

[denis smith 4Participant @denissmith4]

But aren't you causing friction, and what about wear n tear, do you not use any lube at all, what about the bearings, I must be honest I'm quite surprised, but you guys no better

[Malcolm FraryParticipant @malcolmfrary95515]

Nobody said "don't lube". What was said was that there is precious little agreement about what form the lube should take, mostly for the reasons that Shipwright mentioned in his post.

Heavy grease does introduce drag, the lower the temperature, the worse it gets, but on a slow model, not that important. Light oil is great for fast revving shafts, but needs very regular replenishment. Huge amounts of discussion between. A quick google for "model boat prop shaft lube" will give lots of information.

[Colin BishopModerator @colinbishop34627]

Don't be misled Denis, most people do use some form of lubrication but there is no real consensus as to what is best! Ashley, is of the 'less is more' view!

He does have a point in that the lower bearing is immersed in water which provides its own lubrication but I do think you then need something at the inboard end of the shaft as well.

Some people like to stuff the prop tube with grease, not just for lubrication, but also to prevent water finding its way into the boat, particularly if the inboard end of the tube is below the waterline. In practice thrust washers between the propeller and the outer end of the tube and between the locknut and the inner end will largely prevent this. It is normal for a few drops of water to accumulate inside the model by the end of a run and nothing to be concerned about.

The problem with using conventional 'sticky' grease is that the outer layer sticks to the inside of the tube and the inner layer sticks to the shaft. So when the shaft turns you get a torque converter effect between the two which creates a lot of friction. The longer the tube, the worse the amount of friction and this can actually absorb a great deal of power – I know, I have measured it!

My personal preference is to use car engine oil to lubricate the shaft. It is 'sticky' enough not to be washed away but not sufficiently so to introduce a significant frictional effect.

However, just about everyone on here has their own pet preference so there is no absolute 'correct' answer!

Colin

[ashley needhamParticipant @ashleyneedham69188]

I have ventured into the flexishaft style of propshaft for one boat and this does need cleaning, drying and re oiling after every run, as it is not rustproof, and also the entire length of flex rubs on the Teflon.nylon liner so it needs more attention than normal. BUT.

As Colin says, I am a minimalist lubricator. A drop on the inner bearing before a run possibly, and even a small drop on the outer bearing now and then but only if it is bronze. Nylon bearings I do not lube at all, water does it, and is the best lubricant with a stainless steel shaft.

ON a previous argument discussion a fast racy boat chap swore by grease and said everyone he knew used it. I was going to add my thoughts on grease lubrication, but it would be best to have a look, as suggested, at previous propshaft threads.
Ashley​

Edited By ashley needham on 20/12/2015 10:29:13

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