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[red181]

Hi all,

I have been trying to achieve this for ages, here is my Orca jaws boat, I want a shark to surface and sink behind the boat, I ahve been so close a few times!!

 I am using a tesco rc shark, its a little smaller than scale, I have weighted it like a yatch to keep it upright, and have tried various fins etc to keep it level.

The hull has a bracket underneath the water, I use some rod from this, then the shark is tied on with string, the theory being when  the boat stops it wont keep coming into the rear of the hull and get tangled with the prop. The wire is in a sleeve, so it will move up and down, I wanted the shark to surface when the boat is running, so you see the dorsal fin come up, and when the boat slows and stops, the weight will cause the shark to sink, out of view!

It would be great if it was a rc model, but that is asking too much, (unless the sub guys have a cheap alternative??)

ideas please!    

[essex2visuvesi]

What about the mini beast?
http://www.cornwallmodelboats.co.uk/acatalog/rtr.html

[pompebled]

Hi Red,

This will need some tinkering...
The shark has to be just heavy enough to sink and will hang down in the water from the line that pulls it, like a sinker on a fishline.
The trick is, when the boat starts to move, that the shark follows with the right side up and doesn't start to rotate behind the boat, which would spoil the effect somewhat.
To this effect, the ballast in the shark must be as low in (or under) the shaft as possible and the tailfin should act as a rudder.

You'll have to adjust the breast fins so the shark gets pushed up to the surface to cause the dorsal fin to break the surface.

The breast fins will be the tricky part, as I know from experience; I had a 80 cm wooden sub ballasted down to the deck, with all the weight bolted underneath the hull.
I pulled the sub behind our 1:1 boat on a double line, attached to a horizontal shaft, which moved the foreward diveplanes up, or down a few degrees.
The idea was to be able to make the sub dive and surface while it was being towed.

Only when the sub was towed  at a very low speed, this would work, if the speed went up, the turbulence behind the big boat and the slight differences in the dive plane angle and surface area would cause the sub to start rotating, making a mess of the two lines, rendering the diveplane controll inert.

As your shark is considerably smaller, the rotating issues may occur even at the low speed the ORCA reaches.

Let us know if you get it to work.

Regards, Jan.

[Rottweiler]

there used to be quite a few of r/c sharks on e bay for about a tenner! I have one,which works perfectly well.The tail moved on it as well.
Dont see any on e bay at the moment tho!

[Rottweiler]

 look on this link        http://www.ebay.co.uk/itm/Radio-Controlled-Sharks-/320919421119?pt=UK_ToysGames_RadioControlled_JN&hash=item4ab849c0bf
good luck

[red181]

thanks for the links chaps, the first one is interesting, but think it is too small, second one is what I already have (I think!)

Hi Jan, long time no speak, you have exactly nailed what goes on with what I have, I even tried a rc helicopter flybar with the paddles, did it in a way they where adjustable to alter the rise and fall, it was ok, but you could see the paddles and it all looked a bit rubbish!, I need to fabricate some sort of stabilising thingy from clear plastic so it cant be seen, someone on here WILL have the answer!, the problem is feel a bit silly, grown man, on his own at the lake, playing with a toy fishing boat and towing a toy shark..... I need to find another hobby!

[tobyker]

Can you not tow the shark on a strip of clear perspex - or polycarbonate cut from an old crash hat visor/ With suitable brackets this could stop the shark rotating, then it would be a matter of weight/fin adjustment to get it up and down appropriately.

[john s 2]

Another way is to fit the shark with an inflatible bladder with a slow leak.Pump air from boat via plastic tow tube to raise as required. All this is sub technology. John.

[red181]

wow john, what technology, great idea!

Problems are, I think taking the shark apart will cause it to fall apart, its only a cheap thing, but I will certainly consider this, I dont really want too much coming from the boat, anything like the tube, plastic etc will be difficult to remove when the boat runs without the shark, here is what I have so far



the rod is just a metal coathanger, held on with a pair of collets, just remove one via grubscre, and it all comes off. After the rod the shark is attached with string, this makes the shark move about, so its not rigid, looks more realistic. Like Jan says previously, as the boat picks up speed, the shark needs to plane, and rise. You can see I even tried helicopter paddles, worked ok, but not great , boat stops, rod can pivot in the tube, and the weighted shark sinks. On the odd occassion it works, it does look quite good

[red181]

another pic with shark


I suppose if anybody has an idea reegarding a rc shark that works, as a previous post, it would be the ideal answer, but could I control two things! I struggle with just one, if it worked though, it would be good, maybe I need to keep an eye on ebay for a cheap small rc sub and give it a shark skin!

[Sven]

Hello,

I remember when I was going out for fishing there were small fish from plastic which were diving by drilling the line in. Maybe it can work in the other way too?
I beg your pardon, but my english is not that good to explain in better way. Maybe here are some other guy going out for fishing which can explain in better wy.

Sven