Mr Krabs build

[Xzessperated]

Slim while I was writing the following I lost my internet connection so I saved it and now I am posting it here and I can see the others agree with what I said...

"Slim the first thing I want to know is how big is that bathtub you are running in? How long and how wide? Is this your first fast boat? If so that pond is no place for someone with little experience. I might be wrong but from what I can see I would not think about running my fast boats in there. It looks way too small to me. I think you will never see your boat at full throttle in there and be able to stop it before it hits the wall. I know cameras often lie so that is why I ask the size of the pond.
I think at best you could make some slow turns (a bit faster than you are in this video) but it still looks too short for a high speed run. Let us see it out on a bigger lake where you can do some high speed turns safely. You need to be able to get the boat up to high speed and have a slow down area or a wide area where you can do a fast turn.
What do you other guys think?
Andym is the only guy I know that would run fast in there.
To be fair to yourself and your boat you need a larger pond where you can get to know your boat and chage the setup and see if it makes it better or worse. I think if you continue to run in there you will one day destroy the boat and that is a lot of hard work and money gone.
All that said, it looked to be running quite well. I could not see much spray coming from the sponsons so it looks to be balanced ok.
I will be very interested to hear what others say about the size of the bathtub."

[slimshady]

Boring post

You are all very very right this is my local club pond where slow but very nice detailed sail boats and fast IC’s are raced and now the dawn of reasonably fast electrics are slowly entering the club down the pond – Sadly they are mostly brushed motors with NiMhs and 7 cells at that. My brother-in-law (the one taking the video) and I are slowly taking fast electrics to a new scale at the club – He owns a very and I mean very fast Gozilla Mono 2 (50 + MPH) – the reason I got a SAW was to p1$$ him off and reach higher speeds, I certainly did that because he now owns a ply wood rigger a bit smaller than the Express 2. His acceleration is much higher than Mr Krabs with a smaller prop and he can reach full pelt but his is unstable at the moment and needs a bit more setting up, if he lets me I will post some video of his on the same pond.

Going back to the pond yes it’s too small for what I want but the Norfolk broads might help me, this time of year they are very choppy in the wind and I need a boat (real one) to rescue him.

My thought was to set him up in the pond in the winter ready for a bigger calmer lake in the summer – unfortunately I think I have already outgrown the pond.

The reason I need help with my setup is the turn fin – I have tried countless designs (well 3) but cannot get it right.

The first caused the boat to pull insanely to the right (sharpened both edges and small) but broke off after 1 or 2 runs (carbon fibre pics earlier).

The second bigger aluminium one caused the boat to dig in and flip over onto his back (advantage of the pond and fishing line) again sharpened both sides but fixed this time.

The third, a bit smaller than the first and only sharpened on the outer edge caused him to veer to the right and once again smash the sponson struts on Saturday.

The forth, removed everything and completed the less than adequate runs at ½ throttle but he was straight.

Help I need to turn, I have tried the smallest to the biggest with bad results every time. The turn fin extension seems to work the best so far but as you can see from the video I need most of the pond width and a slight tinkering with the throttle to turn round. If I turn at high and I mean higher speeds than seen in the video he simply turns but carries on straight, by that I mean drifts sideways, and crashes into the wall.

His butt is sitting in the water a bit better now I have replaced the 4 AA batteries with a UBEC and therefore moved the weight forward, but you can still hear a bit of bounce – should I place lead at the stern or move more weight forwards, to plant him more?

The pond is about 150m x 25m but that is only a guess. As mentioned before a high speed run is less than 2 seconds before crashing into the end or the side. Look at the vid and see how long the power at ½ throttle is on compared to the deceleration and turn time required.

Sorry too many questions and a very boring post from me once again.

Slim

[Xzessperated]

The pond is about 150m x 25m but that is only a guess. As mentioned before a high speed run is less than 2 seconds before crashing into the end or the side. Look at the vid and see how long the power at ½ throttle is on compared to the deceleration and turn time required.

Sorry too many questions and a very boring post from me once again.

Slim

Slim,
remember the old saying about walking before you run? Well 25 meters is not a safe distance for someone that is just learning his boat to try to make a high speed turn. I am sure Andym will agree with me when I say that if you want a good turn fin, contact Andrewg through the following link and ask him does he have a Taipan turn fin suitable for a Mr. Krabs boat. Andrew sells and races Mr. Krabs. I use one of the Taipan turn fins and it is the best fin I have ever used. I have them for all my riggers now if I want to go in circles and not SAW.

http://www.fastelectrics.com/default.asp

Keep the questions coming and your posts are never boring.
Paddy

[slimshady]

Exact dimensions of the pond is 134M X 24.3M http://www.nmbc.fsnet.co.uk/page6.html

Yes you are right walk then run – my philosophy – but I think I have out grown the pond quicker than I had hoped. My supplier has let me down again and need the following items:

1) 45mm 2 blade 1.6mm pitch brass prop with M4 fitting
2) 45mm 3 blade 1.4 – 1.6mm brass prop preferably with an M4 fitting but 3 blades usually come with 3/16” dog drive
3) A convertor for the above so I can use the 3/16” prop with my M4 fitting shaft.
4) A big turn fin for Mr Krabs to enable me to turn at speed and not cause me to crash and flip into the side or the end walls on SAW runs
5) And more importantly a good LiPo – 4 – 5S with 4000 – 5000 mah and more than 25C continuous

The budget has some of the above in but not all. The ASD is high at the moment and the GPB rubbish so ordering from Australia / Adam is out of the question at the moment.

Slim

[Xzessperated]

Exact dimensions of the pond is 134M X 24.3M http://www.nmbc.fsnet.co.uk/page6.html

Yes you are right walk then run – my philosophy – but I think I have out grown the pond quicker than I had hoped. My supplier has let me down again and need the following items:

1) 45mm 2 blade 1.6mm pitch brass prop with M4 fitting
2) 45mm 3 blade 1.4 – 1.6mm brass prop preferably with an M4 fitting but 3 blades usually come with 3/16” dog drive
3) A convertor for the above so I can use the 3/16” prop with my M4 fitting shaft.
4) A big turn fin for Mr Krabs to enable me to turn at speed and not cause me to crash and flip into the side or the end walls on SAW runs
5) And more importantly a good LiPo – 4 – 5S with 4000 – 5000 mah and more than 25C continuous

The budget has some of the above in but not all. The ASD is high at the moment and the GPB rubbish so ordering from Australia / Adam is out of the question at the moment.

Slim

Slim,
I know how you feel about the money exchange rate. The US dollar is making it hard for us to buy from the US at the moment. 12 months ago it was almost $ for $ but now our $ is only worth 63 cents US. Soon we will all be running Chinese boats and motors over here if things do not improve. I have been experimenting with Chinese motors just incase and they are good value for your buck. To me nothing beats a Neu so I hope things do not get much worse.
If you want to buy from GB I guess you will have to search for GB model shops. If I were you I would look at the OSE shop in this forum....

http://www.offshoreelectrics.com

IMO Steven is the best vendor out there.
Yeah I know I am a but I have been called worse and by experts --------> (Andym)

[andym]

Slim just change the m4 out and replace with a 3/16 flax and shaft . There are alot more props avalible . As far as running on small ponds fast you need to get that boat hooked up in the turns. My hydros and riggers can all turn in 25-30 mtr radius full throttle, it helps if you back off for a split second as you throw it into a turn and then hit that throttle

[Simon.O.]

it helps if you back off for a split second as you throw it into a turn and then hit that throttle

Sounds like the same technique that I applied for years in my Mk2 Cortina GT

Slim
I think it is clear now that you need a bigger pond. Andy Green would not run the SSC on the main at Heathrow, and you should not run a Xcess-3 on that pond. End.

For all Xcess-3 owners.
As you will be aware I am building a rigger based on this fine hull. Before I make some more cuts in wood I need a couple of dimensions.
A. Transom to the rear most face of the motor.
B. Tub bottom to table measured in a line where the sponson touches the table.
C. Transom bottom to table. I see references to 17mm etc.

I will be back for more later, I am always watching

[NativePaul]

Slim, I visited your club site and read

We run 7 Cell & 12 Cell racing, we also have "Drag" racing for all types of electric models and then the most powerful of all - the Internal Combustion section or IC as its known!

with interest and a with certain amount of mirth at the last part, how often do they have the drag races? I would like to visit and have a go with a FE if they don't clash with the Electra oval racing I do.

[Xzessperated]

Sounds like the same technique that I applied for years in my Mk2 Cortina GT

Slim
I think it is clear now that you need a bigger pond. Andy Green would not run the SSC on the main at Heathrow, and you should not run a Xcess-3 on that pond. End.

For all Xcess-3 owners.
As you will be aware I am building a rigger based on this fine hull. Before I make some more cuts in wood I need a couple of dimensions.
A. Transom to the rear most face of the motor.
B. Tub bottom to table measured in a line where the sponson touches the table.
C. Transom bottom to table. I see references to 17mm etc.

I will be back for more later, I am always watching

Simon did you check your email? I sent some Mr. Krabs pictures and many more to come. I finished those dimensions you wanted. I will measure these new ones and let you know how mine is setup as far as motor placement goes etc. IMO my motor is a little too far forward.
Your parcel went yesterday and it is registered airmail and they said you will have it in 7 days.
You were a lucky man to have a Mk2 Cortina GT.

Paddy

[Xzessperated]

Slim, I visited your club site and read with interest and a with certain amount of mirth at the last part, how often do they have the drag races? I would like to visit and have a go with a FE if they don't clash with the Electra oval racing I do.

Paul be careful racing those Most Powerful Of All IC drag boats. You might embarrass them.

[slimshady]

Paul be careful racing those Most Powerful Of All IC drag boats. You might embarrass them.

LOL, I chuckled a bit when I read that, and its true the IC boys still think petrol is better than eclectics, as a car man petrol is better than most other fuels but in light weight boats, electrics win hands down. My brother-in-law and I tend to stay away from club meets, simply because we need the whole length of the pond and slow sail boats weaving about is an accident waiting to happen.

One of the main reasons I crashed Mr Krabs on Saturday was the sail club still had the boys out and I had to navigate diagonally down the pond to miss them, that coupled with a loose rudder servo, a crowd of spectators and a lot of adrenalin, did not help.

As for the drag racing – I have never witnessed it (how can you drag race an IC without a clutch fitted?) anyway I have seen some fast IC’s but I think even the very slow runs of Mr Krabs (as posted) would give them a run for their money in a straight line drag. I have seen a couple of races with the ICs and this is not something I wish to put Mr Krabs through, although saying that one member wants me to race in a hydro event.

I do not want to race unless it is a drag race, A) I can’t turn and B) I don’t want to crash – Mr Krabs is my enjoyment only why do I need to prove speed, speed to me is a personal gain and not a race experience, bring on the GPS.

Slim

[NativePaul]

Slim, you should check out Electra for some oval racing, Mr Krabs would make a very good hydro2, we have 6-8 races a year through the summer months spread around the south east of England, none in Norfolk but there's a few in Essex which isn't too far, we run on wider lakes with soft banks not walls, only have buoys to mark the courses we run and lave lots of fun. Come along to a race and see what its like, don't forget to bring your boat in case you feel like having a go, and you can get lots of good advice about it at a race if you have it with you too, I know Vaughan designs his own riggers and would be happy to talk through your turn fin issue with you.

Graupner do a M4 thread to 3/16dog adapter, it's available at a good price from Allan at Aztec Models here as well as that you will either need a small length of K&S brass or alloy tubing to sleeve the 4mm shaft to 3/16 and a nut or one of these devices which does both at the same time and removes any possibility of slop if the threads on the shaft are cut undersize.

To everyone else, sorry to drag your thread off topic, very nice Mr Krabs you all have, I wish you all the best with them.

[Xzessperated]

Slim, you should check out Electra for some oval racing, Mr Krabs would make a very good hydro2, we have 6-8 races a year through the summer months spread around the south east of England, none in Norfolk but there's a few in Essex which isn't too far, we run on wider lakes with soft banks not walls, only have buoys to mark the courses we run and lave lots of fun. Come along to a race and see what its like, don't forget to bring your boat in case you feel like having a go, and you can get lots of good advice about it at a race if you have it with you too, I know Vaughan designs his own riggers and would be happy to talk through your turn fin issue with you.

Graupner do a M4 thread to 3/16dog adapter, it's available at a good price from Allan at Aztec Models here as well as that you will either need a small length of K&S brass or alloy tubing to sleeve the 4mm shaft to 3/16 and a nut or one of these devices which does both at the same time and removes any possibility of slop if the threads on the shaft are cut undersize.

To everyone else, sorry to drag your thread off topic, very nice Mr Krabs you all have, I wish you all the best with them.

Paul,
You just gave Slim some great advice about going to race meetings and helping each other is right on topic here so do not worry. Some Aussies drive almost the length of England to go to race meetings so Essex is not a long drive at all.

[Simon.O.]

Righto chaps back to the job at hand. As you are aware I am about to build a rigger based on this fine hull design. That is the last time I need to say that I hope.
Paddy has spent a LOT of time sending me dimensions that I have asked for and a lot of photos.
I now know where the motor should be, or can be.

I still need a few key measurements before I can begin cutting the material.
For those of you running 4S packs, does the front of the pack go forward and therefore under the rear sponson support tube that goes through the hull.

Where is your CoB, CoG, Point of balance aft of the sponson rear. ??
Paddy, I know yours, I want to see the others.

Put your boat on your set-up board or table.
What is the dimension from the bottom of the tub to the table at the rear of the sponson, and at the transom.
I need to know the clearance at the sponson rear and the transom.

I appreciate (online) all help given.

For those who are interested, Paddy has provided me with a 7XL and a couple of 4S packs at a price that CAN NOT be beaten.

I wil build a 4S rigger based on the Mr Krabs, it will be mostly wood and a few metal parts.
I do hope that I can gain knowledge from thisthread and possibly help from time to time.

[slimshady]

Hi Simon, I think Paddy is your man with respect to advice on Mr Krabs but if I can help at all please ask.

My CoG now (after installing a UBEC) is about 120mm back from the rear part of the Sponsons that touch the water, not sure if this is correct for a rigger but hopefully someone on this site will correct me.

I cannot fit the Lipos under the boom of the rear sponson mount due to the thickness of them (LiPos that is, approximate gap under the boom is 25mm) I have now moved my receiver into this space to maximise the distance between the motor / ESC and the receiver to hopefully eradicate any chance of interference. The rest of the space is filled with Styrofoam in the event of sinking.

Most people will tell you to stick as much weight as forwards as you can to stop the tail bouncing and plant your rigger – once again I cannot substantiate this, but the advice seems to work with Mr Krabs.

Use metal props not plastic ones because they disintegrate under load and get the height of the prop correct with respect to the base of the hull. This makes a massive difference in performance.

Hope a bit of this helps and I also hope I am corrected by people that know better than me, most of them will, and that’s good for development to Mr Krabs.


Good Luck


Slim