Mr Krabs build

[slimshady]

Bugger!!!!

Finished / Bodged Miss Krabs ready for the pond this morning, but I experienced major communication problems. Others in the club have experienced problems due to a new video surveillance camera being installed close to the boating lake. I am not entirely sure this is the problem, looking back now I suspect it could be my set up, I have mounted the areal onto the rudder mount – brass on Ali – both conductive materials coupled with the fact the Ali rudder obviously sits in a more conductive substance, water.

After first problems I took the boat out of the pond and decided to do a radio check by walking back across the park wiggling the rudder, I managed about 100m but then the motor spun up unexpectedly, I walked back with no problems and thought what the hell, let’s have another go.

The rear end sank low in the water but then the motor finally spun up, this actually pleased me for about a second because a very amazing sight was experienced, the whole boat raised and when I say raised, I mean the boat actually pulled itself out of the water and skimmed on it. Coms then let me down and I had no control. Waiting for the boat to drift to the side she took on water through the areal hole and sank leaving only the top of the boat above surface level.

Fortunately a very kind club member got his fishing rod out of his car and helped pull her back in.

Sorry Paddy, now I am stealing your most excellent thread but I did not know where else to post.


Can anyone help / advice with respect to the coms issues? Is the areal a matched length and therefore mounting it in the middle of the boat with an aerial extension bad or could I blame the bad coms on the external aerial, or the fact it is in the water.

Paddy, is Mr Krabs hard to steer at very low speed, i.e. not planning yet, I could not steer it at low speed (saying that I did not reach high speed)?

Sorry again for steeling your thread


Slim

[Xzessperated]

Can anyone help / advice with respect to the coms issues? Is the areal a matched length and therefore mounting it in the middle of the boat with an aerial extension bad or could I blame the bad coms on the external aerial, or the fact it is in the water.

Paddy, is Mr Krabs hard to steer at very low speed, i.e. not planning yet, I could not steer it at low speed (saying that I did not reach high speed)?

Sorry again for steeling your thread


Slim

Slim,
My antenna pole is located very close to the receiver so quite a bit of my antenna wire is just laying in no particular manner on the floor of the hull. My antenna pole is silasticed to the bottom of the hull and sealed with silastic as it leaves the hull to stop water getting in. Your hull must be water tight. Before I even go to the pond I do a range test of my radio in a farmers field. I can walk so far from my boat that I can no longer hear the motor fire up ( yes I know we should not start our motors up and let them spin freely). It would be about 500 meters. I suggest you do this with a friend who can wave his arms to let you know it is working. Radio equipment needs to be good quality so be prepared to spend a few Pounds or Euros. What radio gear are you running? Most of the guys have gone 2.4 Ghz but for the moment I am sticking to my old JR R-1 setup until hell freezes over and the wife lets me buy a new one. If things go well out in the field then maybe your friends are right about the surveillance camera. A good radio will overcome this problem I feel.
Motors should never spin up unexpectedly. If you are in anyway suspicious that your radio is not working correctly never put it in the water. Get this issue fixed on dry land before it becomes a safety issue or costs you money. That boat has cost a lot of money and it would be a shame to see it lost to the pond monster. With my radio I can set it so that if it loses signal it just cuts out and sits on the water waiting for me to come and get it. It might be worth investing in a rubber dingy for retrieval purposes. As to suggesting what type of radio for 2.4 Ghz then it might be better to ask that question on the Q & A section of the forum as I have no experience with that.
Slim, never feel like you are stealing my thread. I think a bit different to most people and view it this way.... I just started the thread but it belongs to all of us. I like to have a bit of fun so not all of what I say has anything to do with boats. If people like everything in it's own little pigeon hole then they come to the wrong thread.
I have no problems steering Mr. Krabs at any speed. Can you post a picture of your turn fin?

[SteveReesor]

Slim,

It looks to me like you have the strut on backwards.

I would never mount the antennae on the rudder bracket. It should be isolated from the hardware hanging off the back. Can you come up with another location for the antennae to come up through the hull somewhere?

The rudder linkage looks a little kinked. IMO the fullers type hardware is not the appropriate hardware for that boat.

Can you post a pic looking straight on at the transom?

Steve Reesor

[Xzessperated]

Thanks Steve.
Slim, Steve is a guy that knows how to build a fast rigger so you will do well to listen to what he says. There is a video somewhere on the forums of one of his riggers that is incredible to watch.

[Viking]

Antenna

Hey Slim;
If that is a metal rod, or rigid wire coming out of what appears to be part of a lamp, the threaded tube. both things are bad and the way they seem to be in relation to each other is bad too.
If that rigid wire can move inside the threaded tube at all, it would be a very bad thing for the radio. Metal moving on metal will cause radio interference.!!
Back to basics, never cut your antenna wire, the antenna is a length that is in direct relation to the frequency of the radio.
Do not coil up the antenna wire, of ball it up, the antenna wire should leave the reciever and go straight up, if possrble. Leaving a pile of antenna wire or a coil inside the hull in effect shortens the antenna, Not Good. Do not use any metal, use a plastic antenna tube. If the antenna wire is too long for the plastic tube then just let it fly. You might bend it over the end of the tube and put a short piece of fuel line over the end of the tube to keep the wire from sliding back down.
If you are running a brushed system, keep the antenna as far as possible from the motor, and ESC. Brushless motors do not create much radio interference(no brushes sparking).
FYI
Viking

[Xzessperated]

Hey Slim;
If that is a metal rod, or rigid wire coming out of what appears to be part of a lamp, the threaded tube. both things are bad and the way they seem to be in relation to each other is bad too.
If that rigid wire can move inside the threaded tube at all, it would be a very bad thing for the radio. Metal moving on metal will cause radio interference.!!
Back to basics, never cut your antenna wire, the antenna is a length that is in direct relation to the frequency of the radio.
Do not coil up the antenna wire, of ball it up, the antenna wire should leave the reciever and go straight up, if possrble. Leaving a pile of antenna wire or a coil inside the hull in effect shortens the antenna, Not Good. Do not use any metal, use a plastic antenna tube. If the antenna wire is too long for the plastic tube then just let it fly. You might bend it over the end of the tube and put a short piece of fuel line over the end of the tube to keep the wire from sliding back down.If you are running a brushed system, keep the antenna as far as possible from the motor, and ESC. Brushless motors do not create much radio interference(no brushes sparking).
FYI
Viking

Slim all that Viking wrote is very true. A 2.4 Ghz radio has a much shorter antenna than my 36 Mhz antenna and that is why I suggested you get one of those if you do not have one already. My system is ultra reliable at 500 meters and so that is why I never worry about the extra wire just laying on the floor of the boat. I have a plastic pole that has the antenna wire going through it and hangs out of the top as much as it is safe to do so. I once had a little too much hanging out and the prop done a little pruning of the antenna wire. In an ideal world what we are after is an antenna that is vertically polarized all the way from the receiver to the tip of the antenna. This is much more easily achieved at the 2.4 Ghz frequency.
I will post a picture of where I put my antenna later.
Paddy

[slimshady]

Hi paddy, Steve and Viking thanks for posting back, I am using a 2 channel Acoms with 27MHz on band 10 (black) in theory it usually cuts out when out of range, not sure why it fired up unexpectedly.

The threaded part you can see is the areal base in a sprung coil although thinking about it there is a threaded bolt connection (M8 I think) after the spring with a nut that I have used on the underside to attach it to the 90deg rudder mount. I have just removed it from the boat and noticed the attachment is made of plastic and therefore wouldn’t conduct through aluminium, although saying that the bottom part was sitting in the water. So I think the best thing to do would be to move it onto the back of the hull.

I have now dropped the rudder down to the next level giving me an extra 12mm in the water, but I am still unsure if this is enough, I must admit I was slightly disappointed when I received the ETTI unit due to its small size.

I have taken some more photos for you to study.

Thanks for the advice guys

Slim

[slimshady]

Sorry, Forgot to mention, I do not have any turn fins yet, I thought of making some out of CF but the thought of screwing them into the sponsons fills me with fear. What if the side wall is not thick enough, and after yesterday, what if it leaks water, after all the sponsons stopped her from sinking. I know you and others have achieved this but I don’t what to do this until I am sure how too.

[Xzessperated]

Sorry, Forgot to mention, I do not have any turn fins yet, I thought of making some out of CF but the thought of screwing them into the sponsons fills me with fear. What if the side wall is not thick enough, and after yesterday, what if it leaks water, after all the sponsons stopped her from sinking. I know you and others have achieved this but I don’t what to do this until I am sure how too.

OK Slim. Well you found out why they call them a turn fin. LOL
They sure turn a lot better with them but for a SAW boat they need to come off. When I start going faster with mine the turn fin will come off. I know what you mean about drilling holes in the sponsons. The whole boat is spoiled by the lack of instructions. I found no wood inside my sponson when I cut the slit in it for the CF bracket I made for my turn fin. I will look at the pictures on the CD that comes with Mr. Krabs after I get some sleep and see if I can figure out what they did.
Paddy

[slimshady]

Thanks for that Paddy now I am thinking of using CF and resin it on the inside of the sponson to fit mounts and then use either 316 stainless steel or CF for the fin. I looked inside the hull earlier and noticed it wasn’t drying as quick as I had hoped so I decided to remove her guts.

I discovered the following:

I think the rudder had stopped working because I used resin to fix the servo cable to the top of the hull and it had snapped off so no correct movement. I am still looking for a micro servo so I can mount it in the stern exactly like yours, I tried to fit this one but it’s too big.

The servo is turning fully over to the right on powering up the transmitter, I have only experienced this once when the batteries were dead and it’s not the case this time, tried new ones. I will try again when they have all dried out

The LiPo has some black marks across the charging lead and I am now worried about charging it, perhaps wait a bit for it to completely dry out first.

The ESC has some water on the board so that needs drying out.

The motor looks ok at the moment.

The hull was damp so I have crammed some kitchen roll inside.

All in all a bit of a bummer – now looking on flea bay to find a micro servo and new radio gear


Slim

[andym]

Is this for real, Slim is this your very first boat? If so I think you have realy jumped in at the deep end. If not can we please see some of your other projects. I think you should have asked some more questions before starting. As a project engineer you would know that obtaining all relivant information before such a large under taking is manditory. Good luck and have a real good read of all of this thread and go from there. By the way your strut is still on backwards and will be a great help in the reverse races.

[andym]

Mate I would remove all that hardware and the stuffing tube ( heat epoxy with a hair dryer).The strut angle is to steep because you have not bent the stuffing tube and that much angle is not good 1-2 deg at most. This is great hull Please Please start again

[Xzessperated]

Mate I would remove all that hardware and the stuffing tube ( heat epoxy with a hair dryer).The strut angle is to steep because you have not bent the stuffing tube and that much angle is not good 1-2 deg at most. This is great hull Please Please start again

Slim,
Andy and I have just been talking on the telephone about the pictures you posted. I can only agree with Andy. You really need to pull all that hardware off and start again. The stuffing tube needs to have a bend in it so that your prop can be at 90 degrees to the water. You have the prop facing down and that will cost you speed and cause other handling problems. The strut is on backwards. I notice in the middle picture that the strut bracket is not inline with the hull. You need to get that fixed. Range check that radio and if it will not work at 400 meters then I would not use it. I know we never take our boats 400 meters away from us but it is good to have a safety margin. These boats can injure or even kill if you lose control of them. Andy cut a snake in half with the prop on one of his boats. The rudder needs to be vertical and be at 90 degrees to the bottom of the hull.
Paddy

[andym]

Mate I think you mean parallel with the water or at approx 90 deg with the hull.
The stuffing tube needs to have a bend in it so that your prop can be at 90 degrees to the water.. Paddy has let the cat out of the bag about the snake ( protected species) I was runnig at a lake 1 hr from home, it realy is in the bush as where I live is a little town in the middle of Nowhere. Flipped the DF33 at full noise 55+ mph for no reason. Waded out as the water is only 5' deep and when I got near the boat I thought I had hit a stick as did the campers watching! Then the bloody stick started to move . It was a very angry half dazed eastern brown snake missing some of it's tail. Now these things are fairly comon around here but as they are one of the most agressive and deadly venomus snakes on earth I nearly *!***!***!***!** myself!!! As it got its bearings I stood very still chest deep in water. Thank goodness it slowly swam to the bank and into the grass. You may not believe this tale but it is true as the pic of that backwards strut.

[Xzessperated]

Mate I think you mean parallel with the water or at approx 90 deg with the hull.
The stuffing tube needs to have a bend in it so that your prop can be at 90 degrees to the water.. Paddy has let the cat out of the bag about the snake ( protected species) I was runnig at a lake 1 hr from home, it realy is in the bush as where I live is a little town in the middle of Nowhere. Flipped the DF33 at full noise 55+ mph for no reason. Waded out as the water is only 5' deep and when I got near the boat I thought I had hit a stick as did the campers watching! Then the bloody stick started to move . It was a very angry half dazed eastern brown snake missing some of it's tail. Now these things are fairly comon around here but as they are one of the most agressive and deadly venomus snakes on earth I nearly *!***!***!***!** myself!!! As it got its bearings I stood very still chest deep in water. Thank goodness it slowly swam to the bank and into the grass. You may not believe this tale but it is true as the pic of that backwards strut.

Andy you young whipper snapper, when I go boating my boat and the water are both horizontal and the prop is vertical or at 90 degrees to both of those. Maybe you do it a different way or you went to a different school. I guess you also do the vertical cha cha. LOL