Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: hedgerowwpete on November 22, 2011, 07:08:51 pm
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I am working on a boat as you do,
I will probably have to install an electric motor to start with. I can see the quantity of batteries needed for when I want to play all day being the cost killer so is the recharging of all these batteries where I want to play , theres no double sockets at the local pond.
Now size wise we are looking at a metre long model about 300mm square but will weigh about the 14 kilo mark with batteries, speed wise it will need to do at least 5 to 10 knots not 60 knots.
So the question is, can I use a petrol style type of engine, I believe IC is the generic term.
All the ones I have seen are designed to run at 10,000rpm and to propel boats at 400 knots.
Do we know of slow running engines or are gear boxes needed if so Wheres a good place to look at them
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Have a look at a Honda GX25, revs to 7000rpm, added a little creativity with the throttle stick and a pulley gear system and you can get it as slow as you like.
Andy :-)
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Most of the IC engines are not designed to run all day What type of Batteries and motor have you looked at? With a good sized gel cell and a low amp motor you should be able to run for six or seven hours. You could also try solar cells which will allow you to run as long as the sun shines. Failing that you could try a Sail Boat.
Regards,
Gerald.
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what I am trying to copy is this baby!
as well as the one i have already started from the model boat plans from the magazine we have for my son
http://www.aquacat.co.za/
but without the £1,500 bill, someone who has one, has posted that his uses one set of batteries for two trips, now these trips are not on your average park pond. Its 500 metres out to sea running against the tides and weed carrying two sets of fishing tackle say a total load of 2kilos plus weight of boat 14 kilos with batteries.
An average fishing trip is 4 hours, rebait every 15 Min's individually thats a trip count of 8 per hour minimum 32 trips each 1,000m return thats a distance of 32 Km in four hours all mainly done at night so the solar which by the way is a fantastic idea is binned, sorry
thats a middle of the road calculation use, it could be a lot less or a lot more so the batteries could only last a couple of trips before needing to be recharged or i have a long session on the beach or i find another sort of propulsion?
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500 meters?? would you even be able to see the boat that far lol
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Getting that kind of performance for that length of time in those conditions from an electric boat would require batteries with a lot more capacity in a lot less weight than any currently known technology.
Combustion engines of any type require air to breath, which is normally got through a hole in the top. In waves like that, stopping it becoming water breathing would be the trick. With a hole in the top, stopping it becoming water logged would be another good trick.
The conventional answer would be to do like the buggy drivers - take a spare car battery (or a deep discharge leisure type battery) and recharge from that. That way you get to use a smaller, lighter drive battery in the boat, and gain either improved payload or performance.
The one shown has the brightly coloured ball for better visibility at distance and presumably as a righting aid. For night use, fitting the ball with bright LEDs would help, arranged in the usual nav light layout so you could get some idea which way it was pointing. It also seems to be carrying a long aerial. This could be one of those cases where 27MHz RULES.
I'm not sure that the catamaran hull styling is anything more than style - it behaves like a submarine a lot of the time. The idea of twin hulls on a cat is that you have two long narrow hulls in the water, and the load carrying area between them out of the water avoiding that drag. Submerging it loses that benefit.
To carry the energy store if electric, or carry some form of air store to allow the motor to run with water coming over the top, I think the quote that covers it is "You're gonna need a bigger boat." (Brody, Jaws).
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i use baitboats, not in the sea,though i do sea fish as well as course fishing, however i doubt any currently available in the uk would handle it on waves alone, an ic as has been posted needs air - lots of it so unless your in flat calm you chance drawing water in and hydraulicing the motor
500 yards plus out is a hell of a long way, a running out tide, bit of offshore wind and chances are you may not get the boat back
so have you really looked into fishing at that range, needs on hell of a reel to hold that much line unless your using braid, braid though having near nothing stretchwise also has a habit of pulling the wieght out if the waters a bit rough, add to that i doubt you will be able to keep up your 15 mins rebait schedule's, takes a fair bit of time to reel in 500 plus yards, more especially with a fish, never mind a ball of weed, then you have to rebait and get it back out there, ive fished at 300 yards by casting at the low water and then walking back with the tide - big fish bait for thornbacks and tope, at 200 yards of reeling your wrists are feeling it, at 300 your arms are like lead, god only knows what 500 plus will be like
personally i would look more into something like this
http://www.youtube.com/watch?v=-6tB0R0XY0k
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If you're worried about water ingress, then fit an air trap to the lid of the boat, just a sheet of metal pointing down infront of the engine that forces the water to the bottom of the boat, while still allowing air in.
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If you're worried about water ingress, then fit an air trap to the lid of the boat, just a sheet of metal pointing down infront of the engine that forces the water to the bottom of the boat, while still allowing air in.
And a dirty great bilge pump %%
Ned
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Surely it must be easier to learn to cast long distances?
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so lets look at the idea again shall we.
first 500metres is the maximum distance i want , 250metres is about average maybe some times nearer 300metres, but since i am going to all this trouble then why not do the full 500 metres as a DESIGN POINT, it does not have to be 501metres nor 499metres. according to the forum there is no real limit to the radios apart from line of sight so i was thinking the modern 2 gig systems rather than the lower freq. whats the general opinion on thoses ideas
where it will be used does have a strong tide, the maximum on the charts is 12 knots but i was planning on using the boat with the tide rather than against it, there fore theoretical speed 5 to 10 knots.
when I normally sea fish I change baits every 15 Min's on average some times less some times more but 4 a hour is a good average, two rods there for 8 trips per hour each trip has a maximum distance of 500 metres each way so lets average that down to 300 metres each way 600metres over all, that a total of 8 times 600m, equals 4,800metres or 5 KM for ease and speed and thats per hour, I normal fish for four hours so thats 32 trips average, according to their blurb they get 2 trips per battery so i will need 20 battery sets plus charger or 10 battery sets and two chargers.
An IC motor will properly run for 5 Min's max per trip and ten Min's cooling so the motor wont cook under full loading for hours.
air traps on a boat someone has built before , i cant believe i am the first person in the history of model boats that has decided to try salt water and An IC motor! may be I am as a newbee about to show all the old hands a new trick??? lol
the hull design i was looking to play with was a standard motor boot hull with a single keel leg to hold some ballest to help keep it upright, and also the foam ball on a fibreglass stick to help too, the drive and prop i was thinking about a 900 electric motor and a 40mm prop as a starting point but thats because i have seen other models with similar sizes running those
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ye s it is easier to learn to cast but the limit with baited hooks is around 200 to 250metre metres and i am no where neer that skill level yet by a long way, so why use brawn when brains will do :-))
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ic boats have been used on the sea many times, but thats usually while your allready at sea in a boat yourself. The problem is the surf and getting your model boat threw the surf without it flipping or getting your ic engine full of water. secondly if you were to make a boat at say 3 ft long at 150 meters you would barely be able to see it, even with nav lights on.
id suggest that in order to power yourself through the sea you will need a fast powerful motor, large prop and lipos to power it all. you will be able to charge the lipos on the beach with a car battery.
how big is your boat?
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OK so now I have seen the video of what you are trying to do!!!!!
I am one of these daft gits who like to put petrol engines in model boats.
I run a 52" Arun class lifeboat with a Honda 4 stroke engine in it. I'm not sure in those waves it would work. The engine needs a COLD air supply to run for any lenth of time. I have made up a radiatorand water pump system on mine but after about 20 Min's it slows down and I have to bring it in PDQ.
There are ways to stop the water getting into the engine bay but it is not easy at all. So you will have to fit a bilge pump.
What happens if the engine dose stop???? You will have a job to get the boat back into shore.
I think sadly that an electric motor set up would be better and you don't here me saying that every day.
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If you are carrying two baited lines beyond the surf why not carry an extra line attached to the boat as a recovery aid if and when it is needed
Ned
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thanks for the help lads, i have found another web forum that deals with ic cars and someone is helping me out there, I will do like the rest and stick to electric motors only in the boat forum, i will let you know how my son and i are getting on with the kit we have as and when it goes forward.
I think the petrol sea bait boat was just a too radical idea for for this forum
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nobody said it cant be done, try it.
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So we are looking at a sealed hull using a petrol engine, surely the answer is a snorkel with a safety device in case the boat capsizes or runs through waves taller than the snorkel. Sounds like the basic idea of a submarine snorkel http://en.wikipedia.org/wiki/Submarine_snorkel (http://en.wikipedia.org/wiki/Submarine_snorkel).
One thing to consider is how much air the motor requires and therefore how much flow you need in the system. If my calcs are correct then we have a 23cc engine at 5000rpm requiring 23 x 5000=115000cc of air/min or almost 2000cc /sec.
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i think a simple long vertical pipe with an upside cup on the top would do it.
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the spud gun link i posted should be a hell of a lot cheaper, no worry about lost boats either
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Why not recharge the battery.s. from a small gen that you take and then you can make a cuppa as well :-))
Just a thought
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the spud gun link i posted should be a hell of a lot cheaper, no worry about lost boats either
hes allready started the boat
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thanks for the help lads, i have found another web forum that deals with ic cars and someone is helping me out there, I will do like the rest and stick to electric motors only in the boat forum, i will let you know how my son and i are getting on with the kit we have as and when it goes forward.
I think the petrol sea bait boat was just a too radical idea for for this forum
Now i have raced at Weymouth my off shore boat so IC on the sea is not a "radical idea" at all. OMRA carry out most of there race meeting on the sea. Maybe you could contact them for some help!
Which ever was I hope you short it out and keep us all posted.
Cheers for now :-))
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is it me or is the whole forum not very IC friendly
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I think the petrol sea bait boat was just a too radical idea for for this forum
Hardly radical, perhaps just a little old fashioned. It's how powered model boating started and even made some history .... http://www.vintagemodelworks.co.uk/?page_id=9 ....... What you have here on this forum are experienced model boat builders of all types, some from the early days of ic engines, who know what they are talking about... the fact that you don't like what they say, doesn't make them wrong.
However modelling has always been about innovation and developing new answers to old questions so I'm sure we'll all be very interested to know how you get on. You'll come across some practical problems, some of which were solved in the 1950s, so us oldies may still be able to help.... :-))
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Strangely enough its for those exact very reasons why I am dealing with Dave on the car forum because he is old enough to have been there and done it way before I was crawling. The main thing is that over the course of this one single thread and the searching I have done, I have not got any where trying to find answers and a mentor which is what I really need. Someone local and willing to help, where as on the car forum they ask the more experienced people to offer mentorship, either on line or in person so newbees like me can work though our ideas.
the main reason I would like to use petrol is the simple fact of cost, over the charging of batteries on the sea shore. but in the forum there is no ic section, sections for every thing else but not ic, so i feel its ic unfriendly the same is caused by the simple point that every single reply to this thread is pro electric and no one has offered to give advice or help with the idea of ic, so like i said i will stay on the mayhem with the balsa wood kit we have brought because its battery powered and the mentor Dave will help me with the bigger boat for the sea fishing idea
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half the problem is most of the waters that allow boats are totally ic unfriendly, so guys have been dragged kicking and screaming to fast electrics, they have forgotten the art
one thing i would look into, electric starting, worst case scenario she cuts out on you at distance, at least you will have a chance of cracking the motor into life again
whats behind the idea ?? long range with big soft baits for cod :-))
keep posting on here if you will, i for one being a sea angler find the idea interesting, may be better radio wise working with 27 or 40 mhz, 2.4 is magic untill you get water in the way and if your fishing in waves you will lose sight of it behind waves
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Could you explain why the lower freq suggestions, after reading the forum posts i was under the impression that everyone was moving to 2.4G . i think its because the other freq have small pox sent via them. lol
Its is only the submarine lads that wanted the lower frqs to go throught the water. I like the idea of using the lower older freqs because i can buy a top quality second hand set off flea bay for the same amount of money as a cheap new set or i just buy a new set at lower costs,
I was under the impression that lower quality sets have lower signal strength???? and its the distance i could do with i was also going to install a longer aireal on the boat.
The big thing realy is the size and weight of the boat, i can see it at the moment getting so well equiped that it starts to look like that beautifull 12 foot submarine on the other threads, to keep it practical i would like it to stay under three foot by one foot square and preffer less than 20 kilos maxed out, someone did suggest 2 car batteries as a power supply which ment the boat going to five foot long!
As for the reason why, you hit it straight on the head, big soft baits dont cast well, especial when you want to get them pasted the power casters how do the 150 to 200m marks
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As regards transmitter power - there is a legal limit on power for model use - I dont know of any hobby grade TX that transmits noticeably below this. Obviously, none transmit above that power. The toy grade ones (the ones that come in set that costs less than a decent set of batteries) usually run off a PP3 and have a bit of bent wire for an aerial, and have a range beyond arms reach, but not much. Range, for hobby grade, is more a question of line of sight, the quality of the receiver and siting of the aerial, as a rule of thumb, the higher the better.
2.4GHz signals tend to bounce off water much more readily than lower frequencies, and are very line of sight. Salt water tends to absorb any signals very readily, thats why transmissions to real submarines happen on very low frequencies, and to receive them the sub has to trail about a mile of wire and be very near the surface. Model ones work great in fresh water, but lose signal very close to the surface. At least, the ones that I have seen do.
In most boats running on calm water signal pick up is no problem, the small aerials are easy to hide and still work fully effectively. On 27 I have "controlled" at yacht at 400 yards. On 2.4 the furthest I have done is about 200 yards, but that was a 3 foot long warship painted in camo, so any further and just seeing which way it was pointing would have been a problem.
When the aerial vanishes down a trough between waves, signal will be lost. Just how long it takes for the signal to be re-established and what the controls do in the meantime is a matter of guesswork. In the linked vid, there appeared to be a long whip aerial, indicating a lower frequency setup. This is much more likely, in the conditions shown, to get a usable signal for more of the time.
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This rc trent lifeboat is about 3ft long and demostrates the affect of the sea on it and the obsticles you will need to overcome.
http://www.youtube.com/watch?v=xrVnbCO48Qg
at 4:50 going through the break water the waves are going over the top.
if you use a nitro ic engine, its necessary after every outing to dismantle clean and reassemble the engine, and they dont run on petrol but nitromethane.
if you use a petrol zenoah. you will need the top open to stop overheating:
(http://s8.postimage.org/p449qjc9d/100_5581.jpg) (http://postimage.org/image/p449qjc9d/)
as you can see if the water is crashing over the top on that lifeboat then its going to fill the hull with an open top is seconds. To counter this you can either build a bigger boat over 4ft to handle the waves or build an air tight one so the waves going over the top wont sink the boat.
Sub johns 12 foot gato is a sea going submarine and built to that scale to handle sea conditions.
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With regards to casting big soft baits over long distances, have you thought of wrapping the bait in a PVA bag? That way you get your bait out in one piece, the PVA dissolves in seconds and you're ready to go.
You can wrap the bait into a nice torpedo shape, and tie it off with PVA string, or wrap the whole lot around the lead weight.
Rich
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Possibly the last post on this subject. Have you thought about petrol electric? Using a petrol engine to drive a genney along with a battery feeding a electric motor.Should the petrol lump fail youve still got power to recover the boat.Yes its more complication but ive seen it done in a model tug.Some 50cc motorcycle engines are water cooled and four stroke,also with electric start. Why not ask the big tank boys again i belive a few are pet/elec.Good luck. John.
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I think i will stick with the IC motor idea as the other forum guy dave has sorted out alot of these problems already, about 40 years ago.
I think i will just stick to the elctric versions on the mayhem thanks,
the other things i have been speaking about to dave is the ideas of using items i already have rather than buying new. again thats a no no on the mayhem forum
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the other things i have been speaking about to dave is the ideas of using items i already have rather than buying new. again thats a no no on the mayhem forum
Now I know you're just trolling... %)
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I think for me this thread is finished, I have more questions to ask but i will do it in the other parts of the forum more suited to there requirements.