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[hedgerowwpete]

 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

[andyn]

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

[steamboatmodel]

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.

[hedgerowwpete]

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?

[MikeA]

500 meters?? would you even be able to see the boat that  far lol

[malcolmfrary]

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).

[treeboa]

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

[andyn]

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.

[Netleyned]

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

[Patrick Henry]

Surely it must be easier to learn to cast long distances?

[hedgerowwpete]

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 








                                                   

[hedgerowwpete]

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

[MikeA]

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?

[Bill D203]

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.

[Netleyned]

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

[hedgerowwpete]

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

[MikeA]

nobody said it cant be done, try it.

[w3bby]

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.
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.

[MikeA]

i think a simple long vertical pipe with an upside cup on the top would do it.

[treeboa]

 the spud gun link i posted should be a hell of a lot cheaper, no worry about lost boats either

[catengineman]

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

[MikeA]

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

[Bill D203]

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

[hedgerowwpete]

is it me or is the whole forum not very IC friendly

[Artistmike]

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....