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[speaker monkey]

Hello everyone.

I am in the process of designing and planning a model RC boat, having never built or run an RC boat before.  However I am alright with my hands and have a keen understanding of basic engineering/DIY principles.  My plan is to use an IC and the boat is being modelled to reflect classic wooden river boats with a sporty edge about 1m long.  I'm not looking to race, just have fun.

I would be very grateful if people could comment on any of my ideas below and whether I am proposing any big "NO-NO's" within model building.  I started a thread named "Diesel Power" a few months ago, I now am a bit further I think...

So far I have the concept for my boat designed, the next step for me I think is to buy the engine, RC equipment, rudder, drive shaft, prop etc then work out their positions & relationship within the boat.  From there I can recalculate the buoyancy, stability & flow and refine the hull etc where I need to.  Obviously this is a big step and so I don't really want to trip myself up at the first hurdle at the cost of some expensive kit.

The first thing I think you may say is "Hold on! Find out where you can use IC and then proceed" as I am aware most boat clubs don't allow IC for various reasons.  I have found two fairly near me (Redhill, Surrey) one at Elmbridge and another at Shoreham Lagoon.  I understand boat clubs also have certain rules regarding IC, pollution and noise so I will find these out too before proceeding to splash my cash.  Apart from not using lots of ferrous metals, is there anything that I need to take into account if I am planning to run the boat on salt water?

I am planning on building my hull using (what I hear is called) the "bread and butter" approach of layered balsa wood and leaving cavities where I need to.  The layers will be along the length of the boat (several sections of the breadth and depth profile).  I am doing this for a few reasons - its easy, flexible to change during the building process, sturdy and once finished guaranteed to be water-tight.

Regarding engines I definitely want to go for IC because I like the idea of having my own little engine that I can tinker with and I think electrics are always a bit impersonal.  Originally I was looking at diesel (or pressure ignition) due to the higher torque and lower running temperatures.  But finding a dearth of suppliers within boat engines and reading about how tricky they can be to start I am thinking glow plug is the way forward for a first build.  When researching "diesel" I was interested in PAW as they are British manufacture, does anyone know of any British glow engine manufacturers?  Not so keen on petrol as you have to have the batteries for the spark on board giving extra weight.

I had a look at the CMB engines Martin recommends on the site and although they look great, they are perhaps a little out of my price range for a first build.  I tried searching for Rossi engines but couldn't find anything worthwhile.  The one that keeps on popping up when googling is this:

http://www.sussex-model-centre.co.uk/shopexd.asp?id=27260

Good price and size, does anyone know about these engines at all?

Another thing I have had on my mind is where the best place for the water intake for the cooling head is.  I have found quite a few rudders that have the intake at the bottom and an attachment at the top.  Is this a well practiced thing?  What do you like to do?

I have bought and read Model Power Boats by Norman. G. Taylor which I found very interesting and useful although some parts are quite outdated.  An author that is recommended on the technical pages that caught my eye was John Finch, a search on amazon showed that two books he wrote can be bought at £49 and £129.  I don't suppose anyone is willing to part with a copy for a better price or where I can get my hands on one?

Wow, this has turned out to be quite a long and waffly post!  It would be great to hear some constructive criticism and I will post photos of the build if anyone is interested.

thanks

monkey

[Andyn]

Don't touch CMB engines with a barge pole, especially the new VAC or the old Valvola. They're terrible engines, way overpriced and with the exception on the 90 all they do is break. People buy them because they're sheep

Marine spark engines use Magneto ignition, not batteries. First question of course is where are you?

Andy

[gwa84the2nd]

for nitro engines for hobby use and for racing you cant go much wrong with just engines asp marine range verry good quality and at a price to satify even the lowest bugets 

[speaker monkey]

Magneto ignition? Sounds very cool, what is that?  I am based in Redhill, surrey.

I'm a bit behind the times with the types of fuel, are most glow and spark engines nitro or only specific types?

PS I think I may have pressed "report to moderator" on one these replies by accident. Just got a smart phone and I'm not used to it yet, so I am truly sorry if that happened

[scoop]

for nitro engines for hobby use and for racing you cant go much wrong with just engines asp marine range verry good quality and at a price to satify even the lowest bugets  

Just engines website is www.justengines.unseen.org/   the ASP nitro range are very good and are winning races, check out the results and photo's on the BMPRS website....   www.bmprs.co.uk

If your boat is approx 1m in length the ASP 46M (£66.37 plus p&p) is the one you will need, use a mocom 1818 or 1919 prop.  

Cheers
Scoop

[Andyn]

Magneto ignition? Sounds very cool, what is that?  I am based in Redhill, surrey.

I'm a bit behind the times with the types of fuel, are most glow and spark engines nitro or only specific types?

Magneto ignition uses a flywheel on one side of the engine, that has a pair of magnets on it. As the magnets fly past the coil they induce a charge. This is then amplified by the secondary coil and sent to the spark plug. Is an age old way of doing things, but is incredibly reliable.

'Nitro' fuel is a mixture of a percentage of Nitromethane, generally 5-60%, around 20% oil and the rest is Methanol.

Spark ignition engines use good old petrol, and in two stroke engines (which most model engines are) a mix of oil too.

[john s 2]

An example of Magneto ignition is your two or four stroke Lawnmower, strimmer Etc. john.

[Andyn]

I had no idea it cut my lawn by magnetism? I though grass was made of grass?

[speaker monkey]

So just to avoid confusion a magneto engine is still a petrol run spark engine? What keeps the flywheel going if it's on the side of the engine? (sorry if being dumb here)

Thanks

[Andyn]

It's on the back or front of the engine, and it's attached to the crankshaft. See attached picture

[john s 2]

As regards Oil pollution. You can buy Biodegradeabel oil for your motor. Noise is controllerble by a suitable silencer. Why not go to your nearest club that run i/c? Chat to the lads its a great way to learn and make new friends. John.

[amber1]

I was interested in the comment about CMB engines. I assume is made with a bad experience in mind.
These engines are used great deal in high performance circuit racers. off shore and multi and indeed one class record with tethered hydro`s of over 124 mph so they cant be that bad. However they are not the engine for your project a good sport 7.5cc-10cc glow engine is good place to start. Just Engines as mentioned else ware is a good place to start

[Andyn]

My opinion on CMB engines is based on the fact they're total rubbish, and I've seen more of them go pop than any other engine. For example, Dave Marles is already rumoured to have done in 3 of the new 26cc petrols, one of which I saw, and Ian Folkston has done one of them in.

The 45's and 21's are the main offenders, I've broken a 21 and I've seen so many of them go. There's no doubting they're fast engines, they're just far too fragile.

But that's just my opinion, what do I know?

[amber1]

If you treat a motor with enough abuse it will go bang. Use it within its design parameters and it will give excellent results

[dodgy geezer]

Hello everyone.

I am in the process of designing and planning a model RC boat, having never built or run an RC boat before.  However I am alright with my hands and have a keen understanding of basic engineering/DIY principles.  My plan is to use an IC and the boat is being modelled to reflect classic wooden river boats with a sporty edge about 1m long.  I'm not looking to race, just have fun.

Your requirement - a classic wooden river-boar with an IC engine - immediately makes one think of the 1950s Aerokits range of models. Here are some pictures  http://www.lesromodels.co.uk/shop/index.php?cPath=85_104 Is this the sort of think you are looking to do?

So far I have the concept for my boat designed, the next step for me I think is to buy the engine, RC equipment, rudder, drive shaft, prop etc then work out their positions & relationship within the boat.  From there I can recalculate the buoyancy, stability & flow and refine the hull etc where I need to.  Obviously this is a big step and so I don't really want to trip myself up at the first hurdle at the cost of some expensive kit.

It's unusual to start with the motor, rudder, prop-shaft etc and then design the boat. It's much more usual to design the boat and then decide how to power it. And calculating stability/flow etc is almost never done at model sizes, because the raw data is rarely there. Competition yachts and racing hydroplanes are perhaps an exception. Boats are usually designed by gaining experience with a shape and then modifying it in the light of that experience. To start with, most people chose to work from a plan or buy a kit, which ensures that their first boat has an effective hull. In your case, you might consider one of the Aerokits range - perhaps the 'Sea Commander'?

I am planning on building my hull using (what I hear is called) the "bread and butter" approach of layered balsa wood and leaving cavities where I need to.  The layers will be along the length of the boat (several sections of the breadth and depth profile).  I am doing this for a few reasons - its easy, flexible to change during the building process, sturdy and once finished guaranteed to be water-tight.

Bread and Butter is quite an old technique - usually used for displacement hulls. If you are looking for a hard chine planing hull you would find it easier and quicker to make one using bulkhead formers, stringers and then ply skins, like the Aerokits. Balsa is a soft wood, prone to get dented, and it can't be easily sealed. If you really want to use Bread and Butter, for a 39" boat I would use Obeche, or perhaps a harder timber like Deal...

Regarding engines I definitely want to go for IC because I like the idea of having my own little engine that I can tinker with and I think electrics are always a bit impersonal.  Originally I was looking at diesel (or pressure ignition) due to the higher torque and lower running temperatures.  But finding a dearth of suppliers within boat engines and reading about how tricky they can be to start I am thinking glow plug is the way forward for a first build.  When researching "diesel" I was interested in PAW as they are British manufacture, does anyone know of any British glow engine manufacturers?  Not so keen on petrol as you have to have the batteries for the spark on board giving extra weight.

Glow plugs are a good power plant - make sure you get a marine one. I use OS motors - if you want a British one you may need to buy an old one off ebay. I understand that you don't want racing speeds? A Sea Commander (36") will plane easily on a 3.5cc, and go fast on a 6cc. 7.5cc - 10cc motors are probably appropriate for boats of 40" or more...

[amber1]

Hello
Unfortunately there are no longer many British glow motor manufacturers In fact the only one I can think of is The Irvine .40 6.5cc very good engine and reasonably priced. Good motors don`t have to be home grown as I mentioned in a earlier post Just Engines stock a range of marine engines for a beginner I would suggest an ASP 40 6.5cc reasonably cheap and easy to start (cord or electric starter).
As long as you take notice of the operating intructions you should be no problems.
 

[phillnjack2]

Oh dear, someone dont like CMB engines.

CMB are about the best engines for marine use in terms of racing.
They hold more world records and titles than any other model engine maker of all time.

yes many do go bang, but this is only due to owners trying to get more even power out of a very powerfull engine
direct from the factory.

Dave marles will break engines ,he probably breaks all sorts due to getting them to their limit of destruction and then
backing off a touch for a race winning formula.
How do you think he learned to be an engine guru ? he is almost a god when it comes to cmb engines.

All the top engine tuners will destroy many race engines untill they come to the conclusion of what is the max before destruction.
Yes ive seen many who have snapped the conrod,broke a crankshaft,blown up the head,melted the crankcase etc.
all this is normally due to so called tunning...
Ive got a year 2000 cmb evo 2 testarossa 90 that is bullet proof.
its been on the lake the river the sea and it just keeps on running like a dream.Never been touched by any tuners or
even been stripped fully,yet still producing tons of power and pretty reliable...
12 years old and ive never owned another engine like it.


Now someone says good things about ASP, well they are rubbish when it come to speed but ok for just having fun.
Leo are another cheapo engine and loads more like them from the far east.
If you do want ASP then go to mcgreggor industries, they were the first importers of them.


Also irvine engines make some very good sport engines that are nice to run and easy to start,
just make sure you keep them oiled up when not in use.
the oil to use is automatic transmission fluid, nothing else just ordinary auto car gearbox oil.
you can spend a fortune and buy so called special lay up oil,but its the same stuff.


ive also got a SC91, now if you want to talk rubbish then this is the ultimate piece of rubbish.
I realy dont know why i ever bought this,it was obviously never going to be any good.
Hard to start,cant even keep it running for more than 10 minutes without having to make carburettor setting changes.
took the first one back as when it did start it was banging like a hammer.
do not buy sc, they are trouble from the word go..............
the engine is still like brand new due to being such a B.....D to start that i cant be bothered with it most of the time.
it takes 24volts on the starter to get it turning over, and yes thats even with the plug a touch loose.

phill