What type of Engine required for model boat?

Just the boat engine stuff here

Moderators: Frank Klenk, SteveM

What type of Engine required for model boat?

Postby tarbee » Thu Dec 10, 2009 9:44 pm

Hello All,

I am going to be building from scratch a wooden model fishing boat 1/7th scale - 20 inches across by 66 inches in length. I would really like an engine with a nice realistic sound and not a buzzing sound of a regular 2 stroke/ high rpm engine.

Could anyone recommend a nice realistic sounding marine engine to me that I could use - I am open to all suggestions!! :D

Many thanks in anticipation!

Paul
tarbee
 
Posts: 5
Joined: Thu Dec 10, 2009 9:36 pm

Postby chiefss » Thu Dec 10, 2009 9:58 pm

Years ago, OS made a 40 size four cycle marine engine. I don't think anyone makes them anymore. You might check Ebay but I don't think you're going to find one.

Electric is your best bet.
chiefss
 
Posts: 611
Joined: Sun Sep 30, 2007 1:22 pm
Location: Bremerton, WA

Postby SteveM » Fri Dec 11, 2009 6:29 am

Another option to a glow motor is electric as they can provide much more realistic scale speeds. You can also buy electronic diesel sound devices that connect through the speed control and increase and decrease with the throtle. Robbe and Graupner make some of the nicest units but there may be others.
SteveM
 
Posts: 242
Joined: Mon Nov 20, 2006 10:33 am
Location: Ottawa, Ontario, CANADA

Postby tarbee » Fri Dec 11, 2009 9:10 pm

Hi


Many thanks for the advice. I really don't want to use a motor and really want an engine-brum-brum!!

If anyone else has any ideas it would be very much appreciated?

:D
tarbee
 
Posts: 5
Joined: Thu Dec 10, 2009 9:36 pm

Postby propwobble » Fri Dec 11, 2009 10:21 pm

Have you thought about using and fan and duct on an air cooled 4 cycle? It seems to have worked in a lot of automobiles. There are thermometers that you could use to help design and experiment. It is also not impossible to make a water jacket to fit just about any engine but I'd think it would be really difficult to deal with the complicated shapes on a four stroke even for a good sheet metal guy. I'd try the duct and fan.
propwobble
 
Posts: 101
Joined: Tue Aug 26, 2003 4:53 pm
Location: Pacific Northwest

Postby chiefss » Fri Dec 11, 2009 10:23 pm

Your options were pretty much stated. Try and find an old OS40 four cycle marine or use an electric motor. The only other relatively common marine four cycle was the OS60 and they are very hard to find and expensive. It would make a boat your size into hydrplane.

You don't like whiney two cycles so those are pretty much your options.
chiefss
 
Posts: 611
Joined: Sun Sep 30, 2007 1:22 pm
Location: Bremerton, WA

Postby tarbee » Sat Dec 12, 2009 6:28 am

The duct and fan idea sounds great. Is there anywhere I can have a peek at a picture of a setup perhaps? This seems so far the best route for me to go.

Many thanks!!!

:D
tarbee
 
Posts: 5
Joined: Thu Dec 10, 2009 9:36 pm

Postby propwobble » Sat Dec 12, 2009 10:10 am

It is something that has been done but is not common and I cannot point you to a specific design. It is an alternative to the option of finding a water cooled four stroke or going electric. The idea is to simply provide a fan (not propeller) on the the drive shaft of the motor that will move sufficient air across the cooling fin surfaces of the engine. If you really feel up to making this, you should probably be up to researching it.

:wink:
propwobble
 
Posts: 101
Joined: Tue Aug 26, 2003 4:53 pm
Location: Pacific Northwest

Postby tarbee » Sat Dec 12, 2009 10:57 pm

Thats great! Many thanks for all your assistance with my query. I shall now go away and do some research...

Cheers!

:wink:
tarbee
 
Posts: 5
Joined: Thu Dec 10, 2009 9:36 pm

Postby propwobble » Sun Dec 13, 2009 11:31 am

I know I have seen a fan cooling system in one of the old model mags at some point but I can't recall where as it was years ago. I am not a boat guy by nature but the concept of a buried engine intrigued me and caused me to build a radiator for a water cooled two stroke. I wish I could remember the article,sorry. I used a thermometer, which I got from tower hobbies with a remote sensor to measure head temp . They no longer have it but I know there are others out there. A model engine tachometer will be helpful in your process as well.


Your application will be similar in some ways but not truly like a ducted fan jet airplane model where the fan provides thrust, with yours, the fan needs to consume much less power to just push air. For ease of finding an appropriate fan, one of the type for a ducted fan aircraft engine with a few ( perhaps half or more depending on if it pushes enough air) blades removed might do the trick. The less air pushed= more power to the drive shaft. For any fan system, the pitch, diameter and number of blades plus the size of the duct and the number of bends you have to put in i twill determine the power consumption and the air flow. The fewer bends the better. Of course the goal is to put enough air over the cooling fins of the engine, especially the head and definitely in the area of the exhaust valve. Heat increases with engine speed but so does shaft speed/fan speed half good, half not so good. You might even be able to use a fan from a computer fan if you can figure out how to attach it to you drive shaft; I think I'd prefer one from the model ducted fan industry. If you go another way, it would be wise to try to use a fan that is designed to run at speeds more than what you will run but still be efficient. Fans can come apart if run over-speed. Four strokes vibrate too, so a nylon type fan with a good sized hub might be best. Vibration is an enemy and causes metal fatigue, avoid a metal fan.

Clearly you get the idea and if you are willing to experiment, you will likely succeed. Be careful, use a protective shield some sort (clear plexiglas or better yet: lexan)_ when you are exposed to the running system until you confirm it is safe.


The boat you are building sounds like an ambitious project that will take some time to construct. The fact that you are thinking in terms of satisfying a specific desire and seem determined to create a realistic model indicates you have the tenacity to figure it out.


If you could find a water cooled four stroke you would save yourself a lot of time. In addition to the OS there is one from the UK called Gannet that occasionally turn up as well. They are out of production and spendy. They are spark ignition 15cc. There also is British Magnum out of production, not the Asian Magnum, made a glow marine four stroke of 15cc.

You might want to look at Ebay #150396257487

best of luck
propwobble
 
Posts: 101
Joined: Tue Aug 26, 2003 4:53 pm
Location: Pacific Northwest

Postby tarbee » Mon Dec 14, 2009 6:52 am

Thanks Propwobble thats some great info you have given me there. I will certainly look into the ducted fan side of things and contenders for my 4 stroke engine. I definitely want to do this so I am willing to put-in the time/research and get what I need.

I just have this image of a lovely engine in my boat chugging away with plenty of smoke and a nice sound as well!! :D
tarbee
 
Posts: 5
Joined: Thu Dec 10, 2009 9:36 pm

Postby zeroskin76 » Tue Dec 07, 2010 12:45 am

long overdue knowledge

best place to find help with converting 4 stroke for marine use is with current modlers using four strokers for buggy and rc trucks
better sound
better torque(wheelies on demand)
ive seen webra,os and enya four strokers in more modern build on ships with dual mounted micro computer fans
just enough cooling and they can run for upwords of an hour on a lipo cell
zeroskin76
 
Posts: 5
Joined: Mon Dec 06, 2010 9:24 pm
Location: utica

Postby propwobble » Thu Dec 09, 2010 11:39 am

Good point . Weight not being a big issue with boats allows for the simplicity of an electric fan. The only drawback I can see is if the fan fails for some reason and you are not aware of it, the engine goes without cooling.
propwobble
 
Posts: 101
Joined: Tue Aug 26, 2003 4:53 pm
Location: Pacific Northwest

Postby fersanda4 » Fri Apr 08, 2011 1:22 am

good post!!!thank you!!!
fersanda4
 
Posts: 3
Joined: Wed Apr 06, 2011 11:37 am
Location: UK

Postby chiefss » Fri Apr 08, 2011 10:57 am

OS's original FS60 and FS40 came as marine engines. I have them both.
chiefss
 
Posts: 611
Joined: Sun Sep 30, 2007 1:22 pm
Location: Bremerton, WA

Re: What type of Engine required for model boat?

Postby zflyer2 » Tue Jul 08, 2014 10:04 am

Just a thought I have seen a 25 cc weedwacker 4 cycle no mixing of gas and oilair cooled by flywheel fan,that would give you a engine (low power) and drive cable settup Inital cost aeound 200.00 USD but cheap fuel
zflyer2
 
Posts: 1
Joined: Tue Jul 08, 2014 9:52 am


Return to Marine Engine Topics

Who is online

Users browsing this forum: No registered users and 3 guests

cron