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hughess 02-03-2009 02:19 PM

Need Help First Boat Ever Undertaken
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hello all

please be kind im new on here

what it is ive bought a nitro powered boat just to give yu the specs as it is now

webra 40 engine
hand crafted hull ?
no servos need help on chosing
no radio gear what so ever but planing on using traxxas transmitter and reciever

i have a photo here whether it works or not is a different matter
in the pictures yu can see the engine and where the electrics should go

all help needed and welcome

many thanks lewis

i normally race 1/8 scale buggies so a boat is totally different

MiniMental 02-03-2009 02:43 PM

RE: Need Help First Boat Ever Undertaken
Firstly, let me say Welcome to the Forum and beware, it IS addictive, (the boating thing AND the forum).

Ive seen this hull somewhere before, cant think where though. As for servos, your best bet if your on a budget would be Futaba 3003 or 3002 servos, thats what i use n they never steered me wrong. Since you based in the UK here are some links where you can find various things you may need. Are you only new to the boat scene or new to the nitro scene aswell?


They are good sites, if your wanting servos, SMC is probarbly the better one.


hughess 02-03-2009 02:47 PM

RE: Need Help First Boat Ever Undertaken
no i have run nitro buggies for 3 years now race a mugen most weekends

im hoping that i can get it up and running

i am new to the boat scene though
thank you for the links my lhs shall supply me with them

what sorta spends would yu expect from a 40 engine

anymore help please give tell me

the webra 40 engine beleive is a aircraft engine may be wrong but dont no

need a starter for it aswell can you recommend.

MiniMental 02-03-2009 03:06 PM

RE: Need Help First Boat Ever Undertaken
Yeah certainly looks like an aircraft one... aircooled head although im sure i can see fittings on the head for water lines. Where u said spends did u mean speeds? Im assuming you have the majority of the gear for the engine then.. although you may need a 12 volt starts and a starting belt to get it fired up. Im sure i have seen that hull somewhere... i could swear i saw an electric one that looked just like it at my local lake..

Sussex model center sell starters although i dont think they sell belts.... Prestwich sell belts but im not sure on starters. lol. just have to have a look. If you dont have one already for your car.. you will need some sort of field box for your starter which has a 12v battery or something.

Hope this helps. feel free to ask about anything you dont understand and people on the forum will help as much as possible


hughess 02-03-2009 03:18 PM

RE: Need Help First Boat Ever Undertaken
yep i ment speeds. the throttle on the boats goes from a linkage at the back of the boat all the way thro to a servo horn at the front of the boat which moves the carb how does this work

the engine does have water cooling jacket and a air cooled head ?

just servos and make a lid for the boat iit which is water proof
yes engine is all in it and fuel tank which is huge holds around 1/2 gallons

many thanks for your help


MiniMental 02-03-2009 04:01 PM

RE: Need Help First Boat Ever Undertaken
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well, speed depends on the length of your boat, the performance of the engine, the drive setup, for instance, the pics show my current boat with a surface drive system, im assuming yours is a submerged prop system. Also depends on the material the boat is made from, wood is heavier than fiberglass, hence more weight to push.

The pics of mine show a surface drive setup.

throttle works the same way as in a car engine. Servo pushes the linkage and hence, the throttle arm on the carb.

You dont really need a lid as long as you can waterproof your radio box. Mine doesnt have a lid, just a watertight radio box.


jetpack 02-03-2009 05:20 PM

RE: Need Help First Boat Ever Undertaken
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Your Webra is a marine version, not a converted aero motor. It is a strong runner, uses low to no nitro fuel.

Do not go above 10% or 15% nitro with it without lowering its compression with a head shim, or it will have pre-ignition problems. They are built as high compression alcohol engines. I love my collection of them. Mine that I have pictured is a .60 version that I have recently restored, but I have all kinds.

Webra's are economical to run, very strong and last forever. It is when you start adding nitromethane to the mix is when fuel consumption starts to go way up on them. Running straight alcohol and oil is the way to go, and only add nitro to help with idle.

An alky motor is designed to make the same power as a nitro motor, only more economical. They use a different head design, and slightly different port timing. The rpm's will not be as great as a nitro design, but you can count on more grunt out of them, meaning a larger, more steep of a prop can be used.

Adding a header and a tuned pipe will help any two-stroke motor to gain power. [link=http://www.macspro.com/prodline.asp]Here[/link] is a popular supplier of boat headers, however Webra does offer their own in chromed steel and also aluminum fabrication. Take time to download the Adobe Acrobat catalog at the link, it is where the boat headers are hiding along with dimensions and notes.

You can forget your 1/2gal fuel tank...that would be good for two full seasons running the Webra with only one top-off of fuel.[sm=teeth_smile.gif] A 10-12oz tank is the norm for what you have for a good 20-30 minute run. SLEC makes nice sturdy fuel cells, and would be a nice replacement if your interested.

Making your own fuel for them is very easy, it does not have to be hobby shop fuel. Just 80% methanol and 20% castor oil is all you need at home to do it. You can also change to a castor/sythetic blend to help keep exhaust mess down if you wish.

Adding 3% acetone to the mix will take the place of 5% nitro, and will help starting and idle characteristics. If you're interested in mixing your own fuel instead of buying hobby shop fuel, here is a handy fuel calculator for determining amounts and percentages of any size batch: [link=http://www.nitrorc.com/default2.asp?Introduction=http://www.nitrorc.com/fuelws]Fuel Calculator[/link]

Pictured is the factory fuel recommendations, and if you need more help with documentation I will be glad to help. [sm=thumbup.gif]

If you can provide more pictures of it, I can determine what model number it is for you, plus part list and diagrams. Good to see you aboard!

Espiga 02-03-2009 06:04 PM

RE: Need Help First Boat Ever Undertaken
This hull is for sure a multi racing class hull, probably from the the begining of the 80s. It is no longer competitive, but it will be a nice sport rc boat.
Prestwich models offers you a wide range of items for that kind of boats.

MiniMental 02-03-2009 06:08 PM

RE: Need Help First Boat Ever Undertaken
My bad, just looked so much like one of my aircraft engines lol.

jetpack 02-03-2009 06:46 PM

RE: Need Help First Boat Ever Undertaken
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In a respect they are aircraft engines, but with a water jacket band across the upper fins. They left the head as air cooled but they did make "speed" versions, which is more of a heli motor the way it is timed, and run an ABC cylinder instead of a ringed piston with a water cooled head button and jacket. This allows the water jacket band to be left off and a full wall of cooling fins to complete the job. If you study Webra engines, their marine verisons (RCW's) use a differently timed sleeve and piston than their aero counterparts which tunes them to boating characteristics.

Here is one of Webra's later offerings for the example, it is my restored Speed .40 with Dynamix carb. Still an alky burner and completely a marine design. Most have fallen into the idea if it isn't a rear-intake drum induction engine, they don't qualify as a marine engine for some reason, and I can never help myself to dispute that! :D It's my pride for Webra's that do it...lol.

If you look at the head button and compare it to a nitro head, you will see a major difference in band width area before the combustion dome.

Webra's are a little bit of a different animal than what people are used to seeing in model engines, but once you understand them and what they require, you'll be more than happy with them.

What Lewis will see if he pulled the head off of his is a baffled piston, and a recessed head to accept the baffle thats on the piston. This is the early design of scavenging exhaust gasses, one step before "scnerule" ported sleeves. Glow plugs that include an idle bar across them is almost necessary with a baffle piston to keep the glow plug from drowning at idle.

Espiga 02-04-2009 10:54 AM

RE: Need Help First Boat Ever Undertaken
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Once in the 80s I raced a geared webra speed 20. I made the gearbox and I only can say this was a wonderfull engine. I still have it. The gearbox was inspired on the speedy 1.8

hughess 02-04-2009 02:01 PM

RE: Need Help First Boat Ever Undertaken
thank you so much everyone but the boat is now a no go thank you for the engine

reason for this is that the engine is down on compression. not worth me puttin a new engine in on my budget and piston is gna be hard to find

i am seeling this boat and am hoping to buy another boat in the future

boat is for sale on ebay.

many many thanks

ill be back on here soon with another boat


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