Jblake55

Hi everyone,

First off i just want to say that i am new to this forum, and new to RC boating.

I have so many questions to ask so i can know more about RC boats, but first i wanted to know more about the engine that is in my boat.

I had a SC truck 1/10 scale with a 3cc nitro SH engine, with a extra 2.5cc OS max nitro racing engine i was trying to sell, when i was approached by someone who wanted to make a trade for a boat, and Ive never owned a RC boat, and so i did the trade. what you guys think did i get a good trade or not?, the boat haul is new never been in the water, and the engine starts on one pull with low use on it. my truck was basically new i only broke in the SH engine, and the OS max engine was brand new

The boat i got is 55 inches long, wood haul, i measured from the nose of the boat to the back turn fin, is that how you measure a boat?

I was told that its a cracker box boat, on the bottom of the boat there is a fin in the middle. do you guys know if that is what kind of boat i have, or would a picture be better?

the gas engine is a 30cc cobra, it has water cooling and a clutch. I would really be grateful with information about this engine please!

can you guys tell me if its a good engine?, what the HP is? whats the highest rpms it does? who makes this engine? what would you rate this engine 3rd best or should i be looking to upgrade to a Zenith down the road, i hear they are the best, then enforcers?? how fast do you think my boat will go? the guy i got it from said 50 miles an hour, i know water conditions, prop can factor in, just looking for a general speed.

from what Ive read its a home-lite engine converted into a RC boat engine, what do they do to convert it? or is it just a weedeater motor with water cooling?

and lastly what is the oil mixture to gas ratio for this engine?


thanks so much for taking the time to help me out here, the more i know about my boat the better ill be prepared when i put it in the water shortly!

Joe

crapshooter

sounds like you might have a CrackerBox hull, pics would be nice. the Homelite Cobra 30 from what i remember is a modified 30cc Homelite whipper snipper engine that has abit of port work plus a water cooled head plus a better carb i think, again pics would be nice. gas oil ratio is the same as what you would use with your whipper snipper .

Justaddwata

My Feedback: (3)

Hi Joe,

Welcome aboard!!

Would be helpful if you could post a few pictures of the hull, motor, and hardware - be easier to see what you have and perhaps even suggest or identify areas where you might want to give it some attention.

As mentioned above - the cobra is a modified homelite motor - the cobra has been out of production for over a decade though a decent enough motor for having some fun on the water - just not a race competitive option these days.
Not sure of HP believe claims were in the 4 to 5 hp range but dont read too much into that - ratings for most small motors are more marketing than a real reflection of excitement. But they are a decent motor - just considerably heavier than the Zenoahs that superseded them as the standard for the industry for the last decade or more.

Jblake55

here are pictures of my boat, and engine, and parts.

thanks so much for helping me out, anything you see that i should upgrade let me know!

i might have to send the pictures over a few reply's

Jblake55

more pics

Jblake55

more pics of the engine

Jblake55

and more of the engine, the spark plug is a champion, there must be a better one to buy for the engine???

Jblake55

here is the engine bay, and water pump. I have a few more of the rudder to upload, sorry for so many but i cant seem to upload more then 2 at a time

Jblake55

the rudder, and back end of the boat

Jblake55

here is the prop, what do you guys think? right size, or is there something better that will make the boat go faster??

Jblake55

and finally the bottom of the boat, you can see the fin in the middle

of the bottom of the boat, hopefully that will give you an idea of what kind of haul i have, but i think its a cracker box.

that is it for pictures, i can always upload more if you want to see a close up of one part. i have I V bags for the fuel, i heard that is the best, but i don't know the run time on a bag, any ideas?

I do need a radio for this boat, i do have3 radios, two are 2.4, and one is the old type, but i don't think the radios i have will do long range. can someone recommend the best radio for me to buy on a low budget. my budget is about $150 Canadian dollars

what do you think the value of this boat is? i think i got the better deal on the trade.

thanks so much for the help!

Joe

Jblake55

I almost forgot to included this picture, this is the silencer add on i got with the boat, can you tell me if it reduces horse power or not?

i have to figure a way to attach it to the boat haul with a metal fishing leader just in-case it falls off while I'm running it, i don't want to lose it.

Joe

crapshooter

Looks like you have a good crackerbox there . hardware looks good on the stern, good prop [ octura maybe ] what you should change is; that clear water and fuel lines , the fuel line should be Tygon brand yellow and all water cooling lines should be silicon hose. also not sure on the tuned pipe to manifold set up as this pipe was designed for whats called a [ wrap to center ] manifold but the manifold you have does look to be alot longer than a straightned out wrap to center manifold. you can buy a manifold that is set at 90 degreese plus it has a drop down so the tuned pipe stays low in the hull just like you have now, i would buy this manifold and set the pipe length from middle of the 2 cones to where the manifold bolts to cylinder head at 14 inches then run the extension to the back of boat keeping the muffler inside the hull. the current pipe / manifold set up will not benefit the engine much atall due to this length set up and the water going into pipe so toss that as well [ no water inside pipe ] the manifold i am talking about has a water cooled plate where it bolts to head. if you can replace the throttle servo all the better as it looks like a standard plastic gear type , you should run metal geared servos on these gas boats. you will have alot of fun with this boat when all is right.

Tidnab

My Feedback: (51)

Your hull looks like a Dumas crackerbox and came in kit form.The hull length is 47" from the bow to the back of the transom.The rudder,bracket and strut blade are made by Octura and the strut extension bracket was made by Warehouse Hobbies.That setup was intended for a deep vee hull using a surface drive out the back of the transom.The flex tube out the bottom is too short and should come closer to the ferrule than the one in the pic. Your's leaves the flex cable exposed and could cause flopping of the flex cable and result in vibration and stress on the strut blade.You could find a piece of the same size flex tube and use a sleeve soldered to it to extend the flex tube to the ferrule or replace the whole flex tube. The thrust washer looks to be nylon,which will wear quicker than the usual metal and fiber thrust washer setup.There should be ones between the drive dog and the strut blade also.As crapshooter said the tuned pipe setup is wrong for a Homelite and is untunable in it's present location.I ran modded Homelites and used a 0 band pipe which tuned between 12" to 13" from the exhaust port on the engine to the center of the of my tuned pipe.Most fell into tune at about 12 1/4" to 12 1/2" A good prop to start with on a crackerbox with a Homelite is a Prather 275. That engine should be capable of 50 mph. My modded 25cc converted to a full crank with all modifications possible by chipbreakr ( Jim Johnson) did 51 mph in a 48" deep vee and when he tested it it ran a little over 54 on a gps ,so it's possible.That hull looks a lot like the one I sold,except mine didn't have the accent colors and the windshield,but was black inside and the same type of radio box.Better spark plug is an NGK BPMR6F.
[ATTACH]2211689[/IMG]
[ATTACH]2211690[/IMG]

[ATTACH]2211691[/IMG]

Ron Olson

My Feedback: (1)

Will your boat as you got it do 50? No. 35 maybe if you're lucky. Sellers sometimes tend to exaggerate things a bit.
Crackerboxes aren't meant to go fast. The early ones were ill-handling beasts but these are kind of made to be that way.
You can find 2.4 Gig radio systems for very good prices now. You don't need anything fancy.
Will that muffler slow it down? No again. The terrible (sorry, I tend to be brutally honest at times) exhaust system is.

Jblake55

Thanks so much on that info, it was great. I actually became friends with the guy i got the boat from. I actually went and saw him today, I had a few parts for him, and he had some parts for me. The parts i got are 3 flex shafts, and 2 tubes, which might be longer, if not will do what you have said and solder on a piece so it goes the whole way. I will also fix the nylon issue, i see it now. I will also get that prop, i want to have extra parts for things that would break, so i will get that prop and use it, as its a faster prop, and hang on to this one as my extra spare part.

The exhaust seems to be the biggest problem, and i will need to fix this, but reading what needs to be done to it im not really understanding. do you have a picture of a proper exhaust, seeing what you mean will be very helpful to fix the issue.

Because of the issue with the exhaust everyone has pointed out, i asked my new friend to see his 25cc Zenoah motor, and first thing i looked at was how the exhaust was connected to his motor, and what i saw was the part that is connected to the motor, and comes up a little bit and then a bend in it so it faces towards the back of the boat, and then a silicone sleeve and the tuned muffler or exhaust pipe, sorry not sure what to call it. that was it, and the pipe was about 12 to 14 inches long. its a different motor then mine so I am not sure if that set up will work with my hommie motor. That's where pictures would be so great. please if you have pictures please share with me.

I do have a small gps computer that goes on my road bike (like a 10speed bike, not a gas bike, just my legs lol) so i plan to mount it where my radio gear is so it doesn't get wet, and then i can share the speed, and distance, and time i was running the boat.

As for a radio i bought a Futaba 4PLS 2.4Ghz radio. here is a link to it: Futaba 4PLS 4-Channel T-FHSS Radio System

What do you guys think about this radio i bought?

it has telemetry for rpm, temperature, and voltage, which is info i would like to know, because im the type of guy that likes stats! and its also full of features, it was a bit over my budget by $80 dollars, but its the only radio i will need since can program all my RC toys to this one radio, plus its a big boat, and there is some good money into this boat, so i felt that i should get something id like.

Jblake55

Its suppose to be really warm and nice out tomorrow, and now that i bought my radio, its time to test out the boat, its never been in the water, and the motor has barely been run. so with my bikes GPS i will find out how fast he goes.

thanks you for being honest, that's why i am on here, im new to RC boats, and i need to learn everything, and you being honest only helps me out, so thanks again.

my post before this one has a link to the radio i bought, let me know what you think! probably more then i need, but i like the telemetry part to it.

Joe

crapshooter

Joe, if its a new engine don,t go running it flat out until you have put atleast half a litre through . keep it rich on the carby needles [ running the engine in. ]

Tidnab

My Feedback: (51)

You can try that tuned pipe you have ,but you have to shorten the distance from the engine exhaust port to the center weld of the pipe.Start with about 13" and if it needs shorter,you can cut off a little at and time and run it to see how it performs.A good article on tuning a pipe is Tuning a Tuned Pipe
You could shorten the rudder setup a bit by taking out the extension bracket that's bolted to the transom.I believe it about 2".You can get a shorter rudder bracket from Octura which would shorten it up even more,but that's more expense.Most setups have the rudder offset to the right of the center of the strut.There's other things you can do to a crackerbox,but you have to run it on the water to see which you might need. You'll find out that the crackerbox is unlike any other boat and has to be driven and not just pointed like a deep vee.It will slide,flip,catch in the corners and barrel roll.
The 0-band I used had copper fittings to make the header and used 90 deg and 45 deg fittings to achive the correct distance or drop of the pipe.
Another thing I notice is that your trim tabs are way too long. Some crackers can be run without them and are used only to adjust the ride of the hull.
Also with everything ,except fuel,in or on the hull check the CG of the hull.I usually go by 27 to 30% of the length of the hull which is 47"(don't count the hardware) with a Homelite.A lighter ,more powerful engine may change the CG.You could move the engine a little to change CG. That black nose piece could come off to move it towards the transom,if needed and if you wanted to run without a clutch, that also would shorten the engine for movement . These also loose a little weight.

Jblake55

thanks to both of you for the info, and that picture, i now understand what i need to do!

now the question i have is: after shortening the exhaust, can i put a straight pipe piece at the end of the exhaust so that way the exhaust still goes out the back of the boat? or will adding that piece effect the performance? the water comes out the exhaust and back into the water, if i shorten the exhaust the water will fill up the haul of the boat, that is why i am asking if its OK to just add a piece of pipe so it fits back threw the hole that is already drilled in the transom? and also to attach the silencer, or maybe i could attach the silencer inside the boats haul, and just add a peice of pipe to it so it goes threw that hole and exits the ransom. That way i dont have to rig something up so i dont lose the silencer if it happens to rattle off?

thanks

Joe

crapshooter

Yes, many offshore type hulls have the tuned pipe set up to correct length [ eg; 13 inches ] then have an extension tube coming from the rear of pipe and out the back of boat [ transom ] you can keep the muffler inside the hull as well and just have the end sticking out to clear exhaust oil from transom. you are killing performance by leaving the water cooling into the pipe area, maybe look at buying or making a water cooled manifold . look at the pic of the tuned pipe and manifold and notice how they both join together , this eliminates the silicon joiner that burns out in no time with petrol [ gas ] powered engines. its a slide in fit and held with a clamp.

Ron Olson

My Feedback: (1)

Yes you can. I used this on my Jersey Skiff as I had to do it to meet the rules in the class.
Transom Exhaust Outlet Model Boat - $8.00
There's also a silicone coupler you can use between that fitting and the pipe. He also has the the header you'd need, a 2" offset to get around the radio box.

Hydro Junkie

I run the 4PLS in my sport and scale hydroplanes and haven't had any issues with it. I would recommend that you slow down the rudder throw setting on the transmitter as it will make the boat easier to handle. Also, if the rudder servo doesn't have at least 200 inoz of force, replace it with one that does.

crapshooter

one other item i just spotted., that 4 cell battery holder. get rid of it before it lets you down with a run away model. what happens with those holders is the spring pressure forces the plastic end to expand or break then contact at the terminal is lost [ no power ] there a big NO NO

Hydro Junkie

When I ordered my radio, I ordered a LiFeSource 6.6 volt 3C 1900MAh pack and charger to power the transmitter. I still use the standard Futaba NR4J flat 4.8 volt pack for the receiver. I know some will say that's not enough power for the receiver but for an S9156 high torque servo, I still get an advertised 272 oz/in at .21sec/60degrees using the 4.8 pack. My throttle has an S3151 which only takes 4.8 volts so it works for me